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Soils and food sufficiency. A review
- Lal, R.
- Agronomy for sustainable development 2009 v.29 no.1 pp. 113-133
- accelerated erosion, biochar, biofuels, biotechnology, carbon sequestration, climate change, cover crops, crop residues, crop yield, cropping systems, cultivars, economic factors, ecosystem services, energy, energy costs, fabrics, farming systems, food security, forage, income, limited resource farmers, mulches, no-tillage, nutrient management, nutrients, politics, soil amendments, soil organic matter, soil structure, starvation, terrestrial ecosystems, water stress, Asia, Sub-Saharan Africa
- Soil degradation, caused by land misuse and soil mismanagement, has plagued humanity since the dawn of settled agriculture. Many once thriving civilizations collapsed due to erosion, salinization, nutrient depletion and other soil degradation processes. The Green Revolution of the 1960s and 1970s, that saved hundreds of millions from starvation in Asia and elsewhere, by-passed Sub-Saharan Africa. This remains the only region in the world where the number of hungry and food-insecure populations will still be on the increase even by 2020. The serious technological and political challenges are being exacerbated by the rising energy costs. Resource-poor and small-size land-holders can neither afford the expensive input nor are they sure of their effectiveness because of degraded soils and the harsh, changing climate. Consequently, crop yields are adversely impacted by accelerated erosion, and depletion of soil organic matter (SOM) and nutrients because of the extractive farming practices. Low crop yields, despite growing improved varieties, are due to the severe soil degradation, especially the low SOM reserves and poor soil structure that aggravate drought stress. Components of recommended technology include: no-till; residue mulch and cover crops; integrated nutrient management; and biochar used in conjunction with improved crops (genetically modified, biotechnology) and cropping systems, and energy plantation for biofuel production. However, its low acceptance, e.g. for no-till farming, is due to a range of biophysical, social and economic factors. Competing uses of crop residues for other needs is among numerous factors limiting the adoption of no-till farming. Creating another income stream for resource-poor farmers, through payments for ecosystem services, e.g., C sequestration in terrestrial ecosystems, is an important strategy for promoting the adoption of recommended technologies. Adoption of improved soil management practices is essential to adapt to the changing climate, and meeting the needs of growing populations for food, fodder, fuel and fabrics. Soil restoration and sustainable management are essential to achieving food security, and global peace and stability.