Assessment of the degree of degradation of sloping cropland in a typical black soil region

Abstract

AbstractEvaluation of the degree of sloping cropland degradation in black soil regions of China is essential for the sustainable use of sloping cropland. However, the existing methods used to evaluate sloping cropland degradation are mostly based on point or management levels, and information at the regional scale is lacking. In this paper, we employed bibliometrics and frequency analysis to identify high‐frequency indicators to construct a total index set (TIS) for evaluating the degree of sloping cropland degradation. Soil measurement data from sloping cropland in typical black soil regions in Northeast China were used to construct a minimum data set (MDS). The TIS included 10 indexes: A‐horizon thickness, clay content, organic matter content, pH, slope gradient, ridge‐slope angle, gully density, bulk density, large water‐stable aggregate content, and cation exchange capacity. The first six of these were included in the MDS. Undegraded soil, mildly degraded soil, moderately degraded soil, severely degraded soil, and extremely severe degradation soil accounted for 11.6%, 28.7%, 34.1%, 22.9%, and 2.7% of investigated sampling plots, respectively. Ridge‐slope angle and slope gradient were the main factors affecting soil degradation. Soil degradation was mainly presented as worsening soil physicochemical characteristics and soil acidification. The significant positive correlation between ridge‐slope angle and soil degradation degree might indicate that the contour tillage management, which is usually adopted when slope gradient is steep, would lead to severer degradation level than the downslope tillage applied commonly where slope is gentle.