Nitrogen nitrogen and potassium fertilization on sorghum biomass - yield and fiber quality.

In recent years the worldwide demand for alternative fuel sources has been increasing, and sorghum emerges as a promising plant for the production of ethanol. Therefore, for a competitive exploration, biomass productivity, as well as its fiber quality, some aspects need to be considered. Thus, this study aimed to evaluate the effects of nitrogen and potassium fertilization on yield and fiber quality of sorghum biomass for lignocellulosic ethanol. Experiments were conducted with cultivars CMSXS 7020 and CMSXS 652 in the experimental area of Embrapa Maize and Sorghum in experimental design of randomized blocks with three replications. Treatments of each experiment consisted of a 4x4 factorial, involving four N doses (0, 80, 160 and 240 kg ha-1) and four of K2O (0, 60, 120 and 180 kg ha-1) topdressed. In general, only the total dry matter of the CMSXS 652 cultivar was affected by N rates, and maximum yield was obtained with the dose of 130 kg ha-1, with no effect of doses of K. Fertilization with N and K increased the amounts of cellulose and hemicellulose and reduced lignin and ashes.