An annual crop nutrient management plan is needed to ensure an adequate supply of nutrients to sustain profitable crop production, and to balance nutrient inputs (including manure) with crop nutrient needs. Title 130 of the NDEQ requires that a permit application include a nutrient management plan with manure sampling and analysis procedures, soil sampling and analysis procedures, and planned land application rates, methods, and frequencies.
The annual crop nutrient management plan has four required and two recommended components:
- nitrogen management plan
- phosphorus management plan (recommended)
- action plan and records (recommended)
- soil testing
- manure nutrient analysis and application
Planned activities for some components are likely to be similar from one cropping season to the next, but each should be reviewed and revised annually to adjust for current conditions. Nitrogen inputs must be matched with crop nitrogen needs for each growing season because of the possibility of excess nitrate-nitrogen leaching to groundwater. Manure applications may provide phosphorus for several years provided the surface soil phosphorus does not accumulate to levels that cause unacceptable chances of phosphorus loss to surface water.
Nitrogen Management Plan
Manure should be applied so it does not exceed the crop nitrogen requirements, according to NDEQ Title 130. Consequently, producers need to determine the total nitrogen requirement for the planned crop, and then decide how and when to apply that amount of nitrogen. All of the nitrogen may be derived from manure, or producers may desire to apply commercial nitrogen fertilizer prior to or at planting, or as a sidedress application. Remember to allow nitrogen credit for sources such as soil residual nitrate-N, preceding legume crops and nitrate in irrigation water.
Once nitrogen credits and nitrogen applications from commercial fertilizer are subtracted from the crop nitrogen requirement, the remainder can be supplied from manure. A laboratory analysis of the manure source is helpful in determining the manure application rate. A lab analysis will provide the amount of ammonium, nitrate, and organic nitrogen in the sample. Nitrate-N will be 100 percent available the year of application, although nitrate-N levels are usually quite low in manures. Ammonium-N can be 100 percent available if manure is incorporated immediately or injected. If manure is broadcast and not incorporated, the ammonium-N would be unavailable due to ammonia volatilization to the atmosphere. Organic-N availability will depend on the manure source. If manure is to be applied in successive years, credit also needs to be given for nitrogen mineralization from previous years’ manure application. For more information to calculate manure nitrogen credits, see the Nitrogen Dynamics page.
Phosphorus Management Plan
If manure is regularly applied to cropland, phosphorus levels are generally adequate for excellent crop performance. A phosphorus management plan is useful to avoid excess levels of soil test phosphorus.
In a manure phosphorus plan, the phosphorus balance for the field after crop removal in the harvest, or harvests, following manure application is estimated. The amount of phosphorus applied is estimated from the rate of manure application and the phosphorus concentration of the manure. Other phosphorus credits, such as from fertilizer, are added to the amount applied. Crop removal of phosphorus is estimated from the yield and the phosphorus concentration of the harvested product. The difference is phosphorus added to the soil. A very general rule of thumb is that soil phosphorus levels will be increased one ppm for every 15-20 pounds of phosphate applied in excess of crop removal.
Action Plan and Records
The purpose of the action plan is for the livestock manager to communicate to employees the specifics of how manure is to be applied. The action plan ties everything together for a given year – which fields (or areas within fields) are to receive manure, how much manure should be applied and when and if it should be incorporated, as well as plans for application of commercial fertilizer. The action plan provides a brief summary of plans for the year in an easily accessible format. Great detail is not necessary – more information can be found if needed by going back to components reflected in the Annual Plan, such as manure and soil analysis, nitrogen and phosphorus management plans, etc. The Annual Plan should condense the necessary details into a useful reference that can be carried to the field.
Once manure has been applied, write down any relevant deviations from the plan before details fade from memory. More detailed information on recordkeeping is available in other sections of this course.