Matéria orgânica e resiliência de Latossolos argilosos sob sistema plantio direto

Abstract

The objective of this work aims to evaluate in the field the implications of soil organic matter (SOM) content on the resilience of clayey Oxisols under no-tillage system (NTS) subjected to states of soil compaction (0, 1, 3 and 5 passes of a tractor). The experiment was carried out at the Experimental Center for Agricultural Engineering (NEEA) - UNIOESTE, campus Cascavel - PR and at the Institute of Rural Development of Paraná (IDR-Paraná) - regional pole of Santa Tereza do Oeste - PR, in the soybean harvests, 2020 /2021 and 2021/2022. The NEEA and IDR-Paraná areas have an average SOM content of 2.5% and 4.5% respectively. In Chapter 1, evaluations of the soil subsurface were carried out before and after the establishment of compaction states and after soybean harvest, evaluating the physical-water attributes of the soil: soil density (Ds), total porosity (Pt), macroporosity (Ma), microporosity (Mi) and saturated soil hydraulic conductivity (Ksat), in soil layers of 0-0.3 m, correlating these attributes with soybean productivity. In Chapter 2, soil surface evaluations were carried out using a profilometer before and after the establishment of compaction states, after each soil wetting/drying cycle and after the soybean cultivation cycle, evaluating the roughness indices (IR), of the soil surface, the residual percentage of soil deformation (Presidual-DS) and the percentage of recovery of soil deformation (Precovery-DS). The experimental design was entirely randomized. Sisvar software version 5.6 was used for data analysis. The Tukey test was applied (p<0.05). The results of Chapter 1 showed that the areas of NEEA and IDR-Paraná presented physical resilience, according to the SOM content. The soil wetting/drying cycles contributed to the recovery of deformations imposed by the established states of compaction. Ksat after compaction was reduced, however, after harvesting, it was reestablished in both areas. The treatments did not compromise soybean productivity, especially in the experimental areas of IDR-Paraná with the highest SOM content. The results of Chapter 2 showed that the soil in the IDR-Paraná areas obtained approximately 1.0% more IR recovery compared to the NEEA areas. The Presidual-DS of the IDR-Paraná areas was 58.33% and the NEEA areas was 59.27%. Precovery-DS in the IDR-Paraná areas was 41.67%, while in the NEEA areas it was 40.73%, showing greater soil regenerative capacity in the IDR-Paraná areas due to the higher SOM content. Soil wetting/drying cycles favored the action of soil expansion due to elasticity conditioned by SOM.