Soil Degradation and Decline in Productivity
Over the past decades, the cumulative loss of productivity of cropland has been estimated at about 13%. However, aggregate global food security does not appear to be under a significant threat.12,51 There is no conclusive evidence that soil degradation has in the past affected global food security. We cannot conclude to such relationship because 1) the database on the extent and magnitude of various types of soil degradation is inadequate and 2) the impact of soil degradation on land productivity is very site-specific, often anecdotal and difficult to quantify at regional and global levels. In fact, globally, per-capita food production has increased by about 25% since 1961 when the first production surveys were conducted by Food and Agriculture Organization of the United Nations (FAO)J121 The yields per unit area of the major cereals (i.e., wheat, rice, maize) have steadily increased and are still rising.11,121 This, however, does not imply that sufficient food is—and will be—available in all countries and regions. Food is not necessarily produced where it is most needed. A top priority should therefore be to improve inventories of land degradation at regional, national, and subnational levels.
However, the evidence is conclusive that soil degradation affects food security at the subnational and national levels in the developing countries by the gradual decline of the land’s productive capacity and that this trend will continue in the future. We therefore have to assume that, eventually, land degradation will constitute a serious threat to global food security by its particular impact on the developing countries. According to most scenarios, these countries are most vulnerable to degradation induced by increasing pressure on their land resources, the effects of climate change and their inability to finance programs to rehabilitate affected areas and prevent further degradation and decline of productivity.
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