The Economics of Desertification, Land Degradation, and Drought

More documents

Recommendations

Info

Effects of Land Degradation On-Site Effects The direct on-farm impacts of soil degradation on agricultural production can be experienced by farmers through declining yields, which are a result of the changes in soil properties (Clark 1996). A global study based on 179 experiments from around the world regarding the relationship between soil erosion and crop yield (den Biggelaar et al. 2003) provided the best available evidence of the impacts of soil erosion and crop productivity. As shown in Figures 2.24–2.26, yield losses of the three reference crops (maize, wheat, and millet) due to soil erosion are substantial, ranging from about 0.2 percent for millet to almost 0 for all three crops. Loss of yield productivity was larger in developing countries than in Europe or North America, thus showing the severe impact of land degradation on crop productivity and its variability across regions, which is partly due to mitigating practices taken to address degradation. For example, U.S. farmers apply fertilizer worth about $20 billion annually to offset soil nutrient loss due to soil erosion (Troeh et al. 1991). Figure 2.24—Impact of soil erosion on wheat yield 0.25 0.2 0.15 0.1 0.05 0 0.101 0.02 0.081 0.04 0.051 0.01 Source: Modified from den Biggelaar et al. 2003. Figure 2.25—Impact of soil erosion on maize yield 0.25 0.2 0.15 0.1 0.05 0 Asia Australia North America Source: Modified from den Biggelaar et al. 2003. 0.026 0.026 0 54 0.2 Europe Latin America yield loss per year (tons/ha per 1 cm topsoil lost) % yield loss 0.111 0.04 0.092 0.01 Asia North America 0.128 0.03 0.215 0.05 Africa Latin America yield loss per year (tons/ha per 1 cm topsoil lost) % yield loss . .
Figure 2.26—Impact of soil erosion on millet yield 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 0.015 0.057 0.02 0.01 Source: Modified from den Biggelaar et al. 2003. 0.187 All theses mechanisms are closely interlinked and have spiral feedbacks on crop yields. However, it is important to mention that the extent to which erosion actually reduces yields depends on the types of crops, implying that the crop management system can have an influence on crop yields and the effects of land degradation. In the long run and in instances of serious degradation, the effects of land degradation might lead to temporary or permanent abandonment of plots and to a conversion of land to lower-value uses (Scherr and Yadav 1996). According to Bossio, Geheb, and Critchley (2010), there is a strong link between land and water productivity, implying reduced water productivity due to land degradation, which leads to greater demand for agricultural water. Water quality and storage may both be reduced due to land degradation. Socioeconomic on-site effects include the increase of production costs due to the need for more inputs to address the negative physical impacts of land degradation. Income losses arise as a consequence of erosion and land degradation, as farmers are not able to pay for inputs and to invest in improved land management methods (Bojö 1996). These costs can be measured as productivity losses through fertility and nutrient loss, soil loss through erosion, or a reduction in the vegetation cover—or even as changes in groundwater supply, loss of wood production, loss of grazing and hunting possibilities, carbon sequestration, nature conservation, and tourism. Other ecosystem services are lost due to land degradation. For example, tree cutting reduces the availability of fuelwood, which in turn increases the labor input required for collecting fuelwood (Cooke et al. 2008). Degraded lands lead to loss of biodiversity, which in turn leads to reduction in other ecosystem services used by households. Soil erosion reduces the absorptive and storage capacity of water, which in turn increases the demand for water on eroded plots. Moderately eroded soils absorb 7–44 percent less water per hectare per year from rainfall than do uneroded soils (Murphee and McGregor 1991). An increase in the demand for irrigation water implies higher production costs, low yields and plant biomass, and consequently lower overall species diversity within the farm ecosystem (Walsh and Rowe 2001). Overall, food security in particular is a major concern for households. Reduced land productivity leads to food insecurity. Off-Site Effects Land degradation may also have important off-site costs and benefits, including the deposition of large amounts of eroded soil in streams, lakes, and other ecosystems through soil sediments that are transported in the surface water from eroded agricultural land into lake and river systems. The deposits raise the waterways and make them more susceptible to overflowing and flooding; they also contaminate the water with soil particles containing fertilizer and chemicals. The beneficial off-site effects of soil erosion include the deposition of alluvial soils in the valley plains, which forms fertile 55 0.29 0.011 Asia North America Africa Europe yield loss per year (tons/ha per 1 cm topsoil lost) % yield loss 0.03 .
