Manure Application Guidelines for Minimizing Environmental P Loss

Managing Manure for Sustainable Agriculture

By Jean-Paul McDonald
Farms.com

Manure, a valuable resource for fertilizing crops, can contribute to environmental phosphorus (P) loss if not managed carefully. To address this concern, the publication Assessing Nutrient Loss Risk in Ohio, NRCS, 2020 provides guidelines for manure application based on the Soil Test Phosphorus (STP) level in a field.

The guidelines may also be useful in other jurisdictions.

The guidelines categorize STP levels into three risk categories: moderate, higher, and very high.

Each category is associated with specific manure application recommendations to minimize environmental P loss.

Moderate Risk (STP 50-120 ppm): 

• Limit manure application to the planned crop rotation's P removal rate.
• Apply manure to fields with at least 30% cover or incorporate it into the soil. 
• Maintain sensitive area setbacks.
• Avoid surface application in spring without a growing cover.
• Implement erosion control measures.

Higher Risk (STP 120-200 ppm):

• Limit manure application to 50% of the planned crop rotation's P removal rate. 
• Apply manure to fields with at least 50% cover or incorporate it into the soil. 
• Maintain sensitive area setbacks. 
• Avoid surface application in spring without a growing cover. 
• Implement erosion control measures.

Very High Risk (STP >200 ppm): 

• Refrain from manure application. 
• Drawdown P levels by implementing a more intensive crop rotation that includes forages, if possible.

These guidelines emphasize the importance of tailoring manure application practices to the specific STP level of a field to minimize environmental P loss and promote sustainable agriculture. By following these recommendations, farmers can effectively utilize manure while safeguarding water quality and maintaining the long-term sustainability of their farming operations.