Decomposição de resíduos orgânicos e liberação de nutrientes sobre o solo

Abstract

To recover degraded soils, a promising practice is the addition of organic waste that brings the benefits to the physical, chemical and biological attributes of the soil. It is important to know that the composition of these residues, as well as its potential of release nutrients to the soil. Starting from these hypotheses that the evaluated residues present nutrient contents that they confer potentials of use as organic fertilizers; the organic residues don’t present chemical elements that cause preoccupation with possible contaminants of the soil and that those who have low relations of C/N, C/P and C/N are degraded and release nutrients to the soil faster than the residues with high values of these relations. The aim was to characterize the organic compounds and to evaluate its decomposition after the disposition under the surface of the soil, as well as to analyze the soil as the chemical attributes of fertility after the withdrawal of the organic residues at the end of the experiment. The experimental design was a randomized blocks (DBC), with subdivided plots and four replications. In the main plots the five organic residues: T1- Residue of shrimp farming; T2- Carnauba bagana; T3- Residue of the avian agribusiness; T4- Organic compound produced with residues of small ruminants and T5- Residue of the agribusiness processing of guavas. In the subplots, six collect epochs were evaluated: 15, 30, 45, 60, 75 and 90 days. The data of mass loss and nutrient release by the organic residues were submitted to analysis of variance (ANOVA) and the averages of the treatments were compared by means of the Tukey test at 5% of probability. The release of nutrients from the residues along the collect epochs was adjusted by the means of the regression models. The adjusted models of the regression equations were chosen based on the significance of the coefficients of the equations and the determination coefficients. From the results of the chemical characterization of the organic residues it was stayed evident the ability of the same ones to contribute to the nutrition of plants and recovery the fertility of the degraded soils, beyond not present possible contaminants chemical elements of the soil. The residues present low values of the relations C/N, C/P and C/S, which favors the mineralization, however, they were verified by the characteristics of each material different patterns of nutrient release. The use of organic residues presents great potential for soil fertility recovery in semiarid regions.