Source: University of Minnesota Extension
By Daniel Kaiser, Nutrient Management Specialist
1. Don’t expect too much.
Tissue sampling is not an exact science, so take care to get the most information you can. Optimal nutrient concentration values are specific to a plant part sampled at a particular stage. Sampling the correct part and the correct time is critical when using book values to determine nutrient sufficiency.
2. Know which nutrients are most likely to be deficient.
Crop species vary in their sensitivity to deficiencies of specific secondary- and micronutrients. Think about which nutrients are more likely to result in yield reductions before you make decisions.
3. Understand that uptake of one nutrient can affect the uptake of another.
Macronutrients such as nitrogen, phosphorus, potassium, and sulfur can limit plant growth and the uptake of other nutrients. When interpreting results, make correcting macronutrient deficiency a top priority. Any perceived micronutrient deficiency may disappear if you correct the deficiency of an element needed in larger quantity.
4. When in doubt, refer to another source of information.
If you send samples to multiple labs, you might get similar nutrient concentration values, but the interpretations can vary based on who ran the samples. One of the best things to do is find an alternative source of information to compare interpretations of results. Interpretations for micronutrients are especially troublesome. There is likely little to no local data linking micronutrients concentration to yield response, unless a crop is highly sensitive to a deficiency of a specific micronutrient.
5. Try to determine where the interpretations come from.
Research on optimal plant tissue nutrient concentrations has been conducted for well over fifty years. That research has helped to establish optimal concentration levels, but it’s not always clear on a report where that information came from. Ideally, you want data from yield response trials. In reality, though, if a crop is not responsive to a micronutrient, it’s nearly impossible to find local response trial data. Average nutrient concentration values are commonly used in lieu of response data. Therefore, you won’t likely be able to make decisions with yield in mind, so take care when interpreting data for minor elements.
Support for this project was provided in part by the Agricultural Fertilizer Research & Education Council (AFREC).