PROPERTY CHANGES BY EROSION OF LOAMY SAND SOILS IN EAST SHROPSHIRE, UK

Erosion affects the physical and chemical properties of soils. A study was conducted to determine changes in the textural and chemical composition of a loamy sand (psammept) in east Shropshire, UK, over a 6-year period from 19 December 1985 until 20 May 1991. Soil properties were measured using an array of ten 25-m(2) runoff plots at the Hilton experimental site. Fifty plot soil samples were taken on 19/12/85 and 22/4/91 and field readings of runoff and erosion collected regularly. Over the total period, average cumulative erosion on these bare arable loamy sand soils was equivalent to 47.2 t/ha. The mean coarse fraction (>2 mm) of the plot soil samples significantly increased, from 9.74 to 12.18%. Mean sand (2 mm-60 mu m) content increased from 57.55 to 64.69%. Both mean silt (60-2 mu m) and day (<2 mu m) contents decreased, from 27.76 to 19.57% and 4.95 to 3.56%, respectively. There were positive associations between erosion rate and soil textural change, which were especially evident on plots which experienced cumulative erosion rates >30 t/ha. Soil organic matter decreased from a mean of 2.54% on 19/12/85 to 2.04% on 22/4/91. Both soil macronutrient (K, Ca and P) and micronutrient (Fe and Cu) concentrations decreased during this period, the loss of K and Ca being statistically significant. Exposure of bare soil. allowed mean soil pH to fall from 5.55 to 5.05. Measurements suggest that erosion rates which regularly recur on arable soils in northern Europe have serious long-term implications for soil fertility.