Boron is included in the Standard Soil Test. The level of soil boron is “insufficient” or “low” when extractable boron is less than 0.1 pound per acre. Soil boron is found in both organic and inorganic forms that are made available to plants as either or both soil organic matter is decomposed and/or boron-containing minerals dissolve. There may be between 20 to 200 pounds boron in the surface layer of South Carolina soils, but only a small portion is available to plants. Boron, as the borate (BO3 3-) anion, is mobile in the soil and can be easily leached from the surface soil.

Calcium, potassium, and nitrogen concentrations in both the soil and plant can affect boron availability and plant function, the calcium:boron (Ca:B) ratio relationship being the most important. Therefore, soils high in calcium will require more boron than soils low in calcium. The chance for boron toxicity is greater on low calcium-content soils.

Major Functions of Boron in Plants

Boron plays a key role in a diverse range of plant functions including cell wall formation and stability, maintenance of structural and functional integrity of biological membranes, movement of sugar or energy into growing parts of plants, and pollination and seed set. Adequate B is also required for effective nitrogen fixation and nodulation in legume crops.

Boron deficiency commonly results in empty pollen grains, poor pollen vitality and a reduced number of flowers per plant. Low B supply can also stunt root growth,

Boron Deficiency Symptoms

Most crops are not able to mobilize B from vegetative tissues to actively growing, meristematic plant tissues such as shoots, root tips, flowers, seeds or fruits. Rather, B transport occurs primarily in the xylem channel, resulting from transpiration. Because of this, deficiency symptoms first develop in newly developed plant tissue such as young leaves and reproductive structures

Content: 

Boron (B)

Crops

For All Crops