PRODUÇÃO DE FITOMASSA E DECOMPOSIÇÃO DE RESÍDUOS CULTURAIS DE PLANTAS DE COBERTURAS NO CULTIVO DA SOJA EM SUCESSÃO

Abstract

The plant species used as ground cover preceding the commercial crops cultivation in the Cerrado must be adapted to the climate and soil of the region, so they have high biomass productivity and offset the decomposition high rates that occurs in these regions. This study aimed to evaluate the biomass yield and the decomposition rate of residues of different cover crops preceding soybean cultivation in Uberaba-MG, Brazil. The experiment was conducted in 2011/12 period in a randomized complete block design in plots with 2 m2 with treatments comprise the following covers: jack bean, millet, sunn hemp and brachiaria. It was evaluated: the dry biomass yield, the decomposition rate through of the bags decomposition, productivity, number of beans per plant, and mass of 100 soybean grains. The millet was the plant cover that showed the highest yield of dry biomass (5.22 Mg ha-1) during the study period. The decomposition of crop residues occurred at accelerated rate until to complete 120 days and after that the rate slowly up until 240 days. Sunn hemp and jack bean were the cover crops with the decomposition highest rates and the smaller half-lives were observed; soybean yield was not affected by the soil covers.