Nitrogen fertilization on cotton cropped under straw formed by seed proportions of crotalaria and brachiaria

Resumen

No-tillage cotton production system, using association of leguminous and grasses plants as cover crop, has benefits such as soil protection and increased nitrogen fertilization by biological nitrogen fixation. The present study aimed at evaluating if straw formed by seed proportion of Crotalaria spectabilis and Urochloa ruziziensis increases the total nitrogen contend in mulching and minimize nitrogen fertilization on cotton. The experiments followed a randomized block in split-plot design. In plots Urochloa ruziziensis associated with proportions of Crotalaria spectabilis seeds (0:8, 8:8, 12:8, 16:8 and 20:8 kg ha^-1 of seeds) were sown, and in subplots were used four doses of nitrogen (0, 40, 70, and 110 kg ha^-1 of N, source urea) applied as side dressing. The straw of different quantities of Crotalaria spectabilis associated with Urochloa ruziziensis do not interfere with phytomass yield and N contend. The nitrogen rates do not impact leaf nitrogen, number of bolls per plant and seed cotton and fiber yield.