Níveis de palhiço e qualidade físico-hídrica de um latossolo vermelho cultivado com cana-de-açúcar

Abstract

The intensive use of machines in sugarcane harvest where they occur frequently in inadequate moisture contents acts directly on soil compaction, consequently affecting the physical attributes of the soil. The objective of this study was to evaluate the structural quality of a Oxisol under different levels of soils at the soil surface, through, limiting water range and soil load bearing capability. The study was conduceted in the Monte Verde - Bunge, Ponta Porã, MS, in the agricultural year 2013/2014, in Oxisol. The experimental design was in blocks, in a strips scheme, with five treatments and five replications. Two layers, 0,20 and 0,40 m were evaluated with volumetric rings collected centralized at 0,10 and 0,30 m, respectively. The straw levels left on the soil were: “T0” No-straw; “T1” 5 Mg ha-1; “T2” 10 Mg ha-1; “T3” 15 Mg ha-1 e “T4” 20 Mg ha-1. After the mechanized harvesting ratoon sugarcane 2° cycle (September of 2014), soil samples were collected with structure preserved in metal cylinders, study depths. The treatment without addition of straw was the one that presented lower structural quality. The treatments where there was soil maintenance at the soil surface provide the greatest amplitudes of the least limiting water range and lower preconsolidation pressures, presenting better structural qualities. The load bearing capacity for the Oxisol was at a pressure of 430 kPa with volumetric humidity of 0,29 m³ m-3 in the depth 0,10 m and a pressure of 310 kPa with volumetric moisture of 0,32 m³ m-3 in the depth 0,30 m in the treatments where there was addition of straw. The permanence of up to 15 Mg ha-1 would be ideal for maintaining the structural quality of the soil.