Executive Summaryon the results of the

Collaborative Project on EnvironmentalRisks of Pesticides and SustainableDevelopment of Integrated Pesticide

Management Systems (IPMS) in NepalConsidering Socio-EconomicConditions (IPMS-Project)

Andreas Herrmann & Sybille A. Schumann

Contents

Contents 1

List of Figures 3

List of Tables 4

List of Abbreviations 5

1 Introduction 7

2 Project results 142.1 Basic project results . . . . . . . . . . . . . . . . . . . . . . . . . 14

2.1.1 Geography, hydrology and agriculture . . . . . . . . . . . 142.1.2 Socio-economy . . . . . . . . . . . . . . . . . . . . . . . . 152.1.3 Pesticide awareness . . . . . . . . . . . . . . . . . . . . . . 162.1.4 Capacity building and achievements . . . . . . . . . . . . 17

2.2 Scientific results on pesticide contamination . . . . . . . . . . . . 182.2.1 Complementary, compound specific results . . . . . . . . . 192.2.2 Pesticide transport mechanisms . . . . . . . . . . . . . . . 242.2.3 General conclusions on study methodology and on param-

eters influencing the pesticide transport and fate behaviour 26

3 Risk assessment 273.1 Scenario definitions and restrictions . . . . . . . . . . . . . . . . . 273.2 Risk assessment for the soil ecosystem . . . . . . . . . . . . . . . 29

3.2.1 Dimethoate . . . . . . . . . . . . . . . . . . . . . . . . . . 293.2.2 Metalaxyl . . . . . . . . . . . . . . . . . . . . . . . . . . . 313.2.3 Fenvalerate . . . . . . . . . . . . . . . . . . . . . . . . . . 323.2.4 Conclusive recommendations for pesticide usage and en-

vironmental protection measures in the study area . . . . 34

4 Methodological considerations and research needs 364.1 Pesticide fate dependency on environmental factors– a method-

ological progress . . . . . . . . . . . . . . . . . . . . . . . . . . . 364.2 Specific pesticide trailing in soil and soil water samples . . . . . . 364.3 Sampling techniques for Preferential Flow (PF) transport pro-

cesses – the need for capturing the mobile phase . . . . . . . . . 37

1

4.4 Risk analysis based on modelling–the need of considering hydro-logical studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

4.5 Transfer and regionalisation of results . . . . . . . . . . . . . . . 42

5 Conclusion on the point of carrying out environmental researchprojects in developing countries 43

Bibliography 45

A Recommendations of the IPMS-Project workshop 51

B Photographic impressions of khet land 55

2

List of Figures

1.1 IPMS-Project Nepal: Working steps and foreseen final aims . . . 91.2 Location of the study sites. . . . . . . . . . . . . . . . . . . . . . 101.3 Khet-land in late August . . . . . . . . . . . . . . . . . . . . . . 101.4 Bari -land in late September . . . . . . . . . . . . . . . . . . . . . 111.5 IPMS-Project partners and their main research activities . . . . 13

2.1 Conceptual hydrological model as valid for khet conditions duringmonsoon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

3.1 Dimethoate risk scenarios . . . . . . . . . . . . . . . . . . . . . . 303.2 Fenvalerate risk scenarios . . . . . . . . . . . . . . . . . . . . . . 32

B.1 Photographic impressions of the cultivation cycle in khet land . . 56B.2 Photographic impressions on project activities . . . . . . . . . . . 57

3

List of Tables

3.1 Pesticide application scheme for the risk analysis scenarios . . . . 283.2 Risk data for Dimethoate . . . . . . . . . . . . . . . . . . . . . . 29

4

List of Abbreviations

AGROOEK Institute of Geoecology, Department of Agroecology and En-vironmental Systems Analysis of the Technical University ofBraunschweig

BBA Biologische Bundesanstalt der Bundesrepublik Deutschland.Meanwhile fused in the Bundesamt fur Verbraucherschutz undLebensmittelsicherheit (BVL).

CEAPRED Center for Environmental and Agricultural Policy Research,Extension & Development

CEP Cooperative Extension Program

CES Cooperative Extension Service

DC Developing Countries

DHM HMG Department of Hydrology and Meteorology

DOA HMG Department of Agriculture

EU European Union

FEFLOW Finite Element subsurface FLOW system

GDP Gross Domestic Product

GIS Geographical Information System

GIS Geographical Information System

GSF-HYD GSF-Research Centre for Environment and Health Munich, In-stitute of Hydrology

GSF National Research Centre for Environment and Health

GTZ Gesellschaft fur Technische Zusammenarbeit

HKH Hindu Kush-Himalaya

HMG His Majesties Government of Nepal

ICIMOD International Centre for Integrated Mountain Development

5

IfW Kiel Institute of World Economics

IPMS-Project Collaborative Project on Environmental Risks of Pesticides andSustainable Development of Integrated Pesticide ManagementSystems (IPMS) in Nepal Considering Socio-Economic Condi-tions

IPMS Integrated Pesticide Management System

IPM Integrated Pest Management

MACRO A physically-based, one-dimensional, numerical model of waterflow and solute movement in macroporous soil

MOA HMG Ministry of Agriculture

MOF HMG Ministry of Finance

MOST Ministry of Science and Technology

NARC Nepal Agricultural Research Centre

NPC Nepal National Planning Commission

OEKOTOX Institute of Ecological Chemistry and Waste Analysis of theTechnical University of Braunschweig

PAPL Pesticide Analysis Preparation Laboratory

PELMO Pesticide Leaching Model

PFP Preferential Flow Path

PF Preferential Flow

PGWL Perched Groundwater Lenses

PHYSHYD Institute of Geoecology, Department of Hydrology and Land-scape Ecology of the Technical University of Braunschweig

PPD Plant Protection Directorate

TER Toxicity Exposure Ratio

TES1 Tracer Experimental Site 1

TES2 Tracer Experimental Site 2

TES Tracer Experimental Site

TU-BS Technical University of Braunschweig, Germany

TU Tribhuvan University, Central Geography Department

VB Vitasin Blue FCF 90

VDC Village Development Committee Panchkhal

6

Chapter 1

Introduction

In the last decades, many agricultural systems in Developing Countries (DC)have been subject to enormous changes due to increasing population pressure,resulting in new cultivation methods and the introduction of new species andvarieties, as well as in the utilisation of chemical fertilisers and pesticides.

In Nepal, the traditional peasant communities of the mid-hill region havebeen forced to intensify their agricultural methods as well. They changed fromthe traditional shifting cultivation to wet-rice growing on terraced fields withartificial irrigation, brought along with the immigration flux of Indo-Aryan castscoming from the North-Indian plains (Seeland, 1984). Hence, these changeshave not been merely technological alterations, but actually an adaptation toanother traditional culture leading to changes in the social situation and tointense changes in the ecology and hydrology of the region.

Seeland (1984) states in the mid eighties that most of the foreign develop-ment experts predict an increasing ecological crisis, that will shake the wholeHimalayan ecosystem during the coming years. In 1990, Nepal has included theprovision for environmental protection into her constitution (Panday, 1992). Astudy published in 2001 by UNEP (2001) informs in detail on the Nepalesestate of the environment, highlighting on five environmental priorities of Nepal,among those soil and water.

One of the causes for an increasing environmental crisis in Nepal, that hasonly been marginally touched by UNEP (2001), can be the fortified applicationof fertilizers and pesticides, which are mainly imported from India, due to theincreased agricultural production.

An overuse of pesticides can result in unwanted effects such as reduced cropyields due to the development of chemical resistances of the pests, or the damageof farmers and consumers health. According to Baker & Gyawali (1994) theseeffects have reached worrying levels in Nepal.

Besides, the excessive use of pesticides can cause direct adverse effects onecology, such as the reduction of biodiversity or the contamination of soils,surface water and groundwater.

To investigate the risks of environmental contamination due to pesticideuse in a subtropical environment by means of a case study, an interdisci-plinary collaborative research project, the Collaborative Project on Environ-

7

mental Risks of Pesticides and Sustainable Development of Integrated Pesti-cide Management Systems (IPMS) in Nepal Considering Socio-Economic Con-ditions (IPMS-Project), was initiated and funded by the VolkswagenStiftung(Germany).

The IPMS-Project The project started its work in Nepal at the beginningof 1999 and stopped to operate in 2002. Its main aims were to investigate risksof pesticides in subtropical environments and to develop a knowledge-baseddecision support system for tentative pesticide reduction measures resting on aknowledge-based rule system for pesticide pollution (Herrmann & Schumann,1999). Figure 1.1 summarizes the main working steps with the finally to beachieved aims.

The focal research topics were internally categorized as follows:

Environment studies concentrating on possible contamination and contami-nation paths in the environment (soils and water resources) by pesticides.

Pests and Pesticides studies concentrating on pest identification and pestcontrol through an Integrated Pest Management (IPM) and the analysisof pesticides including degradation and sorption experiments.

Socio-Economy studies concentrating on the socio-economic background ofthe farmers and the value of pesticides and pesticide use for the nationaleconomy.

The project was headed by Institute of Geoecology, Department of Hy-drology and Landscape Ecology of the Technical University of Braunschweig(PHYSHYD) and incorporated Nepalese and German project partners, com-prised of research institutions as well as governmental institutions and non-governmental organisations (NGOs and INGOs). Figure 1.5 summarizes theproject’s organisational structure, highlighting on all participating partners andtheir major tasks. Herrmann & Schumann (1999, 2002a) inform in detail onthe IPMS-Project research concept and structure.

For project field works three exemplary study sites were chosen (see Fig-ure 1.2), representing terraced and irrigated lands (khet) and a typical rainfed-agricultural area (bari) in the Nepalese Hill-Districts. Latter districts accountfor 41.7% of the total national area (UNEP, 2001). A typical khet and a typicalbari situation are shown in Figure 1.3 and Figure 1.3, respectively. The studysites were situated along the Arniko highway at about 50 km east of Kath-mandu, in the Jhiku-Khola catchment of the Kavhre district. The compara-tively good infrastructure allows for a market-orientated intensified agriculturewith up to three harvests a year which relies on crop irrigation and the useof pesticides. According to CEAPRED (2001a), the Kavhre district is amongthose districts in Nepal with the highest traded pesticide volumes.

Research was primarily based on a number of permanent scientists of allproject partner institutions, i.e. in Nepal:

8

Assessment of farm-related expense/incomeconditions considering- labour- fertilizer, pesticides- crop yield

Production of maps of- landuse and crops- fertilizer and pesticide applications

Identification of- socio-economic and property and structures- farming practices on

(monsoon) land(irrigation) land

- pesticide supply and distribution(agents, retailers etc.)

bari

khet

Proposal for IPM Measures

Development of Knowledge-based Decision Support System (DSS)for Tentative Pesticide Reduction Measures (TPRM)

Development of Knowlege-based Rule System (RS)for Pesticide Pollution

Socio-economic development and “poverty”and “health”-risk analysis for differentpesticide reduction scenarios and prospectives

Conceptual modelling of- farmer-agent-retailer interrelationships- intrabasin socio-cultural and economicinterrelationships

- per capita income distribution patterns

Socio-cultural/economic and agricultural issues

- model systems optimization- evaluation of environmental hazards and

risks of pesticide pollution for differentscenarios and prospectives

Mathematical modelling:- calibration and validation of

mathematical flow and transportmodels for water, pesticides anddissolved matter in the hydrologicalsystem and sub-systems

- pesticide pollution of the environment

Assessment of basin-related balances of- water- sediment

Development of ideas about- origin and age of runoff components

Production of- pedohydrological and hydrogeological

maps- model concepts for transport and storage

of water, major ions and compounds,sediment and pesticides

Identification of- hydrological and aquifer systems

(structure, extension, boundary conditions)- pedohydrological units- hydro-climatological network demands

Environmental and experimental issues

Final

Model scenarios

EnvironmentallyandEconomicallyorientated

AdvancedModellingandSimulationStage

BasicSurvey(Questioning)and BudgetingStage

GovernmentalRegulations

Step 1

Step 3

Step 4

Step 2

Database

Figure 1.1: IPMS-Project Nepal: Working steps and foreseen final aims.

9

0 10 20 30 km

Thamaghat: thamaghat horticulture farm

Tinpiple: khet + bari catchment

Figure 1.2: Location of the study sites. The detailed map is represented by theblack rectangle in the outline map of Nepal.

Figure 1.3: Khet-land in late August: Paddy cultivation on small terraces. Onthe terrace ridge, soy bean are cultivated for stability purposes. The fencesurrounds TES1, one of the IPMS-Project installations).

10

Figure 1.4: Bari -land in late September: Maize cultivation on sloped, rain-fedlands. The photo pictures a transition period, i.e. great parts of the maizecultivations have already been harvested.

• HMG Department of Agriculture (DOA)

• HMG Department of Hydrology and Meteorology (DHM)

• Tribhuvan University, Central Geography Department (TU)

• Center for Environmental and Agricultural Policy Research, Extension &Development (CEAPRED)

• International Centre for Integrated Mountain Development (ICIMOD)

and in Germany:

• Institute of Geoecology, Department of Agroecology and Environ-mental Systems Analysis of the Technical University of Braunschweig(AGROOEK)

• Institute of Geoecology, Department of Hydrology and Landscape Ecologyof the Technical University of Braunschweig (PHYSHYD)

• Institute of Ecological Chemistry and Waste Analysis of the TechnicalUniversity of Braunschweig (OEKOTOX)

• GSF-Research Centre for Environment and Health Munich, Institute ofHydrology (GSF-HYD)

• Kiel Institute of World Economics (IfW)

11

Furthermore, the participating universities contributed to the research pack-age with four masters theses at the Tribhuvan University, Central GeographyDepartment (TU) and five “Studienarbeiten” at the Technical University ofBraunschweig, Germany (TU-BS). Herrmann & Schumann (2002a) briefly sum-marize selected results and conclusions drawn from the IPMS-Project untilNovember 2001. The scientific core of the IPMS-Project was formed by fourPhD-theses, all in care of TU-BS:

1. Vinke (2003). She aimed on fate and behaviour of target pesticides insoils under laboratory and field conditions.

2. Apel (2002). He aimed on an environmental fate modelling and risk as-sessment of pesticides as well as on population dynamics and treatmentstrategies of Phytophthora infestans.

