This work consisted of seven experiments carried out at UNESP Botucatu-SP Brazil to evaluate the allelopathic effects of Brachiaria decumbens collected in different seasons on the initial growth of corn, rice, wheat, soybean, bean, cotton and B. decumbens and to evaluate nitrogen dynamics in the soil. The upper part of B. decumbens was collected during the dry and wet seasons in a pasture area located in the district of Botucatu-SP. The dry matter was ground and incorporated into the soil in 3% w/w. The experimental design was arranged in completely randomized plots with 5 replications. Starting from the transplanting day, the experiment was conducted for 21 days for corn and bean, 24 days for soy and wheat, 28 days for rice and 30 days for cotton and B. decumbens. The growth of those plants was reduced with the addition of B. decumbens collected during both seasons. Among the seven tested crops, B. decumbens was the most affected. The inhibitory effects were most intense for B.decumbens collected during the rainy season. B. decumbens dry matter reduced significantly the contents of nitrate in the soil in all the experiments carried out.
allelopathy; annual cultures; Brachiaria; nitrogen
