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.

The objective of this study was to evaluate the chemical and physical attributes of soil, and the productivity of Eucalyptus cultivated in monoculture and silvopastoral systems. The experiment started in 2009 and evaluated the following four systems: native vegetation system (Cerrado), a degraded pasture, a Eucalyptus urograndis monoculture (E. urophylla × E. grandis) and a silvopastoral system (E. urograndis combined with Brachiaria brizantha cv. "Marandu"). The experimental design used was completely randomized. In each system, four soil samples were collected from the 0-20 cm depth layer, and the chemical and physical attributes of the soil were evaluated. The diameters of all Eucalyptus trees at 1.30 m above the ground as well as the total height were measured. Subsequently, the trees dimensions were measured and their individual volumes obtained by applying the Smalian formula. The correlation between the parameters for Eucalyptus production and soil attributes was established using the Pearson's correlation coefficient method. The planting of Eucalyptus in monoculture and silvopastoral systems contributed to the improvement of the soil's chemical and physical attributes, which indicates the potential of these systems for recovery of degraded pastures. The silvopastoral system yielded the highest average volume of wood per tree (0.2228 m 3), with a productivity of 111.4 m 3 /ha. The Eucalyptus monoculture yielded 0.1895 m 3 per tree and 315.71 m 3 /ha due to the higher density of the crop. The growth and productivity of Eucalyptus showed highly correlation with the soil attributes, thus suggesting that well-managed crops are an indicator of the soil quality recovery.

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Often unable to regenerate naturally, areas degraded by ore tailings must follow measures aimed at their environmental recovery. The revegetation and the use of bio-stimulants can contribute to the improvement of soil fertility leading to increased production of plant biomass and the cycling of nutrients between soil-plant.The objective was to evaluate the dry matter production, accumulation and nutrient export rates by pig beanplants (Canavalia ensiformis) and Crotalaria juncea cv. IAC-KR-1 as a function of the application of humic substances and diazotrophic bacteria. The experiment was conducted in a greenhouseusing iron ore tailings as substrate. An experimental design of random blocks (4x3x2) was used with four repetitions, four doses of humic substances, applied at 3 different times, with or without inoculation of diazotrophic bacteria. The supply of humic substances and mainly the inoculation in both species increased the dry matter production, reaching 70% of the average increase in pig beans. Inoculation in pig bean plants increased the absorption and transfer factor of Fe and P, and reduced the transfer factor of K, Ca and Mg, and in crotalaria plants increased the absorption of Mg, P and Mn, and reduced the absorption of Fe. The high content of Fe in mining tailings culminated in high absorption and mobilization of this element in the roots of the plants as an alternative to minimize toxic effects caused by its excess.