NUTRIENT AND COLIFORM LOSSES IN RUNOFF FROM FERTILIZED AND SEWAGE SLUDGE-TREATED SOIL

Surface runoff losses of fertilizer elements from forage plots on Loring silt loam soil were monitored from three separate studies during an 11-month period. Incorporating approximately equal amounts of N and P from commercial fertilizer and sewage sludge did not significantly affect differences in N and P losses. Surface application of sewage sludge resulted in higher N and P losses than those from incorporated sewage sludge. The surface-applied sludge plots in the second experiment had the highest N and P runoff losses of 3. 24 and 0. 39 kg/ha, respectively. These losses were due to a heavy rain that fell early in the test period. The highest K losses came from the fertilized plots. In all sewage-treated plots, K losses were approximately equal to or lower than the control values. Precipitation was found to contain substantial quantities of NH//4-N and NO//3-N with respect to losses of these ions in the surface water. Fecal coliform indicator bacteria (FC) counts in surface runoff waters from sewage-treated plots were very high in the first 11 to 17 days of the second and third experiments.