Have you ever collected a “good” vs. “bad” tissue test only to find that the “bad” sample comes back with equal or possibly higher nutrient levels? When the ALGL agronomy staff reviews tissue test reports this quite common.
For a normal or average corn plant at VT, or tassel emergence, the elements on the tissue test only account for 5 to 10% of the plant’s total dry weight biomass. For an average R3 soybean plant the tissue test only reflects 6 to 10% of the total plant dry matter. So, what is the other 90-95%? Carbon, hydrogen, and oxygen mostly in the form of carbohydrates and structural components. A plant is accumulating the combination of carbon, hydrogen, and oxygen from the atmosphere and soil at a 10x faster rate than those nutrients reported on a tissue test.
Plants manufacture carbohydrates during photosynthesis to be used as energy and the building blocks of the structural components of the plants. A plant that is struggling due to compaction, lack of water, or a host of other factors so that the plant may not be able to assimilate carbon, hydrogen, oxygen at a 10X rate to the other nutrients. As a result, the plant takes up soil nutrients at a relatively greater rate than the assimilation of carbon, hydrogen, and oxygen thus causing the percentages and ppm of the soil derived nutrients to increase in the resulting tissue test data.
When the tissue test data from a “good” and “bad” plant are the same, it is showing that the plant issues are most likely not fertility related. The fact that a plant is smaller does not mean that the nutrient concentrations in the tissue tests will be lower.
A simple example. Fort Wayne, Indiana is home to Debrand Fine Chocolate. If you go into their store to buy chocolate, you can custom build a box of chocolates. If you get the 10-piece box and fill it with 2 fruit filled chocolates and 8 caramels, the fruit filled chocolates would comprise 20% of the chocolates in the box. You could also get a 5-piece box with 1 fruit filled chocolate and 4 caramels, resulting in a box containing 20% fruit filled chocolates. While both boxes are comprised of 20% chocolates containing fruit, most likely the larger box of cholates will have a bigger contribution to yield as measured by the size of your waist.