In citrus, boron increases nitrogen efficiency, bloom size with thicker petals and larger fruit size (photo by John Fair Photos. Used by permission.) Continued from Page 15 lowed. Other products may be allowed depending on the material and the rules used for certification. There are some soils with a pH below 6.0 that still have a sufficient level of calcium to justify a safe and effective boron application. But there are also soils with a pH of 8.0 that have such a low base saturation of calcium that even half the normally safe rate for that soil with a pH below 6.0 could be toxic even with the same crop growing there. There may be several reasons why, and this is in no way meant to imply anyone is trying to deceive the growers. First of all, too many assume that soil pH is all you need to determine whether boron will be a problem in plants. This is a false assumption. It is not soil pH that accurately determines boron toxicity. It is whether each soil has enough available calcium or not. We recommend and use plant tissue testing for evaluating nutrient levels in plants. However, in certain cases where micronutrient levels are in question, the plant analysis will come back showing a sufficient level when the soil test shows there is still a need for more to achieve the best results. When it comes to the use of micronutrients, we follow and trust the guidance of the soil tests we use over that of plant analysis. For example, leaf testing for boron content will tell growers they have enough when soil tests will show boron as still not being there in sufficient amounts for the crop in question. Growers should be cautious when considering whether their soils need boron or not. There is a great disparity between plant testing and soil testing to show when more boron is needed. For example, when sufficient boron is applied to the soil to reach the ideal level for the best response and growth for citrus, leaf tests from this same grove may report toxic levels in the leaf. This type of warning has been given even when there is no sign of toxicity in the leaves or other plant parts, and, in fact, those who know citrus best would actually choose those trees as the best of the best based on looks, plant response and fruit production. Boron is an anion, which means it can be leached out of the soil because it is not attracted and held by the clay colloids in the soil. Humus is able to attract and hold some, but generally far too little to keep sufficient boron levels for the crops to be grown there from year to year. Like nitrogen and sulfur, boron can be easily leached from the soil. Consequently, though in some heavier clay soils it is possible to build boron sufficiently enough that, for a year or two, adding more is not necessary, most soils need at least some build up every year. Although needed in very small amounts, boron enables plants to utilize needed nitrogen, helps increase size in fruit, grain or seed production, and at excellent levels along with adequate copper, helps in preventing and controlling rust and fungus diseases. Apply boron based on actual need as determined by soil tests. Using too little or too much can be extremely costly. Do not guess. You cannot manage what you do not correctly measure. Neal Kinsey is owner and President of Kinsey Agricultural Services, a consulting firm that specializes in restoring and maintaining balanced soil fertility. For more information please call (573) 683- 3880 or see www.kinseyag.com. Comments about this article? We want to hear from you. Feel free to email us at article@jcsmarketinginc.com 16 Organic Farmer <strong>Dec</strong>ember/<strong>Jan</strong>uary <strong>2020</strong>
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