Calcium Products - Items filtered by date: August 2016
Calcium Product 98G

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Calcium Products - Items filtered by date: August 2016

  • Published in Corn

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

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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).

 

Sources:

Al-Kaisi, Mahdi. 2014. Myths and Facts about Residue Breakdown. Iowa State University Extension and Outreach. (http://crops.extension.iastate.edu/cropnews/2014/04/myths-and-facts-about-residue-breakdown)

Bundy, L.G. and T.W. Andraski. 2002. Final Report to the Wisconsin Fertilizer Research Council. Project 175-99. (http://bulletin.ipm.illinois.edu/print.php?id=1565)

Coronel, E. and F. Fernandez. 2014. Effect of Fall Nitrogen on Corn Residue Breakdown in Illinois. SSSA Abstracts, Long Beach, CA. (https://scisoc.confex.com/scisoc/2014am/webprogram/Paper87666.html)

 

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Soil pH – The Foundation for Nutrient Availability

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Every nutrient's availability is affected by soil pH.

Soil pH is the foundation and main governing parameter of soil fertility. Every nutrient’s availability to plants is affected by soil pH – some more so than others – which is why correcting and maintaining soil pH at adequate levels is so important.

Phosphorous (P) availability is the most affected nutrient by pH because the chemistry of P is such that it loves to react with other minerals in the soil at varying pH levels. At high pH, P is very attracted to calcium, while at low pH, P is very attracted to aluminum and iron. When P reacts with calcium, aluminum, or iron, it forms insoluble compounds that plants cannot easily access.

Nitrogen (N) and Potassium (K) are also affected by pH, but not in the same way as P. At low pH, aluminum and iron increase in availability and “out-compete” nutrients like N and K in the soil, leaving N and K susceptible to leaching from the soil profile.

Maintaining proper pH protects fertilizer investments.

With the substantial investment made on N, P, and K fertility programs, it is easy to see why maintaining appropriate pH is paramount to protecting fertilizer investments. Further, crops need sufficient access to these nutrients in order to obtain maximum yield and further return the investment growers make on these important nutrients.

Our philosophy is that soil pH should be corrected and then maintained with yearly or every-other-year, lower rate applications to avoid the pH rollercoaster that can occur with 4- or 5-year aglime application regimens. Our product, 98G, is a pelletized lime that corrects and maintains soil pH. It’s easy to apply and works well in variable rate application programs.

By measuring and managing soil pH, you are ensuring that growers are set up for a high-yielding crop and fertilizer investments are being put to work.

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