Soil Nutrient management
Micronutrients
Boron
Boron uptake is the result of the passive assimilation of undissociated boric acid (H3BO3).
Of all the micronutrients boron is one of the most commonly deficient. Most crops are not able to mobilize boron from vegetative tissues to actively growing, meristematic plant tissues such as shoots, root tips, flowers, seeds, or fruits. Because of this, deficiency symptoms first develop in newly developed plant tissue such as young leaves and reproductive structures.
Boron toxicity is characterized by yellowing of the leaf tips, interveinal chlorosis, and progressive scorching of the leaf margins. Symptoms progress to necrosis (browning) and premature drop of foliage.
Somewhat like nitrates, boron is not readily held by the soil particles and moves down through coarse-textured soils, often leaching below the root zones of many plants. Because less leaching occurs on fine-textured silts and clays, these soils are not boron deficient as often as sands. Clay soils with high organic matter levels are usually highest in boron. However, in some heavier-textured (clay) soils, plant-available boron may be low due to the strength by which boron is held on the clay surfaces.
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