Status of Soil Resources in Lebanon

By Roger FRANCIS

CNRS-National Center for Remote Sensing

Jordan – Amman 1-5 April 2012

Status of environment and coastal ecosystem State of the art on soil studies in Lebanon Early soil studies in Lebanon addressed:

– Soil mapping with the reconnaissance soil map of Lebanon at 1:200.000 scale (Geze, 1956),

– Pedogenesis of red soils on hard limestone (Lamouroux, 1968), – Soil irrigability and fertility (FAO, 1969) using the old French soil

classification. Further studies targeted:

– Soil toposequence in arid climate (Verheye, 1973) – Soil formation on basalt (Osman, 1974), – Genesis of calcareous soils (Tarzi and Paeth, 1975), – Phosphorus retention (Ryan and Ayubi, 1981), – Mineralogy of Lebanese soils (Darwish et al., 1979; Sayegh et al.,

1990) – Mountain soil formation and genesis (Darwish et al., 1978; Darwish

and Zurayk 1997) using the French Russian and American

More recent soil studies addressed: – Soil salinity on the southern coastal strip (Solh, 1987), – Causes and impact of soil salinity on the Lebanese coast (Atallah

et al., 2000; Atallah et al., 2009), – Soil vulnerability to erosion with GIS models (Bou Kheir et al.,

2001), – Descriptive soil erosion within two Lebanese watersheds (CoLD,

2005), – Land degradation (Zurayk et al., 2001; Darwish et al., 2004; Youssef

et al., 2009; Darwish and Faour, 2008), – Soil vulnerability to desertification for NAP to combat

desertification in Lebanon (Darwish, 2003), – Nitrate and heavy metal pollution risk and status (Moeller et al.,

2003; Nsouli et al., 2004; Darwish et al., 2008; Francis et al., 2011), – Pesticide adsorption and degradation on soil particles (Thomas et

al., 2005), – Soil resilience and the adaptation of agricultural sector to climate

change (Hamze et al., 2010),

Soil information updated with : - Digital soil map of Lebanon at 1:200.000 scale (Darwish et al.,

2002) - Creation of the new soil map of Lebanon at 1:50.000 scale

(Darwish, 1999; Darwish et al., 2006)

FAO-UNESCO, WRB legends and USDA soil taxonomy

BA

ALB

AC

K

JEZZ

INE

Monitoring the status of land degradation in Lebanon Several natural and human-induced factors contributed

to land degradation in the country: • Natural

– Rugged topography with 64% of territory having complex landform with sloping and steep slopes,

– Old deforestation, – Poor drainage, – Weak lithology, – Torrential rainfall. – All these factor cause:

• Flash floods • Erosion • Mass movements and landslides

• Human induced – Forest fires – Chaotic urban sprawl amplify the negative

impact of deforestation. – Inappropriate irrigation practices and fertilizer

application secondary soil salinization. – Improper practices also lead to deterioration of

groundwater quality and soil contamination hazards.

Urban encroachment on arable lands

1. At the national level

Urban expansion over different lands in Lebanon

Landform

Urban area by category,

ha

% of area

Level land 40.992.12 17.91

Rolling 23.991.3 13.3

Slopping 33.820.12 12.01

Steep 29.204.62 12.31

Very steep 6.050.17 11.61

Karst 756.86 2.073 Urban sprawl into different lands in Lebanon (Landsat 2005)

Soil aptitude to agriculture

Class Productivity Km2 % I High 313.36 03.09 II medium 1346.61 13.27 III low 2958.24 29.14 IV Very low 3882.13 38.24 V Non arable 1650.53 16.26

Land capability classification for Lebanon

Recent urban sprawl 2000-2010

A total loss of 30800 ha of productive lands

Land cover/use of Tripoli area in 1964 Urban sprawl on productive lands in 2000

2. At the regional level

Classes Surface

1964 (ha)

Surface 2000 (ha)

Change

(ha) %

Horticulture 928 581 -341 -36.7

Olives 3055 2121 -934 -30.6

Forests 32 137 +105 +328.1

Shrubs 133 246 +113 +84.9

Grassland 333 318 -15 -4.5

Non productive lands 769 92 -677 -88.0

Urban area 722 2223 +1501 +207.9

Total area 6053 6053 - -

Impact of quarrying practices on land resources

• Multi temporal analyses of landsat images and Ikonos between 1996 and 2005 revealed: – Nbr quarries increased from 711 to

1278 – Quarried area increased from 2875 to

5283 ha. • Modeling the risk of abandoned

quarries on land resources in Lebanon using parameters like: – Slope, – Climate, – Previous vegetation cover, – landuse, – Soil and rock types – Groundwater

• 65.9% moderate impact • 8.2% high impact

Soil erosion

Potential soil erosion as a function of soil characteristics:

- Soil depth, - Soil structure, - Soil texture, - Organic matter content, - Structural stability, In relation to: - Geomorphology - Climatic conditions

