Except for iron and zinc, micronutrients not warranted

decrease font size  Resize text   increase font size       Printer-friendly version of this article Printer-friendly version of this article

Plants require seven micronutrients: boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), and zinc (Zn). In Nebraska, deficiencies of iron and zinc can be common, depending on soil properties, but deficiencies of the other five micronutrients are rare.

One case each of boron deficiency has been reported on alfalfa and sugar beets, both on sandy soils. We do not know of any other confirmed micronutrient deficiencies on agronomic crops in Nebraska. With the exception of iron and zinc, the probability of profitable yield response to micronutrients is very low.

However, toxicity associated with misuse of micronutrients is a risk and has been confirmed in Nebraska.

With relatively high crop prices this year, there has been increased interest in products, including micronutrient fertilizers, that are marketed to promote crop growth. Some dealers have even gone to the extreme of mixing such products with commonly used fertilizers, often without informing producers before the invoice is sent.

Do high yield crops need exceptionally high soil availability of micronutrients? More yield means more nutrient removal. However, high yield crops have the potential to be highly efficient in nutrient uptake and utilization. High yield crops are freed from much stress, such as soil water deficits, that low yield crops encounter. High yield crops typically have healthy and extensive root systems capable of efficient nutrient uptake and healthy plants capable of efficiently converting nutrients and carbohydrates to yield. This high efficiency has been repeatedly shown for high yield corn, especially for nitrogen, but also for phosphorus and potassium. There is no evidence to the contrary for micronutrients.

Zinc

Zinc deficiency is most likely to occur on low organic matter, calcareous soils, but can occur on other soils. Corn is relatively sensitive to zinc deficiency, and the zinc soil test is a reliable indicator of the probability of profitable response to zinc application. When selecting between inorganic (e.g., zinc sulfate) and chelated (Zn EDTA) zinc products, consider the rates and relative costs. Inorganic zinc (not the product) is applied at two to four times the rate of chelated zinc. The chelated form should be considered for deficiency correction only. If soil test zinc is above 0.8 ppm and application is to build or maintain a high level of availability, use an inorganic form.

Iron

Iron deficiency is most common on calcareous soils. Soybean, dry bean, and sorghum are especially sensitive. Planting tolerant crops and varieties is important to management of iron deficiency. Seed dressing with iron EDDHA at 0.2 lb/ac iron has been as effective as applying 50 lb/ac iron as iron sulfate. Use this as a guideline in comparing costs.

Boron

Boron application is much promoted; however, the probability of profitable response is extremely low. Applying boron in the seed furrow can be toxic at germination and emergence. Building soil test boron levels is not feasible as it is easily leached from the soil. Irrigation typically supplies enough boron to meet crop needs.

Manganese

In some parts of the Corn Belt, glyphosate-tolerant soybean often respond to soil and foliar application of manganese. In trials conducted in southeast and south central Nebraska soybean did not respond to manganese application. In Kansas there was a response to both soil- and foliar-applied manganese at one of four locations. A case of very serious manganese toxicity due to misapplication by a dealership has been verified in Nebraska.

Chloride

Crop response to chloride application has occurred in Kansas. There were no yield increases with chloride application in trials conducted with corn in southeast to south central Nebraska and with winter wheat in western Nebraska.

Copper and Molybdenum

There is no evidence of crop response to copper and molybdenum in Nebraska.

Interpreting Micronutrient Test Results

What if foliar analysis indicates a micronutrient deficiency? Such results are often used to promote micronutrient application. Treat these results with caution.

First, foliar nutrient concentration can vary with rate of growth, growth stage, variety, weather conditions, and time of day. With many samples taken and several nutrients considered, there is potential for seeing occasional low levels, even with high soil fertility conditions.

Second, labs and service companies differ greatly in their interpretation of foliar analysis results with some considering low to be anything below an average result, and others basing their interpretation on research relating plant response to nutrient application relative to the tissue nutrient levels. Foliar analysis for agronomic crops in Nebraska should be used to guide soil testing and additional foliar analyses for future crops but, it is not a sole justification for a nutrient application.