3. Piepho (2003). She evaluated the hydrological behaviour of a small, khetsample catchment with the semi-distributed deterministic model WaSiM-ETH, developed by Schulla & Jasper (1999).

4. Schumann (2004b). She aimed on the identification of the major hydro-logical processes in khet catchments and specifically on the identificationof the dominant water fluxes which serve as the transport medium forpesticides in khet environments.

12

GSF-HYD Isotope hydrology. Isotope tracer experiments.

PHYSHYD Project leader

Hydrological and climatological measurements and modelling. Soil and groundwater hydrology: flow and transport. Tracer experiments.

AGROOEK Modelling of pesticide degradation. Environmental risk analysis. Development of an expert system for Integrated Pesticide Managment.

OEKOTOX

Residue analyses of pesticides. Interpretation of analytical results. Investigation of degradation & sorption.

ICIMOD Advice on ecological and hydrological issues. Data transfer.

TU-BS

TU Assistance in environmental field survey.

DHM Hydrological measurements and data. Water balances. Pesticide analyses preparation laboratory.

IfW National economy; Development of control strategies

CEAPRED Socio-economic and agricultural surveys.

DOA Collaboration in socio- economic surveys. Plant protection and extension measures. IPM field experiments.

Assistance in socio- economic surveys.

Environmental issues

Pest and Pesticide issues

Socio-economic issues

Figure 1.5: IPMS-Project partners and their main research activities accordingto environmental, pesticide and socio-economic focuses.German Partners: Technical University of Braunschweig, Germany (TU-BS),Institute of Geoecology, Department of Agroecology and Environmental Sys-tems Analysis of the Technical University of Braunschweig (AGROOEK), In-stitute of Geoecology, Department of Hydrology and Landscape Ecology ofthe Technical University of Braunschweig (PHYSHYD), Institute of Ecolog-ical Chemistry and Waste Analysis of the Technical University of Braun-schweig (OEKOTOX), GSF-Research Centre for Environment and Health Mu-nich, Institute of Hydrology (GSF-HYD) and the Kiel Institute of World Eco-nomics (IfW).Nepalese Partners: International Centre for Integrated Mountain Development(ICIMOD), HMG Department of Hydrology and Meteorology (DHM), HMGDepartment of Agriculture (DOA), Center for Environmental and AgriculturalPolicy Research, Extension & Development (CEAPRED) and the TribhuvanUniversity, Central Geography Department (TU).

13

Chapter 2

Project results

The final goal of the project could actually not been reached, mainly due to thedifficult working conditions throughout the whole project and the prematurefinalization of field works and on-spot cooperation due to Nepalese politicalinstabilities IfGG (2002).

However, the project could generate a great number of results, some thatcontribute to reduce the vast knowledge gap on pesticide behaviour in sub-tropical environments, and some that give way to a better understanding ofhydrological processes in subtropical, irrigated, terraced catchments. Further-more, methodical results are worth mentioning.

In the following shall be shortly summarized how the IMPS-project Nepalcould contribute to enlarge the knowledge on socio-economy, irrigation, ge-ography and hydrology as well as on the main project task, the pesticide fate,transport and contamination risk under Nepalese environmental conditions, de-spite the unfavourable working conditions in Nepal, which are probably not anuncommon example for the problem struck Developing Countriess (DCs).

2.1 Basic project results

Within the framework of the project, a number of scientific results were gener-ated, that are shortly summarized in the following. The respective references,for more detailed information are given.

2.1.1 Geography, hydrology and agriculture

For environmental studies, physical- and human geographical knowledge aboutthe study area as well as the understanding of hydrology are indispensable.Hence, a number of works focussed on the formulation of the respective projectresults:

• Knowledge about irrigation patterns, systems and of history, as well associalisation of agricultural water distribution in the mid-hills of Nepal.These findings have been summarized and compiled in the two academicworks, by Acharya (2003) and Adhikari (2003).

14

• Detailed results on land use, cropping pattern and specific pesticide use inan khet area of the Nepalese mid-hills. These results have been compiledby Pujara (2000) in a masters thesis.

• A scientific study on geomorphological risks, i.e. above all the landsliderisk in agricultural areas in the mid-hills of Nepal. The results are com-piled in a masters thesis by Prasai (2001).

• Study of heavy metals transport through khet and bari environments inthe Nepalese mid-hills. The results are summarized in two thesis, one byHelfrich (2002) and one by Zelle (2002).

• The hydrology of khet catchments has been investigated in detail. Theworks include two studies on the hydrogeology of khet catchments, oneby Leseberg (2000) and one by Schulze (2000), in addition, two modellingstudies. One aimed on a hydrogeological modelling with FEFLOW (Bahr,2002) and the other one targeted on the hydrological behaviour in khetcatchments. Latter has been published in Piepho (2003). A hydrologi-cal process study for a khet catchment topped the hydrological studies offand resulted in a comprehensive summary on the hydrology in khet catch-ments of the Nepalese Mid-Hill region. The latter results are compiled inSchumann (2004b).

2.1.2 Socio-economy

Comprehensive results have been generated on socio-economic issues. For thefirst time in Nepal, khet and bari catchments of the mid-hills have been anal-ysed separately with regard to their socio-economic characteristics and pesticideapplication procedures. The most important results have been summarized byHerrmann et al. (2001) and Shrestha & Neupane (2002). The detailed find-ings are reported in CEAPRED (2001a) and the actual figures are availablefor further scientific use in a data base at the Center for Environmental andAgricultural Policy Research, Extension & Development (CEAPRED), Nepaland at the Institute of Geoecology, Department of Hydrology and LandscapeEcology of the Technical University of Braunschweig (PHYSHYD), Germany.Specific results on farm budgets identifying cost of production and income arepublished in CEAPRED (2001b) and this data is also readily available at theabove mentioned data bases in Nepal and Germany.

A final conclusion which can be drawn from the socio-economic studies con-cerning pesticide reduction and health measures are (Herrmann & Schumann,2002a):

• “Feasibility of measures for environmental protection, hence of project results,is difficult due to lack of money, resources and control instances and the relativeeconomic unimportance of pesticides.

• The regional infrastructure of the Nepali government on district scale serves asa good basis to educate farmers about hazards and risks of pesticide use, and onproper choice and use of pesticides.”

15

Results from a dynamic cost-benefit analysis for an Integrated Pest Man-agement (IPM) education program carried out by Wiebelt (2000) show, thatthe adoption of IPM could contribute substantially to the intensification ofNepalese agriculture in a sustainable manner. Using an optimal control frame-work, IPM benefits are compared with the costs of a public IPM technologytransfer program for the aggregate Nepalese agricultural sector. The impact ofIPM technology on input and output prices is taken into consideration in deter-mining the optimal rate of technology transfer in the form of an exposure ratethrough educational programs of the Cooperative Extension Service (CES).By influencing the exposure of technologies, the rate of farmers’ technologyadoption can be controlled by the CES. Given a new technology and the costsof exposing the technology, the optimal path through time of farmers’ avail-ability and exposure to the technology are determined. In the case of IPMadoption, the appropriate level of CES-programs designed for educating farm-ers concerning IPM may vary through time depending on the percentage offarmers adopting IPM and the long-run equilibrium level of adoption. Moreeducational programs are needed in the early stages of adoption when only afew farmers have implemented the technology. When many farmers adopt thetechnology, the number of educational programs can be reduced and the natureof the programs changed to best reach the remaining farmers.

The results of the dynamic cost-benefit analysis indicate that CES-basedIPM programs should be targeted to maintain about 50% of Nepalese agricul-tural production in IPM. Such a program would reduce chemical applicationsonly slightly because the reduction in chemical use resulting from IPM is damp-ened by the fact that agricultural production expands. However, agriculturalproduction will be less chemical intensive with the program, i.e. the programwould be environmentally effective. The government costs of IPM and the re-sulting net social welfare would amount to 0.1% and 0.69%, respectively, leadingto a benefit-cost ratio of 7.9 to 1, i.e. the program would be economically effi-cient. The efficiency would even improve if the program would be financed bytaxes on pesticides. Most of the gross benefits accrue to agricultural producerswhich, on average, are poorer than consumers, i.e. the program would also im-prove the distribution of income in the country. Finally, it is important to notethat the benefits measured by Wiebelt (2000) are only market effects, resultingfrom changes in prices and quantities. Accounting for the externalities of healthand environmental benefits from IPM would result in a socially optimal adop-tion rate that would be higher than the optimal rate indicated solely by marketforces with positive impacts on the effectiveness, efficiency and distributionalconsequences of the IPM technology transfer program.

2.1.3 Pesticide awareness

Backed on the scientific results, awareness for pesticides risk on environment hasbeen broadened in Nepalese public and governmental institutions by the IPMS-project. Beforehand, the few publications on the “Nepalese pesticide problem”,e.g. by Baker & Gyawali (1994), focussed more on the common approach ofidentifying pesticide residues in agricultural products and on improper pesticide

16

use in respect to farmers health. Waibel et al. (1999) state in this respectthat “most of the concern, especially in developing countries, is about negativehuman health impacts of pesticide use”.

A major role in creating a scientific and political awareness for pesticide riskon environment played the close scientific cooperation of the research projectwith officials from Plant Protection Directorate (PPD) of HMG Department ofAgriculture (DOA). Furthermore, the organization of an International Work-shop on Environmental Risk Assessment of Pesticides and Integrated Pesti-cide Management in Developing Countries, 6-9 November 2001, which washeld in Kathmandu to disseminate the scientific results drawn from the re-search project, and to discuss these results with international scientists espe-cially of the Hindu Kush-Himalaya (HKH)-Region. All scientific papers pre-sented during the workshop are published in Herrmann & Schumann (2002b).Based on results and discussions, the workshop participants worked out con-clusions and recommendations on pesticide and environmental issues as wellas IPM, risk assessment and pesticide regulations for consideration in Devel-oping Countriess (DCs). Latter were handed over to the HMG Ministry ofAgriculture (MOA) and DOA as well as the Ministry of Science and Tech-nology (MOST) for consideration. The conclusions and recommendations arepublished in Herrmann & Schumann (2002b) and are attached to this report(Appendix A).

Public awareness was pushed through the broadcasting of two documenta-tions on TV Nepal, each with a duration of 15 minutes, one in Nepali and onein English language, on project results, the afore mentioned concluding work-shop, and the worked out conclusions and recommendations on pesticide andenvironmental issues as well as IPM, risk assessment and pesticide regulations(SEJ, 2002).

2.1.4 Capacity building and achievements

Besides the vast knowledge increase by the German scientists throughout theproject, the Nepalese project scientists gained competence by the access to newtechnologies and scientific knowledge. Knowledge was transferred either byclose cooperation during data collection and scientific interpretation or throughtraining measures, e.g. laboratory training for pesticide analysis. Furthermore,Nepalese scientific staff got access to new technologies, more especially software,and working methods. The DOA staff got introduced to field experiments onpesticide monitoring, degradation and transport, while HMG Department ofHydrology and Meteorology (DHM) staff got introduced to transport studiesin the vadose zone. Furthermore, IPM measures were developed for the controlof late blight (Phytophthora infestans).

The close cooperation of PHYSHYD and Tribhuvan University, Central Ge-ography Department (TU) led to knowledge transfer to the Department ofGeography of TU and to the introduction of Geographical Information Sys-tem (GIS) tools.

Following the recommendations of Mezger et al. (1994), the project con-tributed to a sustainable development in Nepal, because the knowledge of local

17

scientists has been employed and extended throughout the project duration, i.e.the scientific knowledge and knowledge gain was not predominantly exportedout of Nepal.

In this context it should also be mentioned that the short working visits ofthe Nepalese counterparts in Germany —in the context of a project workshop—did contribute to a new or extended experience of the Nepalese scientists. Ac-cording to Mezger et al. (1994) this is particularly important for those whowill in future take leading posts within the technical or organisational bilateralcooperation. Within this research project it has been experienced that thisextends to scientific research projects, too.

2.2 Scientific results on pesticide contamination

The scientific core of the IPMS-project results are the four PhD-theses whichwere carried out within the framework of the project. Among other scientificfocusses, three of the PhD-theses, Apel (2002), Vinke (2003) and Schumann(2004b), were concerned with pesticide degradation and transport studies, whileone (Piepho, 2003) was solely aiming on the establishment of a hydrologicalmodel for khet environments. Those theses concerned with pesticide mattersfocused on the same target compounds, i.e. the organophosphorous insecticidesDimethoate and Malathion, the fungicide Metalaxyl and the pyrethroid Fen-valerate, all four being commonly and extensively used in Nepal. Vinke (2003)worked additionally on Mancozeb, a dithiocarbamate, which is applied in highamounts to potato crops in Nepal.

Vinke (2003) carried out laboratory batch experiments for a range of soiltemperatures and soil moistures on pesticide degradation. Since results drawnunder laboratory conditions often differ from results under actual field condi-tions, field experiments and monitoring programs were run together with Apel(2002) in order to allow for a quantification of pesticide transport. Vinke (2003)also worked on the degradation and sorption parameters of Mancozeb, which re-quired the development of a new analytical method that allows a differentiationof the transformation product from the control substance.

Apel (2002), based on results worked out by Vinke (2003), developed a riskanalysis model which uses reactive transport modelling and accounts for thepesticides’ degradation and sorption kinetics. In order to simulate preferentialflow under saturated soil water conditions a two-flow domain model was im-plemented, coupling two stationary convection-dispersion equations. Pesticidekinetics were modelled assuming 1st order decay and one-site kinetic adsorptionto the soil matrix in both domains. The model allows the forecast of contamina-tion risks of pesticide applications under the observed agricultural and climaticconditions. For this work, field experiments on plot scale were carried out, to-gether with Vinke (2003), in order to investigate the one dimensional transportof water and pesticides, using Bromide as a control media. These experimentswere based on the sampling of soil samples by the Nmin sampling method. Apel(2002) furthermore developed, based on a population dynamic model, treatmentrecommendations for the control of the late blight (Phytophthora infestans), a

18

fungal disease commonly destroying potato and tomato crops in Nepal. De-tailed results on the latter are published in Apel et al. (2003).

