Interrill Erosion on Random and Geometrically Ordered Rough Surfaces.
Salvador F. Acuna and L. D. Norton. USDA-ARS National Soil Erosion Research Laboratory, Purdue Univ, 275 S Russell St, West Lafayette, IN 47907
Soil erosion has been studied from different perspectives. This paper presents results interrill erosion for three different potential management practices for farming land, to determine if these may help in controlling soil erosion. Small interrill plots (0.74 m2) were packed with sieved soil and brought to saturation from below for a 24-hour period, and subjected to de-ionized rainfall at a rate of 44 mm h-1 at three different slopes (2, 5 and 10 %). Immediately prior to rainfall a -10-cm tension was applied and rainfall applied until steady state conditions occurred. Samples of runoff were collected at 5-minute intervals. Soil loss was determined gravimetrically and sediment concentration and runoff calculated as a function of time. Three replications for each treatment were performed. In addition to the randomly rough control, the other treatments consisted of a geometrically ordered soil surface roughness (GOSSR). Different slopes and treatments showed a significantly different erosion rate at a P>0.01. Another part of the study consisted in comparing additional treatments at a slope of 5%. Treatments were randomly rough control, GOSSR with slope direction, GOSSR accross slope direction and GOSSR accross slope direction amended with surface applied anionic polyacrylamide (PAM) at 20 kg ha-1 and gypsum (CaSO4x2H20) at 1000 kg ha-1. Soil loss and erosion rate showed greater values in soils without amendment and were significantly different (P >0.01). Soils without amendment showed also more surface sealing and crusting.