Influence of temperature on soil aggregation assessed by two methods

Abstract

The burnings raise the soil surface temperature and may reduce its aggregation. The objective of this study was to evaluate the influence of soil temperature on its aggregation from different soil management by water and dry sieving method. The experiment was conducted at the soil physics laboratory of the State University of Bahia (UNEB). The soil characterized as Oxisol was collected in a soybean plantation area under a no-tillage system and in a preserved cerrado area (Cerradão), close to the soybean area. The experimental design was completely randomized in a 2x2x6 factorial scheme, with four replications. The first factor was soil management (no-tillage soybean and preserved cerrado), the second factor was the method (water and dry sieving) and the third factor was the temperature range (27°C, 150°C, 250°C, 350°C, 450°C, 550°C). The variables analyzed were the percentage of aggregate for classes > 2 mm; 2-1 mm, 1-0,5 mm; 0.5-0,250 mm; 0,250-0,106 mm and less than 0,106 mm. Weighted mean diameter (WMD) and geometric mean diameter (DMG) were also evaluated. The exposure of the soils to high temperatures reduced their aggregation and this reduction was more noticeable by the dry sieving method. Soil monoculture, even under no-tillage system, reduced the stability of the aggregates when compared to the preserved cerrado vegetation.

Keywords:
Burned; Aggregates; Management; Soil conservation