|Rotz, Clarence - Al|
Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/2007
Publication Date: 6/17/2007
Citation: Crosson, P., Rotz, C.A., O'Kiely, P., O'Mara, F.P., Wallace, M., Schulte, R. 2007. Modeling the nitrogen and phosphorus inputs and outputs of financially optimal irish beef production systems. Applied Engineering in Agriculture. 23(3):369-377. Interpretive Summary: The potential of agricultural production to contribute to the declining quality of ground and surface waters is now well recognized. In Ireland, this has resulted in legislation to prohibit management practices which can lead to environmental denigration and also to cross-compliance requirements prior to the receipt of farm support payments and subsidies. Coupled to these requirements is the cost-price squeeze on farmers due to the inflationary increase in input costs and decreasing commodity prices for farm output. Mathematical models provide a method of identifying optimal systems of production within the range of resources available and the constraints imposed on farmers. Models can also provide information on how these production systems impact the environment. Whole-farm analyses of beef production systems in Ireland were conducted to determine how projected price changes resulting from recent policy changes of the European Union may impact farms and their environment. Model results suggest that as future beef prices increase, production intensity on farms will likely increase with more incentive for using integrated calf-to-finish systems rather than calf-to-stocker production systems. This intensification will increase potential negative impacts of the farms on the environment. These results allow policymakers, farm advisors and farmers to take a broader perspective and to make better informed decisions in planning the future of beef production systems in Ireland.
Technical Abstract: Challenges currently faced by beef farmers in Ireland include reducing their adverse environmental impact and maintaining farm economic margins. Fertilizers are essential for productive farming but they can be harmful to the environment when applied to crop and pasture land inappropriately or excessively. A linear programming model was used to identify financially optimal strategies for calf-to-stocker and calf-to-finish beef cattle production in high price and low price market scenarios. The high price scenario resulted in an increase in gross margin of $1,700 and $13,000 on a 40 ha farm for the stocker and finisher options, respectively. The impacts of these systems on environmental indicators were investigated through farm simulation. In general, the high price scenarios were more intensive and had greater environmental impacts when compared to the low price scenarios. Nitrogen leaching losses were quantitatively the most important environmental indicator on well drained soils with a maximum annual loss of 72 kg N/ha. Volatilization and denitrification losses of nitrogen were also relatively high where more intensive production was practiced with annual losses of 48 and 23 kg N/ha, respectively, in the most intensive scenario identified. Predicted phosphorus losses were small although annual accumulations in the soil of up to 7.5 kg P/ha may lead to greater losses in the future. On poorly drained soils, volatilization losses were greatest with leaching losses in this case the lowest of the loss pathways investigated. Further reduction in inorganic nitrogen application has the potential to reduce N losses, but predicted concomitant reductions in farm gross margins were also considerable.