Abstract
Ideally, a tree species used in alley cropping should create a suitable micro-environment for the companion crop and provide additional income. Inga edulis and I. samanensis were evaluated for firewood and green mulch production in an organic maize (Zea mays L.) alley-cropping practice in the humid tropics of Costa Rica. In 2001, trees were pruned and leaves plus twigs were distributed evenly in the alleys for green mulch and the branches were removed for firewood. Phosphate rock was applied at a rate of 90 kg P ha-1 to half of the treatments one week after pruning. Maize was planted in the alley- and mono-cropping plots immediately after P application, and was harvested 120 days later. The experiment was repeated three months after the first maize harvest. There was no response to P applications. At first harvest, both tree species were similar for green mulch and firewood production, averaging 6.2 and 9.5 Mg ha-1, respectively, for 2001 and 2002. Nitrogen content in the green mulch averaged 168 kg ha-1.Maize grain yields in the monocropping plots averaged 3.5 Mg ha-1 compared to 1.9 Mg ha-1 in the alley-cropping plots. At second harvest, maize grain yields in the monocropping plots declined to 1.9 Mg ha-1, and were statistically similar to the alley-cropping plots at 1.7 Mg ha-1. Because the alley-cropping plots produced both maize and firewood, they were more productive by the second harvest. Alley cropping maize with I. edulis or I. samanensis could provide tropical farmers with much needed firewood while maintaining maize yields.
