Selective Erosion of Soil Fertility Constituents

Abstract

AbstractRunoff samples from experimental plots at four locations in Wisconsin were analyzed for total soil material, organic and ammonia nitrogen, available phosphorus, and exchangeable potassium. Correlation studies were carried out in an attempt to relate the selectiveness of the erosive process for a given fertility constituent to the quantity of eroded soil and concentration of suspended solids in the runoff. The relationship was found to be highly significant with multiple correlation coefficients of 0.63 for available phosphorus, 0.79 for nitrogen and for organic matter, and 0.87 for exchangeable potassium. The selectiveness of the erosive process for the four fertility constituents determined increases in the order: organic matter, organic and ammonia nitrogen, available phosphorus, exchangeable potassium. At the average values of erosiveness encountered in this study, the eroded soil material contained 2.1 times as much organic matter, 2.7 times as much nitrogen, 3.4 times as much available phosphorus and 19.3 times as much exchangeable potassium as the soil proper. The selectiveness of the erosive process for given runoff conditions appears to be greater on Fayette silt loam, 20% slope, than on Almena silt loam, 3% slope, or on Miami silt loam, 9% slope.