Bacteriological Quality of Surface and Subsurface Runoff from Manured Sandy Clay Loam Soil

The bacterial quality of surface waters determines their acceptability for both drinking and recreational uses. Since livestock activities have been implicated as sources of fecal contamination, information on the bacterial quality of runoff from manured cropland is required. Bacteriological parameters (total coliform [TC], fecal coliform (FC], and fecal streptococcus [FS]) were monitored in spring surface and subsurface discharge from continuously corn-cropped sandy clay loam that was amended with either liquid dairy manure, chemical N-P-K fertilizer at about recommended rates, or no fertilizer. Liquid manure was applied for 6 years at three rates, which averaged 105, 263, and 420 m ha"' year', plowed under after harvest, in spring prior to seeding, or split between spring and fall. Liquid manure was also applied directly to snow or frozen ground. With the exception of winter-applied treatments, neither rate nor time of manure application significantly affected organism contents in spring surface or subsurface discharge. Winter manure applications resulted in significantly higher FC and FS counts in surface runoff and FS counts in subsurface discharge when compared with other application times. Fecal coliform and FS counts did not increase with increased winter application rates. Fecal streptococcus populations of winter-applied manure changed little during the first 100 days after application, while both TC and FC counts declined in the manure to low levels 24-40 days after spreading. Additional Index Words: fecal coliform, stream pollution, liquid dairy manure. Culley, J. L. B., and P. A. Phillips. 1982. Bacteriological quality of surface and subsurface runoff from manured sandy clay loam soil. J. Environ. Qual. 11:155-158. Potential human and animal health risks from waterborne pathogens can exist in fecally contaminated 'Contribution no. 1-275 and 115 from Engineering and Statistical Research Institute and Land Resource Research Institute, respectively, Research Branch, Agriculture Canada, Ottawa K1A OC6. Received 26 Mar. 1981. 1 Hydrologist, Land Resource Res. Inst., and Agricultural Engineer, Eng. and Stat. Res. Inst., respectively. water. Fecal contamination has been observed in runoff from feedlots (Miner et al., 1966), dairy farms (Janzen et al., 1974), grazed pastures (Kunkle, 1970; Doran and Linn, 1979), fallow and sod amended with poultry litter (Giddens and Barnet, 1980), grassland treated with dairy manure (McCaskey et al., 1971), and sewagesludge treated land (Dunigan and Dick, 1980). Development of management guidelines to minimize degradation of runoff quality from manured land requires that both times and rates of application be evaluated. In eastern Ontario, snowmelt usually occurs either in late March or early April. Since > 50% of the total annual runoff from two of the major agricultural catchments, the Rideau and South Nation, occurs in March and April (Water Survey of Canada, 1977), particular attention to runoff water quality during this period is warranted. The objectives of this study were to (i) investigate the bacteriological quality of snowmelt surface and subsurface discharge from corn (Zea mays L.) cropland receiving different rates of liquid dairy manure at different application times, and (ii) to measure survival rates of indicator organisms in winter-spread manure. MATERIALS AND METHODS Experimental Design A gently sloping (0.8%) field of imperfectly drained Manotick sandy clay loam (Aquic Eutrochrept) was divided into 14 plots, each 75.6 by 11.6 m. Plots have been cropped in silage corn since 1973. Each plot was instrumented so that both surface and subsurface (plastic tile) waters could be measured and sampled. After an initial year when no manure was applied, liquid dairy manure treatments, at three rates and four different application periods, were randomized and assigned to each plot for a period of 6 years. During this 6-year period liquid manure (average solids 8.8%) application rates averaged 105, 264, and 420 m ha' year', and were either plowed under after corn harvest, plowed under prior to seeding, split between fall and the following spring, or applied to snow-covered or frozen ground during the winter. Selected chemical and microbiological properties of the manure, as listed in Table 1, were determined. Chemical fertilizer was J. Environ. Qual., Vol. 11, no. 1,1982 155 Table 1--Nutrient Idry weight basis~, solids, and bacterial contents in liquid dairy manure applied to sandy clay loam over 6-year experimental period.