Overland Flow and Erosion from Runoff Plots on a Mollisol in Northeast China.

Soil erosion and rainfall-induced runoff are well studied although under field conditions remain somewhat enigmatic. This study quantifies the relationship between rain, overland flow (runoff), erosion and size characteristics of the sediment in China’s northern “corn-belt” during the 2016 growing season. The study site was at the Heilongjiang Experimental Farm (47º23′N, 126º51′E), which is located near Guangrong village in China’s core Mollisol region. Two tillage treatments were evaluated: no-till and conventional till. Each treatment was replicated on runoff plots having 5° (9%) and 7° (12%) slopes. The 5° plots were established in 2006. The 7° plots were established in 2009. Plot size is 20 m long and 4.5 m wide. The experimental control plot is bare soil plot on 5° slope. Results are 394.3 mm rain fell during 54 events between May and November 2016. Runoff as overland flow occurred 14 times in the control, accounted for 25.9% of the precipitation and caused 54.5 tons/ha erosion. At the other end of the data, runoff only occurred twice in the 5° no-till plot and caused only 0.2 tons/ha erosion. Detailed analysis of three rain fall events further validated significant differences in runoff and erosion with each treatment as well as significant differences in size distribution of transported soil solids. Soil solid size distribution and amounts were valuable for describing and analyzing runoff and soil loss processes under different treatments.