Plant Testing and Sampling

During the growth of your crop, it is beneficial to monitor the nutrient levels within the plant to identify the fertility needs of the crop. We have established some guidelines for you to follow when sampling and testing plant tissues. Please consider the following.

Plant Sampling Guidelines

Proper plant sampling techniques are essential for meaningful evaluation of crop fertility. Be sure to use clean sample bags which breathe freely. Collect a sufficient number of samples to represent the field--at least 25 to 30. Collect the samples from representative parts of the field. Stay away from odd areas unless they are to be sampled separately.

What Part of the Plant to Collected and Analyzed?

For specific crop sampling procedures see this excellent resource from New Mexico State University.  Feel free to contact us with any additional sampling protocol questions. Label the sample bag and fill out the request sheet. Ship or deliver plant samples to the laboratory as quickly as possible.

Potato Petiole Sampling


It is essential that the correct petiole be sampled. Nutrient levels are not constant throughout the potato plant. University and industry calibration data are based upon the nutrient levels of the 4th petiole down from the top of the plant (see diagram).

The whorl of small undifferentiated leaves at the top of the plant are counted as leaf #1. The leaves are counted downward until leaf #4 is identified. Remove the entire leaf from the stem. Hold the leaf by its stem end and strip off the leaflets. The bare petiole that remains (see right side of diagram) is the plant part saved for analysis.

We recommend that a sample area or transect be identified in each potato field. From 25 to 35 petioles need to be collected at each sampling in order to provide the laboratory with enough sample for accurate analysis.

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