Calcium Products - Applying Nitrogen to Enhance Corn Residue Decomposition: Does it Work?

Applying Nitrogen to Enhance Corn Residue Decomposition: Does it Work?



Applying nitrogen in the fall to enhance corn residue decomposition occurs with some frequency in the Midwestern United States. The purpose of this application (normally applied as AMS or UAN) is to deliver a nitrogen source to feed microbes and increase the speed at which corn residue is decomposed. The main reason this topic seems more prevalent in recent years may be related to current hybrids and farming practices. Modern genetics have selected for stronger stalks and larger plants, while increases in corn-on-corn rotations and reduced tillage have resulted in more residual biomass. Combined, these result in greater demand on microbes to minimize the impact of residue on the following season's operations.

Rationale Behind "Stalk Burndown"

The rationale behind applying N to aid in stalk decomposition is related to the carbon-to-nitrogen (C:N) ratio, which indicates how effectively microbes decompose different materials. The C:N ratio is important because it denotes how many units of carbon are found in a given material in relation to the units of nitrogen. The ideal C:N ratio (think diet) for microbes is 24:1 and corn stover is about 60:1. This means that microbes must scavenge for additional nitrogen to keep things humming along when feeding on corn residue. Additional nitrogen typically comes from available nitrogen in the soil - and this is where the rationale of adding nitrogen to the corn stover comes from - to effectively narrow the C:N ratio of the residue and allow the microbes to more rapidly decompose the material as they wouldn't have to scavenge for available nitrogen.

Hurdles for Microbial Decomposition Rates

The problem is that the C:N ratio is not the only thing that governs microbial decomposition. Other factors such as moisture, and especially temperature (both soil and air) are very important with respect to biological activity. When liquid applications of UAN or AMS are made to corn stover, the nitrogen can be washed off by rain - defeating the purpose of the application. More importantly, microbial activity is reduced by decreasing air and soil temperatures in the fall, which can leave the applied nitrogen unused by microbes and susceptible to leaching with well-known environmental consequences.

Research Shows No Benefits from N Applications to Increase Stalk Decomposition

Several research projects have attempted to justify this practice to no avail. Researchers at the University of Wisconsin in 2002 found no benefit from fall application of nitrogen to increase microbial decomposition of corn stover (Bundy and Andraski, 2002). A collaborative research project between the University of Minnesota and University of Illinois ultimately concluded that fall applications of N had minimal to no effect in increasing residue decomposition and were not warranted, even when applied as early as September when air and soil temperatures were adequate to sustain microbial activity (Coronel & Fernandez, 2014). Lastly, a study conducted at Iowa State University found no differences in the rate of stover decomposition as a result of N application - from economic and environmental perspectives, N application had no effect in achieving the intended results of facilitating residue decomposition (Al-Kaisi, 2014).



Al-Kaisi, Mahdi. 2014. Myths and Facts about Residue Breakdown. Iowa State University Extension and Outreach. (

Bundy, L.G. and T.W. Andraski. 2002. Final Report to the Wisconsin Fertilizer Research Council. Project 175-99. (

Coronel, E. and F. Fernandez. 2014. Effect of Fall Nitrogen on Corn Residue Breakdown in Illinois. SSSA Abstracts, Long Beach, CA. (


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  • 98G Calculator Instructions

    This calculator is intended to utilize your soil test data to calculate an application rate for 98G.
    • Start by selecting in the first drop down box which target pH you are trying to achieve. This will depend on your geographic location, soil type and which crop you are trying to grow. Next, in the second drop down box, select your tillage type. Tillage type influences the application rate by exposing a different volume of soil to the 98G application.|

    • In the third box, enter the 'Buffer pH (or Buffer Index)' data from your soil test. In the fourth box, enter the 'Soil pH (or Water pH)' data from your soil test. 

    • The rate should automatically calculate for you after you enter the soil pH into the fourth box, and the larger box to the right titled '98G Rate' should flash blue and show you the application rate calculated for the information you entered on the left. You can also click on 'Calculate' to ensure the calculation has been executed correctly.

