Description

Nutrient management is a strategy employed to match the amount and timing of nutrient applications to the temporal and spatial needs of a crop. The emphasis in IAMP is on the reduction of synthetic N fertilizers and improving N use efficiency. Incentives are provided for management that reduces applied N during a specific cropping year by at least 15% below the verified baseline. Growers must ensure nitrogen fertilizer rates do not exceed University of Idaho fertility guides for the specific crop (UI fertility Guides) based on fertility analysis of pre-plant soil samples and/or analysis of petiole samples taken from the field. By focusing on reduction from ‘baseline’ practices, the IAMP project encourages those without any nutrient management plan to start following fertility guides. Growers who already follow UI fertility guides and interested in exploring other opportunities to further reduce fertilizer rates through more advanced strategies (e.g. variable rate fertilizer, N-inhibitors, slow release fertilizers, sap analysis, and other suggestions in Idaho NRCS 590) can also receive incentive payments as long as there is a clear 15% reduction from baseline practices.

Benefits

Optimizes fertilizer efficiency and crop yields; minimize agriculturally based nonpoint source pollution to surface and groundwater; minimizes legacy effects to soil health including soil acidification; reduces input costs to a grower; reduces N₂O emissions.

Soil Carbon Impacts

Nutrient management practices will likely lead to increased soil carbon if the strategy results in increased crop biomass. Whether crop biomass increases will depend on the crop, the baseline nutrient management and baseline biomass of the crop.

Greenhouse Gas (GHG) Impacts

Increased N use efficiency and reductions in overapplied N fertilizer leads to reduced N₂O emissions. Excessive nitrate nitrogen in a soil during warm and wet soil conditions can result in large releases of N₂O. Variable rates and timings of applications that avoid excessive nitrate at the most susceptible times of the year will likely have the greatest reductions. N₂O emissions can be associated with increased CO₂ emissions from soil through enhanced microbial decomposition of labile forms of C.

Considerations for Success

• Use realistic yield targets and available information on nutrient use efficiency to aim for economically optimum application rates.
• It is not in the interest of the IAMP project or from a grower perspective to reduce crop yields however a reduction of fertilizer could result in reduction in crop yield. Incentive payments are geared to assist growers in accepting this risk however the IAMP program will not be covering yield losses. Developing a proper management plan should help to minimize the risk of nutrient management strategies on crop production.
• Equipment for variable rate is expensive and the project cannot underwrite those costs. If employing a variable rate fertilizer strategy, growers may need to hire a custom applicator with the technology to apply variable rate zones.
• Modifying the timing of fertilizer may require additional labor and field costs over traditional practices.
• The type of fertilizer employed (particularly slow-release fertilizers) may be more expensive.

IAMP Preferences/Considerations

The IAMP project particularly encourages practices that result in a net reduction in GHG and increase in soil carbon. IAMP will require a nutrient management plan similar to the NRCS requirement but simplified to focus on improved nutrient efficiency within the boundaries of a field rather than a complete farm plan that considers nutrient budgeting for the entire farm. The IAMP Implementing Partner representative will work with the enrolling grower to develop this plan.

Specific Details

A IAMP field-scale Nutrient Management Plan is required that adequately describes the baseline and the planned fertilizer management strategies and will be developed in consultation with the implementing partner. The plan will include the following:

