Optimization of rainfed tropical cropping in semi-dry areas: A case study

Abstract

An approach to upgrading rainfed tropical cropping, based on the optimization of rainfall water use, is presented. As an example, two stations in Costa Rica, with a rainy season of six to eight months and a dry period in the rainy season (veranillo) were used. These stations represent a large portion of the Pacific coast of Central America. The potential to grow two rainfed crops per year instead of one was evaluated with the model AQUA, which is based on daily water balances using actual precipitation and on rainfall probabilities. Major aspects considered were (a) the earliest safe planting date at the start of the season; (b) the effect of veranillos; (c) prediction of the characteristics of late-season rainfall; (d) analysis of the period for late-season crop growth; and, (e) the length of the dependable rainfed cropping season. These and other considerations were integrated into potential cropping schemes. The analyses showed that it should be possible to safely grow two rainfed crops per year in these and similar regions that suffer from prolonged periods of water deficit, but exhibit calculated dependable rainfed cropping seasons of over 200 days. The methodology described is applicable to a wide range of tropical conditions; and approaches like the one presented may be an answer to intermediate development needs.