Schumann (2004b) aimed on the specific trailing of the mobile phase as theleading phase for pesticide transport and on the identification of the dominanthydrological transport mechanisms for pesticides.

2.2.1 Complementary, compound specific results

Basically, it can be stated that no pesticide residues for Malathion, Dimethoate,Metalaxyl or Fenvalerate could be detected in any monitoring samples for soils,discharge or groundwater within the project period. This is surprising ase.g. Malathion and Metalaxyl are detectable in German groundwater resources(Akkan et al., 2003).

This fortunate situation in the studied area in Nepal seems to be caused bythe intense insolation favouring photolysis of the pesticides, high soil tempera-tures reaching up to 30 ◦C in the upper 15 cm, relatively loamy soils favouringadsorption processes, and agricultural practices which promote the establish-ment of a rather impermeable dasyc pan (plough pan) resulting in minimizedpercolation rates and therefore practically stagnant transport conditions.

In the following, the IPMS-project compound specific results for the activesubstances Malathion, Dimethoate, Metalaxyl and Fenvalerate will be summa-rized.

Malathion

In all the three works referred to, this insecticide has shown to be the leastrisky.

According to Vinke (2003) the disappearance times (Dt50) of Malathion,determined in the laboratory, are with 0.1 to 1.0 d very low. Due to the fastdisappearance a dependence of the Dt50 on temperature or water content couldnot be clearly proved. In field experiments, it has been proved that on day 2only 4% Malathion was left in 0–5 cm depth.

The studies presented by Schumann (2004b) confirm that Malathion couldnot be detected in soil samples 3 days after pesticide application. Further-more, Malathion could not be traced in the soil water. Very low quantitiesof Malathion could be traced, though, three days after the application tookplace, in the groundwater of Perched Groundwater Lenses (PGWL), which areperched, isolated water lenses that exist within the vadose zone, most of themconfined. They show no hydraulic interconnection among themselves, and arenot bound to one distinct soil layer. 11 days later, the Malathion had disap-peared in the PGWL.

Apel (2002) refrained from risk calculations as all prior results did not in-dicate any possible risk due to too rapid substance degradation.

As a matter of fact, Malathion was not detected in any soil or groundwatermonitoring sample during the whole project duration.

It can be concluded, that Malathion, due to its very short Dt50, does notconstitute a risk for the bari or khet environments though it might reach greater

19

depths and groundwater by Preferential Flow (PF)1 when ponding irrigation isapplied.

Dimethoate

For the Dt50 of Dimethoate, Vinke (2003) has determined a clearly positiveinfluence of higher temperatures and a negative influence of increased watercontents on the disappearance reaction kinetics. Under ponding, she generallyobserved a strong reduction in disappearance velocity. Based on the results byVinke (2003), Apel (2002) calculated an optimal disappearance for Dimethoateat 38.8 ◦C and 19.2% volumetric soil water content. For standard laboratoryconditions and khet soils, a Dt50 of 8 d was determined. However, in fieldexperiments the Dt50 have proved to lie below the laboratory values (Vinke,2003).

The determined dependence of the reaction kinetics on temperature leads,in the modelling for Dimethoate (Apel, 2002), to a clear visibility of the sea-sonal temperature variation in the degradation, and respectively in the residueformation within different cropping periods, i.e. the degradation is much slowerin winter than during summer. During summer, degradation processes increaseso much, that they actually result in a reduction of residues (Apel, 2002).

Modelling shows, that long term residue formation in the soil is possibleon the basis of the present mean application rates, although only in hardlydetectable quantities (Apel, 2002).

The field studies described in Vinke (2003), which were all based on a Nmin-sampling procedure down to 30 cm depth and in a second experiment downto 50 cm depth, show a major accumulation of Dimethoate in the upper 5 cmof the soil. However, after 2 days, only 58% of the applied substance2 wasstill present in the upper 30 cm. Besides the accumulation in the upper soil, atransport of Dimethoate down to 50 cm depths has shown to take place within5 days after application, amounting to 13% of the applied Dimethoate mass.Vinke does not exclude the possibility that Dimethoate is leached even furtherinto the ground.

This has been corroborated by the modelling results of Apel (2002), whoquantified the solute flux leached into greater soil depths by fast domain flow3

to 1319 µg m−2 a−1 when Dimethoate is applied on average doses. If, how-1PF is principally defined as a flow that bypasses part of the soil matrix (“bypass flow”)

and is bound to faster flow velocities than usually observed for uniform flow. PF combinesgenerally the flow through macropores and fingered flow (Fank et al., 2001). Some fewauthors also identify funneling as a separate PF component.

2Note: Vinke (2003) backs the recovery, i.e the pesticide amounts still present in therespective depths, on total pesticide amount determined from the sampling of the uppersoil right after pesticide application (day 0). Therefore, these recoveries are not directlycomparable with those used for normalization which account for recoveries in respect to totalapplied mass in hydrological studies as used in Schumann (2004b).

3Apel (2002) restricts his modelling work to stationary saturated flow conditions. The fastdomain flow has an estimated volumetric water flux density of 0.85 cmd−1 and is set equal to10% of the volumetric soil moisture at saturated flow conditions, while the slow domain flowaccounts for 35% volumetric soil moisture at a defined saturated volumetric soil moisture of45%.

20

ever, extreme doses are applied, not only the residue formation but also theDimethoate flux leached into greater soil depths (17929 µg m−2 a−1) reaches aworrying level.

Schumann (2004b) has proved the actual occurrence of Dimethoate in thepercolation flux and it has been shown in that work that the decisive trans-port mechanisms for Dimethoate leaching into greater depths is definitely byPF, while uniform flow4 does not lead to a percolation of Dimethoate into thedeeper soil. Dimethoate has been proved to occur in the free soil water down to160 cm b.s. and has furthermore been proved to reach into PGWL within threedays after application, reaching concentrations of 0.15–11.5 µg L−1, which arewell above the German drinking water limit of 0.1 µg L−1. The relevant PFtransport fluxes occur only if the antecedent soil moistures are low, thus fluxesare minimized, when the agricultural fields are subject to constant irrigationleading to saturated conditions above the dasyc pan.

At the moment, neither the groundwater nor the soils of the study areashow any indications of Dimethoate residues; all soil and groundwater samplestaken during monitoring did have negative indications. However, results in-dicate that if the applied mean Dimethoate doses are continuously exceeded,environmental problems may arise from a residue formation in soils and ac-cumulation of Dimethoate in groundwater. Therefore it is recommended forauthorities to control application amounts and to establish a monitoring pro-gramme for drinking water wells. Furthermore, farmers should be advised toapply Dimethoate only after irrigation and never onto dry soils before irrigationor before strong precipitation events are expected.

Metalaxyl

For the Dt50 of Metalaxyl Vinke (2003) has determined a clear positive influenceof higher temperatures and also, in contrast to the results for Dimethoate, apositive influence of increased water contents on the disappearance reactionkinetics. Based on the results by Vinke (2003), Apel (2002) calculated forMetalaxyl an optimal disappearance at 33.8 ◦C and water saturated conditions.For standard laboratory condition and khet soils, a Dt50 of 28 d and a lag phaseof 7 d was determined (Vinke, 2003). The same author has shown that the lagphase under khet field conditions with high antecedent soil moistures is shorterthan 7 d or may even be completely missing, resulting that only 15% of theapplied Metalaxyl is still present after 5 d within the upper 50 cm of the soil5.

In contrast, Vinke (2003) also observed that for Metalaxyl, when it is appliedon low antecedent soil moisture before ponding, the lag phases result to be very

4Uniform flow leads to stable wetting fronts that are parallel to the soil surface. It issometimes also termed stable flow and represents best the flow conditions as identified bythe empirical Darcy equation.

5Vinke (2003) draws her results from the standard sampling procedure using the Nmin-method and calculates the recovery (pesticide amounts still present in the respective depths)from total pesticide amount determined from the sampling of the upper soil right after pes-ticide application (day 0). Therefore, these recoveries are not directly comparable with thoserecoveries used for normalization in hydrological studies which account for recoveries in respectto total applied mass.

21

long, and that two days after the Metalaxyl application it could be traced in allsampled soil depths down to 30 cm. Vinke (2003) observed that the amount ofMetalaxyl was decreasing very little and that a tendency of displacement intodeeper soil depths was notable. She furthermore observed, that the degradationof Metalaxyl was accelerated after a previous application of the same pesticide.

The observations by Vinke (2003) are confirmed by the findings of Schu-mann (2004b), that antecedent soil moistures have an influence on Metalaxyltransport, whereby high antecedent moisture contents minimize the transportof the pesticide into greater soil depths. Since under these conditions practicallyno pesticides are transported into greater depths, they remain in the upper soilwhere they are subject to the determined optimal disappearance conditions,when the applied ponding irrigation causes saturated conditions.

The modelling results by Apel (2002) for Metalaxyl are comparable withthose for Dimethoate, though the input doses are considerably smaller and noapplications were modelled for the paddy season. Metalaxyl shows a weaktendency to residue formation and leaching (Apel, 2002). Fortunately however,Metalaxyl concentrations only reach above the quantification limit if very highamounts and frequencies are applied. Latter corresponds to the worst-casescenario defined for Nepal by Apel (2002). Then, due to residue formation,considerable amounts of Metalaxyl remain in the soil profile at the end of oneagricultural year. Furthermore 4340 µg m−2 a−1 Metalaxyl are leached by fastdomain flow into soil depth greater than 120 cm (Apel, 2002).

If Metalaxyl is also applied during the paddy season, residue formation inthe soils will be enhanced and the pesticide amount transported to greater depthwill increase. According to the socio-economic survey compiled by CEAPRED(2001a) Metalaxyl is already applied onto paddy plantations in Thamaghatwhile this agricultural praxis has not yet reached the Tinpiple site.

Schumann (2004b) has proved that Metalaxyl actually occurs in the perco-lation flux and that the decisive transport mechanisms for Metalaxyl leachinginto greater depth is definitely PF while uniform flow plays no role in the per-colation of Metalaxyl into the deeper soil. This is identical to the findings forthe substance Dimethoate. Metalaxyl was found to reach into PGWL withinthree days after application, reaching concentrations of 0.1–3.4 µg L−1, whichare above the German drinking water limit of 0.1 µg L−1. Although the actualconcentrations lie below those found for Dimethoate, the normalized Metalaxylconcentrations lie within the range of those found for Dimethoate. This indi-cates that despite the lower input doses of Metalaxyl, a similar risk potentialas for Dimethoate is given, though the water solubility of Metalaxyl lies threetimes below that of Dimethoate. Apel (2002) also names this similarity in therisk potential and refers this to the longer degradation of Metalaxyl as com-pared to Dimethoate. The importance of the slower degradation time was alsoobserved by Schumann (2004b) as Metalaxyl remains in higher standardizedconcentrations in PGWL water with progressing time.

At the moment, just as in the case of Dimethoate, neither the ground-water nor the soils of the study area do show any indications of Metalaxylresidues. Recommendations for the use of Metalaxyl are similar to those givenfor Dimethoate, since the research results also indicate that a continuous excee-

22

dence of the applied mean Metalaxyl doses may result in residue formation insoils and an accumulation of Metalaxyl in the groundwater. This is more espe-cially the case, if Metalaxyl will also be applied during the paddy season (as e.g.at the Thamaghat site). Also in regard to Metalaxyl, the authorities are advisedto control application amounts and to establish a monitoring programme fordrinking water wells. Furthermore, it should again be recommended to farm-ers to abstain from Metalaxyl applications before irrigation or before strongprecipitation events are expected.

Fenvalerate

Fenvalerate has proved to be the most complex and unpredictable substanceamong the studied pesticides.

For the standard laboratory condition (20 ◦C and 15% soil moisture) andkhet soils a Dt50 of 17 d was determined for Fenvalerate (Vinke, 2003). Whenthe khet soil was put under saturated conditions though, the disappearance ofFenvalerate was slower, at least in some experiments. Under saturated condi-tions, an increase in temperature from 20 ◦C to 30 ◦C resulted in a relativelyfaster disappearance of the Fenvalerate. At 30 ◦C and saturation, the Dt50 wasdetermined to be 37 d (Vinke, 2003).

The same author could not determine a clear correspondence of the Fen-valerate concentration development on soil moisture conditions. A positivetemperature dependence, however, i.e. faster disappearance with higher tem-peratures could be determined (Vinke, 2003). Latter was used by Apel (2002)who aimed on optimising the Fenvalerate modelling parameters for the environ-mental fate modelling. For the optimised parameters, he observed obscuritiesin the sorption behaviour of Fenvalerate: “. . . although the sorption strength isvery high, the sorption kinetic is very slow, resulting in a considerable amountof Fenvalerate in solution despite its low solubility. [. . . ] It also means that theequilibrium between the sorbed and solute phase is reached after a long time.”(Apel, 2002).

Due to its obscure behaviour, the Fenvalerate transport can not be de-scribed with the developed pesticide fate model for the khet field conditions(Apel, 2002). However, for bari conditions, mere degradation scenarios werecalculated. The results indicate a retardation effect due to sorption and thatthe Fenvalerate degradation stagnates after an initial degradation phase (Apel,2002).

