The Arkansas Water Quality Inventory Report for 1994 lists the expansion of confined animal production
as a special state concern. The report indicates that in the areas of animal production, the reduced water quality attributed to agriculture is primarily due to elevated nutrient and pathogen concentrations. The report also mentions an increased incidence of high nitrate concentration in wells and springs in areas of concentrated animal operations.
Modern swine rearing facilities often have large numbers of animals and a relatively limited land base for manure application. Utilization of the manure in a manner that minimizes odor and optimizes nutrient utilization is an increasing concern. Manure is a valuable resource as an alternative
source of fertilizer nitrogen (N), phosphorus (P) and potassium (K) to maintain soil productivity. In fact, improving ground cover tends to reduce runoff volume and erosion. However, application rates greater than crop needs have been shown to result in nitrate (NO3) movement through the soil into ground water and can also result in excessive soil test P levels, leading to increased phosphorus concentrations in runoff water. This can be a problem, since phosphorus is normally the limiting nutrient for eutrophication in freshwater systems. In addition, odor and nutrient problems can both be increased by excessive nutrient buildup in lagoons/holding ponds if manure solids are allowed to accumulate over a number of years.
Arkansas was the twelfth highest swine producing state in the nation at the initiation of this project. Of the 2 million swine produced annually, the vast majority are raised on farms with liquid manure handling systems. On these farms, the animals are housed in total confinement facilities where the manure is handled with the addition of supplemental water. Water is typically used to flush the manure from the barn into storage/treatment basins until it is land applied to supply the nutrient (nitrogen) needs of a forage crop. While this approach has the advantages of production economics, animal health, beneficial use of the manure for crops and environmental preservation (with proper management), there are a couple of points of concern.