Deep liming increases root growth and crop yield in oxisols

Abstract

Soil acidity is still a factor limiting agricultural yields in highly weathered soils. Our goal was to evaluate deep liming as a strategy to improve chemical conditions and root growth in the soil profile along with crop yields in highly weathered Brazilian soils. Lime rates ranging from 0 to 15 Mg ha -1 were incorporated to 0-40 cm depth over three years of cultivation. Soil response to deep liming was evaluated within 0-20 and 20-40 cm depths at the end of each spring/summer crop season as were crop yields. The maize + Brachiaria ruziziensis roots were evaluated at 0-60 cm depth in the third cultivation year. Deep liming increased Ca 2+ , Mg 2+ , pH, and base saturation (BS), with lime rates >9 Mg ha -1 having the greatest impact. Lime rates recommended based on conventional Brazilian methods were below the optimum rates to promote soil Ca, Mg and BS and crop yields, suggesting that the recommendation methods must be updated for current production systems. Deep liming increased crop root growth in the soil profile, which in turn increased rainfed crop yields. The highest annual crop yields were observed under lime rates between 9 and 15 Mg ha -1 . The lime rate should provide an increase in the percentage of exchangeable Ca and Mg to values around 60% and 20% of the CEC, respectively. Overall, deep liming at the correct dose can increase the resilience of agricultural systems to water deficit and the yield potential of annual crops.