Erosion hazard evaluation for soil conservation planning that sustains
life expectancy of A horizon: the Black Soil Region of China
The black soil region of northeast China is one of the most productive
regions of the world. The depth of A horizon is rapidly decreasing due
to excessive erosion. A strategy for erosion hazard evaluation and soil
conservation planning has been proposed and tested on the region.
Climate, geomorphology, DEM, soil, landuse, runoff plot and corn yield
data were compiled. Soil erosion rate, A horizon thickness and corn
yield under six conservation scenarios during 2020~2200
was predicted. The six scenarios include Present (continue present
practices), Contour (contour tillage), Straw (straw incorporated in
tillage layer), Combo 1 (contour tillage and terracing etc.), No-till
(no-till farming) and Combo 2 (partially Combo 1 and partially No-till).
Current soil life expectancy of A horizon (SLEA), which is the time
until a critical horizon thickness needed for sustaining crop production
is reached, was calculated for each scenario. Erosion hazard degrees
were determined with SLEA. Croplands with SLEA of <0 a, 0
a~20 a, 20 a~100 a, 100
a~1000 a and ≥1000 a, were classified as “Damaged”,
“High hazard”, “Moderate hazard”, “Low hazard” and “No hazard”,
respectively. Current area ratio of “Damaged” and “High hazard” and
“Moderate hazard” was found to be 8%, 5%, and 22%, respectively.
The optimum conservation practice was found to be No-till for
“Damaged”, “Combo 2” for “High hazard”, “Moderate hazard” and
“Low hazard” and Present for “No hazard”. An optimum conservation
schedule was also suggested for each township to maintain all soils to
have an A horizon above 20 cm.