THE EFFECTS OF LIVESTOCK MANURE APPLICATION AND MANAGEMENT ON SURFACE WATER QUALITY

Livestock production is an important agricultural industry in Ontario accounting for approximately 54 % of farm cash receipts (approx. $3.1 billion) in 1991. The Agricultural Statistics for Ontario (1991) reported approximately 3 million swine, 0.7 million dairy cattle, 1.6 million beef cattle, and 28.4 million poultry. The disposal of the animal wastes generated by this industry can represent both a valuable agronomic resource and, potentially, an environmental liability. This study has focused on the disposal of liquid swine manure on soils managed under conservation tillage systems and examined the potential for the contamination of surface waters and methods of reducing that contamination. The concern for the contamination of surface water by nitrogen and bacteria constituents found in manure arises from their threat to human health and wildlife habitat. Nitrate-N concerns are related primarily to infant health and in particular methaemoglobinaemia (infant cyanosis or blue baby) (Fraser and Chilvers, 1981). In recognition of this problem a safe limit of 10 mg NO3-N L-1 has been established for drinking water (OME, 1992). While the evidence is less direct, nitrate and nitrite-N have also been linked with cancer by reactions leading to the formation of nitrosamines (Fraser et al. 1980)