Could you have an exceptional situation for response to micronutrients? Such claims are common, often with a high level of certainty. If you are doubtful, do your own trials, but don’t limit yourself to a mere one time, side-by-side comparison which many find to be convincing. Spatial technology makes replicated on-farm trials often easy to conduct. Even with such trials, repetition on three or more fields or years is encouraged for confidence in small yield effects. Extension Educators can help you design such a trial and interpret the results. We would also appreciate you sharing your results with us.


Prev 1 2 Next All



Buyers Guide

Doyle Equipment Manufacturing Co.
Doyle Equipment Manufacturing prides themselves as being “The King of the Rotary’s” with their Direct Drive Rotary Blend Systems. With numerous setup possibilities and sizes, ranging from a  more...
A.J. Sackett Sons & Company
Sackett Blend Towers feature the H.I.M, High Intensity Mixer, the next generation of blending and coating technology which supports Precision Fertilizer Blending®. Its unique design allows  more...
R&R Manufacturing Inc.
The R&R Minuteman Blend System is the original proven performer. Fast, precise blending with a compact foot print. Significantly lower horsepower requirement. Low inload height with large  more...
Junge Control Inc.
Junge Control Inc. creates state-of-the-art product blending and measuring solutions that allow you to totally maximize operating efficiency with amazing accuracy and repeatability, superior  more...
Yargus Manufacturing
The flagship blending system for the Layco product line is the fully automated Layco DW System™. The advanced technology of the Layco DW (Declining Weight) system results in a blending  more...
Yargus Manufacturing
The LAYCOTE™ Automated Coating System provides a new level of coating accuracy for a stand-alone coating system or for coating (impregnating) in an automated blending system. The unique  more...
John Deere
The DN345 Drawn Dry Spreader can carry more than 12 tons of fertilizer and 17.5 tons of lime. Designed to operate at field speeds up to 20 MPH with full loads and the G4 spreader uniformly  more...
Force Unlimited
The Pro-Force is a multi-purpose spreader with a wider apron and steeper sides. Our Pro-Force has the most aggressive 30” spinner on the market, and is capable of spreading higher rates of  more...
BBI Spreaders
MagnaSpread 2 & MagnaSpread 3 — With BBI’s patented multi-bin technology, these spreaders operate multiple hoppers guided by independent, variable-rate technology. These models are built on  more...


Comments (4) Leave a comment 

Name
e-Mail (required)
Location

Comment:

characters left

Mike    
Pullman WA  |  April, 09, 2012 at 09:23 PM

its taken twenty years for WSU Ag Department to realize how wrong the above statement is, Most universities need to open their eyes to private research. We grow 140 bushel dryland with complete programs that include calcium, mag, zinc, copper, chloride and even alittle boron. With that kind of thinking is way the midwest grows smaller wheat crop than the northwest.

Mike    
pullman WA  |  April, 09, 2012 at 09:27 PM

Wake up, complete balance programs always out yield N,P,K & S. We grow 140 bushel dryland wheat in the Northwest, with less moisture tha Neb, I wonder WHY!

bob streit    
Boone IA  |  April, 10, 2012 at 09:06 AM

We and several other major groups are now extensively utilizing tissue testing programs when we see leaf streaking. Those results tell a different story and draw a different conclusion than written here. It seems that this article and such experts as here have never visited with lab managers who do the analyses and have summarized the data to see what is really happening for obvious political reasons. Growers are realizing this and operating in a different fashion with good results. With the use of micros the crops, if determined to be deficient in specific nutrients, have gained in yield and plant health. Also not addressed is the role of biologicals in nutrient availability. Growers and 'experts' in countries are way ahead of us in the U.S.

Gene    
Minden  |  April, 11, 2012 at 04:09 PM

High production corn,which most producers are working for, takes more than just NPK. It wasn't too long ago you didn't think we need suflur either.


Direct Drive Rotary Blender

The Doyle 8, 10, 13, & 16 ton Direct Drive Rotary Blender’s are the industry’s fastest rotary blenders. These units ... Read More

View all Products in this segment

View All Buyers Guides

Feedback Form
Feedback Form