Abstract
ABSTRACT Phosphorus losses in runoff water and eroded sediment may increase the risk of eutrophication. Erosion prediction models can be used to assess and quantify nutrient losses and transport in different soil management scenarios. This study aimed to assess the performance of models to estimate the losses of available phosphorus in eroded sediments and assess their spatial variability pattern. The experiment was installed on a eutrophic Red Ultisol located in Tabapua, northwestern Sao Paulo State, Sao Domingos Stream Watershed. Aiming at estimating and validating the models, measurements were made from 2007 to 2015 at 17 observation points (slopes), determining soil phosphorus content (Psoil), eroded sediments (Psed), and enrichment rate (ERsed). The models applied to estimate the enrichment rates of phosphorus in the eroded sediment and runoff are efficient when in use with the predictions of the model Water Erosion Prediction Project (WEPP). The enrichment rates obtained presented a Nash-Sutcliffe (NS) coefficient close to 1. Losses of soluble phosphorus in runoff above 0.02 mg L−1, a critical value for eutrophication, can be obtained in 81% of the watershed area with a probability higher than 75%.
Highlights
IntroductionWater erosion is one of the main problems of soils and lands worldwide and in Brazil since it involves detachment, transport, and deposition of soil particles, transporting adsorbed organic and chemical elements to aquatic environments
Water erosion is one of the main problems of soils and lands worldwide and in Brazil since it involves detachment, transport, and deposition of soil particles, transporting adsorbed organic and chemical elements to aquatic environments.In this sense, phosphorus stands out among the elements adsorbed in the sediments
The average amount of eroded sediment estimated with the Water Erosion Prediction Project (WEPP) model was 3097.63 kg ha−1, considering a mechanized harvesting without burning
Summary
Water erosion is one of the main problems of soils and lands worldwide and in Brazil since it involves detachment, transport, and deposition of soil particles, transporting adsorbed organic and chemical elements to aquatic environments. In this sense, phosphorus stands out among the elements adsorbed in the sediments. Considering the diversity of research methods to assess the occurrences and consequences of the water erosion process, prediction models are essential since they can be used for soil loss and sediment transport studies in different soil management scenarios due to the union of knowledge and data generated by the physical models With these models, conservationists will be led to the choice of conservation practices able to fit the needs of a specific area (Pieri et al, 2007; Flanagan et al, 2013). This verification has the purpose of assisting in agricultural planning related to soil and water conservation, respecting the limits established by legislation
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