The Economics of Desertification, Land Degradation, and Drought

We selected sorghum, millet, and rice production and estimated the loss of profit due to using
only crop residues. We compared this land-degrading practice with the use of 40 kilograms of
nitrogen per hectare, 1.67 tons of manure per hectare, and the incorporation of 50 percent of crop
residues. Our results (Figure 6.6), show the loss of profit due to the use of land-degrading practices.
Figure 6.6—Loss of profit due to soil nutrient depletion, Niger
Loss of profit (US$ million)
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Source: Authors’ calculations based on simulation.
Rice Millet Sorghum
The transhumant pastoral system is dominated by the Fulani and the Tuareg (Wane 2005),
and overgrazing is a major problem in the Sahelian zone, where the largest share of livestock
population is located. Although relatively lower than in other case study countries, the stocking rate in
Niger is increasing (Figure 6.7).
Figure 6.7—Trend of livestock units per pasture area in case study countries
Source: FAOSTAT.
Notes: TLU = tropical livestock unit. TLU is based on a standard animal with a live weight of 250 kilograms. Conversion
factor to TLU for livestock: cow = 0.9 TLU; goat or sheep = 0.20 TLU (Defoer et al. 2000).
We estimated the effect of overgrazing for Niger using Erosion Productivity Impact
Calculator (EPIC) simulation model. The results show that overgrazing reduces forage yield by 32
percent. A study in the United States found that rotational grazing, as compared with continuous
grazing, increased beef gain per unit area by 35–61 percent and the profit from milk by 61 percent
(Henning et al. 2000). Walton, Martinez, and Bailey (1981) also found a 63.5 percent weight gain of
cows due to rotational grazing. To obtain a conservative estimate, we assumed that overgrazing
reduces carcass live weight and milk production by 32 percent.
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