Formas de adubação fosfatada e compactação do solo em semeadura direta com soja e milho

Abstract

The study consisted of three steps performed in the Chapada dos Parecis - MT in Latossolo, with the following objectives: i) to evaluate the management of phosphorus adopted direct seeding in areas of rural producers; ii) to evaluate the management phosphorus and compaction on soil physical properties, the availability of P, the root system in nutrient content and yield of soybean and corn; iii) assess the availability of P in soil compaction and addition of humic substances as well as the response of corn and soybean to these factors. To meet the first objective survey was carried out in 14 areas under tillage with different management of P fertilization (broadcast, groove or part of the haul and part in the groove). The collection of soil from 0.00 to 0.10 me the 0.00 to 0.20 m in soils under notillage and fertilization in broadcast without incorporation underestimate the availability of P from 0.00 to 0.05 m overestimate the layers below 0.10 m. Fertilization at sowing interspersed with fertilizer broadcasted can be an alternative for farmers seeking greater flexibility in sowing without losing the efficiency of fertilization. For the second objective, an experiment was undertaken in clayey Latossolo in a randomized block design in 2x4x4 factorial arrangement with three replications and two forms of phosphate fertilizer (broadcast and furrow), four levels of P2O5 (0, 50, 100 and 150 kg ha-1 ) and four levels of compression (PT0, PT2, PT4 and PT8 - tillage with compaction induced traffic tractor at zero, two, four and eight passes tractor). The compaction induced by the passages tractor promoted increased density and resistance to penetration and reducing macroporosity and total porosity, but did not change the microporosity. The compression and broadcast application of P reduced the efficiency of phosphorus with altered root system of soybeans and corn and grain yield reduction. Compaction reduced the uptake of N, P, Ca and Mg in soybean and increased the K and S. In corn under phosphate fertilizer, soil compaction increased levels of N fertilization and reduced in the groove, and, regardless of fertilizer increased the K and reduced P. For the third objective experiment was conducted in pots and in the field , both in clayey Latossolo. Potted, was in a 2x2x2 factorial with three replications (absence and presence of the conditioner containing humic substances, absence and presence of compaction; absence and presence of phosphate fertilizer) in a completely randomized design. In the field was done in a randomized block design arranged in 4X4 factorial with three replicates, four doses of organic conditioner (0, 150, 300 and 600 L ha-1 ) and four tracks compaction, the same used in the second study. The soil conditioner base of humic substances improved the availability of P in the soil and reduced the effect of compaction on crop productivity, but at high doses reduced soybean yields when the soil was not compacted by tractor.