Tillage and crop rotation effects on subsurface drainage response to rainfall
1996
Bjorneberg, D.L. | Kanwar, R.S. | Melvin, S.W.
A field study was conducted to determine if tillage and crop rotation affected subsurface drainage response to rainfall. An instrumentation system collected subsurface drain flow data from thirty-six, 0.4 ha plots during the 1993, 1994 and 1995 growing seasons. Response time, time-to-peak drain flow rate, drainage volume, peak drain flow rate and percept preferential flow were compared between two tillage systems (no-till and chisel plow) and two crop rotations (continuous corn and corn-soybean) for 23 drainage events over the three-year study. The influence of preferential flow was estimated for each drainage event using a hydrograph separation procedure based on subsurface drain flow rate changes. Drainage event parameters were not consistently different between crop and tillage systems during this study. Drainage parameter data were highly variable and little correlation was observed between parameters. Percent preferential flow was found to be greater than 10% of the total subsurface drain flow only four times for the 23 drainage events. The highest average percent preferential flows for an event did not correlate with the highest rainfall intensity and varied among crop and tillage systems. Annual averages of drainage parameter data indicated that drainage volume and peak drainage rate may have been influenced more by the experimental plot than by the crop. Overall results indicated that changes occurring in the soil flow system during the growing season may have more influence on preferential flow and subsurface drain flow compared to tillage and crop rotations for these loam soils.
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