Slope, Aspect, and Phosphogypsum Effects on Runoff and Erosion

Abstract

The effect of slope, aspect (windward vs. leeward), and phosphogypsum (PG) application on rain amount, runoff, and erosion from a Grumusol soil (Typic Chromoxerert in Israel) was measured in small field plots (1 by 1.5 m) exposed to natural rainstorms. The amount of effective rain on the slopes, as measured with small rain gauges with orifices in a plane parallel to the slope, increased slightly on the windward aspect as slope increased to ∼58% and decreased thereafter. On the leeward aspect, the amount of effective rain dropped steadily to half of the meteorological rain at a slope of 100%. The amount of runoff was not affected by slope on the windward aspect but decreased sharply on the leeward aspect as slope increased. PG releases electrolytes into the percolating and runoff water, prevents dispersion of the particles at the surface, stabilizes the soil structure, and reduced soil erosion. PG applied at 5 Mg ha −1 reduced runoff to about 25% of that in the control and reduced soil loss to 1 to 3% of that in the control. The dramatic effect of PG on erosion increased with slope steepness.