Interactions at the tree/crop interface in a maize/black locust alley cropping system

In alley cropping annual food crops are grown in the interspaces between rows of planted tree species which are pruned periodically to provide green manure, fodder or mulch. Most of the interactions between the trees and the agricultural crop occur at the tree/crop interface. A field study was conducted at Columbus, Ohio, to determine the potential of alley cropping and to elucidate the interactions that occur at the maize/black locust interface. Below-ground fiberglass partitions were installed to a 100 cm depth to eliminate below-ground competition for some treatments. In the first year of tree growth, neither shading nor competition for soil moisture had a significant effect on maize growth or yield. The trees were too small to compete for light and the yield of the first maize row at the interface was slightly higher than others. The 18% reduction in maize yield per hectare was attributed to the 28% reduction in area planted to maize because the hedgerows replaced some maize rows. In the subsequent abnormally dry year, the results indicated that even under conditions of prolonged drought the effect of the hedgerows, in terms of competition for soil moisture in the top 45 cm soil depth, was restricted to within 76 cm of the hedgerows. However, the taller trees shaded the intercrop. When the established black locust trees were not pruned, up to 60% maize yield reduction was observed. When the trees were pruned maize yield was reduced by 34%, which was greater than the 18% yield reduction noted in the first year. This was partially attributed to the lower maize population compared to the first year.;The study demonstrates the feasibility of alley cropping in Ohio. If producers wish to substitute part of their food crop production with tree production, competition for soil moisture may not be a serious limitation when black locust trees are used in the hedgerows. The reduction in annual crop yield can be compensated by biomass production of the hedgerow, and possibly reducing fertilizer inputs and enhancing soil and water conservation.