NE1024: Whole Farm Dairy and Beef Systems for Environmental Quality
Statement of Issues and JustificationDairy and beef production are major contributors to the economy of the US, but increasing costs of production, the decline of real prices towards a world market price, and environmental issues are jeopardizing the long-term sustainability of these farms. This is causing a continuing trend toward larger farms concentrated in certain geographic locations. More efficient, economical, and environmentally sound production systems are needed to maintain a viable agricultural industry. Integrated research and technology transfer programs are needed to help dairy and beef farmers manage their farms in a cost effective and environmentally acceptable manner and to comply with new farming regulations. Integrated crop, pasture, and livestock farms form very complex physical and biological systems. Most research focuses on one or relatively few components of the system, providing a narrow view of the potential effects of strategic production changes and an inadequate assessment of the farm-level issues of environmental impact and profitability. Modeling and computer simulation provide an effective research strategy for integrating component-level effects and interactions to predict farm level or higher outcomes.
Recently, attention has focused on animal production systems as non-point sources of pollution affecting the quality of air and water resources. In particular, nitrogen and phosphorus may contaminate water following the application of manure or chemical fertilizer to soils (Morse, 1995). Some nitrogen becomes volatilized as ammonia from manure or soils, and eventually contributes to acid rain that endangers forests and water bodies (Luebs et al., 1973). Some nitrogen may be lost from the farm by conversion to atmospheric N2 or nitrous oxides through denitrification, but the majority is normally lost through the other pathways. Phosphorus largely accumulates on farms, mainly as an accumulation in soil, which in turn contributes to accelerated P runoff and the eutrophication of surface waters. On many farms where manure is applied to soil surfaces without incorporation, such as in no-till or pasture fields, potential runoff loss of P can be substantially elevated because much of the manure P is water soluble and thus susceptible to subsequent loss to the environment (Dou et al., 2000, 2002, 2003).
Several technology and incentive programs are aimed at reducing the risk of environmental damage from animal agriculture while maintaining farm productivity. However, in order to better direct these resources, there is a need for routine assessment of which farm management practices are most effective on specific farms. Modeling supported by experimental research provides tools for such assessments. These tools may lead to farm management decision support aids that help producers and their consultants identify the most appropriate strategies for managing nutrients on a farm-by-farm basis. In addition, there is a need to collect and analyze data in the field, so as to identify the most appropriate technology transfer programs to address the problems associated with nutrient pollution in a cost effective manner.
Because the environmental impact of a farm management decision depends on farm characteristics (e.g., size, soil type, climate) and other management selections (e.g., crop rotations, tillage practices, manure storage), the only way to calculate the benefit of a farm practice is to model the changes in nutrient flows through the entire system. Development of integrated mathematical models enables calculation of the environmental benefit from one or more management or infrastructure changes in any management subsystem (crops, soils, feed, and animal). The development of such an integrated understanding of the farm nutrient cycle requires participation by scientists in a number of diverse disciplines.
The NE-132 project has brought together a broad range of disciplines, which led to the development of quantitative models including the GRAzing Simulation Model (GRASIM: http://danpatch.ecn.purdue.edu/~grasim/grasim.html), the Dairy Forage System Model (DAFOSYM : http://pswmru.arsup.psu.edu/software/dafosym.htm), a second generation model called the Integrated Farm System Model (IFSM: http://pswmru.arsup.psu.edu/software/ifsm.htm), the Dairy Nutrient Planner (DNP: http://library.scc.wa.gov/?viewCat=142), and the Whole Farm Balance Nutrient Education Tool (WFBNET: http://www.puyallup.wsu.edu/dairy/data/joeharrison/software/Dairy%20WFNBET%20ver%204.0%20with%20N%20&%20P%20linked%20protected.xls) and FarmSoft. These models are currently being used as tools to evaluate N and P flows through dairy farm systems by university extension and government regulatory agencies. These models integrate years of collaborative research and enable an enhanced understanding of nutrient flows in the farm system. These models need to be further evaluated, validated with real farm data, and adapted to address the immediate needs in the field across the nation related to nutrient management on dairy and beef farms. In the new project, models that were previously developed will be evaluated under diverse farm conditions to identify improved strategies for management of nutrients on farms. The collaborative modeling effort of the group has been critical in identifying knowledge gaps in our understanding of N and P flows in ruminant animal/cropping systems. The models have also helped identify directions for future field/lab research. The broad and diverse research background and expertise of the group has been and will continue to be integrated by the modeling effort.
To advance whole-farm model evaluation and application, a coordinated effort is needed at several levels. First, field studies of nutrient dynamics and cropping systems are needed to calibrate predictions for different geographic locations and to evaluate model components. Second, model refinements and software development are needed to enable use of the models on individual farms throughout the U.S. Third, model prediction capacity must be expanded to more accurately partition nutrient losses into those from volatilization, leaching, runoff and denitrification, and consequences of alternative feeding or crop management systems must be expanded. Finally, models must be applied to planning of dairy and beef production systems to reduce or eliminate problems associated with nutrient management and profitability.
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