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Mulching with Wood Chips (Code 484)

The Natural Resources Conservation Service is offering conservation assistance by encouraging California growers to use new and innovative agricultural emission reduction practices and technologies that provide significant environmental benefits to our natural resources.

The Mulching practice standard improves air quality by applying plant residues or other suitable materials produced off site to the land surface for reducing airborne particulate matter (PM) and dust.  Additional resource benefits from mulching include conserving soil moisture by preventing evaporation, reducing energy use with irrigation, protecting the soil surface from erosion, managing weed growth, establishing vegetative cover, and improving soil health. 

The Environmental Quality Inventive Program (EQIP) applies this practice towards the surface application of chipped woody biomass as mulching materials for reducing windborne PM and dust from croplands.  Each eligible application undergoes a screening and ranking process to consider the air quality benefits of any planned conservation practice, as identified by local, state, and national priorities.  Offered statewide, proposals for applying wood chips as mulch within any PM nonattainment area of California will receive a higher priority.

Program Guidelines:  484 - Mulching

California growers must meet EQIP eligibility requirements to qualify for payments.

  • The contract length is two years.  A single payment in the first year of the contract after the treatment is complete. 
  • The payment pertains towards the area of wood chips applied and not necessarily the total crop acreage or tons of materials applied.  Not available are payments for transporting wood chips to the site, or for site preparation, monitoring or maintenance.
  • Prepare the site by removing trash, weeds, and other debris that will interfere with mulching application, effectiveness or maintenance. 
  • Produced off-site, the wood chips may originate from another producer’s orchard or vineyard removal, a forestry or tree mortality project, or an urban wood-waste operation.  Not included are wood fiber materials applied by hydro seeding.
  • The wood chips should be free of any foreign debris such trash or chemically treated wood.  State law prohibits mulching with chemically treated wood.
  • The size of wood chips should be between ¾ and 2 inches in diameter.  Smaller chips are easier to spread, especially around small plants.  Larger diameter chips are acceptable, but discouraged due to clogging application equipment, damaging crops or trees during application, or taking longer to decompose.
  • Apply a two to four-inch layer of wood chips to the soil surface, which equates to a minimum application rate of 10 tons per acre.  Do not incorporate the wood chips into the soil.  Applying a thicker layer is acceptable, but consider that too much mulch may promote soggy and anaerobic conditions at the soil surface during the wet season or prevent irrigation from reaching the soil during the dry season. 
  • The appropriate amount of woody biomass applied can result in a positive trend in soil organic matter, according to the NRCS Soil Conditioning Index (SCI).
  • Consider planting a cover crop in conjunction with mulching to ensure adequate soil protection from wind and water erosion.  
  • Mulching can reduce greenhouse gas emissions and sequester carbon. Use COMET-Planner  to estimate the potential greenhouse gas benefits from mulching or any other conservation practice treatment.
  • When spreading around trees, keep mulch at least one inch away from the trunk.    
  • Evaluate the effectiveness of the mulch application.  Monitor and control undesirable weeds in the mulched areas.
  • The practice lifespan is one year.

For More Information

For more information about the Environmental Quality Incentives Program (EQIP), please contact your local USDA Service Center, listed in the government section of the phone book under U.S. Department of Agriculture. Information is also available on the Internet at


Updated: 11/15/2017