News

Lab Questions – Impact on Hydrogen and Calcium Base Saturations When Lime is Applied

A question came to the lab. The base saturation #’s look a little out of whack-averages are: Ca-55%, H-23%, K-4%, and Mg-18%. Avg pH is 5.5 but is fairly uniform. Will a lime app bring the Ca up and the H down?

Keep in mind that the base/cation saturation will add up to 100% and the base saturation values are calculated from the soil test results (ppm or lbs/ac) of these nutrients. In some cases the hydrogen saturation is not reported so the reported numbers do not add up to 100%, but the hydrogen saturation is part of the calculations even if it is not reported. Adding any one of these nutrients should lead to a higher soil test result. These higher results will lead to a larger contribution to the base/cation saturation calculation for the applied nutrient and thus a higher percentage. Since the base/cation saturation must add up to 100%, when the percentage of one nutrient increases, the others must go down.

In addition, the H% is calculated from the buffer pH (or soil pH if calculated from TEC), as the soil is limed, the soil and buffer pH increases, leading to a lower calculated hydrogen percent. The reduction of the H%, leads to increases in the other cations.

The Right Source of Potassium

Potassium, or K, is unique in a way that soils have a relatively large amount in the Midwest region.  Some soils can range from 15,000-20,000 ppm total K.  Even though there are large amounts of this macronutrient, it must be in an exchangeable form.  It is estimated to be only 1-5% is available and most soil contains approximately 1-3 ppm in the soil solution. 

Why is potassium so important?  Afterall, when reviewing commercial fertilizers, it is listed as the third number in the grade or analysis.  The functions of K in the plant are numerous.  It plays a key role in cell growth, photosynthesis, stomata function, enzyme activation, nutrient absorption and water retention just to name a few.  Using corn as an example, K deficient plants can experience marginal leaf necrosis, reduced plant height, poor reproduction and stalk lodging. 

There are multiple variables to consider when evaluating soil K levels.  Weather, residue, soil type and sampling habits can all play a large role in test levels.  Weather will affect the uptake of accessible soil potassium simply by not having enough moisture for uptake.  It is important to understand just because the crop is showing signs and experiencing symptoms of K deficiency, that environment dictates uptake of this macronutrient. 

When choosing the right source of potassium, or potash, do not over think what type of K is correct.  The K is nutritionally the same in all fertilizers.  However, many commercial fertilizers are not only K.  Some crops are sensitive to individual nutrient salts.  There are many soils with insufficient amounts of individual nutrients, and this is why it is important to select the correct type of fertilizer for individual cropping systems, soils and maintenance programs.

Here are some examples of potassium fertilizers and their composition.  Potassium chloride (KCI; 0-0-60) This is the most common for bulk blending and row crop agriculture.  This would not be a good choice for crops such as almonds since they are sensitive to Cl^-.  Potassium nitrate (KNO₃; 13-0-44) is an additional source of nitrogen and a good choice for chloride sensitive crops.  Potassium magnesium sulfate (K₂SO₄•2MgSO₄; 0-0-22) used to supplement magnesium and sulfur with K.  Potassium sulfate (K₂SO₄; 0-0-50-18) has a low salt index and includes sulfur.  Potassium thiosulfate (K₂O₃S₂; 0-0-25-17) is a liquid fertilizer and can be used in sidedress applications in dry conditions.  Potassium hydroxide (KOH; 0-0-75 has a high pH.  Often used as a liquid fertilizer that is absent of chloride and best used in acidic soils.   

Sample timing is critical when accessing K levels.  It is advised to pull samples after the same crop each time.  Soybeans, for example, will release potassium back into the soil much faster than corn.  As soon as the cell ruptures K is released and available.  It does not take a microbial process for availability.  This is why soil test levels vary greatly depending on sampling time and previous crop. 

Extreme, dry conditions can also impact soil test K levels as they become tightly bound to clay particles.  When making management decisions for potassium, always sample at the same time of year, after the same crop type, at the same depth/location and be mindful of current weather/environmental conditions when analyzing data.

Source: International Plant Nutrition Institute. (2012). 4R Plant Nutrition: A manual for improving the management of plant nutrition (pp. 40-41). Norcross, GA, USA: International Plant Nutrition Institute

2024 In Review - A Lab Perspective

Editorial by Agronomist Jamie Bultemeier

It seems as if the past few years have found new and intriguing ways to challenge agriculture. 2024 was up to the task and on par with that trend. This year has brought a wet spring for some, a dry summer and fall for most, and a shortened growing season for all. These challenges have also impacted the lab.

