Effect of Contour Reverse Slope Terrace Preparation on Nitrogen and Phosphorus Transport in Sloping Cropland Under Natural Rainfall Conditions

Abstract

[Objective] The rules of land preparation measures on sediment production and non-point source pollutant output of sloping land were analyzed in order to provide a scientific basis and technical support for controlling soil and water loss and agricultural non-point source pollution of sloping land at the source. [Methods] The runoff plots of sloping farmland (15° and 22°) with equi-height reverse slope steps were taken as the research object in Songhuaba at Yizhe watershed experimental area of Kunming City, central Yunnan Province. Rainfall, runoff, and water quality data from 2019 to 2021 were analyzed using a comparative analysis method. The characteristics of flow production, sand production, and nitrogen and phosphorus output of surface source pollutants within the sample plots were studied. [Results] Contour reverse slope terraces used on sloping land with a slope of 22° had more significant effects on the reduction of slope flow and sand production, and the output of surface pollutants nitrogen and phosphorus than land with a slope of 15° under the same rainfall pattern. [Conclusion] Contour reverse slope terraces had significant control effects on sediment yield and non-point source pollutant output on sloping land, and can effectively increase soil and water conservation ability on sloping land, especially on large slopes.

Keywords

• reverse slope terrace
• sloping farmland
• erosion and sand production
• nitrogen and phosphorus output
• reduction rate