Testing Manure for Nutrient Content

Manure testing is necessary to determining the nutrient contest. The following steps outline a simple method of doing this.


What should I sample for:

Manure is variable - that is one sample will not provide a good estimate of the nutrient content for the entire manure pile. Therefore, taking several sub-samples is necessary. The analysis should include moisture content, total nitrogen, phosphorus, and potassium, ash, and organic matter. Ammonia should also be included for liquid manures, but is usually not necessary for solid manures.

Finding a lab to analyze manure:
  • Look in the phone book under laboratories that specialize in agricultural industry.
  • Contact your local County Extension Office and ask them for labs in your area.
  • Contact your local NRCS Office.

IMPORTANT: Contact the lab that will be running the tests before you start sampling, to obtain specific sampling instructions. The following steps are general sampling instructions.

Wet vs Dry basis:

Manure test results can be reported on a wet basis (fresh, as-is) or on a dry basis. Ask the lab to use the wet basis, since this is more practical. (You won't be oven-drying your manure piles before applying them to your fields.)
  • If you are not sure which you have in your report, look at the numbers for % ash, % organic matter, and % moisture:
    • If % ash + % organic matter + % moisture = 100%, it is wet basis;
    • If % ash + % organic matter = %100, it is dry basis.

General Sampling Method:

Collecting Samples from Solid Manure*:

  1. Remove the surface 6" crust and use an auger or shovel to core into the pile.
  2. Take a minimum of six (6) separate sub-samples from different points around the pile.
  3. Combine the samples in a clean bucket.
  4. Mix the samples well and transfer approximately one quart (1 qt.) to a clean plastic bag.
  5. Keep all samples cool until they can be transported to a lab.

Collecting Samples from Liquid Manure*:

  1. Sample from the liquid storage structure, from the outlet pipe, or from the field sprinklers using catch cans.
  2. Collect a minimum of six separate samples (sub-samples).
  3. Combine the sub-samples in a clean bucket, mix well, and transfer approximately one pint of liquid to a clean bottle or other clean, rigid container.

 

For More Information - See These Links

 

* Adapted, with permission, from Utah State University Extension Service, publication "Comprehensive Nutrient Management Planning, A 12 Step Guide."