November 29, 2023

Impact of Soil Sample Location and Depth

When soil sample location or depth change, so can the soil test data. Often when calls come into the lab about inconsistent soil test values overtime, the responding agronomist will look at the impact of sample location and depth first. If the soil sample is collected in a consistent manner including same depth, same time of year, same location/pattern, following the same crop, the values soil test values should be relatively stable over time. There also will be a gradual trend upwards or downwards depending on the nutrient management focus. If the value of the soil organic matter (SOM), phosphorus, or CEC change dramatically, i.e. 30-50% in 2-4 years, further investigation is in order.

Calcium and magnesium are relatively consistent with soil depth. If calcium and magnesium change by more than 20-25% then it is likely that the sample location has changed, or an aggressive application of lime or gypsum has been applied. Since the primary values used in calculating CEC are calcium and magnesium, the CEC should be relatively stable if the sample is collected in the same location.

If the CEC is stable, but the SOM changes by 0.5% or more in soils with SOM levels below 4-5% then most likely the sample depth has changed. Most of the organic matter is near the soil surface and shallow samples concentrate SOM in the sample leading to a higher relative higher SOM. The same is true for phosphorus to a lesser degree. Soil test phosphorus can be more variable naturally in the soil by small changes in locations that may not be indicated by the calcium and magnesium values.

If the samples are sampled using GIS location, be sure to compare individual sample points and not the field averages. Field average can skew what is taking place with individual sample points if all the sampling points are not impacted the same.

November 16, 2023

Are You Putting Enough Soil in Your Sample Bags?

Editors Note: During the 2023 fall sampling season we have noted a large number of small soil samples. Some samples represent less than one sample core of soil. While smaller samples might seem desirable to reduce shipping costs, the greater risk is the negative impact on data quality. Special handling of small samples may result in an additional prep fee. 

Originally posted 1/29/21

Most commercial or university soil testing laboratories provide soil sample bags to you at little to no cost. Every lab designs its sample bags with its own logo and contact information in the hope that a sample will be collected, placed in that bag, and sent back to the lab for analysis. While each lab’s sample bags may look unique, most sample bags have one common feature, a line or some other indication of how much sample should be put in the bag. So why is sample volume so important?

The most obvious reason that a lab indicates this volume of soil, is that we need enough material to process and analyze. We also like to have some extra in case a component needs to be reanalyzed for quality control purposes or should the customer request additional testing.

The less obvious, but possibly more important reason to fill the sample bag to the indicated line is to obtain a valid representation of the area sampled. Soil nutrient levels can vary greatly even in a very small area. By collecting enough cores to fill the bag, your results are more apt to represent the true average of the area sampled. Research has shown that a minimum of 8 individual soil cores need to be collected to make a single sample. Collecting fewer than 8 cores increases the potential that a single unusually high or low testing core will skew the results. Taking a subsample of the collected soil in the field can bias soil test data, whenever possible send all of the collected soil providing it does not exceed the soil fill line on the bag. A lab dried and ground sample mixes and homogenizes much better than field moist samples. 8 soil cores from a 6" to 8" sampling depth fit in the soil bag. 

November 14, 2023

Beyond the Standard: Micronutrient Packages and Applications

It is, without a doubt, that certain soil nutrient levels are analyzed and prioritized above others. This is with good reason, but what are the other soil test packages for, and when should they be utilized?

At A&L Great Lakes Laboratories, we offer an extensive variety of soil test packages.  Our most common being the S1 package, which includes Soil Organic Matter, Phosphorus, Potassium, Calcium, Magnesium, pH, Buffer pH, CEC and Base Saturation of Cations.  This soil test data is the foundation for most applications or amendments.  These key nutritional values must be met before exploring the micronutrient packages offered.  A prime example would be soil pH.  Ensuring the soil pH is correct is the most economically sound decision as it impacts the availability of all nutrients in the soil. 

