Relative Erodibility of Three Loess‐Derived Soils in Southwestern Iowa

Abstract

Measurements of original and present surface soil depth, as indicated by slope and erosion field data and organic carbon contents, were used to determine the relative erodibility of the loess‐derived Monona, Marshall, and Sharpsburg soils in southwestern Iowa. These studies indicated decreasing surface soil depths with increasing slope on all three soils, with the Monona soil having the least and Sharpsburg the most surface soil remaining. The difference in average depth to an arbitrary benchmark, 0.90% organic carbon content, in cultivated as compared with virgin profiles of each soil indicated, however, that slightly lower erosion losses due to cultivation over time have occurred on the Monona soil. Laboratory rainfall simulator studies indicated higher infiltration and lower soil loss rates on the Monona soil than on the Marshall and Sharpsburg soils. The formation of a dense surface seal by raindrop impact appeared to be a dominant factor in the erodibility of these soils. Studies on crusted samples indicated slightly lower soil loss and higher infiltration rates on the Monona even with the crust present.

Effects of Slope Gradient and Rainfall Intensity on Soil Losses with Rainfall Simulator Experiment

“…토양의 유실은 강우의 성질 (Ekern, 1935;Meyer et al, 1969;Wischmeier et al, 1959), 경사도 및 경사장 (Duly et al, 1932), 그리고 식생 (Wischmeier et al, 1965) 등 이외 토양의 성질에 따라 차이가 크다고 한다 (Bouyoucos, 1953;Middleton, 1930;Schmidt et al, 1964;Wischmeier et al, 1969). 우리나라에서는 토양유실에 관한 연구는 농작물 재 배기간 동안 자연 강우에 대한 토양유실 및 토양보전에 대 한 연구 (Oh et al, 1973;Whang, 1966;Woo, 1974;Woo, 1975 …”