Sistemas de pastagem consorciada como estratégia para a sustentabilidade do solo no ecótono Cerrado-Amazônia

Abstract

Soil degradation is one of the most pressing challenges faced by modern agriculture, particularly in transition zones between biomes, such as the Cerrado-Amazon ecotone. Intensive land use without proper nutrient replenishment and adequate management has led to loss of fertility, soil compaction, and reduced biodiversity. These processes are exacerbated by practices such as deforestation, monoculture, and excessive use of agrochemicals, which compromise soil structure and its ability to retain water and nutrients. In this context, intercropping systems emerge as a promising strategy to restore and maintain soil quality by fostering positive interactions between plant species and soil microbiota. Furthermore, these practices contribute to climate change mitigation, as healthy soils have a greater capacity to sequester carbon. This study investigated the influence of integrated pasture systems on soil quality compared to conventional systems and native forest areas. The central hypothesis was that introducing legumes in association with grasses could improve soil fertility by increasing nutrient availability and stimulating microbial and enzymatic activity. Legumes, such as cowpea and sunn hemp, are known for their ability to fix atmospheric nitrogen, enriching the soil with this essential nutrient. Thus, the study aimed to evaluate changes in soil biological and chemical attributes promoted by different management systems, providing data to enhance sustainable agricultural practices. The experiments were conducted in Nova Guarita - MT, and at Embrapa Agrossilvipastoril in Sinop - MT, representative regions of the Cerrado-Amazon transition, where agricultural expansion pressure is intense. The study compared single pasture systems, grass-legume intercrops (cowpea, sunn hemp, buckwheat, and a multiple intercrop called "Mix"), and a native forest area. Soil samples were collected from the 0-10 cm layer and analyzed for biological attributes (microbial activity, basal respiration), enzymatic activity (arylsulfatase and β-glucosidase), and chemical properties (pH, macronutrient content, and aluminum). Statistical analyses included ANOVA, PCA, and network analysis to identify patterns among the studied variables, allowing for a more comprehensive understanding of soil component interactions. The results indicated that intercropping systems, particularly the Mix, significantly improved soil parameters. Microbial activity was more intense in intercropped systems, demonstrating biologically more active and resilient soil, which is crucial for soil ecosystem stability and functionality. There was greater pH balance, suggesting reduced aluminum toxicity, along with a significant increase in β-glucosidase activity, reflecting enhanced carbon cycling. In contrast, the native forest exhibited high acidity and low nutrient availability, typical traits of soils under natural vegetation in tropical regions, while the single pasture system showed lower nutrient cycling potential and reduced microbial biomass, highlighting the limitations of this system for long-term sustainability. These findings reinforce the importance of agricultural practices that integrate plant diversity and sustainable management, especially in biome transition zones where soil conservation is essential for maintaining ecosystem services. Such practices represent a viable alternative for reconciling agricultural production and environmental conservation.