The alley farming index: Preliminary steps towards a more realistic model

This paper presents the Alley Farming Index (AFI), a modification of the replacement value of the intercrop (RVI) index. The RVI index is used to assist in determining the ecological and economic benefits of a polyculture system and is potentially useful in intercropping situations where only annual crops are utilized. Alley farming is a modification of the alley cropping system where food crops are planted in between, regularly pruned, widely spaced trees. Unlike the RVI index the modified equation, presented here, accommodates alley farming where perennials and the amount of tree prunings used as green manure are important parameters. The AFI is presented in two forms, one that assumes a linear relationship between the quantity of tree prunings applied as green manure and annual crop yield, and a second more generalized form which accommodates other relationships between green manure application and crop yield (e.g., logarithmic or parabolic). Although designed specifically for alley farming the modified index can also accommodate alley cropping systems.This revised version was published online in November 2005 with corrections to the Cover Date.