Andrea Rice, Director of Research, Education, and Outreach, Missouri Fertilizer Control Board
Plants have nutrients essential for growth and development. There are 17 elements essential for plant nutrition – six macronutrients, eight micronutrients, and three essential elements. Macronutrients of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S) typically get a lot of recognition, but micronutrients are becoming more popular in conversation. Three essential elements of hydrogen (H), oxygen (O), and carbon (C) are obtained through the air and water.
Micronutrients, also known as trace elements, include boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), and zinc (Zn). The classification of “micronutrient” is designated by the smaller amount of the nutrient needed by the plant, but they play a vital role in the plant’s growth and development. With crop production, a decrease in plant-available micronutrients will lead to plant productivity and likely a decrease in yield.
Why are micronutrients increasing in interest?
When the following factors are combined, farmers and their advisers are led to question if micronutrients should be added to nutrient management plans.
Micronutrients have been removed from the soil through soil erosion and long-term cropping.
Increasing crop yields leads to more micronutrients being removed by the crop.
The decrease in utilization of manures and increased use of mineral fertilizers has reduced micronutrient addition from fertilizer sources.
How are micronutrient deficiencies diagnosed?
Soil testing and plant analysis can be used to diagnose micronutrient deficiencies. One challenge with most micronutrient soil testing is that it measures the quantity of nutrients in the soil but not their availability. Plant analysis (tissue sampling) is a great way to determine if there is a deficiency of micronutrients. Combining plant analysis with soil tests will provide an accurate assessment of the micronutrients in the soils and the ability for the crops to attain them.
How does management of micronutrients play into my nutrient management plan?
The tools and assessments for diagnosing micronutrient deficiencies are not very complex or expensive, especially when comparing to the potential cost in yield or quality loss. The treatment will be more costly, but with the prices of land, labor, and other production inputs, it is likely beneficial to spend the extra funds on fertilizer. Doing so will ensure the crop’s yield is not limited by a micronutrient deficiency. If such a deficiency is not corrected, producers are effectively limiting yield and not maximizing benefit of other input costs, let alone time and energy required to put the crop in.
Adding micronutrient management can be the next step forward for improving nutrient stewardship and maximizing profits.
Upcoming posts will highlight each of the micronutrients and their impact on a growing crop.
Resources
https://soilfertility.osu.edu/extension-and-outreach/nutrient-management-0/micronutrients
https://soilhealthnexus.org/resources/soil-properties/soil-chemical-properties/micronutrients/
https://www.extension.purdue.edu/extmedia/AY/AY-239.html
https://extension.missouri.edu/programs/nutrient-management/nm-other-nutrients