Because 98G is so much more efficient and precise than AgLime, we've developed this custom calculator to illustrate the difference in the amount of product needed and help you make an informed choice. Fill in the fields below to see how pure, pelletized 98G compares.

SuperCal 98G will improve microbial activity in your soil, which, in turn, improves the overall health of your soil.

Acidic soil conditions can inhibit activity of microorganisms that are beneficial to your soil system.

SuperCal 98G will help release unavailable nutrients in your soil.

Acidic soil is one of the main reasons that nutrients become tied up in soil; applications of 98G based on soil testing will help return soil to proper pH and increase nutrient availability.

SuperCal 98G has one of the most complete dissolution rates of any lime in the world.

98G is ground extremely fine before pelletizing to ensure that the maximum amount of surface area comes in contact with the soil, resulting in more pH changing reactions than AgLime, which contains large particles that may take years to react, if ever.

SuperCal 98G pelletized lime creates less compaction.

Because SuperCal 98G is delivered in a tender and spread with a floater, there are no loaders or dump trucks wandering around your fields. This means less trips through the field and reduced compaction. 98G can also be blended with other dry granules to limit trips across your fields.

SuperCal 98G is a more efficient and economical way to change soil pH than aglime.

Although it may cost more per unit weight than aglime, 98G will fully react in the soil and none will be lost to lengthy reaction time or to drift during application. Further, application rates are lower due to its purity and fineness of grind.

SuperCal 98G pelletized lime is clean spreading.

Since SuperCal 98G is spread with a floater and is pelletized, it stays where you put it and does not blow away in the wind. And the moisture content is less than 1% so you are not paying for water weight like you would with traditional ag lime.

SuperCal 98G comes from one of the best limestone sources in the world.

98G is comprised of nearly 98% pure calcitic limestone from one of the best deposits in the world.

SuperCal 98G pelletized lime is safe for organic growers.

Our products are pelletized using an organic binder that is OMRI compliant.

Q: What is 98G?


98G is the highest quality pelletized limestone in the US. 98G is made from finely ground calcitic limestone (98% calcium carbonate-CaCO3), mixed with a binder to produce a pellet. Because the CaCO3 is so pure and so fine you can use 300-400 lbs/A in place of one ton of ag lime.

Q: How can 400 lbs. of 98G equate to one ton of aglime?


See table 1: The average particle size of 98G is smaller than 100 mesh. Therefore, 20% of 199,000 is 39,800 sq. ft., which equates to 91.4% of an acre. The average particle size of aglime is 20 mesh. Therefore, one ton of ag lime will cover 36,000 sq ft., which equates to 82.6% of an acre.

On table 2, notice the fine particle size (98G) increased the pH in two weeks (100 mesh curve), whereas the aglime curve (20-30 mesh) is fairly inactive for 18 months. In addition, 98G raises soil pH higher, faster and for longer then equivalent amounts of aglime.



Table 1. Source: National Stone Association





Table 2. Source: Miller, R.W. and D.T. Gardiner. Soils In Our Environment. 8th Ed. P. 272.



Q: What is limestone?


There are two types of limestone. (A) Calcitic, which is CaCO3 (B) Dolomitic, which is CaMg (CO3)2. The presence of magnesium in dolomitic is how they differ. Dolomitic lime is very insoluble and take much longer to work. It should only be considered on extremely acid soils or soils low in magnesium. To insure soils do not have too much magnesium you can use 98G and/or SO4 to reduce the magnesium.

Q: Is calcium the same as lime?


Calcium (Ca) is only part of the formula for calcium carbonate (limestone), while the carbonate (CO3) is the active part in the reaction that neutralizes the acid (low pH) found in soils. Calcium is left behind after the pH reaction and will seek out and attach to sites on organic and clay particles (cation exchange sites) in the soil, available for plant nutrition.

Q: What is pH?


The measure of hydrogen ion concentration in the soil and stands for potential Hydrogen. The pH test only measures hydrogen; it has nothing to do with calcium!

Q: How does 98G work?


98G is finely ground, very pure limestone or calcium carbonate. The calcium and carbonate parts of 98G will split when mixed with water, and the carbonate will react in the soil with hydrogen, creating water and carbon dioxide.

