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


Andrew Hoiberg, Ph.D.

Andrew Hoiberg, Ph.D.

Let's talk about pH

When thinking about soil pH, it’s easy to get confused with all of the terminology involved. Simply stated, the acidity or basicity of any solution, e.g. soil and water, is defined by its pH. Technically, pH is the negative logarithm of the ionic concentration of H+ (hydrogen) in the solution. As the hydrogen ion concentration increases, the resulting pH number decreases. The reason logarithms are used is because the concentration of H+ is actually very small, even when the soil is very acidic. For example, when the pH of a soil solution is 4.0, the actual concentration of hydrogen ions is 0.0001 moles per liter (one mole is equal to the number of hydrogen atoms in 1 gram of hydrogen).

The true meaning of the lowercase ‘p’ in pH has been purported to stand for different things throughout history. Some suggest that it stands for “power;” others claim “potential,” or even the Latin term pondus hydrogenii, potential hydrogen. In chemistry circles, the lowercase ‘p’ stands for decimal cologarithim of, and the capital ‘H’ is the chemical symbol for hydrogen.

Hard to wrap your head around, isn’t it? Luckily, you aren’t the only ones and long ago, some scientists decided to take the negative logarithm of numbers like 0.0001 moles per liter and change it to a simple number to understand: 4 on the pH scale. One numerical step in the pH scale represents a 10-fold increase or decrease in acidity. So, pH 5 is 10 times more basic than pH 4 and 100 times more basic than pH 3. Therefore, a pH of 1 is ten trillion times more acidic than a pH of 14.

Now that we have a more thorough understanding of what pH really represents, the following are ways soils can become acidic:

1)     Soil parent material. Soils formed from parent material low in carbonates (both calcium and magnesium) are usually acidic, as are soils formed from sandstone and shale.

2)     Climate. Soils that form under high rainfall are subject to extensive chemical leaching and weathering, which removes essential basic cations (Ca2+, Mg2+, K+, Na+), and allows acidic cations (H+ & Al3+) to occupy the empty cation exchange sites.

3)     High yielding crops. Harvested plant parts take a lot of basic cations with them.

4)     Acidifying fertilizers. Ammoniacal fertilizers can contribute greatly to the acidity of soil. This is due to left over H+ ions after microbes transform ammonia and ammonium into nitrate, which plants prefer for uptake, in the natural process of nitrification. Also, as plants uptake ammonium, which they will, even though they preferentially uptake nitrate, they secrete H+ ions into the soil solution to maintain a balance of chemical charges.

Fertilizers that have the highest potential for acidifying soil are: ammonium sulfate (AMS – 21-0-0) and mono-ammonium phosphate (MAP – 11-52-0), both of which are very commonly used in agriculture.

Another issue with acidic soil conditions, namely below 5.5, is that Al and Mn becomes increasingly available for plant uptake and that uptake can quickly cause toxicity within the plant, while excess Al in the soil solution will inhibit root growth and function, and also restricting uptake of certain nutrients like Ca and Mg, which further compounds problems.

With all the inputs farmers have to balance, one issue often pushed to the back burner is pH. Generally speaking, farmers might decide to apply lime every 3-5 years. What other soil amendment or farm input is treated in such fashion? Why take a reactive approach to managing pH when you can be proactive about the problem and not have to worry about a corrective measure every 3-5 years when yields start to suffer? At Calcium Products, we believe farmers should be more proactive about measuring, monitoring and correcting pH on their farms. With the advent of precision agriculture in every aspect of farming, there is no reason we should exclude lime application and pH correction from that process. Yearly applications of SuperCal 98G at rates much lower than with agricultural limestone should be part of your soil management regimen.

As acidity continues to increase, corrective measures to bring back optimal conditions for crops are harder to achieve. Act now to help the soil help your bottom line!

In the next article, I will take a closer look at how acidity works and what characteristics of soil lead to different levels of acidity, and how the current recommendations for lime-based pH correction work.


Soil acidity

Within any given soil, there are two states of acidity that need to be accounted for before liming recommendations can be made. First is the active acidity, which indicates the current pH status of the soil. Active acidity accounts for the H+ ions in the soil/water solution that the laboratory measures. What active acidity doesn't account for, however, is the reserve, or potential acidity.