Available Micronutrient Packages

Once the basic soil test levels included in the S1 package are sufficient, the micronutrient list can be perfected.  Unfortunately, most micronutrient deficiencies are determined in-season.  At this point, it can be too late, or yield loss has already begun.  Such as, when corn is in the younger stages.  It will show interveinal chlorosis, or yellow striped leaves when experiencing sulfur deficiency.  Assuming soil moisture and temperature are not the culprits of poor nutrient uptake, a preseason soil sample and application could have prevented this.

The best practice is to stay ahead of low, or deficient, levels of any micronutrient.  This requires a micronutrient package to be added to the submittal form.  S3 and S6 are the most utilized packages in addition to the S1.  When selecting an additional package, it is not always necessary to add to every sample.  Sometimes it is more economical to put the micronutrient package on a composite, or every other sample.  This is practiced with large data pools over small collection areas.  For more information on soil test packages, please visit:  For help determining the right micronutrient strategy for you, please reach out to your regional ALGL agronomist.

October 23, 2023

2024 Soil Fertility Workshop Dates

Dates and locations are set for the 2024 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 will open later this year, but mark your calendars today!

February 6, 2024 - Fort Wayne, IN

February 8, 2024 - Frankenmuth, MI

February 13, 2024 - Grand Rapids, MI

February 14, 2024 - Rockford, IL

February 20, 2024 - Perrysburg, OH

February 22, 2024 - Fort Wayne, IN

October 17, 2023

Where Does the Dirt Go?

Editor's note: Some agronomists and soil scientists may find the language contained in this article, specifically the repeated use of the word "dirt", to be quite disturbing. While the author attempts to justify his use of such crude language, it may still be shocking to some. To be clear, the curator of this blog IN NO WAY condones the use of such language, and instead prefers the much more appropriate phrase "soil material".

The age old debate continues today, is it soil or dirt? Like a weed is a plant out of place, dirt is soil out of place. When the soil passes through the lab it becomes dirt. After the soil is dried and ground, the structure of the soil is functionally destroyed, so it becomes dirt. The dirt it becomes a slurry when it gets wet and rock hard when it dries out. While some have tried to find practical used for the excess dirt, the loss of soil structure severely limits the functional uses of the dirt.

Every spring and fall sampling season a common question arises, “What do you do with the soil/dirt when you’re done with it?” During the busy fall sampling season, we fill a large roll-off dumpster every other day of dirt. The dirt is taken to the landfill and used as part of the collective material used to line or cover the actual refuse in the landfill. The dirt in the dumpster is excess sample that is not used for analysis, and clean fill. The soil used for analysis leaves the lab in another much smaller dumpster as refuse.

October 05, 2023

Nutrient Recommendation FAQ

We often get questions about nutrient recommendations on soil test reports, below you will find some of the commonly asked questions when requesting nutrient recommendations.

Nutrient Recommendations on ALGL soil submittal form

When do I complete this section of the submittal form out?

Only complete this section you are requesting nutrient recommendations for a given soil test. A minimum of a S1 is required. There is a cost associated with adding nutrient recommendations to a sample. If you do not want nutrient recommendations, simply leave this section blank.

What does the “R” column initiate?

Placing a “x” in this column will indicate that you want the nutrient recommendations in a crop rotation sequence.

What does it mean for nutrient recommendations to be in “rotation”?

Rotation means that the nutrient recommendations will be calculated in crop rotation sequence. This only has an impact on nitrogen recommendations when the previous crop provides nitrogen credit to the following crop. The crop rotations will flow from previous crop to first crop in year one, then from first crop to second crop in year two, and finally from second crop to third crop for year three.

When would you not request nutrient recommendations in “rotation”?

When the nutrient recommendations are not in rotation, the first, second and third year crop are treated as options. For example, the grower may not be certain as to what crop is going to be raised, or maybe there might be more than one crop planted in the field.

How does the “Yield Goal” impact the nutrient recommendations?

