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Erosion hazard evaluation for soil conservation planning that sustains life expectancy of A horizon: the Black Soil Region of China
  • Tianyu Zhang,
  • Glenn Wilson
Tianyu Zhang
Northeast Normal University
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Glenn Wilson
Watershed Physical Processes Research Unit
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Abstract

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.