By Marcus McClure, AgroLiquid Regional Agronomy Manager
We know plants use micronutrients in very small amounts, but they are just as essential for plant growth as primary (N, P, and K) and secondary (S, Ca, and Mg) nutrients. Any one of them can limit growth and yield potential – and even cause plant death when deficient.
Why are micronutrient deficiencies increasingly being seen in the soil? There are several possible causes:
- Increased yields due to various technology improvements have led to increased yields, meaning higher demand by the crop and more removal of micronutrients from the soil
- Any type of land preparation which results in the removal of several inches of topsoil results in a deficiency of certain micronutrients on the cut areas
- High phosphorus levels can cause micronutrient tie-up, leading to deficiencies
Let’s take a look at some of the micronutrients, and why they are important to the plant:
Boron is necessary for cell division and differentiation. It helps maintain a balance between sugar and starch and aids in the movement of calcium. Boron is also essential for the germination of the pollen grains and pollen tubes in plants and has a direct effect on yield. No pollination, no crop.
Cobalt plays a critical role in the overall growth of plants. Cobalt is necessary for the processes of stem growth, elongating the coleoptiles, and expanding leaf discs. A cobalt deficiency will reduce or stunt plant growth and reduce seed germination.
Copper aids in root metabolism and the utilization of proteins. Copper is essential for better stalks or stems and standability. It is also key to seed coat resiliency, disease control, test weight, and seed size.
Iron is required for the formation of chlorophyll in plant cells. It activates respiration, photosynthesis, and symbiotic nitrogen fixation. Low iron levels in the plant result in poor energy transfer from leaves to growing points or fruiting structures thus slowing growth and lowering yields.
Manganese plays a major role in the production of chlorophyll. It directly affects the health of the crop and whether a plant reaches maturity or not. Manganese deficiency is a widespread problem, but is most often found in sandy soils or in soils with a pH above 6.0.
Molybdenum acts as a catalyst in nitrate reduction, and in nitrogen transport and utilization within the plant. Molybdenum is also associated with disease resistance in plants.
Nickel is important in nitrogen metabolism because it is a component of the urease enzyme. Without the presence of nickel, urea conversion is impossible. It is required in very small amounts, with the critical level appearing to be about 0.1 ppm.
Zinc is necessary for chlorophyll and carbohydrate production. High yields are impossible without zinc due to its importance in growth, metabolism, and photosynthesis. High soil phosphorus, soil organic matter, biological activity, and irrigation play a role in zinc availability.
Most growers and agronomists focus on macronutrients to improve yields and crop quality. However, micronutrients obviously play a pivotal role in crop development. If micronutrient deficiencies persist year after year, they will continue to damage crops regardless of the nitrogen, phosphorus and potassium applied. Before adding micronutrients to the soil, it is important to know what the soil already has available. A soil test analysis that includes micronutrients will give a snapshot of what is available to the plant. The soil test is especially important because many micronutrient deficiencies cause similar symptoms in the plant and can be difficult to identify. Deficiencies can also be caused by many factors, such as soil pH, moisture, temperature, and the presence of other compounds or nutrient tie up. If a crop is not reaching its full potential, or the same problems keep appearing, contact you crop nutrition expert to help investigate potential micronutrient deficiencies.