Análise multivariada da resistência à penetração em solo de plantio direto da soja submetido a diferentes níveis de compactação

Abstract

The world's agricultural sector has sought to exploit grain-producing crops planted in conservation management systems, to guarantee an optimum physical and water environment in the soil for the proper development of the plant and its seeds. In the no-till farming system, the soil is managed using conservation principles, in addition to reducing tillage during preparation, which helps to reduce operating costs. However, with the increase in machine traffic on clay soils, in conditions that are often not suitable due to the excess weight transferred or because the water content is higher than the compaction limit, the soil's physical and water structure is compromised. This work aimed to study the effects of different levels of compaction of an Oxisol, with a very clayey texture, caused by tractor traffic on the soil's resistance to penetration. The study was done at the Experimental Farm of the Federal University of Grande Dourados, on an Oxisol, using a randomized block design. The treatments consisted of no-till farming for 10 years and induced states of additional compaction by tractor traffic with 2, 4, 6, 8, and 12 passes over the soil. The soil resistance to penetration was measured using a penetrometer with electronic data acquisition capability. Five sampling points were done between the crop rows. For the resistance to penetration data for each centimeter deep (0-40 cm), multivariate analysis was carried out using the factor analysis method. Polynomial regression analysis was done for the soil resistance to penetration stratified in the 0-0.10, 0.10-0.20, 0.20-0.30, and 0.30-0.40 m depth layers as a function of passes numbers, based on the values of the coefficient of determination and significance (p≤0.01) of the model coefficients. Factor analyses applied to the study of soil with different intensities of tractor traffic make it possible to identify layers of growth, transition, reduction, and stabilization of soil resistance to penetration with depth. The resistance of the soil to penetration increased linearly as the number of tractor passes increased.