Boron is one of the top five micronutrients that can affect crop yield — especially for wheat and canola — in western Canada. Most crops need two to three pounds of boron per acre of soil. Boron is most accessible to plants through borate complexes of calcium, magnesium and sodium and through other naturally occurring organic compounds caused by microbial decomposition.
Plants need boron for pollination and seed production processes. Plants use boron in metabolising nitrogen and forming proteins. The micronutrient also helps in the transport of potassium through the plant to help internal cells maintain proper control of water. Another function of boron is to maintain the balance of sugars and starches within the cells and translocation of sugars and carbohydrates. Finally, boron is essential to normal cell division and the subsequent formation of the cell walls. It is easy to see that boron is essential to the proper growth of plants.
If boron is deficient in the soil it can be seen in the plant growth or structural formation during the growing season. Chlorosis of the leaves is a symptom of boron deficiency in younger plants. In canola, leaves may become distorted or misshapen, and you will find blank or partially filled pods.
In boron-deficient wheat, heads will become distorted and you’ll see chlorosis of leaves. Leaves may also become twisted or spiralled.
Common signs of boron deficiency among all crops are darker leaves that may become retarded or wrinkled and thicker than they should be. Because boron is essential to cell wall formation, shortage can cause a plant to become brittle due to weak cell walls.
WHAT CAUSES DEFICIENCY?
Boron can become deficient in the soil in a couple different ways. Boron comes from soil organic matter, so high tillage operations or any other operation that greatly reduces the organic matter in the soil greatly reduces the primary natural source of boron. Also crops that need to be highly fertilized with commercial fertilizer have been found to return less boron to the soil with their organic matter.
Soils with pH balances above 6.5 tend to have lower levels of boron than soils with pH below that level. The soil can also lose boron through leaching in regions of high rainfall or regions were the soil is very coarse, allowing the boron to move more easily.
HOW TO APPLY BORON
You apply boron in the same two ways as most nutrients. It can be incorporated into the soil as granular fertilizer with the seed as a side dressing. With this technique, it is easy to over-apply the boron or apply it unevenly. The most popular method is to broadcast a foliar application of boron during the growing season after you see symptoms. This has worked well and has shown positive results in canola crops in the more northern parts of the Prairies.
Many different boron products can be applied this way, including Solubor, Borax, boric acid or sodium tetra borate. These products tend to range between 10 and 20 per cent boron.
Boron is an important micronutrient and if your crops are showing signs of deficiency, apply boron in one form or another to bring the soil back to a proper level. One of the main reasons for this is that boron works symbiotically with many other nutrients for proper plant growth and yield production. Boron on its own is also important for strong, healthy productive plants. Without it, a crop such as canola can become weak, brittle, and lose yield with unfilled space in pods. A serious boron deficiency cannot be solved by throwing more nitrogen at the problem.
Jay Peterson farms near Frontier, Sask. He graduated from University of Saskatchewan in 2008 with a Bachelor of Science in Agribusiness.