Diagnóstico das condições químicas e físicas do solo em áreas sob adubação orgânica no município de Ibicaré-SC

Abstract

Brazil is one of the largest producers and exporters of animal protein in the world, standing out as a sector of great economic importance for the country, which nevertheless produces a large amount of organic waste. The increase in the costs of chemical fertilizers, mainly due to importation, emphasize the use of organic residues in agriculture as an option to reduce costs, in addition to the gain with cycling and nutrient replacement. These factors generate demand for accurate information on organic fertilizers, in order to assess the technical and economic feasibility for the disposal of some of these residues in agricultural soils. In this way, the work aims to diagnose chemical and physical attributes of the soil in areas under organic fertilization in Ibicaré city, state of Santa Catarina. For the study, three areas were chosen that received, for more than 10 years, periodically, application of poultry litter (LCF), swine manure (LDS) and cattle manure (LDB) and an area of native forest (MN). The areas were divided in homogeneous plots and the samples were collected in four trenches and at depths, 0.0 – 0.10, 0.10 – 0.20, 0.20 – 0.30 and 0.30 – 0.40 m. At the same time, the penetration resistance (RP) was measured up to a depth of 0.50 c. The chemical parameters evaluated are: pH in water, soil organic matter (MOS), P, K, Al, Mg and Ca contents. The physical parameters evaluated were the soil resistance to penetration, bulk density, total porosity, micro and macroporosity of the soil. The analyzes were carried out in the chemistry and soil physics laboratories of the Univeridade Federal da Fronteira Sul, Campus Chapecó. Organic fertilization favored the increase of MOS, P, K, Ca and Mg in the crops, mainly in the superficial layer. The LCF presented the highest values in P, K, Ca and Mg, with migration of nutrients to the deeper layers. LDS and LDB showed high amounts of P, K, Ca and Mg in the surface layer. MN presented low density and high macroporosity at all depths and also presented the highest percentage of MOS among the managements. In general, the three crops with organic fertilization showed degrees of compaction, limiting root development. With a negative highlight for the LDB that reached less than 10% of macropores in the layers of 0.10 – 0.20 and 0.20 – 0.30 m of depth. All areas with organic fertilization comply with Normative Instruction 11/FATMA, with regard to maximum phosphorus levels, but it is necessary to perform soil analysis annually, since, in the three organic fertilization systems, P it is found at high levels in the surface layer.