The Agriculture Laboratory Testing Association (ALTA) (formerly the Illinois Soil Testing Association) has developed a certification program for soil testing laboratories, Soil Analysis Certification (SAC) program. The objective of this program is to assure soil test results provided to Ag producers in the United States are within industry statistical norms of the test method. Based on this premise, soil analysis results from ALTA-SAC certified labs shall be accepted under the U.S. Department of Agriculture NRCS (Natural Resource Conservation Services) code 590 of nutrient management, revised January 2012. The soil certification program is overseen by the ALTA-SAC assessor.
Soil proficiency samples are submitted to each laboratory participant every four months. The ALTA-SAC assessor performs a statistical analysis and evaluates the SAC data. Laboratories providing soil analysis results for each soil method within specified performance limits, are placed on the ALTA list of approved labs and posted on the associations web site, www.alta.ag. Laboratories that fail to meet performance limits of the ALTA-SAC program, will be offered a retest, and program for reinstatement.
Laboratories that wish to participate in the ALTA-SAC program will be required to:
(1) Be a member of ALTA
(2) Be enrolled in the ALP Program for the calendar year
(3) Provide soil analysis by methods recognized by the ALTA, each ALP cycle.
(Recommended Chemical Soil Test Procedures for the North Central Region. (Revised) 1998. Missouri Agricultural Experiment Station SB 1001.)
The required soil test analyses methods are:
- pH H2O (1:1) /or pH (1:1) 0.01 M CaC12
- Phosphorus: Bray-1 P /or Mehlich 3 P SPEC or Mehlich 3 P ICP
- Potassium: NH4OAc Extractable /or Mehlich 3 K
Additional soil tests are encouraged, but currently no required:
- Buffer pH (SMP or Sikora)
- LOI OM (SOM-LOI)
- Exchangable cations- Micronutrients
Assessment of laboratory certification will be based on the laboratory analysis of five ALP soils (ALP test Code 801) each proficiency cycle by the SAC proficiency assessor. Soil analysis performance limits criteria are listed in Table 1 by analysis method. Individual laboratory soil analysis results exceeding the method performance limits of the statistical median, for each soil analysis method will be flagged for failure. ALTA certification shall be based on a 80% level of performance for each soil analysis method, across the five soils of each proficiency cycle. A maximum of only one (1) soil test failure is permitted, to meet certification requirements of the ALTA-SAC program each proficiency cycle.
Laboratories failing to meet SAC performance requirements shall be offered a retest soil sample set for the soil analysis method in question, and with a successful retest, certification reinstated. Retest soil sets can be requested within 14 business days of an ALTA-SAC report. The ALP Program Technical Director will provide a retest soil sample set at a cost of $175. Laboratories which choose not to retest or provide retest results within 14 days will be removed from ALTA-SAC certification.
Laboratories failing the retest soil sample set, shall have an independent consultant audit the lab’s soil analysis method operation and performance at their cost. With the approval of the ALTA-SAC assessor, the lab will be provided a 2nd retest set at an additional cost of $100. Laboratories failing the 2nd retest set will be removed from the certification list for one (1) year. Once annually a year-end report is provided to each ALTA-SAC laboratory listing a summary of the laboratory performance.