No risk prediction could be made on a possible groundwater contaminationby Fenvalerate on the basis of the modelling results (Apel, 2002). Schumann(2004a), however, has proved, that there exists an observable risk since Fen-valerate reaches the PGWL within three days after application, though in con-centrations of 0.2–0.4 ng L−1 that lie below the German drinking water limit of0.1 µg L−1. Fenvalerate could also be proved to reach into the deeper soil (up to2.40 m b.s.) after an experimental application and was proved to be arbitrarilypresent in soil water. The transport of Fenvalerate below the upper soil wasalso observed by Vinke (2003). The same author and Schumann et al. (2002)assign the transport into the deeper soil to an adsorption of the Fenvalerate

23

onto micro particles which are actually displaced. After German (1990) thistype of particulate transport already starts at pore diameters of >0.03 mm.

This thesis has proved that the decisive transport mechanisms for Fenvaler-ate leaching into greater depth is definitely PF while uniform flow does notallow for Fenvalerate transport.

During the study period, neither the groundwater nor the soils of the studyarea do show any indications of Fenvalerate residues in soil and groundwa-ter samples. Recommendations for the use of Fenvalerate are difficult, due toits complex sorption behaviour and the unpredictable movement (Apel, 2002).However, since Fenvalerate is predominantely transported by PF mechanisms,farmers should be advised to apply Fenvalerate only after irrigation and neveronto dry soils before irrigation or if strong precipitation events are to be ex-pected. Authorities are advised to control application amounts and to establisha monitoring programme for drinking water wells. Generally, further researchis necessary in regard to Fenvalerate. Meanwhile, also due to its environmentalpersistence and relatively slow degradation (Vinke, 2003) “the regular use ofFenvalerate is discouraged and recommended for emergency use only in order toreduce the risks [. . . ]. Additionally the often reported resistance developmentof major insects in areas of high use of Fenvalerate puts further emphasis on thisrecommendation [. . . ]. And since the physico-chemical as well as insecticidalproperties of Fenvalerate match many of the other synthetic pyrethroids, thisrecommendation is extended to the whole substance class.”(Apel, 2002).

2.2.2 Pesticide transport mechanisms

Both works, by Apel (2002) and Vinke (2003), already indicate that one of thedecisive pesticide transport mechanisms in the study area must be PreferentialFlow (PF). Furthermore they have noted that the applied pesticides do notpredominantly remain in the upper 5 soil cm. According to Apel (2002) thosefield experiments which were based on the sampling of the soil matrix, clearlyindicate a non-ideal transport behaviour for the pesticides. Apel (2002) henceconcludes that the transport cannot be described with an ordinary convection-dispersion model.

Schumann (2004b) has proved, by a separate liquid phase sampling besidesthe taking of composite samples6, that PF is the leading process for pesticidetransport into the deeper soil and into Perched Groundwater Lenses (PGWL),while homogeneous matrix flow can be neglected as a transport mechanismsinto deeper soil compartments. Fast enough homogeneous matrix flow, whichallows for the consideration of a noteworthy pesticide transport, only occurswithin the soil zone above the dasyc pan, which is sort of a plough pan whichis purposely hardened by the farmers during paddy cultivation. It is situatedaround 30 cm b.s. and controls and decreases the percolation flux. The bulkmasses of pesticides do not pass the dasyc pan and therefore remains in theupper 30 cm of soils. If the dasyc pan, however, shows hydraulic leakage, i.e.when it has been poorly puddled, it features cracks due to dry conditions or

6The terminus “Composite samples” represents the inclusion of the two phases, i.e. theliquid and the solid phase which are sampled equally when soil samples are taken.

24

AQUpor(frac) Aquifer, porous (fractured) PONDIRR Ponded irrigation water CONF Confined (AQU) QAQU Groundwater Flow Dasyc Pan Purposely hardened plough pan QD Surface Runoff E Evaporation QFP Flux drawn by preferential flow mechanisms ET Evapotranspiration QIRR Irrigation Water IL Interception Loss QIRR(IMP) Irrigation Water from channel, imported IS Interception Storage QM Flux from Matrix flow mechanisms P Precipitation Qo Infiltration/Seepage Flux PER Permanent (AQU) QR River Water (brook) PFP Preferential Flow Paths USZpor- Unsaturated soil zone- PGWL Perched Groundwater Lenses SSZpor Quasi-saturated soil zone

QIRR

QIRR (IMP)

QR

ET IL

P

IS

PONDIRR

E

QO

USZpor- SSZporPFP

Dasyc Pan

AQUpor(frac) PER - CONF

QOIII

QIRR

QD

QAQU

PGWL

QFP

QFP

QO‘

PGWL

QM PFP

QR

QIRR

QIRR (IMP)

QR

ET IL

P

IS

PONDIRR

E

QO

USZpor- SSZporPFP

Dasyc Pan

AQUpor(frac) PER - CONF

QOIII

QIRR

QD

QAQU

PGWL

QFP

QFP

QO‘

PGWL

QM PFP

QR

Figure 2.1: Conceptual hydrological model as valid for khet conditions duringmonsoon. Dotted lines represent fluxes which are only assumed to exist. Thesum of the fluxes QM and QPF equals to the percolation flux through the vadosezone, i.e. QOII .

when it shows macropores due to biological activity, the dasyc pan can be passedby PF. PF transports the pesticides into deeper soil compartments, where theyare either absorbed onto the soil matrix along Preferential Flow Paths (PFPs),accumulate in flow pockets, or reach into PGWL. The occurrence of this typeof PF is favoured by dry antecedent soil moistures and irrigation occasions (orheavy storms) leading to ponding conditions.

Figure 2.1 summarizes in a conceptual hydrological model the, during mon-soon, relevant water fluxes for the studied khet catchment. It abstains fromfiguring secondary fluxes but concentrates on dominating fluxes only.

25

Higher water-solubilities of pesticides and therefore higher polarities, haveproved to promote the transport of higher pesticide concentrations along PFPunder khet conditions. Even following their application on the bare soil, thewater soluble pesticides are solved in the ponded water phase, and are thenflushed by PF into the deeper soil. However, also synthetic pyrethroid Fen-valerate, which is nearly insoluble, has proved to be transported by PF mecha-nisms, possibly due to retarded or varying sorption processes (Apel, 2002), andadsorbed to soil particles (Schumann et al., 2002).

2.2.3 General conclusions on study methodology and on pa-rameters influencing the pesticide transport and fate be-haviour

Apel (2002), Vinke (2003) and the present work emphasize on the necessity ofsite-specific investigations with respective monitoring programmes. For pesti-cide degradation and residue formation, climatic conditions, soil moisture andthe agricultural system have shown to be of great importance. Therefore, theobtained results cannot be assigned to arbitrarily different geographic condi-tions, i.e. they are actually only valid for the studied climatic conditions andsoils, and the examined agricultural practices.

It has been shown that substance-specific studies are essential since all fourpesticides have shown different fate, adsorption, degradation and transport be-haviours.

Field studies have shown to be indispensable, even if batch experiments arerun with site specific soils and under site relevant conditions for soil temper-ature and soil moisture. It has been shown that pesticide behaviours underactual field conditions differ from those expected from their physico-chemicalproperties and Dt50-values, which are determined from batch experiments. Un-der field conditions, the degradation of pesticides in the upper soil was faster,presumingly due to the intense solar radiation. Vinke (2003) suspects a gener-ally higher adsorption of pesticides in the batch experiments and ascribes thisto the applied laboratory methodology. For the batch experiments the soil wassieved hence the adsorption capacity was higher than under field conditionswhere soil aggregates may be larger (Vinke, 2003). Moreover, the batch exper-iments did not account for any transport phenomena as they were carried outin Erlenmeyer flasks (Vinke, 2003).

Transport field studies are a must, as it has been shown that the studiedpesticides were subject to a water-bound transport into the deeper soil and eveninto saturated compartments. In principle, it should be noted that low concen-trations of pesticides in the upper soil compartments should not be assigned todegradation processes only, and that for the PF mechanisms the transport ofpesticides might not necessarily be correlated to their equilibrium adsorptionconstants determined during batch experiments.

Finally, the dependence of the pesticide fate and behaviour on geographicconditions leads Vinke et al. (2002) to the conclusion that a multi-step controlsystem has to be applied on the basis of standard and specialised laboratory testsystems for an improvement of the pesticide registration procedure in Nepal.

26

Chapter 3

Risk assessment

The environmental risk assessment, based on the environmental modelling anddeveloped by Apel (2002), focusses on soil contamination in terms of residueformation and on possible dissemination pathways from the site of application.The results show that an acute risk of pesticide residue formation in soils anda groundwater contamination under the present situation can be excluded. Inaddition, they allow to name an exceedance probability of < 0.5% for a longterm residues formation, more especially for synthetic pyrethroids, in this caseproved for Fenvalerate (Apel, 2002).

In this context, Schumann (2004a) has discussed the importance of com-paring the risk modelling results presented by Apel (2002) with detailed fieldstudies on pesticide transport and has furthermore formulated the need of a riskassessment for the ecosystem soil based on toxicity values for micro-organismsor molluscs.

In reply, Schumann & Langenberg (2004) have analysed the risk for theecosystem soil, based on the risk analysis by Apel (2002) and on toxicities forsoil oribatid mite and earthworms.

3.1 Scenario definitions and restrictions

The risk assessment is primarily restricted to the soil types actually studiedduring the field trials. The scenarios for the risk assessment for the Dimethoateand Metalaxyl have additionally been defined as follows (Apel, 2002):

• “Vertical transport and degradation on khet land

• Representative high intensity cropping pattern potato–tomato–rice

• Temperature response of degradation as in laboratory experiments

• Representative annual soil temperature variation

• Humidity response constant at saturation1

1This corresponds to stationary flow under a saturated water content, here defined as45%. 10% of the volumetric soil moisture is bound to fast domain flow with an estimatedvolumetric water flux density of 0.85 cmd−1 while 35% is bound to the slow domain flow witha set volumetric water flux density of 0.001 cmd−1.

27

Table 3.1: Dosage and application intervals of Dimethoate, Fenvalerate andMetalaxyl as valid for the risk analysis scenarios. From Apel (2002), slightlychanged.

Pesticide Scenario

Best case Standard case Worst case

Dosage Interval Dosage Interval Dosage Interval

[µg m−2] [d] [µg m−2] [d] [µg m−2] [d]

Dimethoate 8908 14/14/36 25120 10/10/23 59408 7/7/23

Metalaxyl 2442 18/18/– 7405 9/9/– 12848 7/7/–

Fenvalerate 15464 14/14/36 17000 10/10/23 34720 7/7/18

• Solute transport through the unsaturated zone as identified in khet field experi-ments2

• Dosage and application interval variance according to the CEAPRED report(CEAPRED, 2001a)

• Dosage definitions compound specific

• Application interval definitions compound and crop specific

• Empirical assumption of substance proportion applied to soil surface”

The risk assessment has been restricted to three different scenarios, definedas standard, worst and best case scenarios according to the following pesticideapplication variations (Apel et al., 2002):

• “mean-scenario [= standard-case]: mean of all recorded doses & frequency,25% applied to soil surface

• worst-case: highest mean dose +1.96 standard deviations, highest frequency,all to soil surface

• best-case: lowest mean dose −1.96 standard deviations, lowest frequency, 10%to soil surface”

The data source for the defined pesticide dose variations and frequencies isbased on the socio-economic survey by CEAPRED (2001a). The dosage andapplication amounts are summarized in Table 3.1.

For the Metalaxyl scenarios it is assumed that no Metalaxyl applicationstake place onto paddy cultivations. The scenarios for Fenvalerate are basedon mere degradation scenarios without any transport only. No scenarios werecalculated for Malathion due to its rapid degradation in laboratory and fieldexperiments. Any acute or long term risk by Malathion is excluded by Apel(2002) due to its generally rapid degradation.

2By the field experiments of Apel (2002) and Vinke (2003) transport was based on aBromide tracing experiment. The results of the work by Schumann (2004b) could not betaken into account at that time.

28

Table 3.2: Risk data for Dimethoate. LC50 and NOEC values are taken fromLøkke & Van Gestel (1998). PEC values were calculated.

Parameter Concentration unit Platynothrus peltifer Eisenia fetidain soil

LC50 [mg kg−1] 0.47 98

NOEC [mg kg−1] 0.1 1

PEClt [µg kg−1] 20 200trigger value 5

PEClt [µg L−1] 27 270trigger value 5

PECac [µg kg−1] 47 9.8 · 103

trigger value 10

PECac [µg L−1] 64 13.2 · 103

trigger value 10

3.2 Risk assessment for the soil ecosystem

Based on the scenario results by Apel (2002), Schumann & Langenberg (2004)have analysed the risk for the soil ecosystem in the study area caused by the ap-plication of the pesticides Metalaxyl, Dimethoate and Fenvalerate, with respectto soil oribatid mites (Platynothrus peltifer) and earthworms (Eisenia fetida).

Earthworms were chosen since they are “standard test organsisms becauseof their contribution to maintaining soil structure and fertility and their im-portance in terrestrial food webs” (OEPP/EPPO, 2003). Mites are “one ofthe most abundant groups of animals in the soil-litter subsystem” and “holda great potential for use in ecotoxicology. They are good representatives ofthe structural and functional complexity of soil communities and have severalpeculiarities not found in many other arthropods” (Løkke & Van Gestel, 1998).

3.2.1 Dimethoate

The risk evaluation is based on the two species Eisenia fetida and Platynothruspeltifer and a soil density of 1.35 g cm−3. The LC50 and NOEC values aretaken from Løkke & Van Gestel (1998), who list toxicity data for Dimethoate,although Dimethoate has a Dt90 that ranges between 15 and 27 d for fieldexperiments (Fischer, 2003).

The resulting risk data is shown in Table 3.2. The PEClt values for the twospecies were compared to the three Dimethoate risk scenarios of Apel (2002).The results for the standard and the worst-case scenarios are graphically pre-sented in Figure 3.1. For the Dimethoate best-case scenario, the long-termpesticide concentrations in the soil stay well below the PEClt-values, thereforeno graphical presentation of the best-case scenario is shown.

