Lime incorporation up to 40 cm deep increases root growth and crop yield in highly weathered tropical soils

Abstract

Soil acidity is still a factor limiting crop yield in tropical soils. Our objective was to evaluate lime incorporation into the 0–40 cm depth as a strategy to improve soil chemical conditions and root growth within the soil profile and crop yield in highly weathered tropical soils. Lime rates ranging from 0 to 15 Mg ha−1 were incorporated into the 0–40 cm depth in three Brazilian oxisols. Soil response to lime rates was evaluated in both 0–20 and 20–40 cm depths at the end of each spring/summer cropping season as were crop yields over three consecutive years after lime incorporation. Maize + Brachiaria ruziziensis roots were evaluated within the 0–60 cm depth three years after liming. Overall, incorporating lime significantly increased Ca2+ and Mg2+ contents, pH, and base saturation (BS) in the 0–40 cm depth, with lime rates ≥ 9 Mg ha−1 having the greatest positive impact. By improving soil chemical conditions, the incorporation of high lime doses (≥9 Mg ha−1) increased crop root growth in the soil profile (up to 60 cm deep) and led to higher rainfed crop yields. The highest annual crop yields were observed under lime rates between 9 and 15 Mg ha−1. Finally, incorporating high doses of lime into the soil profile decreased crop yield losses due to droughts. Combined, these results indicate that deep liming (40 cm) at the correct dose can increase the resilience of agricultural systems to water deficit and the yield potential of annual crops in highly weathered tropical soils.