When a portion of a plant is removed from a field the nutrient content of the removed material needs to be replaced as part of the nutrient recommendations. In some cases, quantifying the removal is not practical/possible therefore a yield goal is not required, and an estimation is added to the nutrient recommendation. In other cases, like animal pastures, the nutrients do not leave the field and a large portion of the nutrients are redeposited in the field through the manure of the animals. If the yield goal is left blank and one is required, the lab staff will insert an average yield for the crop.

Do I need to identify the “Previous Crop”?

A previous crop is not required and will only impact nitrogen rates in which the previous crop provides nitrogen credit to the following crop.

Do I need to identify 3 crops?

No, but you can identify up to 3 for each soil sample.

When requesting nutrient recommendations for a cover crop, should it be listed as a crop?

We often get requests for nutrient recommendations for cover crops. Keep in mind that one of the goals of a cover crop planting is to scavenge excess available nutrients, purposely fertilizing cover crops defeats their intended purpose.

What nutrient recommendations am I getting?

The default recommendations are those developed by ALGL unless university nutrient recommendations are requested. That is often done by adding a note in the “Additional Information” box in the lower right corner of the submittal form. We offer Illinois and Tri-State nutrient recommendations on applicable crops.

Why does the resulting soil test report crop not match what was written on the submittal form?

If a plant or crop is included that we do not have defined recommendations for we will either edit the crop to a agronomically/horticulturally similar plant if possible or remove the crop.

Where do I put the request for nutrient recommendations on a Preside dress Test (PSNT) or Corn Stalk Nitrate Test (CSNT)?

These analyses can be used to further refine nitrogen application rates and overall management. Due to the complexity of those recommendations, we cannot collect enough information to make a sound nutrient recommendations on a soil test report. However, your regional ALGL agronomist can help make sense of the data.

Can recommendation be added to GIS collected soil samples?

Yes, you do not need to use the standard soil test submittal form to request nutrient recommendations, but the submittal information from the GIS software will need to contain the same information.

What information will I receive on the report?

Above is an example of what the resulting nutrient recommendations might look like. This field requested corn at 210 bpa and soybeans at 65 bpa in rotation. Note the “(TS-IN)” next to the crops. That indicates Indiana Tri-State Recommendations. If they are the ALGL internal recommendations this would be blank. When lime is required to meet the target soil pH for a crop, a lime rec in tons/ac will be listed, the is intended to be a onetime per sampling cycle application. The remaining nutrient recommendations are based on annual applications for that given crop. The annual recommended nutrient application rate is in pounds of the given nutrient, not fertilizer product/nutrient source. The rates of fertilizer to meet these recommendations will need to be calculated based on the nutrient sources you are using. The nitrogen rate is not listed for Tri-State recommendations as there is no defined way to calculate the rate, it varies based on university data and market price. The ALGL recommendations may be too high for your situation, improved nitrogen use efficiency practices on your operation will lead to nitrogen recommendation reduction. Additional information or notes maybe listed below this chart, such as where to find a calculator to determine a nitrogen rate for Tri-State Recommendations.

September 25, 2023

Tips to Avoid Delays in Your Soil Results

With harvest closely approaching for much of the region, the dry conditions can help the harvest to progress quickly and efficiently. When harvest is efficient, fall soil sampling is efficient, resulting in sample volumes that can challenge our laboratory’s daily maximum capacity. While our goal is to keep a consistent turn-time for all samples, it is not always possible if challenges arise in the process. Following these tips can help reduce delays in the delivery of your results.  

