IAMP-Nutrient Management with N reduction
(NRCS Code 590)

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

IAMP has several requirements for this nitrogen reduction nutrient management practice to ensure fertilizer application rates are not excessive as well as document the effectiveness of the practice from the current nutrient management strategies employed in the field. The cost of analysis of any required soil, crop, or biomass sampling and analysis will be covered by the IAMP project. For an overview of all required sampling for each IAMP practice, see IAMP required sampling. Implementing partners will be assisting with the collection of any sampling related to the practice. Each of these requirements is described below.

1. Baseline strip: Producers will maintain a minimum strip of 80 ft in length and a minimum width of 20 ft where the full baseline synthetic fertilizer rate will be applied as a comparison to the rest of the field. The actual dimensions of the strip can vary to be compatible with the width of implements used to manage the field.
2. Soil Carbon sampling: Paired soil sampling points in the baseline strip and in the treated field at the start of the project and at the end of the project is required to track the changes in soil carbon over the duration of the project, see the IAMP Soil Sampling Protocol.
3. Soil Nutrient sampling: Paired soil sampling points in the baseline strip and in the treated field prior to planting and after harvest every ft down to 3 ft is required (down to 5 ft is preferred) to set fertilizer rates, assess the impacts of the practice on available soil nitrogen, and identify any nutrient deficiencies/benefits from the implemented practice, see the IAMP Soil Sampling Protocol.
4. Crop Biomass sampling: Paired above ground crop biomass measurements at the paired soil sampling locations will be required prior to harvest and will be evaluated for total dry biomass weight as well as the percent carbon and nitrogen, see the IAMP_Crop_Biomass_Sampling_Protocol.
5. Nutrient Management Plan: Using the following NRCS spreadsheet 590_ID_GD_Nutrient_Management-Spreadsheet.xlsx to demonstrate both the baseline and proposed fertilizer management strategy. The proposed nutrient management application rates must not exceed University of Idaho fertility guides. The initial agreement will be approved based on grower provided historic fertilizer rates, actual or estimated pre-plant soil nitrogen. Each year following implementation of the practice planners will ensure nitrogen reduction was at least 15% based on actual soil tests taken as a part of the IAMP practice and that the actual fertilizer rates did not exceed University Idaho fertility guides.
6. Water Quality Risk Assessment: Use the INTRA (Idaho Nutrient Transport Risk Assessment) tool INTRA_041514.xlsm to ensure the proposed practice does not pose a risk to water quality. Any recommendations by the INTRA analysis need to be addressed to meet NRCS compliance and must be included in the plan.
7. Grower supplied field management information:
   • Any specific crop (e.g. potatoes) used to set in-season fertilizer applications such as tissue, petiole, or sap testing.
   • 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 for both the baseline strip and the remaining field).
   • 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. An additional $1 per acre for each additional 1% reduction beyond 15% up to a maximum of 50% (i.e. maximum payment of $90 per acre at a 50% reduction). 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)