A comparison of the calculated PECac values (Table 3.2) with experimentalpesticide concentrations in the soil matrix three days after controlled pesticide

29

PEC (oribatid mite )

PEC (earthworm )

quantification limits

lt

lt

Platynthrus peltifer

Eisenia fetida

PEC (oribatid mite )

quantification limitslt Platynthrus peltifer

120

100

80

60

40

20

0

0 50 100 150 200 250 300 350

conc. [m g/L soil]

last day profile

dept

h[c

m]

Worst-case scenario

120

100

80

60

40

20

0

0 5 10 15 20 25 30

conc. [m

last day profile

dept

h[c

m]

Standard scenario

g/L soil]

Figure 3.1: Dimethoate risk scenarios. Shown are the pesticide concentrationsvs. the soil depth profile at the last day of the agricultural year. The full seasoncovers the cropping pattern potato-tomato-rice. The upper profile representsthe standard scenario while the lower profile shows the worst-case scenario.The following pesticide concentration limits are graphed: laboratory quantifi-cation limits and PEClt for the two species Platynothrus peltifer and Eiseniafetida. For scenario definition and respective pesticide application amounts andfrequencies see section 3 and Table 3.1.

30

application as observed by Schumann (2004b) show that the experimental fieldconcentrations in any soil depth three days after application were not critical.Here, the highest measured Dimethoate concentration in the soil matrix was21 µg kg−1 in 20 cm depth, i.e. a value below the PECac for Platynothrus peltifer.

However, results by Apel (2002) and Vinke (2003) show that the Dimethoateconcentrations reach 2600 µg kg−1 in the surface soil immediately after a con-trolled experimental pesticide application of 0.12 g m−2 onto the bare soil3.Latter concentration lies well above the PECac for Platynothrus peltifer, butstill below the PECac for Eisenia fetida. Results from the same experimentalso indicate that the PECac for Platynothrus peltifer is exceeded in the com-posite soil samples of the upper 10 cm (samples from the surface soil only donot exist) until the first 7 to 13 d after the pesticide application. A detailedanalysis of the modelled Dimethoate concentrations in the upper 5 cm confirmsan expected exceedance of the PECac for Platynothrus peltifer during the first5 d following a standard-scenario application. If Dimethoate is applied accord-ing to the worst-case scenario, the PECac for Platynothrus peltifer is exceededwithin the first 5 cm throughout the agricultural year.

It can be concluded that a long term risk for Platynothrus peltifer popula-tions exists if Dimethoate is applied according an application schedule similarto the worst-case scenario. However, according to Apel (2002) this scenariohas only a probability < 0.416%. The modelled worst-case scenario also re-sults in critical Dimethoate concentrations the upper 10 cm of the soil for theearthworm Eisenia fetida. The mean applied Dimethoate doses which is rep-resented by the standard-scenario, does not cause long term toxication of thetwo selected species.

It can be assumed that the PECac values for oribatid mites are temporarilyexceeded in the uppermost cm of the soil if Dimethoate is applied in concen-trations following the worst-case scenario and if 100% of the dosage reaches thebare ground. This case, again however, has a probability of only < 0.416%(Apel, 2002).

3.2.2 Metalaxyl

For Metalaxyl, only a LC50 of 1000 mg kg−1 soil for earthworms was availableamong possible toxicity parameters (Schumann & Langenberg, 2004).

The PECac displayes an alternation of 1000 times higher than the highestMetalaxyl concentration predicted by Apel (2002) for the one year–last day–long-term profile of the worst-case scenario (Schumann & Langenberg, 2004).No PEClt could be calculated due to lacking toxicity data.

A comparison of the PECac of Metalaxyl with acute Metalaxyl concentra-tions during field experiments shows, that in none of the cases the PECac forEisenia fetida was exceeded. This also holds for the Metalaxyl concentrationsin the surface near soil immediately after a controlled experimental pesticide

3This corresponds to the application amount maximally tolerated by Biologische Bunde-sanstalt der Bundesrepublik Deutschland (BBA) and is above the Nepalese worst-case scenariodosage.

31

22-43% oribatid mite ( ) reductionPEC soil micro-organism ( )

PEC

Platynothrus peltifer

lz nitrogen fixing

ac earthworm (Eisnia fetida)

0 50 100 150 200 250 300 350

0

500

1000

1500

2000

worst case standard best case

k from field experiment

tota

lcon

c.[m

g/so

il]L

days

Figure 3.2: Fenvalerate risk scenarios. Shown are the Fenvalerate concen-trations vs. the days of the agricultural year, covering the cropping patternpotato-tomato-rice. Three scenarios (best, standard and worst-case scenario)are graphed, all based on the field degradation rate of Fenvalerate. Further-more, the following pesticide concentration limits are shown: PECac for Eiseniafetida, PEClt for nitrogen fixing soil microorganims and the Fenvalerate concen-tration which causes a reduction of a oribatid mite population by 22-43%. Forscenario definition and respective pesticide application amounts and frequenciessee Apel (2002).

application of 0.04 g m−2 4. A detailed analysis of the Metalaxyl concentrationsexpected by the modelling for the upper 5 soil cm confirms that throughout theagricultural year no acute risk exists for Eisenia fetida. Due to a lack of toxicitydata for Platynothrus peltifer no prognosis can be made for possible intoxicationof oritabid mites.

It is concluded that no risk is caused through the application of Metalaxylat present rates for the organism Eisenia fetida.

3.2.3 Fenvalerate

For the pyrethroid Fenvalerate the risk analysis is based on the active agentEsfenvalerate, because toxicity data for Fenvalerate are not available as it hasbeen taken off the German market.

Since the risk analysis for Fenvalerate by Apel (2002) was restricted todegradation scenarios only, the long-term and the acute Toxicity Exposure Ra-tio (TER) as well as the concentration of 30 µg L−1 can be directly comparedto the predicted Fenvalerate concentrations in the soil, see Figure 3.2.

4This corresponds to the application amount maximally tolerated by the BBA. The worst-case dosage in Nepal stays well below this application amount.

32

It can be concluded that an acute risk for the reduction of mite abundanceexists in the top soil due to the application of Fenvalerate, even if Fenvalerateis only applied according to the schedule of the best-case scenario. For thenitrogen-fixing soil micro-organisms and the Eisenia fetida population in thetop soil a risk is only given, if Fenvalerate is applied accordant to the worst-case scenario. While the soil micro-organisms are generally at risk during theworst-case scenario, the Eisenia fetida population is only acutely endangered ifthe Fenvalerate concentration has already reached a background concentrationof approximately 800 µg L−1 soil. Here shall also be noted, that the probabilityof the worst-case scenario is only < 0.416% (Apel, 2002).

It needs to be stated, that the risk assessment for Fenvalerate only holds forthe top soil due to its complex sorption behaviour and unpredictable movement(Apel, 2002).

Limitations It is important to be aware that the results are, strictly speaking,only valid for the scenarios and restrictions defined afore. This will be furtherdiscussed in section 4.

Furthermore needs to be noted that the toxicity data used for the risk anal-ysis has not been quite sufficient. Due to the very frequent applications of thepesticides Dimethoate, Metalaxyl and Fenvalerate in the study area (Herrmannet al., 2001), a test on sublethal effects on earthworms would have been gen-erally required, if the EU-guidance would have been applied, as it states (EU,2002):

“The test is always required if the number of applications is greater than6 (regardless of persistence).”

In all three cases, though, the application frequencies for the three pesticidesreached, in the study area, values of more than 6 times per year. In most cases,with the exception being Dimethoate and Metalaxyl applications for the best-case scenarios, the number of applications was even higher than 6 times peragricultural crop, like for tomatoes. In the worst-case scenario the number ofapplications reached 10 per agricultural crop.

The environmental contamination risk by Metalaxyl can be further mini-mized if local farmers follow the Integrated Pest Management (IPM)-treatmentrecommendations for the control of the late blight (Phytophthora infestans).Furthermore, a small economic benefit is expected for the farmers due to areduced usage of Metalaxyl (Apel, 2002).

Finally, it needs to be mentioned that for the elaboration of the risk as-sessment for the soil ecosystem a biological component in the CollaborativeProject on Environmental Risks of Pesticides and Sustainable Development ofIntegrated Pesticide Management Systems (IPMS) in Nepal Considering Socio-Economic Conditions (IPMS-Project) would have been desirable in order toaccount in more detail on soil biology and organisms.

33

3.2.4 Conclusive recommendations for pesticide usage and en-vironmental protection measures in the study area

In addition to the general recommendations, which were worked out by theparticipants of the IPMS-workshop and which are attached in Appendix A, thefollowing recommendations, based on the complementary scientific results byApel (2002), Vinke (2003) and the present work (if not indicated otherwise)can be addressed to Nepalese officials and farmers in order to minimize the riskto the environment caused by pesticide applications:

• Improvement of the foliar pesticide application techniques in order tominimize the amount of pesticides reaching the ground.

• Increased control of application doses, as the contamination risk increaseswith applied doses. Although the mean application amounts lie for mostpesticides below those which are reported for Germany (except for Fen-valerate with a decuple application amount) the great variance in appli-cation amounts (CEAPRED, 2001a) indicates that large differences existamong farmers concerning their personal dosage.

• Establishment of a monitoring programme for drinking water wells, sinceit has been proved that pesticides may reach the groundwater by Preferen-tial Flow (PF). Monitoring should best be established on annual basis atthe interface between pre-monsoonal (e.g. tomato or corn) and monsoonalcrop (i.e. paddy).

• Careful and proper puddling of soils in khet areas. Improper puddling fa-cilitates the existence of hydraulic short-cuts which allow pesticide trans-port by Preferential Flow (PF) into the deeper soil and down to thegroundwater. Proper puddling minimizes the transport risk of pesticidesinto the deeper soil and groundwater.

• General restriction of pesticide application onto dry agricultural fieldsshortly before irrigation or before heavy rainfalls are expected. An-tecedent dry soil moistures facilitate pesticide transport into the deepersoil, more especially by PF mechanisms.

• Cautious use of Fenvalerate. The regular use of Fenvalerate is discouragedand recommended for emergency use only, since the risk of use can notbe well defined due to an unpredictable transport and sorption behaviourof Fenvalerate. Furthermore, resistance developments of major insects inareas of high use of Fenvalerate are often reported.

• Control of the late blight (Phytophthora infestans) by means of treatmentrecommendations developed by Apel et al. (2003), which minimize theusage of Metalaxyl and Mancozeb. Apel (2002) states: “For the controlof P. infestans on potato in the winter season in the Mid-Hills of Nepala regularly application of Mancozeb at the recommended dose in 14 daysintervals is sufficient. The application should start within the first week

34

after crop establishment. In severe cases a Metalaxyl+Mancozeb fungicideformulation may be used to stop the epidemic. In this case a weeklyapplication frequency is recommended.”

• Usage of the existing infrastructure of the Nepalese government on the dis-trict level in order to advise farmers on appropriate pesticide applicationtechniques and risk minimization. Moreover, the relatively well developedinfrastructure should be used to educate farmers on IPM measures. Asshown by Wiebelt (2000), Cooperative Extension Programs (CEPs) de-signed for educating farmers concerning IPM can contribute substantiallyto (1) an ecologically sound intensification of Nepalese agriculture, (2) animprovement of overall welfare, and (3) an improvement of the incomeposition of agricultural households, which belong to the poorest segmentsof Nepal’s society.

• Establishment of a laboratory which has the capacities for pesticide analy-sis. This is needed in order to control the groundwater monitoring samplesfor pesticide content and the pesticide application amounts onto soils byrandom tests (see items above). Furthermore, a product control shouldbe introduced to anticipate presently existing illegal pesticide stocks inthe market, e.g. Lindan. Finally, the laboratory is needed to establisha pesticide registration procedure in Nepal based on a multi-step controlconcept with standard and specialised laboratory tests and long-term fieldstudies which match the Nepalese environmental conditions.

To avert further damage, an improvement of security standards during pes-ticide application should be strived for in order to minimize the adverse effectson the health of farmers. In this context, it is also advisable to facilitate pesti-cide residue analysis for agricultural products in order to minimize the healthrisk for consumers. However, the latter two items were not covered in theIPMS-Project.

35

Chapter 4

Methodological considerationsand research needs

In this section, some of the methodologies, used and developed by the Techni-cal University of Braunschweig, Germany (TU-BS) team members during theproject, are briefly discussed and further research needs are formulated.

4.1 Pesticide fate dependency on environmentalfactors– a methodological progress

The research work, which was carried out together by members of the Collab-orative Project on Environmental Risks of Pesticides and Sustainable Develop-ment of Integrated Pesticide Management Systems (IPMS) in Nepal Consid-ering Socio-Economic Conditions (IPMS-Project), has once more shown thatpesticide fate depends on environmental factors, more especially on soil tem-perature and soil humidity. Apel (2002) and Vinke (2003) have developed amethod which allows, with a relatively small sample quantity, a sufficient gen-eration of data for the detection of the dependency of the degradation rate ontemperature and humidity. In this condensed experimental design “the temper-ature was varied during the batch experiment, whereas the soil moisture washeld constant at three different values” (Apel, 2002).

This method has been successfully used, and it has proved to generate suf-ficient information on temperature and humidity responses of pesticide fate. Itshould therefore be further verified and used in future studies. The method isespecially promising for the use in areas where large soil temperature and soilmoisture variations are expected throughout the agricultural year.

4.2 Specific pesticide trailing in soil and soil watersamples

It has been shown that the use of a colour dye like Vitasin Blue FCF 90 (VB)proves advantageous for the identification of flow mechanisms and the tracing of

36

pesticides. The promising results have led to the conclusion that this is an prac-tical and useful method for the first indication of a groundwater contaminationrisk from applied pesticides, in case of shallow aquifers (Schumann, 2004b).

At present state, however, this method does not allow for any quantifica-tion of water fluxes or pesticide transport. Furthermore, the study presentedin Schumann (2004b) led to the assumption, that the visible VB infiltrationfront actually does not represent the first arrival of the DARCY drawn infil-tration flux. Therefore this method needs further development aiming on thequantification of the water fluxes, e.g. by combining the experimental set-upwith the application of a ideal tracer like Bromide. Besides, the applicabilityof VB tracing for pesticide transport should be further investigated. Whileresults indicate that pesticide transport is fairly well resembled by VB as longas high transport velocities and short residence times are prevailing, i.e. in thecase of Preferential Flow (PF). It seems questionable whether transport by uni-form flow is properly resembled by this. Especially, since the different sorptioncharacteristics of pesticides and VB should be of distinctive importance in thelatter case.

