Effects on soil and crops after 20 years of conventional and zero tillage

Abstract

The aim of this research was to evaluate soil properties and performance of crops after 20 years of cultivation in two management systems in a Humic Cambisol in the south of Brazil. No-tillage (NT) and conventional tillage (CT) were evaluated during the cultivation of maize (Zea mays), bean (Phaseolus vulgaris) and soybean (Glycine max), in two years. Soil samples were collected in three layers at the end of the second year, while the determinations of agronomic traits were carried at the end of each year. NT decreased soil bulk density and increased total porosity, aggregate stability and clay flocculation degree, however it decreased macroporosity at the soil surface. In NT higher accumulations of phosphorus occurred up to 0.05 m, calcium and mag­nesium up to 0.1 m and potassium and organic carbon up to 0.2 m depth compared to CT, and it had a gradient of soil acidification from the surface. Differences in the performance of crops occurred in the second year, being verified in CT a reduction of grain yield of soybean and corn and lower thousand-grain mass of beans compared to NT. Bean and soybean produced low amount of above-ground biomass, independent of soil management, while maize produced high amount and higher biomass in NT than CT.