There is insufficient information about the dynamics of soil organic matter in integrated production systems. Therefore, we aimed to evaluate the variations in soil C and N stocks and microbial attributes as a function of the distances apart from the eucalyptus double rows within a silvopastoral system in the Brazilian Cerrado. Four treatments were considered, consisting of four distances (0.5 m, 1.6 m, 3.8 m and 6 m) apart from the double rows of eucalyptus for soil sampling within the silvopastoral system. The soil C and N contents and stocks, C/N ratio, microbial C (Cmic), soil basal respiration, metabolic quotient and microbial quotient were evaluated. Our results showed that soil C contents and stocks were significantly higher near the eucalyptus trees. Soil C stocks ranged from 99.91 (6.0 m) to 119.64 Mg ha -1 (0.5 m) up to 100 cm soil depth, with an increase of 19.73 Mg ha -1 nearest of the forest component. The same pattern was observed for N stocks, with values ranging from 9.52 (0.5 m) to 7.95 Mg ha -1 (6.0 m) and representing an increase of 1.57 Mg ha -1 near the eucalyptus. We also found an increase of 51.32% in the Cmic at 0.5 m apart from the forest component. Thus, we can infer that the presence of eucalyptus improved the soil quality within the silvopastoral system, indicating that the correct soil sampling and measurements must be performed considering all the transect cultivated with forage grass and double rows of eucalyptus.

No abstract

Agrosilvopastoral systems have been used as sustainable production models that can promote soil organic carbon (SOC) storage. However, there are no simulation studies with the Century model to estimate the SOC accumulation capacity in the long term, analyzing the effects of management and climate change in integrated crop-livestock-forest (ICLF) systems. This study aimed to simulate soil C dynamics in two chronosequences of land-use composed of native vegetation (NV), degraded pasture (DPA) and ICLF system in the Cerrado of Minas Gerais, in addition to designing future scenarios to verify the potential of SOC accumulation through climate change. The results showed that the Century model reliably simulated the SOC stocks in the two chronosequences evaluated. The model predicted an increase in SOC stocks at two sites by converting the DPA system (46.04 and 42.38 Mg ha -1 ) into ICLF systems (54.94 and 51.71 Mg ha -1 ). The Century also predicted that a 20 mm decrease in rainfall and a 2 °C increase in temperature in the tropical regions studied could reduce the SOC stocks more expressively in degraded pastures, while agroforestry systems could show a smaller reduction in SOC stocks. In addition, the results showed that replacing degraded pastures into agrosilvopastoral systems, especially in clayey soils, contributes to increasing SOC stocks. Thus, agroforestry systems are potentially viable to maintain the sustainability of agriculture in the face of climate change.

Background The integrated crop-livestock-forest (ICLF) system is a sustainable production model composed by tree species intercropped with annual crops and forage species. The choice of the tree species that will compose the ICLF is characterized as a fundamental requirement in the adoption of the system. Therefore, this study aimed to analyze the initial growth and adaptation of two eucalyptus genotypes cultivated in ICLF systems in the Brazilian Cerrado. Methods The eucalyptus genotypes (E. cloeziana and E. urograndis) were intercropped with Sorghum bicolor and Urochloa brizantha in two ICLF systems in Minas Gerais State, Brazil. Qualitative data expressed by occurrences of damage and weaknesses, as well as quantitative data measured by survival rates, diameter at soil height, diameter at breast height, and total height of trees were evaluated in four periods. The data were analyzed by a correlation matrix and analysis of variance, and them qualitative and quantitative data to were analyzed in relation to the rainfall distribution during the studied period. Results The occurrence of Trigona spinipes and termite were the main biotic factors that caused damage and weaknesses to E. cloeziana and E. urograndis, respectively, directly impacting the initial growth and survival rate of eucalyptus.. The growth of E. urograndis was higher than E. cloeziana at 450, 630, 1020, and 1320 days after transplanting. On the other hand, E. cloeziana showed the highest survival rate (80.6%) while E. urograndis presented greater tolerance to the water stress. Conclusion The hibrid E. urograndis proved to be more adapted to edaphoclimatic conditions studied in the Cerrado region and can be indicated to ICLF systems implanted in regions characterized by high temperatures and irregular rainfall distribution.