Furthermore it has been shown that Bromide is an acceptable tracing sub-stance for the determination of flow parameters of the mobile phase. Bromidecan be given priority to Deuterium if the study is limited to the mobile phaseonly, more so, as results indicate, that it should be abstained from the usageof artificial isotopes as tracers, because they are liable to high tracer substancelosses and to a tracer enrichment by evaporation, especially in subtropical en-vironments (Schumann, 2004b). Hence, emphasise should be put upon com-parative tracer studies aiming on a tracer combination of Bromide, Deuteriumand pesticides and on a separate sampling of the mobile phase. These stud-ies are needed to prove whether the pesticide transport bound to the mobilephase can be truly resembled by tracer substances, and to identify the ap-plicable reaction-transport model. The use of Deuterium in combined tracerexperiments is necessary to identify the possible role of the immobile phase inpesticide adsorption, absorption and exchange mechanisms. First approachesin this direction are e.g. realised by Maloszewski & Klotz (2002), though basedon titrated water, and by Beulke et al. (2001).

4.3 Sampling techniques for Preferential Flow (PF)transport processes – the need for capturing themobile phase

Research on pesticide transport, aiming on a risk assessment for groundwatercontamination by pesticides, should also focus on fast pesticide transport pro-cesses bound to PF-mechanisms. It has been shown in Schumann (2004b) andin a number of other works, e.g. Flury et al. (1995), Zehe & Fluhler (2001),Jørgensen et al. (2002) and Reichenberger et al. (2002), that PF may play aleading role in pesticide transport. To understand and describe the respectivePF transport processes, it should be abstained from sampling the soil matrixonly, more over as it has been shown in Schumann (2004b), that the standard

37

Nmin sampling technique for instance, fails in capturing PF mechanisms. Thishas also been stated by Flury (1996), who concludes that the homogenization ofsoil samples, which are taken with an auger, results in a dilution of the chemicalconcentration in the soil sample. Hence pesticides, which are concentrated alongcracks or flow channels, may not be detected. Therefore, it seems inevitable toalso base the studies on pesticide concentrations measured in the mobile phaseas, due to the fast water-bound transport and short contact times with thesoil matrix, the parametrisation for the pesticide physico-chemical behaviourand the exchange kinetics between the different phases cannot be described byparameters obtained by standard laboratory batch experiments. Flury (1996)even states that “there is evidence that even strong absorbing chemicals canmove along Preferential Flow Path (PFP) and that travel times of pesticidesare comparable to those of conservative tracers.” Latter has been proved truefor khet conditions (Schumann, 2004b). Furthermore, transport of pesticidesalong with mobile micro particles can be registered (Zehe & Fluhler, 2001; Schu-mann et al., 2002). Another argument for the sampling of the liquid phase isbrought up by Barlund (1999), who raises the fact that the pesticide analyticsof water samples bear a higher analytical precision and that hence even smallpesticide quantities, which might be of environmental relevance though, maybe recorded. A main condition for this approach is of course, a guaranteedavailability of enough drainable liquid phase for analysis.

In this context, it should generally be aimed for a model calibration andvalidation based on soil samples combined with a mere liquid phase samplingin order to ensure that also those fast transport processes are described, whichmay be of a prime importance for a groundwater contamination. This approachis presently followed in a few studies on model development and validation, e.g.by Klein (2002) who upgrades PELMO by a macro-pore module for solutetransport.

In concern of a mere sampling the liquid phase, and more especially of thesampling of the very fast domain flow passing through PFPs, further develop-ment is needed on easily implementable sampling devices. This is, above all,true for field studies aiming on regionalisation and for studies in developingcountries. The present “state of the art”, which allows for a sampling of allphases is definitely the lysimeter, all the more, as it allows for a quantificationof water fluxes. While most lysimeters permit for a continuous sampling proce-dure for the liquid phase, the soil sampling, and hence the acquisition of data onthe composite phases can only be realized once or at the end of experiment. Al-though it has been shown by Herzel & Schmidt (1979), during an investigationon the leaching behaviour of different herbicides, that a satisfactory correlationbetween small columns and the experimental set-up of lysimeters exists, thesmall column method is not applicable because it does not account for fieldconditions. The research work of the IPMS-project scientists has clearly shownthat a risk assessment needs to be based on real environmental conditions.Also Schroll et al. (2002) have summarized the necessity of real environmentalconditions, by stating that laboratory conditions can provide high-quality in-formation on distinct processes, but that only the interaction of processes (e.g.impact of rainfall events, dry-out of soils, biotic activity in soils, soil-physical

38

parameters) allows for a collection of realistic data and hence a environmen-tally relevant conclusion. They conclude by stating that the employment of alysimeter is indispensable. However, lysimeter field studies are expensive anddifficult to employ and hence it should be strived for comparative studies withother sampling techniques.

Schumann (2004b) has shown that one starting-point for an alternativesampling methodology, could be the combined employment of suction cups,piezometers and soil samplings as it allows at the one hand for the sampling ofthe composite phases (soil samples) and on the other hand for the mere sam-pling of the mobile soil water of the uniform flow (suction cups). The suctioncups may also capture PF mechanisms, especially fingered flow, but generallynot satisfyingly, in particular when macropores are involved. The simultane-ous use of piezometers though, allows for the capturing of PF along the filterlength, admittedly only qualitative at present. However, this experimentalset-up would need a proper comparability study with a lysimeter and furtherdevelopment on quantitative evaluation. Another promising approach, whichincludes an area-related quantification of fluxes, is the use of monitoring boxes.Latter have been tested and validated in experiments by Bischoff et al. (1999).

4.4 Risk analysis based on modelling–the need ofconsidering hydrological studies

The environmental risk assessment, based on a deterministic process model de-veloped by Apel (2002) has served to exclude an acute risk of pesticide residueformation in soils and of groundwater contamination under the studied condi-tions.

Although the model accounts very well for the general trend in the transportof Dimethoate and Metalaxyl, it has also reached application limits, e.g. it hasnot been applicable for the pyrethroid Fenvalerate due to the pesticides’ complextransport and sorption behaviour.

Furthermore, it has shown weaknesses in the reproduction of elevated pesti-cide concentrations in the deeper soil, i.e, in cases, where the field data indicatedhigher pesticide concentrations in greater depths than in depths closer to thesurface (Schumann, 2004a).

Already Apel (2002) and Vinke (2003), indicated that Preferential Flow(PF) is one of the decisive transport mechanisms in the study area. Schumann(2004b) has shown, that the transport of pesticides into greater depths is actu-ally dominated by PF, while the transport of pesticides by uniform flow, intodepths below the dasyc pan, can practically be neglected for the khet sites. Therisk assessment modelling was based on a two-domain solute transport modelwith steady flow conditions, which used an estimated capillary water flow ve-locity of 0.85 cm d−1 for the fast domain (Apel, 2002)1. The actually tracedmean flow velocity of the mobile phase, which was determined by Schumann

1The fast domain capillary water flow velocity was estimated backed on Bromide trac-ing experiments carried out by Apel (2002) and Vinke (2003) which were monitored by soilsampling with the Nmin-technique.

39

(2004b), reached 0.5 to 0.6 cm d−1 above the dasyc pan and 1.1 to 2.5 cm d−1

below the dasyc pan for saturated flow conditions. It can hence be concluded,that the estimated fast domain flow velocity for saturated conditions, whichwas used in the model, was truly a good estimation in respect to the mean flowvelocity of the uniform flow. This explains the good mirroring of the generaltrend in pesticide transport behaviour. However, the hydrological studies haveproved, that another flux exists which has shown to reach flow velocities of atleast 80 cm d−1 and which has furthermore been proved to transport pesticides(Schumann, 2004b). This flux is attributed to a very fast PF component andit has to be assumed that this flux is also the decisive flux which accounts forthe unpredictable high pesticide concentrations in the deeper soil and for theinflux of pesticides into the Perched Groundwater Lenses (PGWL).

The model actually does not account for this third, very fast flow domain.According to Apel (2004), it had been considered to incorporate such a thirddomain into the model but the approach had been discarded since the availabledata base, drawn from the field experiments by Apel (2002) and Vinke (2003),was too weak. Latter was, of course, also conditioned by the experimental set-up in itself, despite the fact that a soil sampling up to 90 cm by the Nmin methodwas already exceptional. Standard soil sampling for this type of problems doesoften only account for a sampling depth of 30 cm.

Unfortunately, it hence has to be assumed that the model does not forecastthe transport behaviour exactly as observed in nature and that its main limi-tations are due to an absent imaging of the pesticide transport bound to thevery fast PF component.

A difficulty in accounting for observed PF mechanisms is also observed byauthors, who applied already existing pesticide transport models, in areas wherePF mechanisms exist. Barlund (1999) for example draws for the two-domainmodel MACRO, which should account for transport by PF, the following conclu-sion: “A model like MACRO can be used to support research and the admissionprocess of pesticides but a precise transport behaviour cannot be predicted andtherefore the deterministic models alone are not sufficient to forecast ground-water or surface water pollution risk.” Also Denkler (1994), based on a workwith an early PELMO version, doubts the applicability of deterministic modelsfor the forecasts of pesticide concentrations in soil depths greater than 30 cm.She ascribed this conclusion, to a disability of the model “to describe herbicidetranslocation by preferential flow”. This is not surprising, as PELMO does notaccount for any PF mechanisms and which has hence stimulated Klein (2002) toupgrade PELMO by a macro-pore module. Beulke et al. (1998) have evaluateda whole lot of existing preferential flow models for the prediction of the move-ment of pesticides to water sources under UK conditions and concluded thatfor a wide range of soils the models show considerable promise, but that stillsome significant problems exist with the selection of input parameters. Theyfurther state that this result gives rise to the question on the predictive use ofsuch models for regulatory purposes.

Thorough need exists for the provision of all existing pesticide transportfluxes in pesticide fate modelling, if these models aim on a forecast of ground-water contamination risk. This also includes the provision for very fast PF.

40

According to Apel (2004) the description of the transport by the macroporecomponent of the PF is, however, most likely to be solved statistically. Inany case, in order to estimate the site-specific importance of PF mechanismsfor pesticide transport and to generate the necessary input parameters suchas dominant capillary flow velocities, hydrological transport studies are indis-pensable (see the above theme on the need of capturing the mobile phase forthe determination of PF processes). Concerning this postulation, the necessarydetermination of a reliable estimation on the spatial quantification of soil vol-umes which are actively transporting pesticides by PF mechanisms and hencetheir embedding in models is definitely problematic. Here however, lysimeterstudies or further methodical developments might allow for scientific advances(see above paragraph on sampling techniques for PF transport processes).

Finally it needs to be recalled that pesticide concentrations in the mobilephase are, in process-orientated models, usually predicted from the pesticideconcentrations and distributions which are determined from soil samples, ide-ally during field experiments. The exchange parameters, which are needed forthe modelling of sorption and desorption are usually determined by laboratoryor field studies. A calibration or validation for the predicted pesticide concen-trations in the mobile phase though, based on actual sampling of liquid phase, isseldom carried out. This approach is questionable when fast PF plays a leadingrole and pesticide transport may occur independently from the parametrisationobtained by standard laboratory batch experiments and pesticide travel timesbecome comparable to those of conservative tracers (Flury, 1996).

The described difficult situation, i.e. that the pesticide transport behaviouralong with PF is not very well mirrored by the presently existing models andthat presently no satisfying methods for the quantification of PF exist, is lessperceptible in cases when uniform flow is the dominant flux and the physico-chemical properties of the pesticides allow for their transport bound to theuniform flow. In such cases the general pesticide transport trend can be de-scribed. In the studied Nepalese khet environments, this is even more true forthe upper soil where the infiltration front progresses ideally by uniform flow.Here the unattended very fast flow domain does not preponderate at mean, forexample in the case of Dimethoate and Metalaxyl. If, however, the physico-chemical properties of the pesticide disfavour its transport by uniform flow, asit is e.g. the case for Fenvalerate, a transport modelling becomes more complex.In respect to the Collaborative Project on Environmental Risks of Pesticides andSustainable Development of Integrated Pesticide Management Systems (IPMS)in Nepal Considering Socio-Economic Conditions (IPMS-Project), the “uniden-tified transport mechanism” (Apel, 2002) for Fenvalerate actually stand for aunknown pesticide exchange processes and transport behaviour along Prefer-ential Flow Paths (PFPs).

It can be concluded that the determination of all existing pesticide transportfluxes by hydrological studies is indispensable in pesticide transport modellingif these models are to be used for the prediction of the movement of pesticidestowards groundwater resources. This is more especially important when modelsare used for regulatory purposes and if a regionalisation is strived for. Toidentify the existing pesticide transport fluxes in respect to their respective

41

significance and hydraulic parameters, hydrological studies should always beconsidered, including a sampling of the mere liquid phase. For any futureworks, it needs to be taken into account that PF may be the most important oron of the leading fluxes for pesticide transport into greater soil depths or intothe groundwater and that hence practice-orientated pesticide transport modelswill have to be laid out to account for more than two flow domains.

4.5 Transfer and regionalisation of results

Apel (2002) rates positively that the obtained results on the risk of soil contami-nation may be transferred to other regions of the Hindu Kush-Himalaya (HKH)as long as temperatures and application doses are known. Since the results arerestricted to the studied soil types, a regionalisation would however requirerespective area-wide information.

A possibility of regionalising the groundwater contamination risk is ruled outby Apel (2002) due to two reasons: “the nature of transport process and poordata”. He states that although a quantitative specific risk assessment could becarried out, it cannot be transferred to other sites because with “increasing scaleor in different regions the uncertainties associated to qualitative statements riseunpredictably”. He therefore calls for further site specific experiments. FromSchumann (2004b) can be drawn, that further site specific experiments are alsoneeded if the irrigation practice is varied.

