Soil sealing and soil water content under no-tillage and conventional tillage in irrigated corn: Effects on grain yield

摘要

The main objective of this research was to analyse the effect of soil management on soil sealing and on soil water content under contrasting tillage practices and its influence on corn yield. The experimental research was carried out in a field cultivated with irrigated corn differentiated into three zones representing a gradient of soil texture (Z1, Z2, and Z3, i.e., increasingly coarser). Two plots under different soil management practices (conventional intensive tillage, CT, and no-tillage, NT) were selected in each zone. The susceptibility to sealing of each soil and the steady infiltration rates were evaluated in the laboratory subjecting the soils to rainfall simulation applied at an intensity of 25 mm h(-1). In addition, soil porosity under each treatment was quantified. Soil water content (0-90 cm depth) was determined gravimetrically at the beginning and the end of the growing cycle and at the surface (0-5 cm) during three growing seasons and continuously at two depths (5-15 and 50-60 cm) during the last growing cycle. Soil water content was simulated using the SIMPEL model, which was calibrated for the experimental conditions. Corn yield and above-ground biomass were also analysed. Significant differences in soil sealing among zones, with decreasing soil sealing for coarser textures, and treatments were observed with infiltration rates that were near twice in NT than in CT, being the effect of soil cover significant in the reduction of soil detachment and soil losses. NT showed higher soil water content than CT, especially in the surface layers. Above-ground biomass production was smaller in CT than in NT, and in the areas with higher sealing susceptibility was 30% to 45% smaller than in other zones, reaching the smallest values in Z1. A similar reduction in corn yield was observed between treatments being smaller in CT than in NT. No-tillage has been confirmed as an effective technique that benefits soil physical properties as well as crop yields in relation to CT, being its impact greater in soils susceptible to sealing.