Assessment of the degree of sloped cropland degradation in typical black
soil region
Abstract
A comprehensive evaluation indicator system is needed to provide a
integrated assessment of the degree of sloped cropland degradation. We
employed bibliometrics to perform statistical analysis on research
studies involving cropland degradation. Frequency analysis was then used
to identify high-frequency indicators with which to construct a total
index set (TIS) for evaluation of the degree of sloped cropland
degradation in black soil region. In addition, soil measurement data
from sloped cropland in Baiquan and Keshan Counties, Heilongjiang
province, China, were used as a basis to construct a minimum index set
(MIS). The TIS included A-horizon thickness, clay content, organic
matter content, pH, slope gradient, ridge-slope angle, gully density,
bulk density, large water-stable aggregate content, soil cation exchange
capacity, and crop yield. The first six of these were included in the
MIS. In the studied area, undegraded soil, mildly degraded soil, and
moderately degraded soil and above accounted for 7%, 48% and 45% of
investigated sloped croplands, respectively. Slope gradient is one of
the main factors affecting soil degradation. Soil degradation mainly
presented as worsening of soil physicochemical characteristics. In
addition, downslope and small-angle ridge cultivation are benefit for
soil organic matter maintenance and the soil structure and nutrient
retention capacity is better than soil with contour or large-angle ridge
cultivation. The reason might be that downslope and small-angle ridge
cultivation are usually employed on soil with small slope. The study
results provide a scientific basis for improving the quality and
productivity of sloped cropland in black soil region.