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Title: SIMULATION OF DAIRY MANURE MANAGEMENT AND CROPPING SYSTEMS

Author
item HARRIGAN, T - MICHIGAN STATE UNIVERSITY
item BICKERT, W - MICHIGAN STATE UNIVERSITY
item Rotz, Clarence - Al

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Increasing government regulation is requiring dairy farmers to adopt new systems to reduce the negative impact of their farms on the environment. To reduce soil erosion, they must adopt conservation tillage systems that leave more residue on the soil surface. New manure storage and application systems are required to reduce nutrient loss to the environment. These two oneeds are not always compatible. Equipment that incorporates manure into the soil to reduce nutrient runoff also tills the soil and reduces surface residue. These new systems are also a substantial economic cost to the farmer. Since milk prices have not increased in fifteen years, these added costs are difficult for many to absorb. A comprehensive systems analysis is required to determine best systems for individual dairy farms. A simulation model of the dairy farm called DAFOSYM was expanded to model tillage systems and their interaction with manure handling. The expanded model provides a tool for evaluating and comparing manure and tillage systems on dairy farms of different size and at various locations. Analysis of Michigan farms shows mulch-tillage with irrigation or surface application of manure to be a good option, but this does reduce the profitability of the farm compared to systems commonly used today. The model and the information that it provides will help farm consultants, producers and policy makers make better informed decisions as they develop the dairy industry for the future.

Technical Abstract: The dairy forage system model (DAFOSYM) was expanded to include submodels for the prediction of suitable days under a range of soil and crop residue conditions, draft of a wide range of tillage and seeding implements, and scheduling of manure handling, tillage and planting operations. Through simulation, the long-term performance, costs and net return for three tillage and four manure handling systems were compared on 150 and 400-cow representative dairy farms in Michigan. The analysis integrated all aspects of manure production, storage and application with tillage, planting, crop growth, harvest, feed storage and feeding. Mulch-tillage was the most economical tillage system, returning $15 to $25/cow-yr over conventional tillage with a 30% reduction in machinery, fuel and labor costs. A modified no-till system provided a higher return than conventional tillage, but when compared to mulch-tillage, savings in fuel and labor with this system were offset by higher costs for seed, fertilizer and pesticides. The highest ne return among manure handling systems was associated with short-term storage and daily hauling, but this economic advantage diminished if credit was not given for the value of manure nutrients with daily spreading. Long-term manure storage concentrated labor for spreading in the spring and fall. This delayed tillage and planting and increased feed costs as much as $24/cow-yr when manure hauling, tillage and planting occurred in series. When labor and machinery were available for parallel field operations, manure handling method had little affect on the timeliness of tillage and planting.