The spring soil sample season began early this year in January. There was a very brief pause between 2023 fall soil sampling finishing up in late December and spring 2024 soil sampling starting in early January. January 2024 produced the 2^nd largest January of soil samples in lab history. January was followed by record February and March sample volumes. The spring rains were just enough to delay planting, but not soil sampling. Strong spring soil sample volumes continued through April and May when in-season sampling began. In season sampling carried the strong soil sample volumes through the month of June.

About the time the spring soil sample season was slowing, plant tissues began. A week or two earlier than normal. There was no break between the two seasons. The rapid fast paced operation of the lab continued without a break at record plant tissue test sample volumes in July.

While soil samples did set more monthly records in the summer months, the lab staff did get a very short, but needed break, in sample volumes in August. However, the break was short lived. The hot dry weather accelerated crop development from north to south in our trade area and the fall soil samples arrived early and without delay. Usually fall soil sample volume ramps up over a 3-4 week period, not in 2024… The lab went from a few thousand to full capacity in about a week. This fall there was no widespread or regional rains to delay or slow soil sampling. The samples came fast, in large numbers, and constantly for weeks. Breaking more monthly sample volume records in September and November necessitating the need for the staff to work several weekends in the pursuit of maintaining a reasonable sample turn time for our customers.

All of the 2024 weather challenges compounded for the lab, yet 2024 was a great year. For the first time since 2020 we had a complete staff, and great fall seasonal staff that stuck with the lab for the entire season along with many that returned from last year. We had amazing support from our customers with unparalleled kindness that grew as the year progressed into fall soil sample season. The positive notes written on shipping box flaps, submission forms, and extra notes shipped with the samples had a bigger impact than you can imagine. We had fun through social media noting the staff’s fondness for candy, and the candy that arrived in sample boxes made the long day easier and gave them more purpose in their work.

Reflecting back on 2024, I sit in awe of what we accomplished in partnership with our customers. While the term partnership is often overused, it is the only term I have to describe the working relationship between the lab and our customers. I can recount numerous examples of the lab and customers working together in full cooperation to meet the needs of our collective customers, breaking records all along the way.

As the year draws to a close, I am reinvigorated with the potential in this industry. The level of professionalism in our customers is outstanding and it only reinforces that we are fortunate to have a great customer base that we can grow alongside.

Weakly Buffered Soils

When adding lime to acidic soils to increase the soil pH, the lime needs to neutralize the acidity in the soil solution along with the acidity released from the soil’s CEC in the process. There is a pool of reserve of acidity on the soil CEC that is released to maintain equilibrium between the CEC and soil solution. The impact of this reserve acidity held by the cation exchange sites will vary depending on the CEC of the soil.

The rate of lime to apply in the goal of neutralizing acidity is determined by using the buffer pH for soils with a CEC above 7, and organic matter below 20%. The buffer pH is a measurement of all acidity in the soil solution along with the reserve acidity held by the CEC of the soil. As soil CEC decreases so does the pool of reserve acidity. Below a CEC of 7 the reserve acidity is small and has little impact on lowering the buffer pH. Therefore, buffer pH is not a good indicator of lime application rate for these soils.

For weakly buffered soils, lime is applied at 1 ton/acre for each 0.3 - 0.4 of desired increase in soil pH, maximum 2 ton/acre. pH adjustments are usually triggered when the soil pH is 0.3 units lower than the target pH for the field.

A weakly buffered soil can have a CEC in high 6’s to low 7’s. To determine if a soil is weakly buffered, calculate lime rate for soils with a water pH of 6.2 or below using the weakly buffered rate above and an equation using buffer pH, use the higher of the two calculated lime rates. For more information on weakly buffered soil, contact you regional ALGL sales agronomist. 

Registration for 2025 Soil Fertility Workshops Is Open!

Dates and locations are set for the 2025 Soil Fertility Workshops. The goal of our workshops is simple: we provide a general overview of fundamental agronomic principles and current university research so our attendees are better able to make nutrient management decisions for their customers or for their own operations. Today’s producers are inundated with information regarding crop inputs and practices. By applying the fundamental principles of agronomy to these inputs and practices, a consultant, agricultural retailer, or producer can evaluate and decide which of those are most applicable for achieving both the short-term and long-term goals of a specific operation.

The workshops are developed and presented by A&L Great Lakes Laboratories’ Agronomy Staff comprised of Certified Crop Advisers, Certified Professional Agronomists, and Certified Professional Soil Scientists whom have a wide range of experience in the agricultural industry.

We will be presenting six workshops in January and February in Illinois, Indiana, Michigan, and Ohio. Registration can be completed online, or by mail/email. Click here for more information and registration.

