Organic farming and agroforestry: Alleycropping for mulch production for organic farms of southeastern United States

摘要

Organic farming offers an alternative that can eliminate many of the environmental problems of conventional agriculture in the industrialized world. Instead of using petroleum-derived chemicals to fertilize and protect crops, farmers manage their fields so as to take advantage of naturally-produced composts and mulches that recycle nutrients, and control pests and weeds. However, organic farming is often logistically inefficient, because these organic composts and mulches are bulky and difficult to transport. Alleycropping as practiced in the tropics may be able to make organic farming more efficient in the southeastern United States. In this form of alleycropping, trees or shrubs, often leguminous, are planted in hedgerows between open spaces (‘alleys’) where the crop is grown. The hedgerow species are periodically pruned (both aboveground and belowground), and prunings fall directly onto or into the soil where the crop is growing. These prunings add carbon and nutrients to the soil, and provide mulch that helps suppress weeds. Use of prunings reduces the need for composting and hauling manures and mulches, thereby increasing the efficiency by which organic material is supplied to the soil that supports the economic crop. In Georgia, dry weight annual production of prunings reached up to 18.4 Mg ha−1, a quantity high enough to maintain crop production. Thus, alleycropping may be feasible for organic farmers in the southeastern United States.