Dairy Farms May Be Impacted By Nutrient Management Changes
Posted:
Gerald Martin, Extension Agent - Nutrient Management
February 1, 2002
Currently, Pennsylvania’s Nutrient Management Law and regulations require nitrogen-based nutrient management planning. However, phosphorus-based nutrient management planning will soon become a reality in Pennsylvania. This article will summarize the regulatory developments that are currently in process and briefly consider how this may impact Pennsylvania dairy farms.
In March 1999, the USDA-EPA Unified National Strategy for Animal Feeding Operations was published as part of Clinton-Gore Clean Water Action Plan. One key aspect of the strategy was the requirement that nutrient management planning address both nitrogen and phosphorus. EPA was required to revise the existing regulations for Concentrated Animal Feeding Operations (CAFO). USDA was required to revise each state’s Nutrient Management Practice Standard (590). Both of these efforts are required to address phosphorus in nutrient management planning requirements. Three options were provided to address phosphorus. It is important to understand the three options, because the potential impact to agriculture varies considerably between the three options. Phosphorus-based planning has two impacts, 1) more land is required to apply manure, and 2) crop nitrogen needs will not be met with manure requiring the purchase of
commercial fertilizer.
What is the current status of phosphorus-based planning in Pennsylvania? The final CAFO regulations will be published in January 2003. These regulations will initially affect larger dairy operations that meet yet to be determined CAFO criteria. The new Pennsylvania Nutrient Management Standard 590 was released in May 2001. Most importantly, it designates the Phosphorus Index as the method of planning nutrient applications. This will affect operations that use Natural Resources Conservation Service technical services or cost-share money. Currently the Pennsylvania Nutrient Management Advisory Board is considering the adoption of the Phosphorus Index process and revision of Act 6 to incorporate that process into program requirements. The Phosphorus Index was selected from three options or approaches. Each option and typical impact on manure application rates is described below.
· Phosphorus Index option: P application rates are based on identification of critical source areas using an evaluation of several factors that measure the potential of phosphorus runoff. Research has shown that approximately 90% of phosphorus loss occurs from 10% of the land area. The Phosphorus Index is used to identify these areas by assigning risk levels. Because manure application is restricted on a small percentage of fields, this option typically has less impact on a livestock operation when compared to the two remaining options.
P Index Rating AFO Guidance Typical Maximum Rates
125 bu/A Corn Crop
Low Risk Manure rate determined using
crop N requirements
Dairy Manure – 40 T/A
Swine Manure – 10,000 gal/A
Poultry Manure – 8 T/A
Medium Risk Manure rate determined using
crop N requirements
Dairy Manure – 40 T/A
Swine Manure – 10,000 gal/A
Poultry Manure – 8 T/A
High Risk Manure rate determined using
crop P removal
Dairy Manure – 13 T/A
Swine Manure – 2,200 gal/A
Poultry Manure – .9 T/A
Very High Risk No manure can be applied No Manure Applied
· Soil Test Phosphorus option: P application rates are based on soil test interpretation (low, optimum, high, excessive) and crop removal as shown below. Approximately, 74% of soils tested in Penn State’s laboratory test optimum or higher, making this option extremely restrictive on most dairy farms that have a history of frequent manure application.
Soil Test P
Category
AFO Guidance Typical Maximum Rates
125 bu/A Corn Crop
Low Manure rate determined using N
crop requirement
Dairy Manure – 40 T/A
Swine Manure – 10,000 gal/A
Poultry Manure – 8 T/A
Optimum * Manure rate determined using 1.5 x
P crop removal
Dairy Manure – 19 T/A
Swine Manure – 3,300 gal/A
Poultry Manure – 1.4 T/A
High Manure rate determined using P
removal
Dairy Manure – 13 T/A
Swine Manure – 2,200 gal/A
Poultry Manure – .9 T/A
Excessive
No manure can be applied No Manure Applied
* Optimum soil test levels for most crops are 30 – 50 ppm.
· Soil Phosphorus Threshold option: P application rates are based on soil test levels that reflect a loading rate or environmental threshold of the primary soil type. Because this threshold is not as low as the agronomic level, this option would not be as restrictive.
Soil P Threshold
Level
AFO Guidance Typical Maximum Rates
125 bu/A Corn Crop
<0.75 TH* Manure rate determined using
crop N requirement
Dairy Manure – 40 T/A
Swine Manure – 10,000 gal/A
Poultry Manure – 8 T/A
0.75 TH to 1.5
TH*
Manure rates determined using
crop P removal
Dairy Manure – 13 T/A
Swine Manure – 2,200 gal/A
Poultry Manure – .9 T/A
1.5 TH to 2 TH* Manure rates determined using
0.5 x crop P removal
Dairy Manure – 6.5 T/A
Swine Manure – 1,100 gal/A
Poultry Manure – .45 T/A
>2.0 TH*
No manure can be applied No Manure Applied
* TH is the soil P threshold level of 200 ppm.
The future with respect to the type and extent of phosphorus-base nutrient management planning is still unclear at this point. However, it is important for dairy producers to become familiar with and prepare for potential regulatory changes. The next article will consider how dairy producers can respond to increasing environmental challenges.