January 28, 2025 - Fort Wayne, IN

February 4, 2025 - Champaign, IL

February 12, 2025 - Frankenmuth, MI

February 13, 2025 - Waldo, OH

February 18, 2025 - Grand Rapids, MI

February 20, 2025 - Indianapolis (Plainfield), IN NEW LOCATION

Different Sources of Phosphorus

To determine the right source of phosphorus, there are several factors that need to be taken into consideration.  First, a background of this macro-nutrient and how it is utilized in the plant.  Phosphorus, or P on the periodic table, has various states in soil.  It can be fixed, active and/or part of the soil solution.  Fixed P is the largest of pools and is not available to the plant.  The conversion of fixed to active is very slow and has little impact on soil fertility.  Active P in solid phase can be released into soil solution easily and replenishes the soil solution as the plant removes.  Phosphorus in a soluble state, or solution, is the only form for plant uptake. 

The role of phosphorus in the plant starts with being the elemental component of ATP-ADP, DNA and RNA.  These are the energy sources for photosynthesis, and transfer energy/nutrients. P plays an important role in fruit set/development and an essential component of cell membranes. 

Manure and biosolids can supply large amounts of P and is usually a direct reflection of their diet.  Before applying these sources, a laboratory analysis must be conducted for proper rates.  Handling, storing and transport of manure sources can be challenging.  This usually creates more inconsistencies from one sample to another.  There are, however, several commercial fertilizer options that are consistent.

Monoammonium Phosphate (MAP; 11-52-0) is water soluble and makes the pH surrounding the granule reasonably acidic at 4-4.5 pH.  This makes MAP one of the more suitable fertilizers in neutral to high pH soils. 

Diammonium Phosphate (DAP; 18-46-0) is one of the most used P fertilizers in North America.  It has a high nutrient content and is easy to handle/store.  Unlike MAP, an alkaline pH of 7.5-8 is formed around the granule.  Ammonium is released from the fertilizer and becomes volatile.  This is only a concern if placed too close to germinating seeds, is not incorporated, or pH is higher than 7.  As bacteria convert the nitrogen to nitrate, the pH is lowered.

Ammonium Polyphosphate (APP; 10-34-0 or 11-37-0) is comprised of orthophosphate and polyphosphate.  50-75% of the P is in the form of polyphosphate.  This makes the other 50-25% readily available for plant uptake.  What is not readily available, will eventually convert to available in a short period of time depending on the environment. 

Triple Superphosphate (TSP; 0-45-0) has one of the highest P concentrations out of all the fertilizers not containing nitrogen.  Over 90% of the total P is water soluble, making it a good choice for fast plant uptake.  This fertilizer will make the soil solution acidic (pH 2-3) as the granule dissolves.  It is a great choice for blending custom applications.

There are several options for phosphorus fertilizers on the market, and these are just a few of the commercial ones available.  When deciding which one to utilize, always apply based on soil test data, and be mindful of the 4Rs (Right Source, Right Rate, Right Time and Right Place). 

Reference: International Plant Nutrition Institute. (2012). 4R Plant Nutrition: A manual for improving the management of plant nutrition (pp. 40-41). Norcross, GA, USA: International Plant Nutrition Institute

Fall Lawn Aeration

Recently the greater Midwest region has been experiencing drought conditions.  This has not made it easy for lawncare, or annual maintenance, that is usually conducted in the fall.  One positive experience when undergoing times of environmental stress is the possibility to see flaws that are usually covered up, or otherwise hidden.  This is a perfect time to access situations like compaction, low grass densities or poor root growth in yards. 

Once a lawn is established, it makes alterations or “fixing” issues very difficult and time consuming.  The good news is that with the right tools, knowledge and some patience most issues if not all can be resolved.  When scouting a lawn during drought conditions the easiest, and most noticeable, concerns will be the different colors.  What makes turf brown, green or a shade in-between starts with the question, why?  Usually, the weeds will still stay green during times of stress, and the grass will go dormant.  This causes large patches to turn brown and if uniform potentially the whole yard. 

This is when the caretaker will notice the sins of the past as well.  There will be brown, or yellow, areas caused by compaction or poor drainage.  This is from the grass not having a vigorous root system due to poor porosity in the soil, or potentially a hardpan from topsoil being brought in then dumped on hard clays during the construction of structures.  High traffic areas will also show signs of abuse as soil moisture declines. 

