Efeito residual da adubação em cana planta e adubação nitrogenada em cana de primeira soca com aplicação de vinhaça

Abstract

The maintenance of sugar cane straw associated with vinasse application, supplemented with nitrogen fertilization, may improve in soil physical, chemical and biological properties, and resulting in the crop productivity gains. The aim of this study was to evaluate the residual effect of fertilization of cane in the previous cycle, on cane plant; and the fertilization of first ratoon cane. There were quantified: stem productivity, straw and tip accumulation; nutrient content and accumulation in stem, straw and spikes; and technological quality of sugarcane material; with and without vinasse application, and nitrogen fertilization under different harvesting systems. The study was accomplished in an area of the ALCON distillery, located in the municipality of Conceição da Barra, Espírito Santo State (Brazil), from 2005 to 2007. The experiment was installed in an Udult soil formed form Coastal Tableland sediments. The cane variety used was RB 86 7515. The experimental design was randomized block with four replications in a factorial 2 x 7, with split plots. The treatments were: control with vinasse application; vinasse + 80 kg N ha-1 incorporated into the soil; vinasse + 40 kg N ha-1 applied as coverage over the soil; 120 kg de K2O + 80 kg N ha-1 incorporated into the soil; vinasse + 80 kg N ha-1 as coverage; 120 kg de K2O + 80 kg N ha-1 applied as coverage ; and absolute control of the experiment. The fertilization was accomplished one month after the cane plant harvesting, and its effect was evaluated in the harvesting of first ratoon. There was no significant residual effect of previous years fertilization in the cane plant stems production. The vinasse supplemented with N incorporated in the soil treatment showed highest productivity when compared to other fertilization rates in the first ratoon cane. The vinasse dosage used was as efficient as the K2O dose applied in the treatments without vinasse application. The straw maintenance over the soil increased significantly the production of stems in the first ratoon cane. The technological quality of the first ratoon cane was not affected by the pre harvesting management of unburnt and burnt cane. The nutrient accumulation and distribution in stem, straw and tip were similar between cane plant and fisrt ratoon.