KWRRI Research Reports


Dairy manure was surface spread on 12 ft x 12 ft plots on an established fescue pasture in the summer and fall of 1981 and 1982. The soil was a Maury silt loam. A simulated rainfall was applied to plots to test the effects of nitrogen loading rate (75, 150, and 300 #N/acre) time delay between manure application and the simulated rainfall events (0, 3, 6, 24, 48, 96 hours and a 120 hour test repeated on 0 hr plot with 300 #N/acre), and type manure (semi-solid - 1981 and liquid - 1982) on the concentrations of pollutants in the surface runoff. The pollutants measured were COD, TSS, FSS, VSS, TS, FS, VS, N03, NH4 , N, P, and K. The simulated rainfall rates were 3.42 in/hr for 1981 and 4.02 in hr for 1982. The average field infiltration rate for the non-manured test plots were 3.40 in/hr in 1981 and 4.42 in/hr in 1982.

The infiltration rates of the manured plots were reduced by 5.8 to 15 percent for semi-solid manure and 23 to 31 percent for liquid manure for zero hour time delay plots. The infiltration rates increased to within 92 percent of the control plots after 120 hour time delay. The pollutant yields increased with nitrogen loading rate except for FSS yield which remained below the control plot yields. The NO3 yields was below the control plot except for 300 #N/acre plots. The reduction in pollutant yields with increased time delay was found to average 46 and 76 percent for the 24 and 48 hour time delays for semi-solid manure and 75 and 94 percent for liquid manure. The yields for TSS, FSS and VSS for liquid manured plots did not exceed the control plot yields until after the 48 hour time delay.

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The work upon which this report is based was supported in part by funds provided by the U.S. Department of the Interior, Washington, D.C., as authorized by the Water Research and Development Act of 1978. Public Law 95-467.