Compacted areas are difficult to manage in established lawns, however, depending on how deep the compaction is, it can be amended.  For the Midwest, the freezing and thawing over the winter months helps.  If it is surface or shallow compaction, using a core aerator will promote better root development over time and help increase the amount of air in the soil.  There are several different turf aerator types on the market.  Using a ride-on, hydraulic core aerator will be the best option for depth and getting the largest core size especially during drought conditions.

More than likely, this will not be a one-season fix.   Depending on soil type, grass species and severity, it may take several seasons.  The core aerator will promote soil contact with the surface of the grass.  This helps with the breakdown of thatch.  Thatch is a layer of dead grass located on the soil surface.  It is when grass accumulates faster than decomposed.

Once the lawn has been aerated, this is a perfect time to overseed, fertilize and adjust pH if necessary.  Some of the larger aeration tools allow a 5” core to be pulled.  This enables a perfect area for pH buffering materials to enter a lower profile.  Soil is then exposed, creating better seed to soil contact and fertilizing, for example nitrogen, will promote the breakdown of the season’s thatch as well. 

Looking Back to 2012

It is hard to predict the impact of the current dry fall on soil sample results. Only after the sampling season is over can we determine if the dry weather impacted soil test results.  What we can do is look back at previous years and learn from experience.

Soil pH is impacted by an increase in soluble salts in the soil solution that haven’t leached downward through the soil profile during a prolonged severe drought. The soluble salts do not actually change the pH, rather it interacts with the soil pH probes there at the lab leading to the lower reading. Given that the drought set in for most of the ALGL service area later in the year after crop establishment. In our cropping systems the main salt inputs are fertilizers and manures. The salt from application in the fall of 2023 should have leached out of the sampling zone over the winter. While spring rain was not heavy in most areas, there was enough to leach most of the soluble salts resulting from spring 2024 applications from the soil. A simple reference is that when tiles are flowing water, water is infiltrating down through the soil profile and taking soluble salts with it.  

For comparison this year is much like 2012 for many areas. During a severe drought, water pH readings may be 0.1 to 0.6 pH units lower than expected. Looking back, pH data from 2012 does not stand out in the long-term data and indicates that the drought did not significantly impact soil pH in 2012.When soils remain extremely dry for extended periods of time, the space between the layers of shrink-swell clays, those that form large crack in dry conditions, gets smaller. This traps potassium between the clays layers that prevents the inner clay layer potassium from replenishing the available potassium in the soil solution as it is diminished through crop uptake. This can show up as a reduction in the soil test level. Also, potassium is easily leached from crop tissue following harvest. With little rainfall, this potassium reserve could remain in/on the crop tissue. One caveat of this, though, is with inadequate moisture to produce normal yields, less potassium may have been taken up by the crop. Looking back, potassium data from 2012 is slightly below trend, it does not stand out in the long-term data and indicates that the drought did not significantly impact potassium soil test level in 2012.

2025 Soil Fertility Workshop Dates

Dates and locations are set for the 2025 Soil Fertility Workshops. The goal of our workshops is simple: we provide a general overview of fundamental agronomic principles and current university research so our attendees are better able to make nutrient management decisions for their customers or for their own operations. Today’s producers are inundated with information regarding crop inputs and practices. By applying the fundamental principles of agronomy to these inputs and practices, a consultant, agricultural retailer, or producer can evaluate and decide which of those are most applicable for achieving both the short-term and long-term goals of a specific operation.

The workshops are developed and presented by A&L Great Lakes Laboratories’ Agronomy Staff comprised of Certified Crop Advisers, Certified Professional Agronomists, and Certified Professional Soil Scientists whom have a wide range of experience in the agricultural industry.

We will be presenting six workshops January and February in Illinois, Indiana, Michigan, and Ohio. Registration will open later this year, but mark your calendars today!

January 28, 2025 - Fort Wayne, IN

February 4, 2025 - Champaign, IL

February 12, 2025 - Frankenmuth, MI

February 13, 2025 - Waldo, OH

February 18, 2025 - Grand Rapids, MI

February 20, 2025 - Indianapolis, IN (near the airport)

Introduction of The ALGL Client Portal

We have made our new ALGL Client Portal available to customers. The goal of the ALGL Client Portal is to provide account holders with single sign on access to lab tools you are already using, with new and enhanced tools to make working with us even easier and more convenient.

Current features of the ALGL Client Portal include:

• Access reports and data files with enhanced global search functionality. This is like our existing eDocs system that will remain active through the fall sampling season.
• Print and/or email UPS shipping labels utilizing our RS shipping program.
• Order supplies.
• View and pay invoices online (for authorized users).

Additional features and tools are in development and will be released as they become available.

For more information and to access the ALGL Client Portal Click Here.