Abstract
Fossil energy sources play a very important role in the production of rice, beans, maize, and soya beans. Diesel oil for tractor, fertilizers, and machinery energy constituted between 70 and 90 per cent of the total energy used. For rice, energy used was 2500 kcal/kg when the field was irrigated and 5650 kcal/kg when the field was not irrigated. The yield of beans was higher during the dry season and required 2157 kcal/kg when only animal energy was used. In contrast, 3189 kcal/kg was used when both animals and tractor were used. Maize yields ranged between 2220 and 2820 kg, requiring 3·04 x 106 and 6.80 x 106 kcal/ha, respectively. The yields per hectare were much lower than in the U.S.A. and could be due to the maize cultivars not being suited to the climate and soil.
