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United States Department of Agriculture

Agricultural Research Service

Title: Economic and Phosphorus-related Effects of Precision Feeding and Forage Management Modeled at a Farm-scale

item Ghebremichael, Lula
item Cerosaletti, P
item Veith, Tameria - Tamie
item Rotz, Clarence - Al
item Hamlett, J
item Gburek, William

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/2007
Publication Date: 8/1/2007
Citation: Ghebremichael, L.T., Cerosaletti, P.E., Veith, T.L., Rotz, C.A., Hamlett, J.M., Gburek, W. 2007. Economic and Phosphorus-Related Effects of Precision Feeding and Forage Management at a Farm-scale. Journal of Dairy Science. 90(8):3700-3715.

Interpretive Summary: The main cause of soil phosphorus buildup in the New York Cannonsville Reservoir Watershed, which in turn heightens eutrophication of the Cannonsville Reservoir, has been attributed to more phosphorus being imported to the farms as feed and fertilizer than being exported from the farm in milk, manure, and other products. A Precision Feed Management (PFM) project involving controlled dietary phosphorus and increased homegrown forage production is being conducted on Cannonsville Reservoir Watershed pilot farms by personnel from Cornell Cooperative Extension (CCE) of Delaware County to act at the root cause of this phosphorous imbalance. In conjunction, comprehensive whole-farm assessments are needed to determine the impacts of these strategies on feed nutrient imports, nutrient losses, and profitability of farms. This study employed the Integrated Farm System Model (IFSM) to evaluate and quantify the economic and environmental impacts of the PFM strategies for farm enterprises. Using IFSM, farm specific PFM strategies that balance farm phosphorus inflows and outflows with minimum phosphorus losses and increased profitability were successfully identified. The location-specific data and strategies simulated in this study provide robust whole-farm assessments of the impacts of pre- and post-PFM efforts on milk production, farm profitability, and farm-level phosphorus losses for New York dairy farms.

Technical Abstract: The Cannonsville Reservoir experiences a high degree of eutrophication due to phosphorus (P) losses from upstream land that is dominated by dairy farms. Structural best management practices (BMPs) have been implemented throughout the Cannonsville Reservoir Watershed (CRW) in an effort to reduce phosphorus losses to the water supply reservoirs. However, long-term water quality control efforts in CRW are believed to be hindered by continuous phosphorus build-up in the soils resulting from dairy farm phosphorus imports exceeding exports. Addressing CRW's phosphorus imbalance problems while maintaining economic viability of the farms requires a system-level redesign of farm management. One such innovative strategy, Precision Feed Management (PFM), reduces soil-phosphorus build-up by limiting feed and fertilizer purchases while increasing high-quality homegrown forage production. This study employed the Integrated Farming System Model (IFSM) on two CRW dairy farms to evaluate and quantify the benefits of PFM farm planning strategies in controlling P imbalance problems while maintaining the profitability of farms and, ultimately, the off-farm phosphorus losses. The IFSM generally performed well in representing the economic and environmental status of both farms based on verification done with farm planners, as well as data derived from a well-calibrated hydrological and pollutant model. Model simulation of more accurate feeding of phosphorus (based on P in animal diets), integrated with increased productivity of grass-forage and the proportion of forage in the diet, resulted in a farm P balance reduction ranging from 78 to 100% and a soluble P loss reduction of 18%. Feed supplement purchases declined by 7.5 kg/cow/year for dietary mineral P, and by 1.02 to 1.35 tonnes/cow/year for protein concentrates through adoption of the improved system. Moreover, when a land use management practice of converting corn to grass was coupled with the precision feeding of P and improved forage management, IFSM predicted a reduction of 7.5 kg sediment-bound P /ha in erosion on average each year for each 1 ha of corn converted to grass. The model also predicted slight increases in grain purchases to offset the reduction in corn silage production and feeding rates, but no appreciable change in the farm phosphorus balance due to land use conversion. Such model-based studies done on a farm-by-farm basis are useful in complementing farm planners’ efforts in exploring innovative farming systems.

Last Modified: 06/27/2017
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