Soil Test P value between 50 PPM and 120 PPM (or "Moderate" P Loss Risk Assessment)

Soil test phosphorus (STP) is a good indicator for the potential risk of phosphorus movement at the edge-of-field into downstream waters. STP is a quick and widely available measure that can be used to identify field level P loss risk potential. Actual measured phosphorus losses from individual fields will be impacted by agronomic management, soil conditions and water movement resulting in higher, or lower, losses than would be predicted from soil test alone.

As STP values increase, the elevated soil solution levels are exposed to loss through tile or surface water with water movement. Edge-of-field testing has shown Dissolved Reactive Phosphorus (DRP) concentrations of 0.02 to 0.4 PPM and 0.1 to 2 lbs of DRP load per acre. Agronomic crop needs are met by current soil-available nutrients and additional nutrient are not needed.

Continued phosphorus application at this STP level on livestock farms would be due to the use of application timing to use manure-nutrient content to replace purchased fertilizer, limited land base, or emergency application due to weather or storage capacity concerns.

Farmers and other professionals should closely watch soil test reports for elevated STP levels. If elevated phosphorus levels exist, the field should be evaluated for potential phosphorus contributions to see what BMPs would benefit water quality. The best tool to evaluate phosphorus losses is collecting water samples for analysis. Water sampling results can identify if water retention or filtering practices at edge-of-field would be cost effective.

Fertilizer rate determination and application practices

Assessing Nutrient Loss Risk in Ohio

Overview of Assessing Nutrient Loss Risk in Ohio criteria for organic nutrient applications at "Moderate" P loss risk assessments is outlined below:

STP Mehlich III

Phosphorus Loss Risk Assessment Rating

Rate of application

STP Management Strategy Ground Cover at Application Sensitive area avoidance Timing of application Erosion

50-120 PPM


< P removal  for annual or multiple year crop rotation with no more than 250 lb P2O5/ac applied annually

Adaptive P Management with plan Drawdown of STP over time >30%
Growing Crop/Cover
Follow setback and vegetative recommendations (Table 3 of Assessment Document) Spring application should be made only if applied to a growing crop or cover crop Sheet and rill erosion managed at < Soil Loss Tolerance and no active concentrated flow erosion (gullies)

Best Management Practices