RESIDUAL EFFECTS OF NITROGEN, POTASSIUM AND VINASSE, FERTILIZATION ON CANE PLANT AND RATOON HARVESTED WITH AND WITHOUT STRAW BURNING

The application of vinasse supplemented with nitrogen fertilizer to sugarcane with stubble maintained on the soil surface improves the physical, chemical and biological soil properties and may result in increased crop yield. The aim of this study was to evaluate residual effects of fertilization on cane plant, as wellas the effect of vinasse application to ratoon cane under different management systems in Conceicao da Barra, state of Espirito Santo. The experiment was carried out from 2005 to 2007, on an Ultisol on the Coastal Plains, in a randomized block, 2 x 7 factorial design with four replications with split plots. The two treatments consisted of green cane and burnt cane and the seven subtreatments of different N and K2O doses as potassium chloride and vinasse, as follows: control (T1), vinasse (T2), vinasse + 80 kg of incorporated N (T3), vinasse + 80 kg of N (T4), vinasse + 40 kg of sidedressed N (T5), K2O + 80 kg of incorporated N (T6), K2O + 80 kg of sidedressed N (T7). No residual effect of fertilization on sugarcane yield was observed. The yield of green cane was higher than that of the burnt ratoon cane. For ratoon cane, fertilization with vinasse supplemented with incorporated or sidedressed N and fertilization with 120 kg K2O in the form of KCl + incorporated 80 kg N achieved best results. No difference in the stalk yield was observed between doses of 40 and 80 kg ha(-1) sidedressed N applied to ratoon cane. Nutrient extraction and return were similar for cane plant and ratoon cane.