Calcium Products - Applying Nitrogen to Enhance Corn Residue Decomposition: Does it Work?
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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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A natural source of calcium and humic substances.

Humic substances derived from leonardite are blended with our calcium products to create a synergistic pellet that will provide all of your calcium and humic needs. Calcium fertility is often pushed aside in favor of concentrating on the ‘big three’. Calcium nutrition is vitally important to overall plant health and SuperCal Humic delivers one of the purest sources of calcium on earth.

Provides sulfur in sulfate form.
Sulfate from our extremely pure calcium sulfate is the main form of sulfur taken up by plants and is immediately available for plant use after the pellets begin to break down when exposed to water.
Provides a chelated form of calcium.
The interaction between organic acids derived from humic substances and calcium results in a chelated form of calcium that will not bind up with other compounds in the soil, meaning the calcium will be available for plant uptake.
Improve plant uptake of soil nutrients, especially calcium, phosphorus, iron, zinc and other micro nutrients.
Humic substances have been shown to help plant uptake of many different macro- and micronutrients.
Increases CEC to improve nutrient holding capacity and reduce leaching.
Humic substances are exceptional sources of organic matter for your soil and their chemical properties can help your soil’s ability to exchange cations and thereby hold nutrients.
Increases soil water holding capacity.
In loosely textured soils, water holding capacity can be an issue. Adding organic matter in the form of humic substances can help increase the water holding capacity of your soil.
Q: What is SuperCal Humic?

A: SuperCal Humic is a humic product consisting of a proprietary blend of humic substances, sulfur, and calcium based products that are mixed with a binder to form a pelletized product.

Q: What are humates?
A: Humates are the mineral (metal) salts of humic acids and the term is often used incorrectly to describe the entirety of ‘humic substance-based’ products in the market.
Q: What are humic substances?
A: Humic substances are mined from deposits in the earth of dark colored substances that have reached the final stages of biodegradation. Think of the term ‘humus’ in soil, humic substances are essentially deposits of humus that have undergone biodegradation and other geological processes for long periods of time.
Q: What are humic acids?
A: Humic acids is a broad term used in commerce and science to identify a class of isolated compounds that can be extracted from natural humic substances in a number of ways, typically with alkali solutions, and then precipitated from the alkaline aqueous solutions by acidification. (From HPTA website)
Q: What are fulvic acids?
A: Fulvic acids is a broad term used in commerce and science to identify a a class of isolated compounds extracted from nautral humic substances that are soluble in both alkali and acidic aqueous solutions. (From HPTA website)
Q: Why should I use SuperCal Humic?

A: SuperCal Humic can increase root growth in plants, which has many subsequent benefits such as increased nutrient uptake (especially those that are immobile in the soil) and increased drought tolerance.

Q: Can SuperCal Humic be applied with other dry fertilizers?

A: Yes, SuperCal Humic can be broadcast with any normal dry fertilizer application device and when applied with fertilizer can increase the availability of the nutrients to the plant.

Q: What rate of SuperCal Humic should I apply?

A: SuperCal Humic should be applied at 200 lbs/acre on any soil. This rate is designed to apply the right rate of humic substances to your plants

Gypsum helps reclaim sodic soils
Gypsum is used in the reclamation of sodic soils. Where the exchangeable sodium percentage (ESP) of sodic soils is too high, it must be decreased for soil improvement and better crop growth. The most economical way is to add gypsum, which supplies calcium. The calcium replaces the sodium held on the cation exchange sites in the soil. The sodium can then be leached from the soil.