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Calcium Product 98G


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. (



Fall 2010 Sulfur Prices

 Our recent work with the Iowa Soybean Association on sulfur strip trials has me thinking about sulfur fertilizer. Past research trials by Iowa State on sulfur fertilizer for corn in northeast Iowa show positive results about 100% of the time on sands, 70% of the time on silt loam soils, 60% of the time on loam soils.

It seems that the word is getting out as the cost of sulfur fertilizers is on the rise. Recent prices on elemental sulfur are in the $0.32 - $0.45/# range or $0.35 to $0.50/# of actual S. But since it has to oxidize down to gypsum to be plant available it really is a big waste of money at any price, not just when it’s high. 

Ammonium Sulfate (AMS) is in the $0.20 to $0.30/# range or $0.83 to $1.25 /# of actual sulfur, not considering the nitrogen or the limestone needed to offset the acidity if causes.

SuperCal SO4 will cost you $0.09 to $0.11/# or $0.52 to $0.65/# of actual sulfur, not considering the calcium.

This fall and next spring make sure you have sulfur in your fertilizer program. Make sure it’s in a form that works, and make sure your not paying too much. Not all sulfur forms are the same some can cost you more upfront and yield in the end! 



Yield Starts Here is a blog for farmers, focusing on increasing yield and profitability by focusing on the soil. It is managed by Craig Dick, a Blogronomist and Sales and Marketing Manager at Calcium Products. Find other articles by Craig and guest writers at 


Ammonium-based fertilizer will change the pH of a soil

From the Ventura County Star, GRANGEVILLE, Idaho (AP)

"Crop soils in north-central Idaho are becoming more acidic, possibly because of the repeated use of ammonium-based fertilizers, scientists say."

"Basically you're adding calcium carbonate to the soil," Sandlund said. The process is effective, but it's expensive, time-consuming and difficult, "usually involving tons per acre."

Read more:  -

At CPI we are not against Ammonium sulfate (AMS), in many cases it can be a great fertilizer. However if you have soils that are already acid, and/or have a low buffering capacity. It may be best to choose another form of Nitrogen and sulfur that is less acidic. 

For every pound of Ammonium sulfate applied, you need 5 lbs of pure calcium carbonate to offset the acidity it causes. 

Urea only needs 1.8 lbs of pure calcium carbonate to offset the acidity it causes. Combine that with a product like SuperCal SO4 to get your sulfur and you have nitrogen and sulfur blend that is priced less initially and causes less soil acidity.

If you insists on using the higher priced ammonium sulfate of low pH soils or low buffered soils make sure you apply 5 lbs of SuperCal 98G when you apply your AMS. This will keep you pH where you need it, and it more effective than waiting for a problem, is not expensive, nor time consuming and is really easy.


Is the solution to your current problem adding problems?

This week in the Iowa Farmer Today, Tim Hoskins reported on “Mineral deficiency cropping up in alfalfa fields”. Iowa Farmer Jeff Ryan turned to Brian Lang Iowa State University crop specialist for Northeast Iowa. Mr. Lang worked out that the poor yield was due to a sulfur deficiency.

It is not clear in the story who recommended the solution, but it will be nothing but headaches for Ryan. Ryan applied 100 lbs. of Ammonium Sulfate (AMS), at a cost of $17 per acre.

Wow! $0.70 per pound of sulfur!

Then factor in the unintended costs of AMS. AMS is one of the most acidifying fertilizers on the market. It takes 5-7 lbs of SuperCal 98G, or 15-20 lbs of AgLime to neutralize the acidity caused by AMS. Add $5 to $20 per acre to the fertilizer bill for lime.

Don’t forget the unintended cost of stand reduction from the added nitrogen in alfalfa. There are many reports that show even 20 lbs on N on established alfalfa can reduce stands up to 2/3 rds. Add the cost of spaying weeds in alfalfa...$6-20 per acre? Add the cost of reseeding with today’s fuel prices...$30-50 per acre?

The cost of applying AMS could easily be over $40 per acre, for 100 lbs.
We think the best solution is SuperCal SO4.

Cost of 100 lbs of SO4 $6.50

Per pound of Sulfur, $0.38 (17% sulfur, in sulfate form)

We just saved Mr. Ryan 50% on his fertilizer bill. Still not convinced?

SuperCal SO4 does not have nitrogen in it. No unintended stand loss, no acidifying effects. The 22% calcium actually helps offset uptake of Potassium. Income from premium for low K alfalfa $$$? Income from higher feed value of alfalfa $$$?

University of Wisconsin studies show as little as 25 lbs per acre of sulfur can increase first and second cutting alfalfa yields by as much as 20%. Our research shows 45% increase in yield when using SuperCal SO4. Including SuperCal SO4 in your alfalfa fertilizer program assures you that your alfalfa has higher protein and feed value, and improves stand density and longevity, creating more tonnage.
Let’s review the choices, do nothing and continue to lose yield, apply AMS and pay $40 for 24 lbs of sulfur and have other problems to solve, Apply 200 lbs of SuperCal SO4 for less than $17 per acre, and create additional income.
Calcium Products, increase yields, reduce costs, higher quality alfalfa!


The Blogronomist is maintained by Craig Dick, head blogronomist and VP of Sales and Marketing. Here you will find a wide array of blog articles from Craig and expert guests on topics related to soil and crop health, farming, and so much more. If it’s not here, ask us!  


Cattle Love SuperCal SO4

Now is the time to start thinking about pasture fertilization. For many cattlemen the cost of fertilizers has them looking for alternatives to high priced N, P and S.

We have had a number of customers comment on the results they have witnessed with SuperCal SO4; higher stocking rate, reduced weeds, better cattle gains, and reduced vet bills. One skeptical customer applied SO4 to only one paddock of his rotational grazing pasture. When he moved the cattle off the SO4 applied section, the next day they busted down the fence to get back to that area. Cattle know where to find the best grass!

In grass legume mixtures SuperCal SO4 has many advantages of Ammonium Sulfate (AMS). First is cost, SO4 is almost half the cost of AMS, it doesn't cause acidity like AMS, and doesn't contain nitrogen. Established grass legume mixtures do not need extra nitrogen. If you fertilizer for the legume it will produce more than enough for the grass. If you fertilizer for the grass it will soon over-take and crowd out the legume.

Finally SO4 will increase water infiltration and holding capacity of your soil. By allowing more water to be held in the soil you can increase stocking rates since there will be more grass.

Fore go the high priced fertilizers and find out why SuperCal SO4 is the better choice for pastures and forages.



The Blogronomist is maintained by Craig Dick, head blogronomist and VP of Sales and Marketing. Here you will find a wide array of blog articles from Craig and expert guests on topics related to soil and crop health, farming, and so much more. If it’s not here, ask us!   

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Maintained by our team of experts, we have a wide array of blog articles from our experts and guests on topics related to soil and crop health, farming and growing tips, and so much more. If it’s not here, ask us!

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