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

Light intensity available in growing environments may influence the susceptibility of plants to glyphosate and decomposition of their residues. This study aimed to assess the productivity, control, and decomposition of forage straw submitted to glyphosate doses and exposed to full sun and 50% shade. Two experiments were carried out, one for Piatã grass (Urochloa brizantha cv. Piatã) and other for Tanzania grass (Megathyrsus maximus cv. Tanzania). The experimental design was a randomized block design with strip-plot and four replications. Two growing environments (at full sun and under 50% shade) were installed in strips in the growing area, combined with six doses of glyphosate (0, 360, 720, 1,080, 1,440, and 1,800 g a.e. ha-1) used for forage desiccation. Shade did not change Tanzania grass productivity (p<0.05), but it reduced Piatã grass productivity (p>0.05), suggesting its low tolerance to light restriction. Tanzania grass is more tolerant to glyphosate when compared to Piatã grass, especially at full sun conditions. In general, the evaluated forages present a high susceptibility to glyphosate as incident radiation is reduced, which allows using lower doses to desiccate them in shaded environments. Straw decomposition of Piatã and Tanzania grasses was slower under shading. In this environment with light restriction, straw is more durable and has a better quality for the no-tillage system.

Os sistemas integrados de produção agropecuária podem promover melhoria da qualidade física, química e biológica do solo. A obtenção de efeitos sinérgicos entre os diferentes componentes de produção permite a sustentabilidade dos sistemas agropastoril, silvipastoril, agroflorestal e agrossilvipastoril. Aumentos na estocagem de carbono podem ser obtidos com a adoção de sistemas integrados de produção, além de maiores retornos econômicos. A diversificação da produção possibilita a redução de riscos frente às oscilações de preços de mercado. Contudo, estudos envolvendo a estocagem de carbono e, principalmente, a viabilidade econômica de sistemas integrados em região semiárida são limitados. Neste contexto, objetivou-se apresentar resultados de estocagem de carbono e retorno econômico obtidos com a adoção de sistemas integrados de produção no semiárido, visando apresentar resultados que possam subsidiar a implementação de projetos futuros, permitindo a obtenção de ganhos nos estoques de carbono e maior viabilidade econômica em condições de baixa disponibilidade hídrica.

Production systems that promote the accumulation of soil organic matter (SOM) must be implemented to maintain the sustainability of agriculture, livestock, and forestry. Since increases in MOS content contribute to improving the chemical, physical, and biological quality of the soil, as well as helping to reduce carbon emissions to mitigate climate change. Therefore, the objective of this study was to evaluate soil organic carbon (SOC) and nitrogen (N) stocks after the implementation of agrosilvopastoral (ASP) systems in a Cerrado-Caatinga transition zone in Brazil. Native vegetation of Cerrado-Caatinga (NV), regenerating stratum of Cerrado-Caatinga (RS), two arrangements of ASP systems cultivating Cenchrus ciliaris L. intercropped with Eucalyptus camaldulensis Dehnh. × Eucalyptus tereticornis Sm. hybrid (ASP1 and ASP2), and intercropped with Eucalyptus urophylla S.T. Blake × Eucalyptus grandis W. Mill ex Maiden hybrid (ASP3 and ASP4) were evaluated. Soil C and N stocks and the C content in the humic fractions of SOM were evaluated at 0–10, 10–20, and 20–30 cm soil depths. The introduction of ASP2, ASP3, and ASP4 systems in an area previously occupied by low productivity pasture increased and restored SOC stocks to levels found in NV, at a depth of 0–30 cm. N stocks were higher in ASP systems, regardless of the arrangement studied. As a result, the ASP systems provided accumulations that ranged from 1.0 to 4.31 Mg SOC ha−1 yr−1 and from 0.33 to 0.36 Mg N ha−1 yr−1. The carbon contents in humic fractions remained higher in NV. The hierarchical grouping and principal component analysis showed that the implementation of the ASP systems was efficient in increasing soil C and N stocks over time. In conclusion, the present study identified that integrated production systems can support land use intensification strategies based on sustainable and low-carbon agriculture in a transition area between the Cerrado and Caatinga biomes in Brazil.