Agroforestry in acid soils of the humid tropics.
Six years of agricultural research conducted primarily at the Yurimaguas Research Station (Peru) in the Amazon Basin is summarized. Alley cropping and managed fallows are evaluated as alternatives to shifting cultivation, the predominant farming system in the region. Species including Inga edulis, Erythrina spp., Cassia reticulata, Inga feuillei, Calliandra calothyrsus and Gliricidia sepium are identified as potentially adapted to acid infertile soils. Data are given on the pruning yields of 11 species and the nutrient contents of prunings of C. reticulata, G. sepium, Erythrina sp. and I. edulis. The decomposition of prunings and their effects on soil chemical properties, weeds and rice and cowpea yields are discussed. Weed suppression and biomass and nutrient stocks in aboveground vegetation in managed fallow systems including Centrosema macrocarpum, Stylosanthes guianensis, and Pueraria phaseoloides, Cajanus cajan and Desmodium ovalifolium are examined. Annual tree crop food production systems, especially peach palm (Bactris gasipaes) are also briefly considered.