Update from Iowa Soybean Association On-Farm Network on Sulfur

A few weeks ago, we had the pleasure of attending the Iowa Soybean Association’s On-Farm Network (OFN) conference in Ames. One of the highlights of the conference for me was the presentation by Dr. Tracy Blackmer about sulfur.

Sulfur application over the past 30 years was generally considered non-essential due to the high levels found in our atmosphere from power plant emissions high in sulfur, thereby satisfying plant needs. Times and emission standards have changed and, as a result, sulfur levels are much lower in atmosphere and soil than they were in 80s and 90s. Dr. Blackmer observed sulfur deficient corn in recent years and even dug out some old photos during his time at the University of Nebraska that showed sulfur deficiencies—at the time unnoticed, which was very surprising to him. Perhaps we have negated the benefits of sulfur application for far too long!

Gypsum (calcium sulfate) is a great source of sulfur and our gypsum product (SuperCal SO4) has been included in strip trials—on both corn and beans—within the OFN for the past few years. Some observations from aerial photography have shown strips that received gypsum are much darker green than those that didn’t. Looking further into the data, these same farms showed a corn yield increase from 0.5 to 8.8 bushel from sulfur application, as well as tissue testing that confirmed sulfur deficiency in the untreated strips. There is some thought that the sulfur being present in requisite amounts helps the plant use nitrogen more efficiently.

We look forward to further investigation of the benefits of sulfur application on corn in the upcoming season and beyond! Our thanks to all the cooperators within the OFN.


Increasing research efforts at Calcium Products

In autumn of 2012, Craig Dick and I began discussing a Calcium Products research agronomist and manager of research & development (R&D). I was thrilled at the idea and gladly accepted the position a few months ago.

I completed my Ph.D. at Iowa State University in May 2012 in horticulture, with a research specialization in turfgrass science. I know that may not equate into corn and soybean agronomy at first glance, but one of the purposes of obtaining a Ph.D. is to show you have learned how to subjectively think about problems and use the scientific method via research to answer them. Although my concentration was in the turf world, I have a well-rounded education that can be applied to any area of plant science. I started part-time with CPI in October while finishing my post-doc work at ISU and started full-time January 1. We have been busy exploring new avenues and expanding existing ones for research and development opportunities.

On-farm strip trials are one area we are exploring. CPI has been doing these for quite a few years, and the idea is to increase product awareness by putting it into the hands of the farmer through our Prove-It program. Sometimes the dialogue between scientist and farmer gets lost in translation; when a farmer talks to another farmer about what worked it's very effective. What better way to spread the message of soil health than through our customers? We put the power in your hands to realize how our products can help your bottom line. We are looking to involve as many farmers and co-ops as possible into our Prove-It program, as well as the Iowa Soybean Association's On-Farm Network, which has been a great cooperative venture we hope to expand in the future.

University research is another area we are starting to increase R&D efforts. CPI has been involved with this in the past, however, cooperating with universities is often a tedious process and can involve considerable cost depending on the intensity of the experiment. We have identified key areas in soil science that involve our products in need of up-to-date research and information. It is our goal to help drive the science to answer these questions and increase the available knowledge base in these areas.

We are also increasing our in-house research efforts. This is where the 'D' of R&D comes in; we are always aiming to improve the physical characteristics of our products to ultimately benefit the end user. We do not simply manufacture a product in the cheapest and easiest way and sell it. On the contrary, we put considerable time, research and money into producing the best product available so we can help growers improve their soils. Beyond the 'D,' we are also looking at small-scale trials with different coatings for our pellets to expand into different agricultural and horticultural markets. Further, we are conducting small-scale experiments on different crops with our existing products to determine what benefits we can offer growers beyond the corn/soybean and turf markets.

Finally, we are always interested in knowing what problems and/or questions growers have for us. Often, these interactions with growers are what spawn new product ideas and research. So, please do not hesitate to contact anyone in the company if you have an idea for a research project or need a question answered about how any of our products work!



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