Comparison of soil carbon stocks under long term continuous and integrated cropping systems in the Brazilian Cerrado.

Land use intensification through no-tillage and integrated crop-livestock systems (ICLS) represents a significant advancement in Brazilian agriculture. This approach, characterized by permanent soil cover, crop rotation, and species diversification, incorporating tropical grasses as cover crops, fosters a dynamic process that typically enhances potential soil carbon (C) storage. ICLS have also demonstrated their effectiveness as a viable strategy for restoring degraded pasture areas in Brazil, estimated to exceed 40 million hectares. The objective of this study was to evaluate the soil C stock in a long-term experiment with 33 years of adoption of continuous cropping and pasture-crop rotation. The experiment was conducted at Embrapa Cerrados, Planaltina-DF, established in 1991, on a clayey Oxisol. The experimental design used was a completely randomized block design with two replications and two land use systems were evaluated: continuous cropping with no tillage (CCS) and integrated crop-pasture rotation in the crop phase with maize as a main crop, and Urochloa ruziziensis cv. BRS Integra as a companion crop (RCS). The grass intercropped with maize was used with a dual-purpose, as cover crop or grass in off-season cattle. Soil sampling was performed at 0-5, 5-10, 10-20, and 20-30 cm depths, with five sub-samples taken from each plot. Total C content was evaluated through physical-granulometric fractionation, using the dry combustion method (CHNS). Based on the total C content and soil density, C stock was calculated, with no significant differences in bulk density. The F test was applied to evaluate land use effect and Tukey’s test to mean comparison (p < 0.05). Carbon (C) stocks within the 0-30 cm soil layer were observed to be significantly higher in the rotational cropping system (RCS) as compared to the continuous cropping system (CCS), with mean values of 75.71 and 61.57 Mg ha^-1, respectively. The total C concentration varied from 14.38 to 36.84 g kg^-1 across the distinct soil layers, with the RCS consistently demonstrating elevated values. The intercropping of maize with Urochloa ruziziensis BRS Integra yielded straw for soil cover and forage, thereby resulting in an augmentation of soil C content and accumulation. This intercropping system represents a sustainable approach to enhance and restore soil C stocks. The implementation of integrated crop-livestock management systems under long-term conditions represents a technology aligned with the 2030 Agenda for Sustainable Development, particularly in its contribution to modifying production patterns through land use intensification.