In-season tissue testing is a valuable tool for monitoring plant nutrition, identifying hidden nutrient deficiency, and making timely corrective in-season action if possible. While foliar application may not always fully resolve deficiencies, the information gained from tissue analysis can be used to make adjustments for subsequent growing seasons.

How to Collect Tissue Samples

Nutrient concentration in plants varies depending on the growth stage and type of tissue collected at sampling, which ultimately affect the interpretation of tissue analysis. Instructions for taking tissue samples are shown below

• After collection, samples should be placed in a breathable paper bag or envelope.
• Clearly indicate the growth stage and plant part sampled when submitting samples to the laboratory to avoid improper interpretation and recommendations.
• Detailed instructions for taking tissue samples for corn, cotton and soybean are presented below or refer to UT Extension Publication W976: Visual Symptoms: A Handy Tool in Identifying Nutrient Deficiency in Corn, Cotton and Soybean.

Interpreting Tissue Test Results

Environmental conditions can affect nutrient concentration in plants.

• Drought stress may lead to higher-than-normal nutrient concentrations due to smaller leaf size.
• Flooded or waterlogged soils can temporarily disrupt nutrient uptake and concentration in plants.

Under the above stated conditions, the nutrients may not be the most yield limiting factor. It’s important to report any unusual environmental conditions when submitting samples to help avoid misinterpretation. Also, plant tissue analysis reflects the nutrient level in the plant and not the status of nutrients in the soil. For example, a cotton leaf may show potassium (K) deficiency even if the soil K levels are adequate. This information should be well-thought-out when considering in-season corrective actions.

Making Nutrient Recommendations

To generate recommendations, tissue test results are compared with an established sufficiency range. The University of Tennessee’s tissue analysis recommendations are based on SERA-IEG-6 publication titled “Reference sufficiency ranges for plant analysis in the Southern Region of the United States”. The table below lists the sufficiency ranges for different nutrients for corn, soybean, and cotton based on growth stage and plant part.

• If nutrient concentrations fall within the sufficiency ranges, they are considered adequate and unlikely to limit yield.
• If the tissue test is below the sufficiency ranges, then the nutrient may be a limiting factor, and corrective action should be considered.