Page 1 and 2:
IFPRI Discussion Paper 01086 May 20
Page 3 and 4:
Contents Abstract vii Acknowledgmen
Page 5 and 6:
List of Figures 1.1—Conceptual fr
Page 7 and 8:
ABSTRACT Attention to land degradat
Page 9 and 10:
ABBREVIATIONS AND ACRONYMS ADB Asia
Page 11:
SCAR Soil Conservation in Agricultu
Page 14 and 15:
In the present report, the conceptu
Page 16 and 17: Framework: Confronting Action versu
Page 18 and 19: understand these arrangements in or
Page 20 and 21: Figure 1.3—Prevention, mitigation
Page 22 and 23: on assessments at the micro level (
Page 24 and 25: does not clearly distinguish betwee
Page 26 and 27: Figure 2.1—GLASOD (1991) global a
Page 28 and 29: International Earth Science Informa
Page 30 and 31: Box 2.1—Continued Normalized Diff
Page 32 and 33: Figure 2.4—Loss of annual NPP, GL
Page 34 and 35: Figure 2.7—Annual loss of NPP in
Page 36 and 37: Table 2.2—Nitrogen application ra
Page 38 and 39: Figure 2.12—Areas affected by hum
Page 40 and 41: output—which is a selection of su
Page 42 and 43: GLADIS also underlines the linkage
Page 44 and 45: Box 2.2—Continued A map on global
Page 46 and 47: Table 2.3—Global land degradation
Page 48 and 49: Table 2.3—Continued Project and d
Page 50 and 51: Table 2.4—Continued Location 10 2
Page 52 and 53: Table 2.6—Extent and severity of
Page 54 and 55: National Level Policies As discusse
Page 56 and 57: Such support has also been directed
Page 58 and 59: Migration, either as outmigration o
Page 60 and 61: The preceding discussion shows the
Page 62 and 63: Results Correlation Analysis Consis
Page 64 and 65: Figure 2.23—Relationship between
Page 68 and 69: soils and higher land productivity.
Page 70 and 71: Acknowledging the work of GLADIS, a
Page 72 and 73: health, education, security, enviro
Page 74 and 75: Box 3.1—Recent major economic ass
Page 76 and 77: An appropriate economic tool for a
Page 78 and 79: Figure 3.4—Cost of action and cos
Page 80 and 81: enefit—for example, income. This
Page 82 and 83: Figure 3.6—Ecosystem services fra
Page 84 and 85: Replacement Cost Approaches The rep
Page 86 and 87: Box 3.2—Measuring land degradatio
Page 88 and 89: land degradation and conservation m
Page 90 and 91: Flooding and Aquifer Recharge Richa
Page 92 and 93: year (Diao and Sarpong 2007). Sonne
Page 94 and 95: Bringing together the different cos
Page 96 and 97: This section discusses the most imp
Page 98 and 99: governing land use patterns (Leeman
Page 100 and 101: promotion of community forest manag
Page 102 and 103: Box 4.3—Reducing emissions from d
Page 104 and 105: Soil Nutrient Depletion Soil nutrie
Page 106 and 107: that the yields of salt-tolerant wh
Page 108 and 109: Figure 5.3—Forest area as a perce
Page 110 and 111: Figure 5.5—Per capita water stora
Page 112 and 113: Introduction 6. CASE STUDIES Five c
Page 114 and 115: Salinity The effects of salinity on
Page 116 and 117:
Third, to correctly decide which ac
Page 118 and 119:
Costs of Action and Inaction We eva
Page 120 and 121:
The NGOs and religious organization
Page 122 and 123:
have a strong influence on NRM (And
Page 124 and 125:
We estimated the cost of action (de
Page 126 and 127:
Figure 6.15—Costs of action and i
Page 128 and 129:
Of interest to us is the strategy t
Page 130 and 131:
7. PARTNERSHIP CONCEPT The review o
Page 132 and 133:
degradation. All this should be don
Page 134 and 135:
Finally, the global assessment of D
Page 136 and 137:
the experience of and lessons learn
Page 138 and 139:
Table 7.3—Example of E-DLDD resea
Page 140 and 141:
8. CONCLUSIONS Since the publicatio
Page 142 and 143:
lowest in the region. From a socioe
Page 144 and 145:
Table A.1—Land degradation assess
Page 146 and 147:
Table A.2—Continued Author Region
Page 148 and 149:
Table A.3—Continued Author Countr
Page 150 and 151:
Page 152 and 153:
Page 154 and 155:
Page 156 and 157:
Table A.5—Costs of land degradati
Page 158 and 159:
Figure B.1—Land use systems of th
Page 160 and 161:
REFERENCES Abelson, P. 1979. Cost B
Page 162 and 163:
Benin S., E. Nkonya, G. Okecho, J.
Page 164 and 165:
Clark, E. H. 1985. The Off-Site Cos
Page 166 and 167:
De Jager a., D. Onduru and C. Walag
Page 168 and 169:
Foster, V., and C. Briceño-Garmend
Page 170 and 171:
Holden, S. and H. Lofgren. 2005. As
Page 172 and 173:
Lapar, M. L., and S. Pandey. 1999.
Page 174 and 175:
Nachtergaele, F., M. Petri, R. Bian
Page 176 and 177:
Pender, J. L. 2009. “Food Crisis
Page 178 and 179:
Sauer, J., and H. Tchale. 2006. Alt
Page 180 and 181:
Tan, Z. X., R. Lal, and K. D. Wiebe
Page 182 and 183:
———. 2010. “Assessment of L
Page 187 and 188:
RECENT IFPRI DISCUSSION PAPERS For
show all

The Economics of Desertification, Land Degradation, and Drought

Create successful ePaper yourself

Delete template?

Save as template?