Micronutrients – Crucial for Crop Growth

BY Dairyland Seed Agronomy Team

2023 In Season Nutrient Management

Micronutrients are essential for crop growth. Micro refers to the amount of these elements needed in comparison to macro nutrients which are Nitrogen, Phosphorus, and Potassium. This is noted well in the figure below.

Although needed in lesser amounts iron, zinc, copper, magnesium, boron, molybdenum, and chlorine to name a few, are crucial to crop growth. It can become a yield limiting factor If one of these elements is not available to the plant in the necessary amounts.

The best visual for this concept are barrel staves and the ability for the barrel to hold water. You can only fill the barrel to the top of the shortest stave. This illustration describes Liebig’s Law of the Minimum which states, “the rate of growth of a plant, the size to which it grows, and its overall health depend on the amount of the scarcest of its essential nutrients that is available to it.” If we imagine the nutrients necessary for plant growth as staves in a barrel and the water held in the barrel as yield, then we can only have as much water or yield in the barrel as the shortest stave will allow. All the staves or nutrients must be present in the necessary amounts to achieve maximum yield.

(Heckman et al, 2003) Nutrients removed from the soil for 300 bu/a corn.

We are able to see if plants are lacking in any nutrients during the season a couple ways.

One is the crop’s response to insufficient amounts of the nutrient. This often appears in striped, or otherwise off-color plants. Some descriptions of these can be found in the table below.
A second option is a tissue sample analysis to see if we have any limiting nutrients in the plants during the growing season. A full discussion on tissue sampling was offered in last week’s agronomy newsletter. If we see symptoms of a nutrient deficiency, and verify that with a tissue sample, an application of the limiting nutrients help the plants along until the necessary amounts of nutrient becomes available from the soil.

If micronutrient deficiencies are noted year after year, and verified with soil and tissue samples, then a fertility plan can be put in place to ensure that the given deficiency does not continue to be a yield limiting factor. An example solution is the addition of zinc in a band of fertilizer when planting corn, often in 2x2, to ensure that the crop has enough for the season or at least to get started. All solutions are not this easy when looking to correct nutrient deficiencies, but there are many viable options. Examples of soils where certain micronutrient deficiencies may be found are shown in the table below.

As stated in many articles this season, our most limiting factor in many areas of the Dairyland Seed footprint is water. All nutrients require water to move to and through the plant. There are many ambulance chaser types who have a quick fix foliar applied solution for drought, gout, hail damage, leaky pipes and colicky babies. Most of these products will not hinder or hurt the crop, but be mindful that if there is no soil moisture or scheduled precipitation, most products may not be able to perform the miracles that they claim.

If you have any questions about micronutrients or soil fertility, contact your local Dairyland Seed DSM or Regional Agronomist.