GREEN EAR YIELD IN CORN GROWN AFTER COWPEA INCORPORATION

Resumo

Under irrigation, maize ( Zea mays L. ) can be grown throughout the year in Northeastern Brazil, which in many areas results in soil degradation. The renewed interest in the study of crop rotations with legumes is targeted at reducing this degradation. The objective of our work was to evaluate the green ear yields of three maize cultivars (AG 8080, AG 9010 and DKB 333B), after growing the Sempre-verde cowpea cultivar (Vigna unguiculata (L.) Walp.), incorporated at three different moments. Two sprinkler irrigated experiments (one involving cowpea and the other with maize) were conducted. The following treatments were applied to the cowpea experiment, in a random block design with ten replicates: no cowpea cultivation; cowpea cultivation and incorporation into the soil at bloom time; or after four green bean harvests; or after three mature bean harvests (dry grains). The maize cultivars were grown in each of the four areas of each block in the cowpea experiment. Therefore, the maize experiment followed a split-plot design with treatments arranged as random blocks with ten replicates. In spite of the differences between the amounts of cowpea matter incorporated to the soil, there were no differences between the chemical characteristics of the soil at maize planting. The incorporation of cowpea at any time, or not, did not have an influence on the total number and weight of green ears and on the number and weight of marketable maize ears, both unhusked and husked. Cultivar AG 8080 presented the highest green ear yields.