Eficiência agronômica do fertilizante ureia com diferentes tecnologias na soqueira de cana-de-açúcar

Abstract

The sugar cane has undergone several modifications in its handling being the mechanized harvest the main operational change, leaving great amount of straw on the surface. The nitrogen application on the surface of the straw can cause losses of up to 50% of the N applied by volatilization and up to 70% by leaching, depending on the soil conditions. This work evaluated the efficiency of urea with different coatings as source of N for sugarcane ratoon. The experimental design was a randomized block design, with four replications and eight treatment, totaling 32 plots. The treatments were ammonium nitrate at 50, 100 and 150 kg of N, conventional urea, urea + NBPT, urea + NBPT + DCD and urea + polymer, all at the dose 100 kg of N and a control without application of N. The number of tillers per meter, chlorophyll A, B and total, leaf N content, theoretical recoverable sugar (ATR), amount of stalks (TCH) and sugar (TAH) per hectare were evaluated. N sources did not differ for tillers per meter, ATR and leaf N content. For total chlorophyll urea + polymer presented better results, while for TCH and TAH, ammonium nitrate in the dose 150 kg of N, presented better results. For nitrate equivalent, the urea + polymer and urea + NBPT sources were more efficient for ammonium nitrate at the same dose.