Effect of soil management and crop rotation on physical properties in a long term experiment in Southern Brazil

Summary

No-tillage system associated with crop rotation increases the amount of crop residues left as mulch on the topsoil, and can be an important and sustainable alternative for soil management in tropical and subtropical conditions. The objective of this work was to evaluate the soil physical properties affected by cover crop, rotation and soil management in a long-term experiment in South Brazil. The experimental site was cultivated for 10 years in a conventional system. Subsequently, the field experiment was established in 1986, and treatments combined six winter cover crop species, and two tillage systems (conventional tillage - CT and no-tillage - NT). The treatments were laid out using a split-plot design in three blocks. The soil samples were collected in October 2005 from trenches at six depths. The bulk density, aggregate size fractions and porosity were determined. The NT system contributed to increase the formation of coarse aggregates and improved the soil aggregation parameters. In the first upper layers, the soil disturbance due to ploughing every season, enhanced the macroporosity and diminished the microporosity on conventional system comparatively to NT. Independently of the type of soil management all winter species increased the higher aggregate size class.