Adjustment of the conservation practices factor calculation in estimating soil loss

Agricultural intensification without conservation practices exacerbates soil loss, affecting productivity and ecosystems. In the Sorocabuçu River Basin, this issue is intensified by agricultural activities. The RUSLE method, used to estimate soil loss, has limitations in calculating the P factor, as it applies the default value of 1 in the absence of conservation practices, disregarding the area's actual conditions. This study proposes adjusting the calculation of the P factor based on data from the Brazilian Agricultural Census (IBGE), including information on conservation practices and property sizes. In 2006, 38.72% of the 935 establishments adopted conservation practices, with an average soil loss of 11.42 t/ha.year; using P equal to 1, this average was 12.0 t/ha.year. In 2017, only 12.5% of the 720 establishments followed such practices, resulting in an average soil loss of 11.44 t/ha.year, while P equal to 1 indicated 11.74 t/ha.year. Contour planting was predominant, adopted by 89% and 88% of properties in 2006 and 2017, respectively. Areas with higher soil loss were associated with large-scale farming without conservation measures. Despite minor numerical differences, the adjusted model proved more efficient, accurately representing the basin's reality. This study highlights the importance of incorporating conservation practices in the P factor calculation for better soil loss estimation and preserving soil and ecosystems in the Sorocabuçu River Basin, with potential applicability to other study areas. Keywords: Water erosion, Soil conservation, RUSLE, P factor.