Soil salinity

Level of salinity

dS/m

Non saline

<2

Very slightly saline

2-4

Slightly saline

4-8

Saline 8-16

Number of samples

Year of observation

1997 2000 1997 2000 1997 2000 1997 2000 75

Proportion % 35.3 15.9 23.5 30.1 31.4 39.3 9.8 14.7

Evolution of soil salinity in a semi arid Lebanese region between 1997 (El Khatib et al., 1998) and 2000 (Darwish et al., 2005)

Soil pollution

450-500400-450350-400300-350250-300200-250150-200100-15050-100

0-50

0 50 100 150 200 250 300

Dep

th [

cm]

Extractable Nitrate [mg/kg soil]

grain-potato rotation apricot tree plantation vegetable cultivation

200

180

160

140

120

100

80

60

40

20

0

0 50 100 150 200 250 300 350

Dep

th [c

m]

Nitrate [mg kg-1]

December 2001 March 2002 September 2002 December 2002 February 2003

Accumulation of soil nitrate in different land use in fall and leaching by spring

200

150

100

50

0

0 50 100 150 200 250 300 350 400

Dept

h [cm

]

Nitrate [mg kg-1]

December 2001 March 2002 August 2002 November 2002

Depth distribution of soil nitrate (Nmin) as a function of different land use

Nitrates in the soil and soil solution

Heavy metals in the soil-Nickel Central Bekaa.

Soil Protection effectiveness

Nitrate contamination of groundwater

y = 0.6117 xR2 = 0.7591

0.000.200.400.600.801.001.201.401.601.80

0.00 0.50 1.00 1.50 2.00 2.50

Log Cle

Log E

Ce

Intensive agricultural practices on the coastal area • In greenhouses on the

coastal area, a steady increase in the ECe from 0.4 dS.m-1 to 15 dS.m-1 was observed (Solh et al., 1987) and explained by poor soil leveling.

• However, soil salinity rise up to tenfold inside the greenhouse compared to outside soil.

• This was associated with excess input of fertilizers (Atallah et al., 2000) and use of saline water in irrigation and Chlorine accumulation in the soil (Atallah et al., 2009).

Frequency of distribution of soil salinity inside compared to initial soil salinity outside the greenhouse on the coastal area

(Source: Atallah et al., 2000)

Soil information and national soil monitoring capacities

Cover Scale Theme Date Type of spatial

object Author Provider

Format GIS1,

Paper2

Soil 1:200.000 Reconnaissance soil

map of Lebanon 1956

Polygons and report

Bernard Geze MoA 1, 2

Soil 1:20.000 and

1:50.000

Soil suitability for irrigation. In

scattered areas 1969

Polygons and report

UNDP, FAO

LARI 2

Soil 1:200. 000 Soil Mineralogy Late 70’s

published in 1990

Polygons and report

A. Sayegh et al.

CNRS 2

Soil 1:50.000 Soil Families of 1973 Polygons

and report W. Verheye CNRS 2

Soil 1:50.000 Detailed soil map 2006 Polygons Database

T. Darwish et al.

CNRS 1, 2

Soil 1:200.000 Soil erosion 2002 Polygons Database

T. Darwish et al.

CNRS 1, 2

Soil 1:200.000 Soil desertification

index 2002

Polygons Database

T. Darwish et al.

CNRS 1, 2

Soil Pollution

1:50.000 Heavy metal pollution, in

Central BeKaa

1999 and 2004

Polygons Database

T. Darwish et al.

CNRS 1, 2

Avai

labl

e so

il in

form

atio

n on

the

Leba

nese

R

epub

lic

• Conservation of diverse Mediterranean soil of Lebanon from: – Sealing – Salinity – Contamination – Erosion – Quarrying

• Bioremediation to remove salts from the soil using a sequence of tolerant crops (El Moujabber et al., 2006).

• A clear national policy aiming at the conservation of Lebanese productive lands and the promotion of rural development and agricultural activities.

• Promote research to estimate future farmland requirements in densely populated coastal areas.

Challenges and capacity building

Challenges and capacity building (Cont.)

• Reconsider current policy and legislation licensing the new quarries in Lebanon.

• The need to accomplish the

descriptive erosion mapping at remaining watersheds to elaborate a draft management plan and sets a series of indicators.

• Elaborate curative and

protective measures to monitor the progress made by the stakeholders at national (government) and local (municipalities, NGOs) levels.

• Disseminate good agricultural practices and awareness is a national priority to protect soil and groundwater from salinity.

• Accomplish the heavy metal content in Lebanese soils.

• Assess soil quality nationwide to control crop cultivation on suitable land quality.

• Elaborate and implement landuse planning to protect arable lands.

• Need to establish collective irrigation schemes notably on the coastal area

• Disseminate the research

results and promote know how transfer to farmers to overcome the weakness of participatory management of land degradation in the country.

• Increase the number of

associated research units supported by CNRS to eradicate the waste of resources and efforts caused by the discontinuity and

Conclusion • Absence of clear policies

and regulations to protect soil resources.

• Chaotic urban expansion results in soil irreversible loss.

• Observed mismanagement of fertilizer and water inputs leads to soil salinity and contamination.

• No policies based on land capability and suitability

• Lack of incentives to agricultural land use systems

• Absence of control of the quality of imported fertilizers (heavy metal content).