Decomposição e liberação de nitrogênio, potássio e fósforo de palhada de milho (Zea mays) em sistema de integração lavoura-pecuária

Abstract

Among the components of the cost of a crop, fertilizers fit into sharply, as they are used on a large scale in the cultures, adding a large portion in the composition of the external costs of farming. Therefore, it is necessary to use quality fertilizers and efficient techniques that make it possible to achieve maximum effectiveness, where they will be absolved quickly and efficiently by culture, without great losses. In this context, a factor that can and should be taken into consideration is the rate of decomposition of residues of previous crop. This shows to be highly effective to recycle nutrients and make them available again to the soil and plants successors. putting in the foreground, the use of the fertilization system or reversal of manuring, which calls for the fertilization of the integrated complex, and nutrient cycling. The objective was to evaluate the process of decomposition and release of nutrients nitrogen, potassium and phosphorus, the residual of corn in an integration croplivestock, due to different heights of pasture and different managements of fertilization. The total area of the experiment was 14.21 hectares and is divided into twelve paddocks, forming the experimental units. In each experimental unit, thirty-two litterbags were positioned, making a total of three hundred eighty-four willing litterbags by total area, initially containing twenty grams of corn stover (20g / litterbag). The results obtained evidenced the behavior of the remaining dry matter, which were, of quick release, initially, and after the first 20 days, stabilized. For the potassium, the half-life time were 7.84 and 14.74 days for the systems where nitrogen was applied in the pasture and in the grain, respectively. In relation to the nitrogen contents of the corn straw, it was verified that these were not influenced by the time of nitrogen application in NP and NG nor by the N rates applied in the grain culture. And the phosphorus levels in the remaining straw were higher when the previous pasture received application of nitrogen.