Price: $25 per sample. Includes soil analysis if sample provided.
Optional Soil Tests: Calcium + Magnesium: $3 | Boron: $3 | Zinc: $3 | Manganese: $3 | Sulfur-Sulfate: $3
Forms & Instructions: Submission Form | Form Instructions | Sampling Instructions
Why test?
Tissue analysis is the best way to evaluate the nutrient levels of plants in order to correct or prevent nutrient deficiencies.
Analysis and Reporting
The report will show the concentration of N, P, K, Ca, Mg, S, Zn, Mn, B, Cu, Fe, Al, and Na in the plant sample. If a soil was submitted with the plant sample, soil analyses for pH, organic matter, P, K, and any special soil test results will also be reported. In addition, the analytical levels of nutrients in the plant and soil will be interpreted to reflect nutrient deficiencies, toxicities, or imbalances by the sufficiency range approach, and if calibration data are available, the nutrient ratio method. When warranted, fertilizer recommendations will be made based on the analytical results. Most commonly grown field vegetables and fruit crops will receive these interpretations and recommendations. For those plant materials where calibration data are not available, these analytical results will be provided without interpretation. View a sample report.
Plant analysis results are interpreted by one or more of three methods: sufficiency range (SR), diagnosis and recommendation integrated system (DRIS) and plant analysis with standardized scores system (PASS). By comparing the three methods of interpretation, it should be possible to arrive at a clearer picture of the plant’s nutrient status than by using only one method.
The SR system is based on the relationship between nutrient concentration and yield-if the soil is deficient in a certain nutrient, then an increase in the supply will increase concentration in the plant and increase yield. The concentration range identified as sufficient is defined to result in 95 to 100% of maximum yield. The system is sensitive to plant maturity and plant part sampled. Interpretations are reliable only when used for the specific plant part sampled at the specific growth stages where interpretations have been developed. The diagram integrates plant analysis and the soil test results where plant analysis sufficiency range and optimum soil test levels are the middle circle. The inner circle indicates deficiency or below optimum levels and the outer circle marks above optimum concentrations. Plant nutrient concentration survey data are substituted when sufficiency range information is not available. Survey data have not been evaluated by yield response calibrations and are to be used only for general comparison.
The DRIS is a method to evaluate various combinations of ratios of nutrient concentrations rather than the actual concentrations. These ratios are combined mathematically to give an index. An index of 0 is ideal while the more negative the index, the greater potential of nutrient deficiency; the more positive the index, the greater potential for excessive concentrations. The sum of these indices for a given analysis must be zero. To avoid errors diagnosing deficiencies when deviations from zero are really random error, an in-balance range is defined as -15 to +25. DRIS norms are available for alfalfa, apple, corn, celery, lettuce, millet, oat, potato, grain sorghum, tomato and wheat.
The PASS system is a hybrid that combines an independent index (INI) as in SR and dependent index (DNI) as in DRIS. The PASS INI section is similar to SR, but instead of a nutrient category, a continuous index based on the statistical standardized score is determined and expressed on the DRIS scale. INI values between -10 and +10 are considered sufficient. An INI value of less than -10 equals the critical level and is considered deficient. The further below -10 the INI values are, the more likely the addition of that nutrient will increase yield. To avoid predicting yield responses when they are unlikely as sometimes occurs in both SR and DRIS, the nutrients in the PASS INI system are divided into 2 groups: those for which yield response is common (dark green bold values) and those for which yield response is rare (light green values). The PASS DNI is similar to DRIS where paired nutrient ratios are calculated and compared to optimum values with the standardized scores approach and expressed on the DRIS scale. The DNI is best used to confirm a deficiency indicated by the INI. Only the nutrients in the common response category of the INI are included in the DNI. PASS norms are available for alfalfa, corn and soybean.
Sampling
Sample collection is critical for plant analysis as plant nutrient composition varies with age, the portion of the plant sampled, and many other factors. Mistakes or carelessness in selecting, collecting, handling, preparing, or shipping plant tissue for analysis can result in unreliable data, which may lead to incorrect interpretations and recommendations. Standards, against which the sample is evaluated, have been selected to represent the plant part and time of sampling that best define the relationship between nutrient composition and plant growth. Deviation from the prescribed protocol severely limits this interpretations capability. It is, therefore, critical to follow a standard sampling procedure. Please see these sampling instructions for more information.
| About Us | Resources | |
| Services & Fees | Procedures | |
| Contact Us | Soil Test Summary | |
| Staff | Forage Database | |
| Our History | WDATCP Labs | |