Objective:
The primary objective of the project is to address current knowledge gaps in understanding and managing the nutrient cycles of modern dairy farms. Under this broad research umbrella are five specific objectives: i) to determine the effects of dairy diets and herd management on manure nutrient excretions and nutrient losses to the environment; ii) to determine the effects of manure and crop management practices on nutrients, sediment, and pathogens in surface runoff and other pathways; iii) to determine the effects of season, dairy diet, and field management of manure on gaseous emissions of NH3, N2O, CO2, CH4, and volatile organic compounds; iv) to determine the effects of mechanical application of dairy manure on nutrient uptake and nutritional characteristics of annual and perennial forages; and v) to develop conventional and organic crop management strategies to facilitate the exchange of N, P, and K as manure and feed between neighboring dairy and cash grain farms.

Approach:
Improved management of dairy farms requires successfully managing its nutrient flows, both to maximize nutrient use by animals and crops in order to optimize profit, and to minimize nutrient loss to the environment in order to optimize sustainability. We will investigate most aspects of nutrient cycling throughout the dairy-farm system with a variety of methods and at different scales (replicated field plots, field-scale paired watersheds, feeding trials with replicated pens of heifers, etc.). Some experiments also include non-nutrient elements such as eroded sediment and pathogens. Specific experiments will investigate only one or two nutrient pathways that, taken alone, may seem unrelated. However, our research team has a longer-term goal that will be achieved in future CRIS cycles, which is to integrate information across experiments to more completely describe, quantify, model, and manage the entire dairy-farm nutrient cycle. Achieving this goal will help ensure the existence of sustainable, profitable, environmentally benign dairy farming for coming decades.