"Good" Vs. "Bad" Tissue Test Data

Tissue samples are submitted to the lab with the sample ID ‘s of “good” and “bad”, and often the tissue test data results are very similar. Sometimes the “bad” sample will have higher nutrient concentrations than the “good” sample.

Tissue test data is a concentration of a given nutrient within the plant biomass. The concentration is the relative amount of a given nutrient within a defined volume of plant biomass.

Impact of nutrient uptake and plant size on tissue test results.

If nutrient availability in the soil is not limiting, there is no reason to expect the tissue test data between a “good” and “bad” sample to be significantly different. If a plant is limited by physical or environmental factors leading to reduced plant growth, the biomass volume of the impacted plant will be less.  Equally decreased nutrient uptake by the impacted plant will lead to a less total nutrient in the plant tissue tested. Often the decrease in plant biomass is correlated to the relative decrease in nutrient uptake. This leads to a very similar sample nutrient concentration. If the plant biomass is severely impacted while nutrient uptake continues the impacted plant could result in elevated nutrient levels. Observation notes and pictures taken at the time of sampling can be very valuable in interpreting plant tissue data.

Getting a tissue test report back form the lab showing that both the “good” sample and “bad” sample have adequate nutrient concentrations to support plant growth does not mean the tissue test did not tell you anything. It means the issue affecting the growth of the “bad” sample is most likely not nutrient related. Contact your ALG agronomy representative for support using plant tissue data in diagnosis situations.