  1. Use good quality new or lightly used, heavy duty boxes for shipping samples. The #1 cause of samples being lost is damaged boxes in shipping. Reusing Amazon boxes is discouraged because the cardboard is often too thin to withstand the weight of soil samples.
  2. Packing tape is cheaper than resampling. Be sure to use plenty of good quality packing tape. Make sure to use multiple strips of tape on all box seams including the vertical seam that joins the box together. This is the most damaged part on a box causing loss of samples. If you are reusing boxes, be sure to reinforce all previously taped seams and joints.
  3. Full boxes with organized rows of samples hold up best during shipping. Loosely packed boxes stand the greatest chance of being crushed during shipping. Loosely packed samples also stand the greatest risk of losing sticker labels or having handwritten information worn off. Samples that are organized improve the efficiency of the lab process.
  4. If possible, pack entire fields in the same box. If this is not possible, please indicate on the outside of the boxes by numbering or labeling with the actual field name. It is fine to have multiple fields in one box but try to avoid spreading multiple fields across multiple boxes. Doing this prevents delaying sample results for multiple fields if one box is lost or delayed in shipping.
  5. Include completed submittal forms that indicate your account number, grower, farm, field, all sample ID’s, and the desired analysis package. Your samples can be processed more efficiently if the submittal forms are in the same box as the samples they represent.
  6. If you are using soil sampling software that allows for electronic submission, be sure to have your information synced, or uploaded prior to the samples being delivered to the lab.

If you have any questions regarding shipping supplies, or sample packaging, please contact your ALGL representative.

September 11, 2023

Corn Stalk Nitrate Testing

The Corn Stalk Nitrate Test (CSNT) was developed by Iowa State University agronomists to determine if growers were using the proper amounts of nitrogen for corn production. Traditional tissue tests work well to evaluate nitrogen availability to the plant at a given point in time, the CSNT helps identify the effectiveness of the season long availability of nitrogen. This is assessed by measuring the amount of nitrate - nitrogen present in the lower portion of the corn stalk around the time the plant reaches physiological maturity.  Corn plants suffering from inadequate N availability remove N from the lower cornstalks and leaves during the grain-filling period.  Corn plants that have more N than needed to attain maximum yields, however, accumulate nitrate in their lower stalks at the end of the season.  Several factors, including weather, can have a profound effect on the results of the test.


Samples should be collected between 1/4 milkline to 3 weeks after black layer has formed on 80% of the kernels of most ears.  Field test areas should not be larger than 10 acres.  Collect 15 stalks and remove an 8” segment between 6” and 14” above the soil.  Place in paper bag (not plastic). Refrigerate if delay in shipping is one or more days.  Do not freeze.



Less than 250 ppm

Indicates high probability that greater availability of N would have resulted in higher yields.  Visual signs of N deficiency are usually observed in this range.


250 - 700 ppm nitrate-N (ISU)

Producers should not be concerned when samples test in this range. N availability was close to the minimum amount needed for maximum yields but should not be the target for good nitrogen management.


250-2000 ppm nitrate-N (Purdue), 700-2000 ppm nitrate-N (ISU)

Indicates that N supplies were sufficient for maximum yields.


Greater than 2000 ppm nitrate-N

Indicates that N supplies were above levels needed to maximize profits.


The CSNT does not directly indicate how much a N application should be increased or decreased.  However, the use of this test consistently from year to year can be a valuable tool when adjusting N rates.  Since the development of this test, nitrogen prices have increased substantially, increasing the need for sound nitrogen management.  In addition, nitrogen in ground and surface waters can be a major environmental concern.  From both an environmental and an economic perspective, any tool that can help a grower manage nitrogen usage should be seriously considered.  Additional information on the corn stalk nitrate test can be found in our factsheet, “Corn Stalk Nitrate Test”, available on our website.

September 05, 2023

What Goes into Making a Nitrogen Recommendation for Corn?

Some common questions that we get asked about soil test results are, where is the nitrogen level on my report, and how do you recommend a nitrogen rate when you did not test the nitrogen level of the soil?

To begin, let’s explain why plant available nitrogen (N) is not part of our routine soil test packages. The simple answer is our climate. In the Midwest and northeastern United States, our “non-growing” seasons are when we receive much of our annual precipitation. That means that any excess applied N from a growing season probably will not carry over to the following growing season. It is likely to be lost to leaching and denitrification. So, we build our recommendations on the assumption that we are starting with little to no plant available N.

