Soil physical quality after the fifth and sixth harvest of sugarcane in Brazilian Cerrado

Abstract

On most cultivated areas with sugarcane the crop cycle allows between five to seven ratoon crops. The longevity of the plantation is determined by physical changes in soil during this period. This study evaluated the changes to soil physical properties after the fifth and sixth harvest of sugarcane using physical quality indicators. The experimental design was completely randomized blocks with two treatments, each with four replications: treatment 1 - sugarcane after the fifth ratoon crop; treatment 2 - sugarcane after the sixth ratoon crop. The physical attributes of soil: soil penetration resistance (PR), soil density (Sd) volumetric water content (VWC), macroporosity (Ma), microporosity (Mi) and total porosity (TP) were evaluated at six depths; while stability of aggregates (AS), mean weight diameter (MWD) and geometric mean diameter (GMD) were evaluated at four depths. Degradation of soil physical properties after the fifth and sixth ratoon crop was detected in this study. The area had a compacted layer between 0.10 and 0.30 m of depth. The correlations between soil density and the other parameters prove their importance as indicators of soil quality, and the need to evaluate soil moisture prior to tillage or harvest of the crop.