Q: How does buffer pH figure in?


Buffer pH is an indication of how much hydrogen, or “reserve acidity” in the soil needs to be neutralized by liming. A high buffer reading (8.0 or above) usually indicates less correction will be needed than it would be if the buffer pH is low, as buffer pH drops below 8.0, more reserve acidity is present in the soil.

Q: What type of cultivation should I use to incorporate 98G?


We recommend using whatever type of tillage fits your operation, additional forms of tillage are not necessary for incorporation of 98G.

Q: Can 98G be applied in furrow?


Yes. 98G can be applied via many methods. We have seen great response from in-furrow or banding when the product is applied in a "T" band. Rates are figured using the normal banding formula.

Q: Can I use 98G in my deep banding or strip-till operation?


Yes. We have seen satisfactory response to 98G being deep placed. This can be done with or without accompanying fertilizer (dry only).

Q: Should I use 98G before corn or soybeans?


Using 98G before either crop will produce satisfactory results. Application is usually determined by which crop receives fertilizer application and then applying at the same time or in the same application with the fertilizer. It can be impregnated at that time also. In some extreme situations, we have recommended putting on 400# prior to corn and an additional 200# prior to soybeans to hasten the relief from very low pH.

Q: Can I apply 98G myself?


Yes, 98G can be applied by any normal fertilizer applicator that you are comfortable running. It is, however, suggested that you follow your dealer's recommendations, and often they are better equipped to apply this material along with your fertilizer, especially if you are considering the use of variable rate technology.

Q: What should I expect to pay for 98G?


Pricing for the product is set by our dealers, but typically cost between $9 and $11 per cwt. As you get further away from the plant, increased freight charges will raise the price.

Q: At what pH should I consider liming?


Low pH creates 2 issues. First is reduction of yield. Second, your fertilizer inputs are limited by pH.


pH 4.7

pH 5

pH 5.7

pH 6.8

pH 7.5



















At a pH of 5.7 you will lose 17% of your anticipated yield, 20% on beans and 58% of an alfalfa crop.

faq pH levels

The bar graph represents the % of nutrients available to the plant at various pH levels. We recommend that you develop a program to keep your pH in a range of 6.5 to 6.8 for most midwest row crops.

  • Steve Pellatz, Nebraska and SuperCal 98G

  • Farnhamville FC Coop uses SuperCal 98G and SuperCalSO4

  • SuperCal 98G and SuperCalSO4 from a farmers perspective.

  • A SuperCal 98G testimonial from the farmer.

What our clients say...

  • Jim has been using SuperCal SO4 as part of his fertility program on his alfalfa. He has an acre of alfalfa that is 30 years old and produces more than 6 ton per year.

    — Jim Jarosz, Cedar Rapids, Nebraska
  • We have been raising cattle on grass for many years, traditional fertilizer didn't seem to be giving us the response we were looking for. We started looked for other options and Gene Zimmerman recommended SuperCal SO4. We were looking for a good sulfur source, but also felt we needed the calcium. The grass responded quite well to 300 lbs/a. We could tell where the spreader ran out of SuperCal SO4, and we have seen a big difference compared to the ground we did not spread any SuperCal SO4 on.
    It has been pretty dry this year so we were not sure what kind of results we would see. The carrying capacity looked better than my neighbors, and the cattle seem to like the grass better, and even started grazing the weeds. I have cows that have never raised good calves; this year they have big calves. Two representatives from the local sale barn came to visit me. My calves were more robust, they wanted to know what I was doing.
    "I would use SuperCal SO4 again, it’s priced reasonably."

    — Morris Stokes, Sullivan County, Missouri
  • have been using SuperCal SO4 for 4 years now and have been seeing it right to the row where I have been using it as my pictures show, I have been banding it at 50 to 100 # rates and have seen anywhere from 5 to 11 bushels increase on my corn yields. The 50# rate was costing me about $3/acre and seeing a 5-bushel yield increase at $3/bushel corn is $15 for a $3 investment. A 5x return on investment works for me.
    Visit Jay’s website:

    — Jay Myers, Colfax, North Dakota