WATER RETENTION AND PORE SIZE DISTRIBUTION IN SOILS CULTIVATED WITH SUGARCANE COMPARED TO A PERMANENT PRESERVATION AREA1

Abstract

The soil structural condition, cultivated with sugarcane, is related to the type of harvest adopted which influences the soil porosity, an important variable in the circulation of the liquid and gaseous phases of the soil. These phases can be directly affected by soil management and cultivation, where mechanized raw sugarcane harvesting can improve them. Thus, this research aimed to evaluate soil porosity (P) and its pore size distribution (PSD) in classes, as well as the soil water content at field capacity (qfc), cultivated with sugarcane under two harvest methods: raw and burnt sugarcane. Thus, three areas were compared: two under different ways of harvesting sugarcane (with and without burning); and one in a native forest as a reference. P, PSD (macro, meso, and microporosity), and q_fc were determined in soil samples collected in volumetric cylinders, by the saturation and tension table methods, respectively. The results point out that the soil under native forest presented the highest values for the evaluated attributes, indicating that sugarcane cultivation, with or without burning, reduces them. Burning promoted negative changes in the soil concerning water conduction and soil aeration, even in a recent cultivation area (five years), promoted by the reduction of q_fc (-62.09%), mainly reflecting the decrease in macroporosity (-31.73%) and microporosity (-24.48%).