Animal Production Systems And Environmental Quality

To fully understand environmental issues, the animal production system has be to dissected into phases, e.g., housing, manure storage, and manure application, and environmental endpoints, e.g., water, soil, or air quality. We can consider the flow of manure through a swine operation as typical animal production and then the linkage to environmental quality can be seen as a series of environmental consequences (Fig. 1). These effects can be altered by the diet of the animal, changing nitrogen excretion, and carbohydrate composition of the manure. The linkages that exist between diet and environmental quality have been demonstrated and remain a viable part of the management options for improving environmental quality.

Environmental quality endpoints occur within the soil, water, or air surrounding animal production facilities (Table 1). These are potential impacts from all phases of animal production; however, air quality emanates from all phases, whereas soil and water quality spring from the manure storage and application phases. These impacts vary with production systems. For example, broiler production in houses does not impact water or soil quality until manure and bedding are moved onto the land for application. In contrast, a beef or dairy feedlot could create a water quality problem from the housing phase, because these animals are in an open feedlot subject to surface runoff during large rainfall events.

Environmental impacts of confined animal feeding operations (CAFOs) in Hamilton County, Iowa, evaluated by Jackson et al. revealed the potential to create nutrient loading too high for the ecosystem to assimilate.[2] Potential outcomes of large nutrient loadings are increased rates of ammonia volatilization, suppression of biological nitrogen fixation, and increased rates of nitrate leaching and runoff from manured soils. Current regulations require individual CAFOs to account for N utilization on cropland, but there is no assessment of these impacts at the regional, local, or watershed scale. Upon completing their analysis, they suggested five policy recommendations: 1) increase research and outreach on alternative production systems to those using liquid-based manure systems; 2) increase regulatory scrutiny of current system and require a public comment period on manure management plans; 3) increase research on nutrient management methods; 4) establish statewide zoning regulations for the density of animal units regardless of size; and 5) increase the diversity of crops on the landscape in order to utilize manure nutrients more effectively.[2] Environmental concerns are becoming a dominant force in shaping management practices for animal production, and manure storage and application. These forces will create changes in how we blend production systems and environmental quality.

Evidence that animal operations create an environmental problem has become a concern among producers and the rural and urban community. Recordings of fish kills in streams where excess manure has created high ammonia levels cause a public concern about the environmental consequences of animal operations. Application of manure onto the soil surface or smells from animal operations create a perception that animal production systems are an environmental problem. These issues define the role of various environmental pollutants from animal agriculture.

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