Quality Control

August 2, 2013

To ensure accuracy with results, the Agricultural Service Laboratory is involved in three different sample exchange programs:

  1. The Association of American Feed Control Officials submits one sample monthly for analysis of protein, minerals, fat, ash, acid detergent fiber and neutral detergent fiber.
  2. The National Manure Analysis Proficiency Program submits samples quarterly for analysis of NH4-N, total N, minerals, nitrate nitrogen, soluble phorphorus, pH, and dry matter.
  3. The Agruicultural Laboratory Proficiency (ALP) submits 5 soil for the routine test, organic matter, soluble salts, and sulfur, 3 water for the special test, and 3 plant samples for N, minerals, Cl, and NO3-N quarterly.

Reports from each of these groups are evaluated and kept on file at the Agricultural Service Laboratory.

The Agricultural Service Laboratory follows several established procedures to ensure quality control on a daily basis:

  1. A tissue sample purchased from the National Institute of Standards and Technology is dry or wet ashed and analyzed on the ICP on a daily basis along with the feed and forage, plant tissue, animal waste, and compost samples.  Solution standards are run at the beginning, midpoints, and end of each set.
  2. A glycine standard is digested and analyzed daily and a standard solution of ammonium sulfate is distilled daily to ensure quality control for analysis of Kjeldahl nitrogen in feed and forage and animal waste samples.
  3. An orchard leaf or peach sample from NIST is analyzed every 15 samples for feed and forage, plant tissue, animal waste, and compost being analyzed for total nitrogen.
  4. A sample provided by the Association of American Feed Control Officials is analyzed with each set of feed samples requiring percent fat to ensure quality control for fat.
  5. A sample provided by NFTA is analyzed with each set of feed samples requiring fiber to ensure quality control for fiber.
  6. Two check soil samples with established results are analyzed daily along with each set of 100 soil samples.  The check soils are used with the mineral analysis and pH determination.  A blank is also included within each set of 100.
  7. Solution standards are analyzed on the ICP for each set of 100 soil samples at the beginning, mid-point, and end of each set.
  8. For pH, along with the two check soil samples, samples at the beginning, middle, and end of every set are rescooped and checked at the end of the run.
  9. Quality control soil samples are analyzed along with soil samples requiring nitrate nitrogen.
  10. An NIST orchard leaf standard is analyzed along with the feed, plant, and manure samples for nitrogen.

The procedures used at the Agricultural Service Laboratory are referenced and documented in the literature.