Section 12 – Nutrient Basis for Manure Application Rates

As explained in Section 6, when manure is applied to the soil over a long period of time and particularly if enough manure is applied to meet the nitrogen requirements of the crop, phosphorus (P) levels can build up and may eventually become high enough to create a risk to water quality.

If manure is being applied to soils with high levels of P, a North Dakota Phosphorus Risk Assessment tool can be used to determine if the North Dakota Phosphorus Index should be calculated. A high index number indicates a high risk of phosphorus impacting water quality. That indicates that applications of manure P should not exceed crop removal.

The North Dakota Phosphorus Risk Assessment and North Dakota Phosphorus Index can be found at:

http://efotg.nrcs.usda.gov/references/
public/ND/North_Dakota_Phosphorus_Risk_Assessment.pdf