Since our recommend rate of N is not based on a soil test result, we use a projected yield goal. When harvested, a bushel of corn will remove about 0.67 pounds of N. To grow a 200-bushel corn crop we must supply a minimum of 134 pounds of N just to cover what is being removed. However, that crop is going to require more N than crop removal because we also need to grow the whole plant to grow the grain. A corn crop will take up about one pound of N in total per bushel grown, meaning that same 200-bushel crop really needs about 200 pounds of N supplied.

If you request recommendations from A&L Great Lakes for a 200-bushel crop, we will recommend 240 pounds. Most agronomists and growers will agree that this is an aggressive rate for 200-bushel corn, and it is. The reason that it is so high is that this is a starting point. We are assuming a worst-case scenario in which all the N is broadcast applied prior to planting. Unfortunately, N becomes more prone to loss the longer it stays in the soil before a crop can utilize it. A corn crop will take up about 70% of its N during the first half of the growing season and the remaining 30% will be taken up slowly all the way through physiological maturity. The likelihood of preplant application of N at a crop uptake only rate making it through the whole growing season is unlikely. The extra N supplied is to help ensure season-long availability. Fortunately, there are practices and tools that we can use to help lower the rate of N that needs to be applied.

The most common practice to lower the total amount of applied N is in-season and split applications. Whether it is sidedressing, high-clearance spreaders, or fertigation, the closer the N is applied to the time of crop uptake, the less likely it is for losses to occur. Most growers using a combination of starter N and a second application around V5 to V6, are comfortable using a rate around 1.1 pounds of N per bushel.

Another tool that can be used to reduce N application rates is the Estimated Nitrogen Release (ENR). In a good growing season, you can estimate that about 30 pounds of N will be mineralized from every 1% organic matter that is in your soil. If your soil has 3.5% organic matter, it has the potential to provide approximately 100 pounds. The problem with the natural mineralization of N is that it may not coincide with the timing that the crop needs it. So, it is not advisable to reduce the application rate by the entire 100 pounds, but 40 to 50 pounds maybe justifiable.

The Maximum Return to Nitrogen (MRTN) model is another option to use and is what the current Tri-State recommendations utilize. The idea of this model is to incorporate years of N response data from your area, N prices, and corn prices to predict the most profitable rate of N to apply.

The greatest challenge with recommending a N rate is that it is impossible to predict the weather and economy far enough into the future to know that the right decision is being made. The best way to go about making a recommendation is to use all of the tools that you have available and learn from your past practices.

August 22, 2023

Water, Salt, and Buffer pH

Increased awareness of different lab methods to measure extractable nutrients has been positive to help understand variations in soil test data from various regions of the country and why they may be different.  Like extractable nutrients there are various lab methods for testing soil pH.

Soil pH - Water vs. Salt

There is 1:1 water which uses equal parts distilled/deionized water and soil to make a slurry for pH determination. This is the common method in most of the eastern US. In drought conditions natural salts can accumulate in the soil that interfere with the pH probes used to measure the pH of the soil and water slurry. This interference can lead to a 0.2 to 0.6 drop in soil pH readings. This drop is also common in arid regions of the Western US. The severity of the drop is based on the salt levels in the soil. To overcome this issue in the arid western regions, low concentration salt water is used to stabilize the readings at 0.5 to 0.6 pH units lower than 1:1 water pH. The target pH is different for 1:1 water vs salt pH.

Buffer pH

Buffer pH is used to determine how much lime application rates. This is similar to soil pH in that it is a a buffer is added slurry of soil and water that strips all of the hydrogen from the CEC of the soil. The more hydrogen on the CEC the greater amount of reserve acidity in the soil leads to a greater decrease in the buffering solution. The greater the decrease of the buffer solutions after stripping the hydrogen from the soil indicates higher lime application rates. There are several buffer solutions that start at different pH’s and result in different buffer pH’s. Common Buffer solutions include:

  • SMP
  • Sikora
  • Woodruff
  • Adam Evans
  • Mehlich

At ALGL our standard methods are 1:1 water pH and Sikora buffer pH.

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