Nutrição e produtividade da cana de açúcar em solo manejado com cobertura morta de casca de coco verde hidrolisada

Abstract

The increasing consumption of green coconut and the industrialization of its water have resulted in a considerable increase in the generation of waste, potentially increasing negative impacts on the environment. In the State of Alagoas, the strategy of using green coconut husks (CCV) as soil cover and incorporating them into areas of sugarcane cultivation renewal would provide a useful destination for this waste. Alkaline hydrolysis could accelerate the degradation of the CCV fiber used as soil cover and anticipate its incorporation into the soil. However, it is necessary to evaluate the possible effects of lime used in the hydrolysis of CCV on sugarcane. Thus, the objective of this study was to evaluate the effects of the application of hydrated lime in the soil cover of CCV on the nutrition and productivity of sugarcane stalks in Alagoas. The study was conducted in an area of commercial sugarcane cultivation renewal, belonging to Triunfo Agroindustrial Ltda., in Boca da Mata, AL. The area was divided into plots of 175 m2 covered with crushed CCV (fresh mass with 81% moisture) at a rate of 200 Mg ha-1 and received application of aqueous solutions with increasing doses of hydrated lime equivalent to the proportion of 0, 1, 2, 3 and 4% of the dry mass of the treated CCV and a control without coverage. The treatments were arranged in randomized blocks with four replications. The CCV remained as mulch for one hundred and sixty-two days, when it was incorporated into the soil. Sugarcane planting took place five months after incorporation of the CCV coverage. Leaf tissue samples were collected, dried and crushed to determine the levels of N, P, K, Ca, Mg, S, Fe, Zn, Cu, Mn and B. Harvesting without burning was carried out fourteen months after planting. The data were subjected to analysis of variance and Dunnett's test (Dunnett, 1984) was used to compare the means of each treatment with the control (without CCV coverage). The results obtained showed that the concentrations of hydrated lime applied on the CCV coverage to accelerate its degradation did not affect the nutrient contents of the leaves or the productivity of sugarcane stalks. However, soil coverage with CCV provided an improvement in potassium nutrition and represented, on average, 20.1% in gains in stalk productivity for sugarcane.