Coberturas vegetais no manejo de plantas daninhas nas propriedades do solo e na degradação de atrazina em condições tropicais

Abstract

The cover crop species Brachiaria ruziziensis, Arachis pintoi, Canavalia ensiformis, and Mucuna pruriens were evaluated for their potential to supply nutrients, decomposition dynamics, and effects on soil quality under tropical conditions of the Amazon. Regarding soil benefits, B. ruziziensis showed the highest phosphorus (P) content in the soil, in addition to promoting increases in organic matter (OM) similar to those observed in M. pruriens. In the foliar diagnosis, B. ruziziensis, M. pruriens, and C. ensiformis exhibited the highest nitrogen (N) contents throughout the 30, 90, and 150 day evaluation periods, while B. ruziziensis and C. ensiformis stood out for their higher foliar P levels, demonstrating high efficiency in nutrient uptake and cycling. With respect to weed suppression, B. ruziziensis and M. pruriens achieved ground cover rates close to 100%, promoting strong competition for resources while positively altering the composition of the weed community and diversity indices in phytosociological surveys, thereby reducing the dominance of aggressive weed species. The decomposition of cover crops exhibited half-life times ranging from 50 to 63 days, being faster in B. ruziziensis and slower in M. pruriens, indicating that the rate of nutrient release varies among species and is closely related to the chemical composition of the residues. These results highlight the importance of combining cover crop species with distinct decomposition patterns, as this strategy promotes efficient nutrient cycling, continuous accumulation of organic matter, and soil protection throughout production cycles. Therefore, the planned and diversified use of cover crops represents an essential strategy for sustainable agricultural management, reducing the dependence on fertilizers and herbicides, improving soil resilience, and enabling management practices adapted to climate change scenarios, in which the conservation of soil resources becomes crucial for maintaining productivity and agricultural sustainability in the Amazon region.