The aim of this study was to estimate water erosion costs associated with nutrient losses in four different rates of artificial cover. The experiment was carried out from 1987 to 1996 in runoff plots to measure soil losses in Campinas, State of Sao Paulo, in an Ferralsol under natural rainfall. The experimental design was completely randomized, with four treatments (0%, 24%, 40% and 90% artificial cover) and three replications. To estimate costs, P, K+, Ca2+ and Mg2+ concentrations in runoff water and soil removed by erosion were summed up, converted into triple superphosphate, potassium chloride and dolomitic limestone and multiplied by their respective market prices. The results indicate that, under the experimental conditions, the greater the percentage of soil cover, the lower the losses of water, soil, organic matter and nutrients. The soil with 90% cover presented reduction of 51.97% in average water losses, 54.44 in soil losses and 54.91% in organic matter losses than the treatment with 0% cover. In bare soil, losses were estimated at 16% P2O5 and 8% KCl in terms of the amount of fertilizers recommended. Costs varied from US$ 107.76 ha–1 year–1 in bare soil (0% cover) to US$ 18.15 ha–1 year–1 in soil with 90% cover. With these values, losses were estimated at 616.5 million tons of soil per year for Brazil, as a result of soil erosion in annual crops, and cost of this process is around US$ 1.3 billion per year.
soil losses; water losses; nutrient losses; economic valuation; environmental valuation
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