Soil Testing and Plant Diagnostic Services

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Orchard and vineyard plant testing

Procedure for sampling vegetables, fruits and trees

Crop Stage of growth sampled Plant part or leaves to sample Approximate number
Apples July 15 to Aug. 15 Leaf from middle of current terminal shoot 60
Asparagus Mature fern (August)Fern from 17 to 35 inches up 20
Beans, snap Initial flowering Young mature trifoliate 50
Beans, table MatureYoung mature leaf 20
Blueberries First week of harvestYoung mature leaf 50
Broccoli HeadingYoung mature leaf 15
Cabbage Heads, 1/2 grownYoung wrapper leaf 15
Cantaloupe Early fruitingFifth leaf from tip 25
Carrots MidgrowthYoung mature leaf 25
Cauliflower ButtoningYoung mature leaf 15
Celery Half-grownYoung mature leaf 20
Cherry SummerMature leaves from new growth 50
Cucumbers Early fruitingFifth leaf from tip 20
Grapes Veraison Petiole from young mature leaf on shoot (one petiole per shoot) 60
Lettuce Heads, 1/2 sizeWrapper leaf 20
Onions MidgrowthTop, no white portions 25
Peaches and nectarines Spring at fruit setMidshoot leaf 20
Peas First bloomRecently matured leaflet 50
Pecan 56-84 days after terminal bud setleaflet pairs from new growth 25
Peppers Early fruitingYoung mature leaf 20
Plum SummerWhole leaf from midshoot growth 25
Potatoes 40 to 50 days after emergenceYoung mature leaf 20
Pumpkin and squash Early fruitingYoung mature leaf 15
Radishes Midgrowth to harvestYoung mature leaf 40
Raspberries First week in AugustLeaf 18'' from tip 50
Spinach 30 to 50 days oldYoung mature leaf 35
Strawberries At floweringYoung mature leaf 20
Sweet corn Tasseling to silkEar leaf 10
Tomatoes First mature fruitYoung mature leaf 20
Walnut, black SummerMature leaf from new growth 5
Walnut, English SummerCenter leaflet from mature leaf 25
Watermelons MidgrowthYoung mature leaf 15

Submitting plant samples

The when and how of plant sampling is very dependent on the crop sampled.

Instructions for sampling and submitting samples as specified by the Columbia lab should be followed. See specific instructions on selected field crops, vegetables, and fruit crops. The recommended time to sample is just prior to the beginning of the reproductive stage for many plants. Please check the listings under the selected crops first.

  • Paired samples
    Where a deficiency is suspected, take samples from normal plants in an adjacent area as well as from the affected area. You will be charged the price of only one sample when an abnormal sample is accompanied by a normal sample. Take a soil sample from each area also.
  • Dusty plants should be avoided
    If dust is present, brushing or wiping with a clean damp cloth may be sufficient. If not, rinse briefly with water while the material is still fresh.
  • Care and handling of sample
    Air dry the sample and put in a clean paper bag or envelope and take it to the county extension Center or mail it to the lab located in Columbia.
  • Sample 25 to 30 plants throughout the area.
    Fresh plant tissue should be air dried before sending. After air drying put the sample in a clean paper bag or envelope.
  • When no specific sampling instructions are give
    The general rule of thumb is to sample upper, recently mature leaves. The recommended time to sample is just prior to the beginning of the reproductive stage for many plants.
  • Completion of the information form
    It is essential for the lab to properly interpret the plant analysis.

Where to submit plant samples

  • County extension centers
    (preferred method)
  • Soil and Plant Testing Laboratory
    23 Mumford Hall
    Columbia, MO 65211
    Phone: 573-882-0623
    Fax: 573-884-4288

Sample submitted directly to the lab should be accompanied by the sample information form and a check for the amount due payable to MU Soil Testing, unless you have an account with us. If you have an account with us fill in the firm and outlet number and we will bill you at the end of the month.

Only the lab in Columbia performs plant analysis. When submitting a sample to the lab the sample information form should be filled out accurately for the lab to properly interpret the plant analysis. Send the original form with the plant sample(s) and retain a copy for your records.

Plant analysis sample information forms can be picked up at the county extension centers or at the MU Soil and Plant Testing Laboratory free of charge or printed from the Web.
Plant analysis sample information form (RTF)

Plant analyses fees

Regular analysis
Nitrogen, phosphorus, potassium, calcium and magnesium and drying and grinding
Micro nutrients only
Copper, iron, manganese and zinc
Regular analysis plus micro nutrients
Ccopper, iron, manganese and zinc
Nitrogen (TKN) $10
Phosphorus (P) $5
Potassium (K) $5
Calcium (Ca) or Magnesium (Mg) $5
Iron (Fe) $4
Copper (Cu) $4
Manganese (Mn) $4
Zinc (Zn) $4
Total Nitrogen (N) by combustion $9
Total Carbon (C) by combustion $9
Total Sulfur (S) by combustion $9
Total C and N by combustion $16
Total N, C, S by combustion $24
Nitrate-N $8
Boron (B) $5
Chloride $6.50
Sample grinding $2
  • 10 percent discount on 30 or more samples
  • A sample preparation fee of $2 per sample will be added to all plant tissues that need to be dried and ground.
  • Testing fee for a good sample accompanying an abnormal sample will be one-half the regular price.

In the labTurnaround time

  • Soil sample analysis
    1.5 working days after samples are received in the lab
  • Plant, compost, greenhouse media and water analysis
    4 to 5 working days after samples are received in the lab

If samples are mailed allow time to and from the lab. Results of samples submitted through county extension offices are mailed first to the county agronomist or horticulturalist for comments or individualized recommendations. The county then mails the recommendations to the person submitting the sample.

Soil test reports can be emailed on request at no charge or faxed for a nominal fee.

Plant test results and interpretations

  • We use the sufficiency and survey ranges as reported in the Plant Analysis Handbook II by Harry A. Mills and J. Benton Jones, Jr. 1996. MicroMacro Publishing, Athens, Ga.

Updated 3/1/11