CO2 Fluxes and Soil Responses to Straw and Herbicide in Peanut

Abstract

ABSTRACT Peanut cultivation plays an important agronomic role in Brazil, especially in rotation with sugarcane, promoting biological nitrogen fixation and improving soil quality. This study aimed to test the hypothesis that the combined use of sugarcane mulch, peanut cultivation, and herbicide application would affect soil CO₂ fluxes, soil chemical attributes (pH, organic matter, soil organic carbon—SOC, phosphorus, potassium, calcium, magnesium, cation exchange capacity—CEC, and base saturation—V%), enzymatic activity (β‐glucosidase and arylsulfatase), and the soil quality index (SQI). The experiment, conducted in Jaboticabal (São Paulo), employed different combinations of mulch, peanut cultivation, and imazapic herbicide. Treatments with mulch and peanut increased enzymatic activity, SOC, and pH, resulting in higher SQI values, while bare soil showed marked degradation. CO 2 fluxes were higher in treatments with both plants and mulch, reflecting greater biological activity; however, in the context of soil degradation, elevated CO 2 emissions may also indicate accelerated decomposition and potential organic matter losses. β‐glucosidase proved to be a sensitive bioindicator of soil quality. Integrated analysis using the SQI and the four‐quadrant model revealed that treatments with mulch and peanut promoted healthy and biologically active soils. It is concluded that conservation practices, such as the maintenance of surface mulch and the cultivation of legumes, are effective strategies for enhancing soil health and sustainability, whereas the absence of vegetation cover leads to soil degradation.