Surface runoff influenced by single and consortia of cover crops in southern Brazil

Abstract

Cover crops (CCs) are essential for mitigating surface runoff and water erosion. This study reports whether different single and consortia of CCs differ in the attenuation of surface runoff in no-till areas in southern Brazil. The experiment was conducted on a Psammentic Paleudult soil using 14.5 × 3 m plots, with six treatments: T1- bare soil (control) (BS); T2- permanent grasses (PG); T3- black oat and forage turnip followed by beans or cowpea (O+T-B/C); T4- ryegrass followed by beans or pigeon pea (R-B/P); T5- black oat and vetch followed by beans or cowpea (O+V-B/C); and T6- forage peanut (FP). After six years of experimentation (medium term), continuous monitoring of surface runoff in 2022 showed that CCs treatments reduce by up to 65 % the number of precipitation events in which surface runoff occurs, delay the onset of surface runoff, attenuate the rise and peak of the hydrograph, and decrease by up to 97 % the annual surface runoff depth compared to BS treatment. The treatment with FP most efficiently attenuated the surface runoff. Treatments with succession or diversification of annual CCs (O+T-B/C, R-B/P, O+V-B/C) showed similar efficiency to FP. Treatment with PG was the least effective in controlling surface runoff. In conclusion, different single and consortium of CCs vary in their ability to attenuate surface runoff in no-till areas in southern Brazil. Increasing live plant biomass input and the spatial and temporal diversification of CCs, especially legumes, are key factors in maximizing the control of surface runoff in no-till areas. Integral control of surface runoff, however, requires complementary measures.