|Robertson, David - Dave|
Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 3/21/2003
Publication Date: 11/1/2003
Citation: GOLLANY, H.T., WUEST, S.B., WILLIAMS, J.D., SCHILLINGER, W.F., BAKER, A.A., ROBERTSON, D.S. SUBSOILING INFLUENCE ON NUTRIENTS IN RUNOFF FOLLOWING RAINFALL SIMULATION. AGRONOMY ABSTRACTS. 2003.
Technical Abstract: Runoff from frozen soil is a major contributor to water erosion and sedimentation in fields after summer fallow in the inland Pacific Northwest. Some producers have used subsoiling, a process of creating 30- to 45-cm deep pits to open a channel to unfrozen subsoil, as a practical solution to reduce runoff and erosion. The objective of this study was to quantify C, N, S, and P losses in runoff from subsoiled vs. control treatments. Two treatments, subsoiled and control, were established using a randomized complete block design with four replications on a Bagdad silt loam soil. After fall rains, a rotary subsoiler was used to create 45-cm-deep pits with 15-L capacity every 0.7 m^2 along to contour of the hillside. In February, rainfall was simulated for 2 hr at a rate of 36 mm/hr. Runoff water was sampled periodically and analyzed for total and soluble C, N, S, and P. Compared to control, decreases in total runoff and total C, N, and S values in the sediment were highly significant (P < 0.01) for the subsoiled treatment. Total sediment loss during simulated rain for the subsoiled and control treatments were 1313- and 3355-kg/ha, respectively. Total C, N, and S losses in the sediments were 24-, 2.3-, and 0.36-kg/ha for the subsoiled treatment, and 72-, 6.9-, and 1.0-kg/ha for the control treatments. Subsoiling reduced runoff and soil loss with consequent reduction of C, N, and S losses.