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Micronutrients in crop production

Around the County

January 9, 2009
From WAYNE SCHOPER, Brown/Nicollet Extension Educator

Fertilizer management in Minnesota concerns itself mainly with the big three of fertilizer management - Nitrogen, Phosphorous and Potassium. These nutrients work to improve both crop yield and quality. There are other soil nutrients that have little if any effect on production and therefore can be classified as micronutrients. However, we do know, through research, that there are some micronutrients that must be present for profitable crop production. So it is important to review and summarize some of these elements to determine which ones to include in our overall soil nutrient package.

ZINC: For Minnesota crop producers, this is the most important micronutrient of all. When soil levels are low, both corn and edible beans will respond. For best results we need to conduct a soil test and follow the recommendations. When we look at soil test results, zinc levels will be reported in parts per million (ppm). When soil test levels of zinc are below .75 ppm, we need to be supplying supplemental zinc. Current prices show that zinc applied in the dry form was about $1.50 per pound. Liquid zinc will be higher. The exact role of zinc in crop production is not clearly defined but we do know that it is necessary for the functioning of several enzymes and when zinc is deficient, we will see abnormal growth and development.

MANGANESE: This element is also essential for many enzyme reactions in plants with no specific, well defined function. However, the use of additional manganese has not increased crop production in Minnesota. So we do recommend additional applications of manganese in fertilizer applications.

Article Photos

Wayne Schoper

IRON: Many soybean growers are familiar with Iron Deficiency Chlorosis (IDC) in soybeans. However, there is no deficiency of iron in Minnesota soils. Under certain soil conditions, iron is not available to the plant and cannot be used by the soybean plant to produce chlorophyll. Research continues to look for methods to control this problem.

BORON: While there is no universal agreement on the role of boron in corn and soybean production, we do know that it is an essential element especially in alfalfa production. A top-dress application of 2 - 4 pounds per acre has increased alfalfa yields when soil test results show that there is a need. However, we need to be cautious as over-application can reduce yields.

COPPER: Small grains such as oats and wheat grown on organic soils have shown a positive response to the application of this micronutrient. However, outside of this, there is no need for additional copper in a fertilizer program.

CHLORIDE: Although the specific function of this element in plants is unknown, we do know that chloride can help small grains resist disease pressure. However, this micronutrient is not needed if we have applied 0-0-60 (NaCl) in the past. Chloride, the Cl portion of 0-0-60 is a salt that is only needed in minute amounts.

Recently there have been some sales promotions which states that micronutrients coated or sprayed on other fertilizer granules will improve crop yields. These claims are not substantiated by research and should be avoided.

Dates to remember:

Private Pesticide Applicator Training:

Feb. 12, 12:30 - 4 pm Brown County Office Building, Sleepy Eye

Feb. 26, 12:30 - 4 pm Lafayette Community Center.

Winter Crops Day: 8:30 a.m.-3 p.m., Arlington Community Center

Research update on weed control, soybean diseases, corn production and drainage. $30 fee includes lunch and all materials.



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