Optimal crop production requires nutrient application. Land application of nutrients is a common practice in Wisconsin and occurs as both animal manure and chemical fertilizers. Conventional practices have involved nutrient application during the spring or fall and at quantities sufficient to ensure adequate supply throughout the growing season. This requires applying additional nutrients to compensate for anticipated losses through both surface and subsurface pathways and/or mineralization in the soil. Mechanisms for these losses can include manure in surface runoff and tiles or nutrients dissolved in stormwater runoff.
Nutrient losses represent a cost to producers as well as the environmental cost from downstream impacts. Nutrients lost from upland areas enter streams, lakes and groundwater resulting in impairment to beneficial use. Oxygen demanding organic matter, bacteria, pathogens and nutrients from manure can pose public health and environmental risks. In addition, it is costly to transport liquid manure from the farm to land application areas. These costs increase with distance along with increased wear on public roads.