Conclusions

Crop production in dryland regions has always been and always will be high risk because of low and highly variable precipitation. It is becoming clear, however, that risk can be reduced and yields can be increased by the adaptation and adoption of practices that maintain at least some plant residues on the soil surface. Maintaining crop residues on the soil surface will reduce erosion, increase water storage and use, enhance SOM, and improve soil physical properties. The adoption of such practices in dryland areas will not be fast or easy. Tillage is an ingrained part of agriculture culture, and it will take many years to change. It also requires more knowledge and better management, and generally a higher level of inputs that increases risk in dryland cropping systems. It is becoming increasingly clear, however, that the sustainability of dryland cropping in many regions will require major changes to prevent further soil degradation. The challenge is even greater in many developing countries in semi-arid regions because of the need for using crop residues for animal feed and household fuel. These short-term gains usually take priority, and that is easily understood. However, the long-term sustainability of crop production in some of these regions may very well depend on policymakers taking difficult and painful actions about how crop residues are managed. At some point, it is essential that some organic matter be returned to the soil.

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