Impacts of tillage and liming on crop yields and soil acidity correction: Insights from a 32-year experiment in Southern Brazil

Soil acidity and tillage methods negatively affect crop yields in tropical and subtropical ecosystems. The goal of this study was to evaluate the long-term (32-year) impact of different soil tillage and liming strategies on crop yields, yield stability, and the residual effects on soil acidity properties of a subtropical Oxisol.

The experiment, established in 1987, included the following management combinations: (i) conventional tillage (CT) without lime, (ii) CT with incorporated lime, (iii) no-tillage (NT) without lime, (iv) NT with surface lime, and (v) NT with incorporated lime. Five lime applications were performed throughout the experimental period. Regional recommended fertilization and crop rotations were maintained, with yields monitored over 32 years for 55 harvests (24 soybean, 8 maize, 9 wheat, 8 barley, and 6 white oat crops). Soil samples were collected in 2019 between 0 to 40 cm depth.

The highest yields for all crops were obtained in the treatments under NT and lime application. Additionally, the highest yield stability was observed in the liming treatments for soybean, maize, wheat, barley, and white oat crops. The stability index that showed the best fit was the adjusted coefficient of variation (aCV), as it eliminates the potential dependence of the standard coefficient of variation (CV) on the mean. Surface lime in no-till soil increased soil pH, exchangeable Ca²⁺ and Mg²⁺, saturation of Ca²⁺ + Mg²⁺ + K⁺, and decreased of that of Al³⁺ and exchangeable Al³⁺ compared to treatments without lime until 40 cm depth.

In soil with liming before NT beginning, surface lime reapplications effectively sustain optimal soil acidity in surface layers up to 10 cm and subsurface layers up to 40 cm, thereby maintaining high and stable crop yields over extended periods under NT in subtropical Oxisols.