Understanding plant tissue sampling

Remember learning about the food pyramid in school? The nutritional diagram recommends the proper amount of nutrients you need on a daily basis in order to be healthy. While there is no fancy pyramid drawing out what a plant needs on a day-to-day basis, the concept remains the same both humans and plants have nutritional needs in order to grow and be healthy. In order to find out if your plant is getting fed the proper amount of nutrients, plant tissue sampling can help you identify nutrient deficiencies in the crop.

What sampling can tell us

A tissue sample analysis provides a grower with current nutrient levels of a plant, allowing them to determine the best course of action in rectifying nutrient deficiencies. This information can tell you a plant's needs at various growth stages during plant development. Brett Reese, agronomist for Southern States Cooperative, explains that the results are a snapshot of where your crop is health-wise at that particular time. "The question you should ask yourself is whether you have enough nutrients to get to the next stage of development, Reese said.

Plant tissue is analyzed in a laboratory for key nutrient levels present in the plant: potassium, calcium, magnesium, copper, boron, iron, manganese, iron, zinc, and sulfur, as well as nitrogen and phosphorous. These are the primary nutrients affecting a crop's ability (or inability) to flourish.

"What we do is take a tissue sample and compare it to the soil sample to be certain the plant has enough nutrients to obtain the desired yields that the farmer is looking for, Reese said.

Routine checkup for plants

Think of tissue sampling in terms of how insufficient nutrients negatively affect humans; if you don't consume enough calcium, your bones weaken. If you eat foods with too much cholesterol or eat unhealthy foods, your body is negatively affected. The same is true for a plant.

Tissue sampling can be equated to us having to go to the doctor for a checkup. The doctor performs tests to see where we are health-wise, and gives us recommendations based off those results. Tissue sampling is a doctor's visit for your plant. It can reveal problems within the roots and other hidden issues that lie beneath the surface of your crop that aren't seen by the naked eye.

Combine with soil testing program

A standard soil test measures nutrients in the soil, but a tissue sample test measures nutrients in the actual plant. The results you obtain from a tissue sample can be used in conjunction with soil tests to help determine the ideal fertility needed for the next growth stage. By comparing the tissue sample results to the soil test results done earlier in the year, you can see what nutrient levels were available compared to the current nutrient uptake by the plant in-season.  "Certain nutrients are more mobile in the soil than others and may move deeper than the plant roots at certain stages of growth, Reese explained. "They may appear to be at sufficient levels on the soil test but may have leached out before the plant can uptake them, so sampling can help identify a problem. Our job is to help provide a solution.

Comparing the results of the two samples can also reveal other issues such as compaction. For instance, if you took a 6-inch soil sample and all looked well and good, but then the tissue sample came back low in a certain nutrient, it's likely that compaction of the top soil layer is limiting root growth and preventing those nutrients from uptake.  You may have healthy soil at the surface of the plant and even a couple inches below but compaction issues further down could halt nutrients dead in their tracks, affecting the growth of the roots and overall health of the plant.

Get to the root of the problem

Tissue samples can also help identify certain diseases that attack the roots of your plants and stem underground. Certain diseases and soil-borne pests attack the roots of the plant quickly, weakening their ability to provide nutrients to the plant. These diseases can produce stress on the crop, hampering its development, which in turn will result in lower yields.

How to use results

It's important to understand that tissue sampling should not be a substitute for a soil testing program.

While tissue sampling can reveal much, it should still be considered a piece of the puzzle rather than the whole solution. "Sampling tells you where to start looking to find out the reason why something is happening, Reese explains.

Because many symptoms of distress look the same, it's important to diagnose the right problem before any treatment. For instance, deficiencies of magnesium, sulfur, and zinc, along with lack of sunlight, can all visibly appear the same. Without testing to determine the precise cause, you could waste time and money on solving the wrong problem. 

Economically and environmentally efficient

The goal is to apply the optimal amount of inputs, no more, no less. By over-applying (or under-applying) unnecessary nutrients, you're not getting the best return on investment (ROI) possible. If you know the nutrient status of your plant, you can fine-tune a fertilizer application effectively and possibly identify hidden problems keeping the plant from reaching its full potential. Incorrectly applying fertilizer and nutrient sources can create toxic levels to the plant and also lead to phosphorus or nitrate contamination of water resources, which is environmentally unfriendly.  The old saying, "too much of a good thing isn't always better rings true when it comes to applying inputs to a plant.

Tissue sampling is another practical, economical and agronomically sound tool to add to the proverbial toolbox. Growers know their land better than anyone, but sometimes the plant itself can reveal hidden issues that ultimately lead to precious yield loss that affects bottom line profit. Analysis can help steer you in the right direction so that your yield goal is reached and your harvest is a success. The end result could be higher yields, increased fiscal profit and an overall improved nutrient management program.

Southern States agronomy professionals provide insight about tissue testing to customers throughout the co-op's trade area. Information about Southern States Cooperative and agronomy locations is available at www.southernstates.com.