Compost and Animal Manure for Ameliorating Soil: an examination of the issues

By Tim Stewart

Introduction

• Organic matter makes up 3-5% of soil mass in the tropics.

• Mineral fertilisers alone cannot sustain high crop yields. Yields from fields cropped continuously for 10 years in Nigeria declined by 80%, and the soil lost 60% of its organic matter.

• Rate of organic matter decomposition is 3-5 times faster in the tropics than in temperate regions. This is exacerbated by cultivation and burning.

• Potential sources of organic fertiliser are often under utilised or completely neglected.

• There may be conflicts of interest such as whether to use manure for fuel or for fertiliser.

• Farmers operate in an environment characterised by risk, uncertainty and variability.

Benefits of applying compost and manure• Important source of plant micro and macro nutrients

– potential nutrients available from cattle manure range from 13.9kg NPK/ha in Nigeria to 158kg NPK/ha in Kenya, per hectare of arable land

• Raises activity levels of soil micro and macro flora and fauna

• Improves physical properties:

– infiltration rate

– water holding capacity

– aggregation and bulk density

– soils rich in organic matter is easier to work

• Improves chemical properties:

– accounts for up to 1/3 of cation exchange capacity

– long-term, slow release source of plant nutrients

Factors influencing farmers’ decision making

on methods of improving soil fertility Sociological factors

• cultural mores and traditions & perceptions

• education

• land tenure

• degree of urbanisation

• demography and population

• Physical factors

• climate (tsetse fly)

• topography

• livestock system/numbers of livestock

Economic factors

• cash or non-cash economy

• price of chemical fertiliser (subsidy?)

• cost of labour and other inputs

Logistical factors

• access to manure/crop residues

• access to labour

• infrastructure

• degree of mechanisation

What method?

Bush fallow

Improved short rotation fallow

Use Animal Manure

Use chemical fertiliser

Do nothing

Use compost

•reduced yield

•land degradation

•pop pressure leads to shorter fallow period

•land degradation

Mulch crop residues

•lack of awareness

•access to materials

•subsequent cultivation more difficult

•use for animal feed or thatch etc

•livestock system/access to manure

•labour requirement

•lack of knowledge

•alternative uses

•lack of knowledge

•labour requirement

•water requirement

•alternative uses

•availability

•expense

•eventual land degradation

Social factors

Economic factors

Logistical factors

Physical factors

Farmers’ decision making process on choice of soil amelioration

method

(Harris, F. 1997)

(Harris, P.J.C. 1997)

Recommendations

• Participatory approaches to organic matter management incorporating local knowledge where appropriate.

• Work with groups of similar land users, e.g. landed and landless farmers, livestock owners.

• Where cropping and animal production are segregated, collaboration should be encouraged. Resources can be traded as commodities, e.g. crop residues for manure

• The impact of any changes on the livestock system and labour use should be considered, monitored and evaluated.

• Projects must consider and make contingencies for the risk of failure.

Bibliography• Agboola, A.A. 1990. Organic-matter and soil fertility management in the humid tropics of Africa.

In; Organic Matter Management and Tillage in Humid and Subhumid Africa. IBSRAM Proceedings 10: 232-243. Edited by Pushparajah, E., Latham. M and Elliott, C.R.

• Fernandes, E.C.M and Sanchez, P.A. 1990. The role of organic inputs and soil organic matter for nutrient cycling in tropical soils. In; Organic Matter Management and Tillage in Humid and Subhumid Africa. IBSRAM Proceedings 10: 171-187. Edited by Pushparajah, E., Latham. M and Elliott, C.R.

• Harris, F. 1997. Intensification of agriculture in semi-arid areas: lessons from the Kano close settled zone, Nigeria. In Integrated Nutrient Management on Farmers Fields: approaches that work. A workshop convened by DFID’s Natural Resources Systems Programme (NRSP), 15-16 September, 1997 at the Department of Soil Science of The University of Reading.

• Harris, P.J.C. 1997. Constraints of the organic approach to sustainable agriculture. In Integrated Nutrient Management on Farmers Fields: approaches that work. A workshop convened by DFID’s Natural Resources Systems Programme (NRSP), 15-16 September, 1997 at the Department of Soil Science of The University of Reading.

• Haque, I., Powel, J.M and Ehui, S.K. 1995. Improved crop-livestock strategies for sustainable soil management in tropical Africa. In; Soil Management: Experimental Basis for Sustainability and Environmental Quality. Edited by Lal, R and Stewart, B.A. CRC Press, Florida, USA. 293-345

• Heidhues, F. 1997. Institutional, political and economic issues of soil fertility management . In; Soil Fertility Management in West African Land Use Systems. Edited by Renard, G., Neef, A., Becker, K and von Oppen, M. 559-563

Bibliography cont...

• Hoffman, I., Gerling, D., Kyiogwom, U.B and Mane-Biefeldt, A. 2001. Farmers’ management strastegies to maintain soil fertility in a remote area in northwest Nigeria . Agriculture, Ecosystems and Environment 86: 263-275

• Juo, A.S.R. 1990. Maintenance and management of organic matter in tropical soils. In; Organic Matter Management and Tillage in Humid and Subhumid Africa. IBSRAM Proceedings 10: 199-212. Edited by Pushparajah, E., Latham. M and Elliott, C.R.

• Manu, A., Coleman, T.L and Juo, A.S.R. Soil restoration in degraded agro-pastoral systems of semi-arid West Africa. In; Soil Fertility Management in West African Land Use Systems. Edited by Renard, G., Neef, A., Becker, K and von Oppen, M. 559-563

• Ofori, C.S and Sant’anna. 1990. Manures and orgtanic fertilizers: their potential and use in African Agriculture. In; Organic Matter Management and Tillage in Humid and Subhumid Africa. IBSRAM Proceedings 10: 213-229. Edited by Pushparajah, E., Latham. M and Elliott, C.R

• Swift, M.J., Bohren, L., Carter, S.E., Izac, A.M and Woomer, P.L. 1994. Biological management of tropical soils: integrating process research and farm practice. In; The Biological Management of Tropical Soil Fertility. Edited by Woomer, P.L and Swift, M.J. 209-227

• Wilson, R.T. 1995. Livestock Production Systems. Macmillan, London.

• Woomer, P.L., Martin, A., Albrecht, A., Resk, D.V.S. and Scharpenseel. 1994. The importance and management of soil organic matter in the tropics. In; the biological management of tropical soil fertility, edited by Woomer, P.L. and Swift, M.J. 47-80