• Soil testing and analysis for nutrient management confirmations:
  • Pre-plant and post-harvest soil nutrient analysis results including the date and a map showing the geo-referenced locations where pre-plant and post-harvest soil sampling will be taken. IAMP will require pre-plant composite soil samples every foot down to 3 ft and preferably down to 5 ft from each fertilizer zone in the field. Soil samples from baseline or control sections of the field are also required.
  • The laboratory used to analyze the soil samples must meet requirements and performance standards of the North American Proficiency Testing Program under the auspices of the Soil Science Society of America and NRCS or other NRCS- or State-approved certification program (see list of certified Idaho labs at the end of this document).
  • If applicable for the specific crop (e.g. potatoes), include in the Nutrient Management Plan the approach for utilizing and setting fertilizer rates based on in-season tissue, petiole, or sap testing to adjust and drive fertilizer application rates.
• Proposed fertilizer application rates that are:
  • No more than University of Idaho fertility guides based on current soil test results. Please use the following spreadsheet to confirm this application rate “590_ID_GD_Nutrient_Management-Spreadsheet.xlsx".
  • The fertilizer application rates must be at least 15% less than historic baseline application rates on the land parcel to receive payment for a specific year. This can also be demonstrated on the “590_ID_GD_Nutrient_Management-Spreadsheet.xlsx".
  • If applicable, manure applications, including rates, date of application, methodology, and manure testing results.
• A water quality risk assessment analysis:
  • To be performed using the INTRA (Idaho Nutrient Transport Risk Assessment) tool (INTRA_041514.xlsm).
  • Resulting recommendations by the INTRA analysis need to be addressed to meet NRCS compliance and will be included in the plan.
• Variable rate prescription and as-applied fertilizer rate maps, if applicable.
• Statements or other documentation of fertilizer rate, application dates and materials applied.
• Crop yield maps (if available) and geo-referenced biomass samples at geo-referenced soil sampling locations (work with implementing partners/UI on scheduling the collection of these samples).
• Fertilizer and pesticide application information (type, timing, rates, methods of application). As applied fertilizer maps are ideal. Include information on any biological amendment or nitrification inhibitor or slow N release products.

Criteria/Verification

• Confirmation that State requirements and regulations have been followed when applying nutrients near areas prone to contamination, such as designated water quality sensitive areas, (e.g., lakes, ponds, rivers and streams, sinkholes, wellheads, classic gullies, ditches, or surface inlets) that run unmitigated to surface or groundwater.
• Soil testing for nutrient management confirmations:
  • Provide geo-referenced pre-plant and post-harvest soil sampling results for the land parcel that will receive the reduced rates.
  • Statements or other documentation (e.g. as-applied maps, receipts) that demonstrate fertilizer rates and materials applied where within the recommendations described in the nutrient management plan for the field (e.g. at least 15% less than historic baseline application rates).
  • If applicable, provide in-season tissue, petiole, or sap testing results that were used to adjust in-season applications of nutrients.
• Water quality risk assessment using INTRA (Idaho Nutrient Transport Risk Assessment) tool (INTRA_041514.xlsm) completed and recommendations addressed to meet NRCS compliance.
• Crop yield maps (if available) and geo-referenced biomass samples at geo-referenced soil sampling locations (work with implementing partners/UI on scheduling the collection of these samples).

Incentive Payments

$55/acre for each year of implementation with ≥ %15 reduction in N below baseline for the specific crop in the rotation. $1/acre additional for each 1% reduction greater than 15%. Incentives will also be added to include funding to cover the additional soil and manure lab analysis costs.

Stacking or Companion Practices

These practices are compatible with other incentivized IAMP practices: Biochar, Cover crops, Conservation crop rotation (>2 crops), Intercropping, No tillage from conventional, Reduced tillage from conventional, Prescribed grazing, Soil carbon amendment.

Sources

• NRCS Nutrient Management (590)

Soil Testing Labs

Idaho based labs meeting requirements and performance standards of the North American Proficiency Testing Program - Performance Assessment Program (NAPT-PAP) under the auspices of the Soil Science Society of America (SSSA):

Stukenholtz Laboratory, Inc. Twin Falls, ID, 83301-6814 Tel: 208-734-3050 Fax: 208-734-3919 lab@stukenholtz.com http://stukenholtz.com	Plant Performance Assessment Program (PPAP) Soil Performance Assessment Program (PAP) Soil, Plant, Manure/Compost and Water Program
University of Idaho Analytical Sciences Laboratory Moscow, ID, 83844-2201 Tel: 208-885-7900 Fax: 208-885-8937 asl@uidaho.edu http://www.uidaho.edu/asl	Plant Performance Assessment Program (PPAP) Soil and Plant Program Soil Performance Assessment Program (PAP)
Western Laboratories Parma, ID, 83660-5519 Tel: 208-722-6564 Fax: 208-722-6550 Cathy@westernlaboratories.com http://www.westernlaboratories.com	Soil and Plant Program Soil Performance Assessment Program (PAP)