Description

Compost and manure are carbon-based amendments derived from animal byproducts with or without plant materials. Compost is a product created through the controlled aerobic, biological decomposition of plant and animal materials. Manure can also be composed of both plant and animal materials that have not been managed for biological decomposition (e.g. fresh scraped manure or stockpiled manure). Both products have plant-available nutrients, such as nitrogen, phosphorus, and potassium, that need to be accounted for in a nutrient management plan. The emphasis in IAMP is on the reduction of synthetic N fertilizers, a greater reliance on organic sources of N and improving N use efficiency. Incentives are provided for management that replaces at least 15% of the typical baseline synthetic inorganic N demand with organic compost and/or manure sources without exceeding the Idaho State Department of Agriculture Phosphorus (P) limits on cropland.

Benefits

Compost and manure supply nutrients to plants and microbes in addition to carbon. They can reduce soil bulk density and overall soil structure.

Soil Carbon Impacts

Manure and compost additions will likely lead to increased soil carbon.

Greenhouse Gas (GHG) Impacts

During the composting process, microbes aerobically consume organic matter and release CO₂ and other gasses. Composting significantly reduces GHG emissions compared to other low-tech, low-input manure management techniques and stockpiled manure or raw manure land application. Very low GHG emissions come from compost if properly managed. Most GHGs, mainly methane (CH₄) and nitrous oxide (N₂O), can be produced within the first 60 days of composting. Formation of all GHGs and other gasses during composting is biologically driven. Management of the composting process impacts GHG emissions. For example, a lower than ideal C:N ratio increases ammonia (NH₃) and CH₄ emissions but does not affect N₂O; an optimal C:N ratio for reducing GHG emissions is 30:1. Compost pile aeration reduces GHG emissions. The larger the compost pile, the more intensely it must be managed to reduce emissions because anaerobic conditions quickly redevelop after turning. However, when N₂O and CH₄ emissions are reduced, NH₃ volatilization is increased, which is not ideal for compost meant to supply nutrients for crop production.

Considerations for Success

• If equipment is not already owned or readily available, growers may need to hire a custom applicator to apply compost/manure.
• If the field is located far from a composting facility and/or higher application rates are used, the cost of compost could exceed incentive payment.
• Application plan must consider and avoid the accumulation of excess soil salts, P, and Potassium (K).

Options

See NRCS Nutrient Management (590) guide and/or NRCS Soil Carbon Amendment (Codes 336 or 808).

IAMP Preferences/Considerations

The IAMP project incentivizes practices that result in a net reduction in GHG and increase in soil carbon. Practices that optimize phosphorus or other nutrients that do not have any clear direct impact on GHG, and soil carbon would be better supported by other programs (e.g. EQIP and CSP). Manure and compost additions to cropping systems should focus on the four R’s (Right Source, Right Rate, Right Timing of Application and Right Place). Developing a nutrient management plan for a field and implementing these plans, can require yield maps, remotely sensed imagery including near-infrared technology (NDVI/NDRE), soil testing. The IAMP project will provide some level of technical support and training to assist in developing these nutrient management plans, however we encourage producers to work with crop consultants or NRCS planners with experience developing these plans to assist in the development of these plans appropriate for the particular field identified for this program.

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).
  • Nutrient Analysis lab results documenting the carbon and nutrient content in the applied manure or compost.
  • 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 show at least 15% replacement of historic baseline synthetic nitrogen demand with manure or compost to receive payment for a specific year. This can also be demonstrated on the “590_ID_GD_Nutrient_Management-Spreadsheet.xlsx".
• 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% replacement of synthetic fertilizer application rates with manure or compost).
  • If applicable, provide in-season tissue, petiole, or sap testing results that were used to adjust in-season applications of nutrients.
• Manure testing and application rate confirmations:
  • Provide manure testing lab results with carbon and nutrient analysis.
  • Manure/compost application rates, date of application, methodology, and manure testing results.
• 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

$60/acre for compost or manure, in each case to replace 15% of inorganic N applications from baseline rates. An additional $1 per acre for every additional 1% replacement of inorganic N applications beyond 50%. Incentives will also be added to include funding to cover the additional soil and manure lab analysis costs.

Stacking or Companion Practices

Manure and compost fertilizing is compatible with other incentive IAMP practices: Cover crops, Conservation crop rotation (>2 crops), Intercropping, No tillage from conventional, Reduced tillage from conventional, Prescribed grazing, Soil Carbon amendment (Biochar). A caveat for stacking with the no-tillage practice is that only compost should be used (N losses from unincorporated manure would be high), and only at lower rates and in areas not prone to runoff. Stacking as part of a reduced total N application is encouraged.

Sources

• NRCS Nutrient Management (590)
• NRCS Soil Carbon Amendment (NRCS Codes 336 or 808)
• 4R Nutrient Stewardship
• Certified testing laboratories