Agroforestry has a high potential to sustain agricultural production in the humid tropics. One specific type of agroforestry, alley cropping, has received much attention as a means of producing staple food crops within an agroforestry system. There is now substantial evidence that alley cropping maintains soil fertility above levels found in pure annual cropping systems. Nevertheless, competition between the trees and crops can significantly reduce yields by the crop. A model is presented of how the balance between the improved soil fertility in alley cropping and competition from the trees determines the final crop performance. Better understanding of the factors that determine crop yield will enable improved design and management of alley cropping systems, and may allow alley cropping to become a more reliable means of improving crop production.
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