Generally, site specific transport experiments should be carried out for eachidentified landscape compartment onto which the results of the CollaborativeProject on Environmental Risks of Pesticides and Sustainable Development ofIntegrated Pesticide Management Systems (IPMS) in Nepal Considering Socio-Economic Conditions (IPMS-Project) are to be regionalised.

Neupane (2002) carried out a study which was aiming on a synopsis onpesticide usage in the whole of Nepal and HKH-region. It has been foundthat the available materials on pesticide use and Integrated Pest Management(IPM)-measures in the study region are so poor that the intention of the study,the provision of a basis for the regionalisation of the project results, was notmet (IfGG, 2002).

It can be concluded that a transferability or regionalisation of results is notpossible at present, due to a lack of necessary large-scale data and informationwhich would allow a designation of landscape compartments. Hence, in Nepalthere exists an enormous need for the collection of reliable data, e.g. in the formof socio-economic censuses, by the mapping of geographic conditions or by theestablishment of time-series of geographic and environmental parameters, inorder to allow for any regionalisation works using GIS tools in future.

42

Chapter 5

Conclusion on the point ofcarrying out environmentalresearch projects indeveloping countries

The Collaborative Project on Environmental Risks of Pesticides and SustainableDevelopment of Integrated Pesticide Management Systems (IPMS) in NepalConsidering Socio-Economic Conditions (IPMS-Project) managed to:

• Generate a small data base and hence reduce a little the enormous envi-ronmental data gap (UNEP, 2001) in Nepal.

• Publish valuable results.

• Generally enlarge the scientific knowledge and in particular the knowledgeon working methods and tools in the German and Nepalese Researchcommunities.

Hence, it can be concluded that the IPMS-Project was considerably suc-cessful, although its final scientific goal, i.e. to develop a knowledge-based de-cision support system for tentative pesticide reduction measures resting on aknowledge-based rule system for pesticide pollution, could not be reached dueto difficult working conditions faced throughout the whole project, which areassumed to be typical for Developing Countries (DC).

The constraints in scientific works though and hence in the generation ofresults were compensated in Nepal by the training of and knowledge transfer toNepalese scientific staff, the education of university students, and the scientificinter-exchange with research staff. The scientific work itself and the appreci-ation of scientists by governmental decision makers has definitely received afortification in Nepal.

In this regard, the value of scientific workshops at all project stages needsto be stressed once more. The workshops boost the scientific communicationand hence advance the generation of results, well-matched working plans andgoals, as well as the articulation of necessary future research works.

43

Research projects in DC are expected to be even more effective and scientifi-cally successful if scientists are aware of the different socio-cultural and politicalenvironments in DC and if they inform themselves opportune on respective, pos-sible limitations. Scientists who have worked in DC should not abstain frompublishing their positive and negative experiences and they should actually goon and publish recommendations for any future works such that the scientificcommunity can gain from their experiences.

A first approach in the pointed out direction was attempted by Schumann(2004b). From these recommendations it shall be once more stressed, that thepresence of a permanent project coordinator, with scientific background, seemsindispensable for a smooth and successful scientific work.

Furthermore, it is desirable that scientific research projects are interlinkedwith projects of financial or technical cooperation so that the partner organisa-tions are strengthened, the acquired knowledge and works are carried on withand that a feasibility of project results is guaranteed. One example of such aninterlinked research project is the “Pesticide Policy Project”, which is carriedout by the Institute of Economics in Horticulture of the University of Hannoverin association with several project partners, among others the Gesellschaft furTechnische Zusammenarbeit (GTZ) (PPP, 2004). In technically complex andcostly cases, it is desirable that also the acquisition of equipment as well as theinstallation and operation of facilities are supported by a financial or techni-cal cooperation. In the case of the IPMS-Project, not only the scientific resultscould have been weightier, but also Nepal would now be in the position to carryout their own, bitterly necessary pesticide analytics.

Despite all research limitations, the necessity of an attachment of scien-tists in DCs to the international research community should not be forgotten,more especially under the progressing globalisation. In order to account for aglobal natural resources management and world-wide environmental protectionit is indispensable to enhance scientific cooperation with DCs. Furthermore,it should be kept in mind how much the German researchers can gain froma cooperation with researchers from DCs. The four PhD theses, which wereattached to the IPMS-Project, stand for it. Scientists and research fundingagencies are, therefore, highly advised to appreciate, facilitate and to carry outcooperative research projects in DCs.

44

Bibliography

Acharya, S. (2003) Management of irrigation. A case study of Jaisidihi Water-shed, Kavrepalanchowk District, Nepal. Master’s thesis, University of Kath-mandu, Central Geography Department. Unpublished.

Adhikari, K. P. (2003) Irrigation management in Nepal. A case study of Tham-aghat at Panchkhal VDC Ward-No.6 in Kavrepalanchowk District, Nepal.Master’s thesis, University of Kathmandu, Central Geography Department.Unpublished.

Akkan, Z., Flaig, H. & Ballschmiter, K.-H. (2003) Pflanzenbehandlungs- undSchadlingsbekampfungsmittel in der Umwelt: Emissionen, Immissionen undihre human- und okotoxikologische Bewertung. Erich Schmidt Verlag, Berlin,315 pp.

Apel, H. (2002) Risk assessment of pesticides in the mid-hills of Nepal — en-vironmental fate and population dynamics modelling. Number 41 in Land-schaftsokologie und Umweltforschung. Institut fur Geookologie der Techni-schen Universitat Braunschweig, Braunschweig, 126 pp. Ph.D. Thesis, Tech-nische Universitat Carolo-Wilhelmina zu Braunschweig, Gemeinsame Natur-wissenschaftliche Fakultat.

Apel, H. (2004) Personal communication.

Apel, H., Paudyal, M. S. & Richter, O. (2002) Environmental risk assessmentof pesticide use based on the modelling of the environmental fate of pesticidesin soil. In: Herrmann & Schumann (2002b), 13–24.

Apel, H., Paudyal, M. S. & Richter, O. (2003) Evaluation of treatment strate-gies of the late blight Phytopthora infestans in Nepal by population dynam-ics modelling. Environmental Modelling & Software, 18, 355–364. URLwww.sciencedirect.com.

Bahr, T. (2002) Modellierung der Grundwasserstromung im IPMS-Untersuchungsgebiet Khetland im Jhikhu Khola-Einzugsgebiet, Nepal. Einze-laufgabe am Institut fur Geookologie der TU Braunschweig. Unpublished.

Baker, S. L. & Gyawali, B. K. (1994) Promoting proper pesticide use in Nepal.Number 28 in Winrock Internat. Report Series. HMG Ministry of Agriculture(Nepal), Kathmandu, 55 pp.

45

Barlund, I. (1999) Simulation des Transportes und der Transformationen vonHerbiziden in der ungesattigten Zone des Bodens. Number 63 in Mitteilungendes Instituts fur Hydrologie und Wasserwirtschaft der Universitat Karlsruhe.Institut fur Hydrologie und Wasserwirtschaft, Karlsruhe, 283 pp. Ph.D. The-sis, Technische Universitat Karlsruhe.

Beulke, S., Brown, C. D. & Dubus, I. G. (1998) Evaluation of the use of pref-erential flow models to predict the movement of pesticides to water sourcesunder UK conditions. Report to the U.K. Ministry of Agriculture, Food andFisheries MAFF project PL0516, Cranfield Center for EcoChemistry, Cran-field University. URL www.pesticides.gov.uk.

Beulke, S., Brown, C. D., Fryer, C. J. & Walker, A. (2001) Lysimeter study toinvestigate the effect of rainfall patterns on the leaching of isoproturon. PestManagement Science, 58, 45–53.

Bischoff, W.-A., Siemens, J. & Kaupenjohann, M. (1999) Stoffeintrag insGrundwasser — Feldmethodenvergleich unter Berucksichtigung von prefer-ential flow. Wasser & Boden, 51(12), 37–42.

CEAPRED (2001a) Baseline survey of pesticide use at Jhikhu Khola catchmentarea. Revised version. Technical report, Center for Environmental and Agri-cultural Policy Research, Extension and Development (CEAPRED), Kath-mandu. Unpublished.

CEAPRED (2001b) Report on the second socio-economic survey. Technical re-port, Center for Environmental and Agricultural Policy Research, Extensionand Development (CEAPRED), Kathmandu. Unpublished.

Denkler, M. (1994) Mikrobielle Toxizitat, Abbau und Verlagerung ausgewahlterPflanzenschutzmittel in Ackerboden aus Loß: Labor- und Freilandunter-suchungen sowie Modellrechnungen. Number 16 in Bonner BodenkundlicheAbhandlungen. Druckerei Schwarzbold, Bonn. Ph.D. Thesis, RheinischeFriedrich-Wilhelms-Universitat zu Bonn, Hohe Landwirtschaftliche Fakultat.

EU→European Commission (2002) Draft working document. Guidance doc-ument on terrestrial ecotoxicology under council directive 91/414/EEC.Technical report, European Commission. Health & Consumer Pro-tection Directorate-General, Directorate E — Food Safety: planthealth, animal health and welfare, international questions. URL http://europa.eu.int/comm/food/fs/ph_ps/pro/wrkdoc/wrkdoc09_en.pdf.SANCO/10329/2002.

Fank, J., Seiler, K.-P. & Berg, W. (2001) Flow Systems, chapter 3, 15–19.

Fischer, R. (2003) Auszug aus Daten zum Zulassungsverfahren von PSM(Dimethoat). Personal communication. Bundesamt fur Verbraucherschutzund Lebensmittelsicherheit (BVL), Braunschweig.

Flury, M. (1996) Experimental evidence of transport of pesticides through fieldsoils - a review. Journal of Environmental Quality, 25, 25–45.

46

Flury, M., Leuenberger, J., Studer, B. & Fluhler, H. (1995) Transport of anionsand herbicides in a loamy and sandy field soil. Water Resources Research,31, 823–835.

German, P. (1990) Macropores and hydrologic hillslope processes. In: Anderson,M. G. & Burt, T. P., eds., Process Studies in Hillslope Hydrology, volume 63,327–363.

Helfrich, M. (2002) Schwermetalle in intensiv bewirtschafteten Ackerboden desJhiku-Kolas (Nepal) 2. Teil — Untersuchungen der Gehalte wahrend derMonsunzeit und Vergleich zur Trockenzeit. Studienarbeit am Institut furGeookologie der TU Braunschweig. Unpublished.

Herrmann, A. & Schumann, S. (1999) Ein Forschungsansatz zu Umweltrisikenvon Pestiziden und der nachhaltigen Entwicklung eines Integrierten Pestizid-Management (IPM) unter Berucksichtigung der soziookonomischen Verhalt-nisse in Nepal. In: Flake, M., Seppelt, R. & Sondgerath, D., eds., Umwelt-analyse — Dynamik naturlicher und anthropogener Systeme und ihre Wech-selwirkungen, Tagungsband GEOokon ’99, number 33 in Landschaftsokolo-gie und Umweltforschung, 235–245. Institut fur Geookologie der TechnischenUniversitat Braunschweig, Braunschweig.

Herrmann, A. & Schumann, S. (2002a) Collaborative project on environmentalrisks of pesticides and sustainable development of Integrated Pesticide Man-agement System (IPMS) in Nepal considering socio-economic conditions. In:Herrmann & Schumann (2002b), 38–48.

Herrmann, A. & Schumann, S., eds. (2002b) International Workshop on Envi-ronmental Risk Assessment of Pesticides and Integrated Pesticide Manage-ment in Developing Countries, 6–9 November 2001 Kathmandu, Nepal, num-ber 38 in Landschaftsokologie und Umweltforschung. Institut fur Geookologieder Technischen Universitat Braunschweig, Braunschweig.

Herrmann, A., Schumann, S., Neupane, F. P., Niraula, B. B., Wiebelt, M.,Khanal, N. R., Pujara, D. S. & Upadhyay, B. P. (2001) Chances of protectingMiddle Mountains environments in Central Nepal from pesticide misuse con-sidering socio-economic condiditions. In: Watanabe, T., Sicroff, S., Khanal,N. R. & Gautam, M. P., eds., Proc. Kathmandu Symp. on the HimalayanEnvironments: Mountain Sciences and Ecotourism/Biodiversity 24-26 Nov.2000, 246–260. Kathmandu.

Herzel, F. & Schmidt, G. (1979) Prufung des Versickerungsverhaltens vonPflanzenschutzmitteln an Lysimetern und Kleinsaulen. Number 3/1979 inWaBoLu-Berichte des Instituts fur Wasser-, Boden- und Lufthygiene des Bun-desgesundheitsamtes. Dietrich Reimer Verlag, Berlin, 16 pp.

IfGG→IfGG TU Braunschweig (2002) IPMS-Project: Technical Report January2001 – June 2002. Technical report, Institut fur Geookologie der TechnischenUniversitat Braunschweig. Unpublished.

47

Jørgensen, P. R., Hoffmann, M., Kistrup, J. P., Bryde, C., Bossi, R. & Villholth,K. (2002) Preferential flow and pesticide transport in a clay-rich till: Field,laboratory, and modeling analysis. Water Resources Research, 38(11), 1246.

Klein, M. (2002) Die Erweiterung des Versickerungsmodells PELMO zurBerechnung des Stofftransports durch Makroporen. Online (13.02.2003). URLhttp://www.ime.fraunhofer.de/publikationen/. Lecturenotes, DeutschePflanzenschutztagung 2002, Bonn. .

Leseberg, T. (2000) Erstellung eines hydrogeologischen Strukturmodells unterBerucksichtigung hydrologischer Parameter fur das Einzugsgebiet TinpipleKhet in Nepal. Studienarbeit am Institut fur Geographie und Geookologieder TU Braunschweig. Unpublished.

