NUTRIENT CYCLING AND CARBON INPUT UNDER LIMING AND FERTILIZATION MANAGEMENT IN SOYBEAN–SORGHUM SYSTEMS

Liming is a fundamental practice for improving soil properties and increasing the efficiency of mineral fertilization, directly influencing nutrient cycling and carbon inputs. Therefore, the objective of this study was to evaluate the effects of liming associated with mineral fertilization on nutrient cycling in a soybean–sorghum cropping succession. The study was conducted through two field experiments, one in a limed area and the other in a non-limed area, in order to compare the residual effects of fertilization resulting from the combination of P and K fertilization in soybean and topdressed nitrogen fertilization in sorghum. The experimental design consisted of randomized complete blocks arranged in a 2 × 3 factorial scheme, with four replications. Nutrient cycling was assessed by quantifying crop residue at sowing and at the R5 stage of soybean and stage 5 of sorghum, and it was estimated based on the difference in macronutrient content between the evaluated periods. Liming promoted greater phytomass accumulation, with values ranging from 5.41 to 8.20 t ha⁻¹ for soybean and from 4.97 to 7.41 t ha⁻¹ for sorghum, whereas in non-limed areas the values ranged from 2.75 to 5.95 t ha⁻¹ and from 2.70 to 5.42 t ha⁻¹, respectively. The greater accumulation of crop residue in the limed area contributed to increased nutrient cycling and carbon input into the system, particularly under mineral fertilization. Therefore, soil acidity correction is essential to optimize plant nutrient uptake and thereby promote more sustainable agricultural systems.

We thank FAPESP for funding this study.