Tracking Mass Nutrient Balance on Delmarva Dairy Farms - The Phosphorous Dilemma J. A. Moore and J. M. Hart, Bioresource Engineering Department and Crop and Soil Science Department, Oregon State University

The production goal for most dairy farms is to maximize income through high milk output combined with low cost, high quality feed input. A dilemma develops as producers monitor and try to minimize soil phosphorus levels while simultaneously trying to achieve production goals. Phosphorus is imported onto a dairy in two forms. One, as fertilizer to meet one of the requirements for optimum forage production and secondly as a dietary supplement for maintaining healthy productive cows. Typical dairies on the Delmarva Peninsula have two exports containing phosphorous, milk and cull cows. Unfortunately the amount of imported phosphorus far exceeds the exports leading to a positive mass nutrient balance (an increase in soil phosphorus). As nutrient management regulations are written in Maryland and surrounding states the phosphorous dilemma becomes more challenging. How will a producer be able to maintain an economically viable number of animal units per acre without exceeding the allowable phosphorous limit (environmental degradation)?

Phosphorous loading within the confine of a dairy farm or any larger geographical area is serious issue large animal production agriculture is facing. The dilemma can be lessened if producers are more aware of the mass balance of nutrients on his or her farm. Software programs are available that track the mass balance of nitrogen, phosphorus, and potassium on dairy farms. All the inflows of these nutrients from fertilizer, feed, bedding, and animal entries are monitored. Also the outflow away from the farm of the same nutrients are measured in milk and animals sold, grains and forages sold, and manure exported. The remaining balance of these nutrients becomes a useful monitor of the accumulation on the farm and/or the potential for unplanned nutrient loss away from the farm.

For more information on the software to track Mass Nutrient Balance contact:

Richard A. Kohn
Department of Animal and Avian Sciences, University of Maryland
College Park, MD 20742
rkohn@wam.umd.edu

Stu Klausner
NRAES, Cooperative Extension
152 Riley-Robb Hall Ithaca, New York 14853-5701
sklausner@aol.com

Al Rotz
PSWMRL, The Pennsylvania State University
Curtin Rd., University Park
PA 16802-3702
alrotz@psu.edu

Source: Monsanto Dairy Group
Author: Hart, Moore