Effects of incorporated crop residue on rill erosion

A two-year study was conducted to investigate the effects of incorporated-crop residue and tillage condition on rill erosion, using simulated rainfall and added inflow. Three study phases were: (1) Rill erosion experiments during the first season after residue was incorporated, (2) Rill erosion experiments on freshly-tilled conditions with no residue, and (3) Rill erosion experiments on freshly-tilled and consolidated conditions, one-year after residue incorporation. Residue incorporation rates were 0, 1.1, 2.2, and 4.5 t/ha. Rill erosion rates and channel geometry were measured 3 times in 1986, and once in 1987. Just after incorporation, rill erosion rates were significantly reduced as incorporated-residue amounts increased from 0 to 4.5 t/ha. At inflow rates of 9.5 1/min, soil loss was reduced by 75 percent for residue rates of 4.5 t/ha compared to no residue. Erosion rates from the 69 1/min inflows were reduced 40 percent for the 4.5 t/ha residue rate compared to no residue. Rill erosion was significantly greater for the first experimental run on each furrow compared to the second and third experimental runs. One year after incorporation of residue, there was a significant 32 percent decrease in soil loss as residue rates increased from 0 to 4.5 t/ha, on freshly-tilled conditions. There were no significant differences in soil loss rates because of the residue, for the consolidated soil condition. Natural soil consolidation may have masked any residue effect. Average soil loss from freshly-tilled conditions was almost twice the loss from consolidated conditions