Calcium Products - Andrew Hoiberg, Ph.D.
Calcium Product 98G

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Andrew Hoiberg, Ph.D.

Andrew Hoiberg, Ph.D.

Localized Dry Spot

Localized Dry Spot

What is localized dry spot?

With an unusually hot start to the late spring/summer season, localized dry spot (LDS) is showing up earlier and more vigorously than normal. LDS shows up as somewhat randomized, dry looking areas of turf. It is generally seen on sand-based greens, but can occur on other turfs that have been heavily topdressed with sand over the years. Sand-based soil has greater propensity for hydrophobic conditions, which is the main sign of LDS.

What causes localized dry spot?
The deeper cause, beyond sand-based soils, are believed to be organic acids and residue that coat the soil or sand particles. These organic compounds are not completely understood, but are the result of typical decomposition of leaf tissue, roots, fungal biomass and organic soil amendments included in the original root zone mix. These compounds tend to have a hydrophobic nature and once they have coated soil particles, lead to LDS. Combine this hydrophobicity with root growth stoppage in heat and soils that already have low moisture holding capacity, and the problem can become bad in a hurry.

How to manage localized dry spot
While there is plentiful research into the causes and potential areas that could be managed differently to delay or correct LDS, the primary management technique has been and continues to be the use of wetting agents or surfactants to allow water to re-infiltrate areas that develop hydrophobicity.

There are several different chemical groups in the wetting agent and surfactant world, but the goal of all of these products is to lower the surface tension of water so it can infiltrate the hydrophobic soil. It pays to do your homework on the types of products available in the market to determine which one will provide you with the best result. Some of the older chemistries can cause phytotoxic effects on plants, so make sure you fully understand what you’ve got before spraying it on your greens.

Be prepared
Unfortunately, there doesn’t exist today a ‘silver bullet’ to cure LDS. The best strategy is to incorporate existing knowledge into new construction and for existing problems, to know when it’s coming and be prepared with a wetting agent or surfactant strategy to minimize the damage and interruption in play. Be sure to know what your local extension has to say about LDS management in your specific area.

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Can 98G and SO4 be Applied on Frozen Ground?

Frozen Ground

We are often asked about applying our products on snow-covered or frozen ground. While it may seem intuitive that products should not be applied to frozen ground, in general, applications can be made during late fall or winter and have similar considerations as other times of the year, such as water and ground conditions.

When determining if conditions are adequate to apply SO4 and 98G, keep these considerations in mind.

Potential for water runoff

Water influences movement of surface applied inputs. When water has potential to runoff and not infiltrate, then perhaps applications should be delayed.

Late fall and early winter before the ground is completely frozen can be a good time to make applications. As long as there’s not a substantial amount of snow on the ground (less than 6 inches), applications of 98G and SO4 can still be made. If snow comes early, there’s potential that it will slowly melt and start breaking down the product, which will help disperse the particles of the pellets and make them more effective come spring.

Even if the ground is completely frozen, applications can be made before too much snow accumulates. An extremely wet spring with multiple, heavy rain events can lead to water, and thus, product runoff and off-target effects, so paying attention to long range forecasting can help inform application decisions.

Slow snow melt and ground thaw is the best case scenario for products applied on frozen ground. Even if there is some runoff, it’s not likely that all of the product will be taken from where it was applied.

Soil tillage

Heavy or primary tillage (moldboard or chisel plow, ripper) is not a recommended practice after application of 98G or SO4. Application should be delayed until after these tillage practices have already occurred, due to non-uniform depth of application and the likelihood that the pellets will be placed too deep in the soil profile to affect meaningful pH adjustment.

If ground is not completely frozen, then there’s still a chance for the product to start working its way into the ground. SO4 should always be surface applied and left to release its nutrients from the surface, so if some tillage is expected after the application, it may be wise to delay application until spring after ground work has been completed. 98G can be incorporated via surface preparation, so the same considerations do not apply to both products in this case – incorporation can also reduce runoff potential for 98G.

Field slope

Slope of the field should also be considered; relatively flat ground is less susceptible to runoff events and will have more leeway with late fall and winter applications.

To summarize, frozen ground applications are acceptable if snowpack and slope are minimal – however, the risk of excess water in the spring and significant runoff are always present.

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Soil pH – The Foundation for Nutrient Availability

Soil pH Blog Image DRAFT1

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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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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