The Agriculture Laboratory Testing Association (ALTA) (formerly the Illinois Soil Testing Association) and the Soil & Plant Analysis Council (SPAC) have jointly developed a certification program for plant analysis laboratories: Plant Analysis Certification (PAC) program. The objective of this program is to assure plant nutrient analysis provided to ag producers in the United States are within laboratory statistical norms of the method. The PAC certification program is overseen by the ALTA-PAC assessor.
Plant proficiency samples are submitted to each laboratory participant three times annually. Once per year the ALTA-PAC assessor performs a statistical analysis and evaluates the PAC data. Laboratories providing plant analysis results for each nutrient 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 method performance limits of the ALTA-PAC program, will be offered a retest, and program for reinstatement.
Laboratories that wish to participate in the ALTA-PAC program will be required to:
(1) Be a member of ALTA.
(2) Be enrolled in the ALP Program for the calendar year.
(3) Provide plant nutrient analysis by methods recognized by the ALTA, each ALP cycle.
The required plant analysis methods are:
- Macro nutrients: N, P, K, S, Ca, and Mg
- Micro nutrients: Zn, B, Cu, Mn, and Fe
- Optional: NO3-N, NH4-N, PO4-P, and CL
Assessment of laboratory performance will be based on the laboratory analysis of twelve ALP plant samples (ALP test Code 802) each year by the PAC proficiency assessor. Plant analysis performance limits are based on participant consensus results by nutrient. Individual laboratory plant analyses exceeding performance limits of the statistical median, for each plant nutrient will be flagged for failure. ALTA certification shall be based on a 84% level, 10 of 12 analysis results within statistical control limits for each plant nutrient, in a calendar year. A maximum of two plant analysis failures per nutrient is permitted each year, to meet certification requirements of the ALTA-PAC program.
Laboratories failing to meet PAC certification requirements shall be offered a retest plant sample set for the nutrient analysis failures, and with a successful retest, certification reinstated. Re-test plant samples can be requested within 14 business days of an ALTA-PAC report. The ALP Program Technical Director will provide a retest plant 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-PAC certification.
Laboratories failing the retest plant sample set, shall have an independent consultant audit the lab’s plant analysis method operation and performance at their cost. With the approval of the ALTA-PAC 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-PAC laboratory listing a summary of the laboratory performance.