Effects of crop residues and winter fallow on the response of corn to nitrogen

Abstract

Direct planting, involving rotation of cultures, requires knowledge of the effects of different winter species on summer cultures. The objective of this study was to evaluate the effects of different winter species plus fallow and nitrogen (N) rates on corn (Zea mays L.) yields and on N content of leaves and grains of corn. Treatments were formed by residues of black oats (Avena strigosa Schieb), common vetch (Vicia sativa L.), and chick pea (Lathyrus sativus L.), besides winter fallow. Subtreatments were made with four rates of N (0, 50, 100 and 200 kg/ha), topdressed on corn. The study was carried out in a split-plot arrangement of a completely randomized block design, during the growing seasons of 1989/90 and 1991/92. Both N rates, and winter species affected corn yields and the N content of leaves and grains. With respect to the winter fallow treatment, corn grown on residues of black oats showed losses of N equivalent to 14,9 and 22,7 kg of N/t of dry matter, in 1990 and 1992, respectively. Chick pea contributed with 43,0 kg of N/t of dry matter, in 1990, and common vetch contributed with 7,3 and 16,2 kg of N/t of dry matter, in 1990 and 1992, respectively.