Løkke, H. & Van Gestel, C. A. M. (1998) Handbook of Soil Invertebrate ToxicityTests. Ecological & Environment Toxicology Series. Wiley, 281 pp.

Maloszewski, P. & Klotz, D. (2002) Modellierung von Migrationsexperimenten.In: Klotz, D., ed., Untersuchungen zur Schadstoff-Migration in Lysime-tern, number 05/02 in GSF-Berichte, 135–142. GSF-Forschungszentrum furUmwelt und Gesundheit. Institut fur Hydrologie, Neuherberg.

Mezger, D., Urban, G. & Warth, H. (1994) Die Instrumente der person-ellen Zusammenarbeit und ihre Eignung fur die Beschaftigung einheimischerFachkrafte. Teil I: Allgemeiner Teil. Teil II: Fallstudie Nepal. Number 112in Forschungsberichte des Bundesministeriums fur wirtschaftliche Zusamme-narbeit und Entwicklung. Weltforum Verlag, Munchen. Koln. London, 217pp.

Neupane, F. P. (2002) Synopsis of use and economic value of pesticides andchances for reduced application rates at different scales in Hindu Kush region.Technical report, Center for Environmental and Agricultural Policy Research,Extension and Development (CEAPRED), Kathmandu. Unpublished.

OEPP/EPPO (2003) EPPO standards. Environmental risk assessment schemefor plant protection products. PP 3/7 (revised). OEPP/EPPO Bulletin, 33,147–149. URL ftp://server.oepp.eppo.fr/EPPO_STANDARDS/PP3_ERA/pp3-07(2).pdf. European and Mediterranean Plant Protection Organiza-tion.

Panday, K. K. (1992) Future of Nepalese Forests and Forest for Future, 59–88.

Piepho, B. (2003) Untersuchungen zum Hydrologischen Reaktionsverhalteneines Kleinen Einzugsgebietes unter Verwendung des Wasserhaushaltsmod-ells WaSiM-ETH. Eine Fallstudie im Rahmen des IPMS-Projektes in Nepal.Ph.D. thesis, Technische Universitat Carolo-Wilhelmina zu Braunschweig,Gemeinsame Naturwissenschaftliche Fakultat.

PPP (2004) The pesticide policy project. Online (21.01.2004). URL http://www.pesticide-policy-project.de.

48

Prasai, A. (2001) Geomorphic Processes and Landscape Modifications. A CaseStudy of Tinpiple Sub-Watershed in Jhiku Khola Watershed, Kavre Palan-chok District of Nepal. Master’s thesis, Tribhuvan University, Faculty ofHumanities and Social Sciences, Kathmandu, Nepal. Unpublished.

Pujara, D. (2000) Spatial Structure of Agricultural Land Use and its Perfor-mance in the Middle Hills of Nepal: A Case Study of Jaishidihi Watershed,Kavre Palanchok District. Master’s thesis, Tribhuvan University, Faculty ofHumanities and Social Sciences, Kathmandu, Nepal. Unpublished.

Reichenberger, S., Amelung, W., Laabs, V., Pinto, A., Totsche, K. U. & Zech,W. (2002) Pesticide displacement along preferential flow pathways in a Brazil-ian oxisol. Geoderma, 110, 63–86.

Schroll, R., Kuhn, S., Dorfler, U. & Ruth, B. (2002) Lysimeterstudie zum Ver-halten der Modellchemikalie Isoproturon. 58–64.

Schulla, J. & Jasper, K. (1999) Modellbeschreibung WaSiM-ETH. ETH Zurich.Report.

Schulze, K. (2000) Erstellung eines hydrogeologischen Strukturmodells unterBerucksichtigung hydrologischer Parameter fur das Gebiet Thamaghat desForschungsprojekts IPM-Nepal. Einzelaufgabe am Institut fur Geographieund Geookologie der TU Braunschweig. Unpublished.

Schumann, S. (2004a) Environmental risk assessment of pesticides in Nepaland Hindukush-Himalayan region. In: Linkov, I. & Ramadan, A., eds., Com-parative Risk Assessment and Environmental Decision Making, number 4 inNATO Series, 83–98. Kluwer, Holland. In press.

Schumann, S. (2004b) Research on Hydrological Processes and Pesticide Be-haviour in Irrigated, Terraced Catchments in the Mid-Hills of Nepal. A Col-laborative Project on Environmental Risks of Pesticides and Sustainable De-velopment of Integrated Pesticide Management Systems (IPMS) in NepalConsidering Socio-Economic Conditions, volume 44 of Landschaftsokologieund Umweltforschung. Institut fur Geookologie der Technischen UniversitatBraunschweig, Braunschweig, 126 pp. Ph.D. Thesis, Technische UniversitatCarolo-Wilhelmina zu Braunschweig, Gemeinsame NaturwissenschaftlicheFakultat.

Schumann, S. & Langenberg, F. (2004) Risikobewertung fur die Schadigung vonBoden durch gangige PSM an einem khet Standort im Mittelgebirge Nepals.Report, Technical University of Braunschweig. Institute of Geoecology. Un-published.

Schumann, S., Langenberg, F., Vinke, C., Kreuzig, R. & Bahadir, M. (2002) ZurIdentifizierung praferentieller Fließwege fur den Pestizid-Transport in Bodenmittels Farbtracer-Einsatz. Poster presentation. GDCh Jahrestagung 2002Umweltchemie und Okotoxikologie. Forschung und Entwicklung im Dienstedes Umwelt- und Verbraucherschutzes, Braunschweig, 6.–8. Oktober 2002.

49

Seeland, K. (1984) Sacred world view and ecology. In: Seeland, K., ed., RecentResearch on Nepal: Proceedings of a Conference Held at the Univ. Konstanz,27–30 March 1984, number 3 in Schriftenreihe Internationales Asienforum,187–198. Weltforum Verlag, Munchen, Koln, London.

SEJ→Society of Environmental Journalists Nepal (2002) 4 days InternationalWorkshop on Environmental Risk Assessment on Pesticides and IntegratedPesticide Management in Developing Countries in November 6–9, 2002,Kathmandu, Nepal. Broadcasted in English and Nepali languages on TVNepal in November 2002. Documentary by Society of Environmental Jour-nalists Nepal (SEJ-Nepal).

Shrestha, P. L. & Neupane, F. P. (2002) Socio-economic contexts on pesticideuse in Nepal. In: Herrmann & Schumann (2002b), 205–223.

UNEP (2001) Nepal: State of the environment 2001. Technical report, UNEP,MoPE/HMGN, ICIMOD, SACEP, NORAD.

Vinke, C. (2003) Zum Ruckstandsverhalten von Pflanzenschutzmitteln in Bodenaus dem Jhikkhu Khola-Gebiet/Nepal. Number 42 in Landschaftsokologieund Umweltforschung. Institut fur Geookologie der Technischen UniversitatBraunschweig, Braunschweig, 122 pp. Ph.D. Thesis, Technische UniversitatCarolo-Wilhelmina zu Braunschweig, Gemeinsame NaturwissenschaftlicheFakultat.

Vinke, C., Kreuzig, R. & Bahadir, M. (2002) Analytical investigations on thefate of pesticides in soils of the Jhikku Khola catchment. In: Herrmann &Schumann (2002b), 265–275.

Waibel, H., Fleischer, G., Kenmore, P. E. & Feder, G., eds. (1999) Evaluationof IPM Programs — Concepts and Methodologies. Number 8 in PesticidePolicy Project Publication Series. Uni Druck Hannover, Hannover, 61 pp.

Wiebelt, M. (2000) Measuring the benefit-cost ratio of public IPM technol-ogy transfer programs: An optimal control framework and an application toNepalese agriculture. Kiel Working Paper, 989, 1–22. URL http://www.uni-kiel.de/ifw/pub/kap/2000/kap989.htm. Kiel Institute of World Eco-nomics.

Zehe, E. & Fluhler, H. (2001) Preferential transport of isoproturon at a plotscale and a field scale tile-drained site. Journal of Hydrology, 247, 100–115.

Zelle, A. (2002) Schwermetalle in intensiv bewirtschafteten Ackerboden desJhiku-Kolas (Nepal) 1. Teil — Untersuchungen der Gehalte wahrend derTrockenzeit — Vergleich Khet- gegen Bari-Land. Studienarbeit am Institutfur Geookologie der TU Braunschweig. Unpublished.

50

Appendix A

Recommendations ofIPMS-Project workshop

51

Conclusions and Recommendations

of the

International Workshop on Environmental Risk Assessment

of Pesticides and Integrated Pesticide Management in Developing Countries

Kathmandu, Nepal, 6-9 November 2001

compiled by A. HERRMANN After three days of presentations and discussion, delegates tackled key issues which had arisen during the workshop. The conclusions and recommendations for improving the utility and effectiveness of future research and extension including education and training were prepared by three working groups. They relate to a number of key issues which were identified during the workshop, and condensed with the following items: • Pesticide issues • Environmental issues • IPM, risk assessment, pesticide regulation Each item was dealt with by a working group. Based on deficits defined by the working groups and on respective recommendations, a number of general recommendations was concluded, and approved by the workshop participants during the closing plenary session of the workshop. The following compilation comprises the recommendations separately for the three main issues and finally for the whole pesticide topic in general. With respect to pesticides it is recommended: • To promote the foundation of an independent non-governmental international organisation

(similar to ICIMOD) for pesticide education, training and transfer issues taking e.g. care of

(i) practical education and training of plant protection officers and farmers with

special demonstration plots. The cooperation with NGOs, schools and universities (for research) is desirable.

(ii) existing farmers field schools which should expand in number. Special demonstration sites would support education and training of farmers in proper pesticide application. Teaching experts would get their own education at the institution to be founded.

• To encourage governments to establish liaison institutions for affected ministries and

authorities to allow

52

(i) better coordination of measures with respect to the impact of pesticides for agriculture, consumption, environment and health;

(ii) putting new tax on new pesticides in the market to use the tax income for proper pesticide disposal.

• To encourage governments to ensure

(i) continuity of governmental staff experts on pesticides and IPM; (ii) to establish two laboratories for (a) pesticide quality and residue analysis, and (b)

monitoring purposes which are independent from each other; (iii) starting international cooperation for knowledge transfer in the fields of residue

analysis and concentration limits, e.g. with the EU; (iv) introduction of licensing pesticide traders, and their punishing for selling banned

pesticides; (v) pesticides being correctly contained and labelled (vi) safety practices in working with pesticides to be regulated and supervised.

With respect to environmental issues it is recommended: • To promote the ecological awareness to all persons and institutions affected by means of

(i) increasing the level of knowledge of farmers and consumers on pesticides; (ii) implementing monitoring networks.

• To point out relevant consequences and/or effects of ecological systems on local and

regional scales and to promote

(i) interdisciplinary research including medicine, agro-ecology, geo-ecology, hydrology, meteorology/climatology, soil science, socio-economy etc.;

(ii) development of adequate monitoring authorities, systems and networks. • To develop guidelines for measures of integrated environmental compatibility and

sustainability for governmental authorities which consider

(i) sophisticated prognostic models; (ii) international project-oriented cooperation and technical and scientific knowledge

exchange. With respect to risk assessment of pesticides, pesticide regulation and Integrated Pesticide Management (IPM) it is recommended: • To promote risk perception and awareness of pesticides, risk assessment and risk

reduction requiring

(i) knowledge of possible risks at all levels concerned (farmers, traders, extension officers, regulation authorities)

(ii) local infrastructure for residue and exposure analyses (iii) appropriate techniques (for risk assessment) (iv) external technical assistance (e.g. laboratory installation and control)

53

(v) strong pesticide regulation and registration according to risk assessed (vi) alternative solutions (e.g. IPM)

To build risk assessment capacities by establishing laboratory facilities and knowledge transfer with competent national and international partners and raising efforts for an international harmonisation of pesticide regulation and trade e.g. within SAARC countries including

(i) harmonisation of trade regulations and prohibition of export of banned compounds;

(ii) subsidy cancellation of pesticides and tax harmonisation. • To put IPM on the priority list of agricultural policies with adequate IPM implementation

strategy considering

(i) governmental and NGO capacity building for education at root level (through e.g.

farmers field schools) by staff training through experts and staff expansion;

(ii) crop pattern regulations by law and subsidies; (iii) creating incentives for better adoption of IPM method.

General recommendations

In general it is recommended: • To improve capacity building (formal and informal) and training on plant protection and

the environment for all persons affected (farmers, consumers, traders, experts, extension workers, regulatory people).

• To promote research and combination of knowledge and experience on all scales (village,

district, region, nation). • To establish adequate monitoring and control instances and networks, including laboratory

and data processing facilities and modelling techniques. • To attribute first priority to IPM in all fields of agriculture with all consequences,

including policy support. • To facilitate proper coordination of adequate measures among relevant institutions. • To promote and survey strict application of international conventions towards pesticide

industry to produce more environmentally-friendly products e.g. in line with IPM regulations.

The recommendations shall be broadly disseminated among workshop participants, governmental authorities, extension staff, the scientific community and affected NGOs, INGOs and international governmental bodies.

54

Appendix B

Photographic impressions ofkhet land

55

(a) (b)

(c) (d)

(e) (f)

Figure B.1: Photographic impressions of the cultivation cycle in khet land:(a) View of the tinpiple project area. In front bari land with maize, in the backkhet land with rice cultivations, (b) Planting of paddy seedlings, (c) Paddy cul-tivation at the onset of a new irrigation interval, (d) Paddy harvesting, (e) Irri-gation furrows for potato cultivation, (f) Area-wide potato cultivations, on theterrace edges mustard is grown (yellow flowers).56

(a) (b)

(c) (d)

(e) (f)

Figure B.2: Photographic impressions on project activities: (a) khet climato-logical station (NPNC) during the maize cropping period, (b) Pesticide appli-cation by a farmer onto potato cultivations, (c) khet discharge weir (NPAK),(d) Tracer application at TES1, late monsoon 1999, (e) TES1, cultivated withpaddy, during monsoon 2000, (f) VB tracer application at TES2. Three plots,each 1× 2 m2. 57