Laboratory experiments on the variation of soil erosion under simulated rainfall

Abstract

Samples from three Canadian Gray-Brown Luvisols were subjected to simulated rainfall in a small laboratory erosion plot. Although great care was taken to control all major factors known to influence erosion, considerable varaibility in wash loss, splash loss and runoff was observed during 60-min rainfall tests, with coefficients of variation ranging up to 28.8%. Attempts were made to isolate the source of variability by examining rainfall intensity, bulk density, various aggregate size and stability parameters and surface microrelief. The results suggest that much of the observed variability is related to complex interactions of aggregation, microrelief, runoff and rain splash. Some of these interactions were examined in detail. The experiments suggest the existence of an inherent variability in soil erosion studies which is difficult or impossible to eliminate. Results were used to plot curves showing the increase in precision of soil erosion prediction with increased test replication under controlled experimental conditions and changes in relationships with increasing test duration.