Project Number:
DNR-039
Other Project Number:
WR86R008
Funding Year:
1986
Contract Period:
Funding Source:
DNR
Investigator(s) and affiliations:
J. C. Converse, University of Wisconsin–Madison;
J. W. Patoch, University of Wisconsin–Madison
Abstract:
Abstract: Soil cores from sixteen grass filter strips designed to treat runoff from dairy barnyards were analyzed to assess the leaching of nutrients below the root zone of the grass and the potential for nutrient movement to groundwater. Two filter strips which showed little movement of nutrients and four which showed evidence of nutrient accumulation were selected for further study of their hydraulic properties and management.
The strongest evidence of nutrient movement below the root zone was found in those strips where the soils remained saturated for long periods of time. Downward movement below the root zone was also observed on one filter were the soil cracked when dry.
Wet conditions were responsible for many maintenance problems. Farmer’s complained of excessively wet filters which made mowing difficult and were easily rutted by agricultural equipment. Design specifications need to be examined and may need to be modified to insure better surface and internal drainage from grass filter strips. In some cases it may be necessary to use sub-surface drains to insure that the soil does not remain saturated for extended periods.