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The Missouri Soil Testing Association (MSTA) Approval Program is designed to assure that results provided by participating public and private labs serving the citizens of Missouri agree with allowable statistical limits. This is accomplished by evaluating the soil testing laboratories in their performance through interlaboratory sample exchanges and a statistical evaluation of the analytical data. Based on this premise, soil test results from MSTA approved labs will be accepted by the U.S. Department of Agriculture, Farm Service Agency (FSA) and Department of Natural Resources and Conservation Services (NRCS) in federally assisted cost share programs and nutrient management plans in the state of Missouri.

Beginning in 1999, MSTA combined its efforts with the North American Proficiency Testing Program (NAPT). The NAPT coordinator sends soil test data from quarterly sample exchanges of the labs participating in MSTA program to the state coordinator.

The MU Soil Testing Lab director serves as the state program coordinator and performs statistical analysis of the data as specified in the MSTA program. If a lab's results fall within the allowable limits, the lab will be placed on the Farm Service Agency's (FSA) list of approved labs. A lab that is not approved may re-apply after six months.

Approval procedures for MSTA labs

The labs that wish to participate in the MSTA program should send a formal written request to the director of the University of Missouri Soil Testing Laboratory. They also need to request the NAPT coordinator to include their lab to the Missouri State Certification list and sign the Missouri release form giving authorization to send test results to the MSTA program coordinator.

Participating labs must use procedures of the Missouri Soil Testing Program in current use as described in the University of Missouri Extension Guide #923 (August, 1983) entitled, Soil Testing in Missouri. An updated version of this guide is available on the MU Soil and Plant Testing Lab's Website at: http://soilplantlab.missouri.edu/soil/soilprocedures.htm.

The lab will be approved for routine soil tests:

• Bray-IP
• ammonium acetate extractable K, Ca, and Mg
• Organic matter
• pH in 0.01 M CaCl2
• Neutralizable acidity (using the Modified Woodruff Buffer test)

The MSTA coordinator will receive results of the quarterly sample exchanges from the NAPT program coordinator on the recommended tests and do the statistical evaluation.

Approval criteria for MSTA labs

The MSTA program uses the median and median absolute deviation (MAD) as used by the NAPT program as robust estimations of central values and variances of all data sets. This statistical approach is less sensitive to influence of extreme values (outliers) than the mean and standard deviation. The MSTA summary report lists the median and MAD values and the lab data. If the lab's data falls outside the range of +2.5x MAD (it is marked as Low or High) and considered to be out of the allowable limit. If the lab data falls outside the limits of +3.5x MAD they are marked as outliers. Test results of 75 percent of the samples must fall within the above allowable limits for each test. Upon meeting these criteria a letter will be sent to FSA to add the requesting lab to the list of approved labs in Missouri. If a lab fails the lab director may discuss with the MU Soil Testing Lab director ways to solve problems at the expense of the requesting lab.

List of MSTA Approved labs

Georgia
Waters Agricultural Laboratories, Inc.,
257 Newton Highway, PO Box 382
Camilla, GA 31730

Illinois
Alvey Labs,
1511 East Main St.,
Belleville, IL 62221

Ingram's Soil Testing Lab,
RR2 Box 309, 7 Oaks Farm,
Athens, IL 62613

Mowers Testing,
117 East Main St.,
Toulon, IL 61483-0518

Indiana
A&L Great Lakes Laboratory, Inc.,
3505 Conestoga Drive,
Fort Wayne, IN 46808

Iowa
A&L Heartland Laboratory, Inc.,
111 Linn St., PO Box
455, Atlantic City, IA 50022

Ag Source Belmond Labs,
1245 Highway 69 N,
Belmond, IA 50421

Kentucky
Waters Agricultural Laboratories, Inc.,
2101 Old Calhoun
Road, Owensboro, KY 42301

Missouri
Custom Lab,
204 C St.,
Golden City, MO 64748

Delta Soil Testing Lab,
University of Missouri, PO Box 160,
Portageville, MO 63873

MU Soil and Plant Testing
Lab, University of Missouri, 23
Mumford Hall, Columbia, MO 65211

Perry Agricultural Lab,
PO Box 418, State Highway 54 East,
Bowling Green, MO 63334

Nebraska
Midwest Laboratories, Inc,
13611 B St.,
Omaha, NE 68144-3693

Ward Laboratories,
PO Box 788,
Kearney, NE 68848

Ohio
Brookside Lab Inc.,
308 S. Main St.,
New Knoxville, OH 45871

Spectrum Analytical,
PO Box 639,
Washington Court House, OH 43160

Tennessee
A&L Analytical Laboratories Inc.,
2790 Whitten Hall,
Memphis, TN 38133

Note: Approval of soil analysis does not imply approval of fertilizer and limestone recommendations.

Manjula V. Nathan, Director, MU Soil
Testing and Plant Diagnostic Service Laboratories
NathanM@missouri.edu