This study aimed to analyze the carbon (C) stock and stabilization of soil organic matter in particulate- and mineral-associated fractions across different land use systems after 32 years of experimentation in the Brazilian Cerrado. The experiment was established in 1991 and was performed in Planaltina-DF. The treatments evaluated included continuous pasture with monoculture grasses; integrated crop–livestock systems under no tillage; continuous cropping under no tillage; minimum tillage; and the preservation of the native Cerrado biome in its original condition. Soil sampling was performed to a depth of 30 cm. Carbon and nitrogen (N) stocks were quantified for the years 2001, 2009, 2013, and 2023, with soil organic matter fractionation performed on samples from 2023. Land use change resulted in significant losses of soil C and N in areas managed with conventional soil preparation practices. Systems that promote plant diversity, such as integrated crop–livestock systems, enhanced soil C and N stocks (72.8 and 5.5 Mg ha⁻¹, respectively) and increased both particulate organic matter and mineral-associated fractions, most of which were in more stabilized forms. Integrated crop–livestock systems are management practices that offer an effective alternative to present methods in terms of combating climate change and supporting ecosystem sustainability.

This study quantified ammonia (NH ₃ ) volatilization, nitrous oxide (N ₂ O) emissions, and urinary nitrogen (N) mass balance across different pasture types in southeastern Brazil. Beef cattle excreta from Mixed pastures ( Urochloa brizantha cv. Marandu + Macrotyloma axillare cv. Java) or Grass monoculture pasture (Marandu palisade grass) were applied in a randomized block design with six replications, during the wet and dry seasons. Although Grass pasture resulted in a tendency for excreta with higher N concentration, reflecting greater levels of mineral N, forage production, and N recovery in forage mass and litter, no significant differences were observed between pasture types in gaseous losses (NH ₃ , N ₂ O). Seasonality influenced N fate. During the wet season, a higher concentration of urinary N was observed in the 10–20 cm soil layer, and greater recovery by Marandu palisade grass at the chamber border, together with lower total ¹⁵ N recovery, suggested greater hydrological N transport (~23% of non-recovered N). During the dry season, there was a difference in losses due to NH ₃ volatilization, mainly from urine (~3.7%). Emission factors were lower than the IPCC’s averages. The soil represented the main destination of urinary N (~54%), and the soil–plant system recovered 96.2% of the N during the dry season and 75.5% during the wet season. Under the conditions of this study, NH ₃ and N ₂ O losses were low, and the ¹⁵ N mass balance indicated limited amounts of non-recovered N under most conditions, with stronger evidence of hydrological N transport during the wetter period.