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Managing Apple Expectations with Nitrogen Regulation

For many cash crops, the more inputs and higher management practices lead to higher yields. A certain amount of nutrition is needed to produce the yield goal and still get a positive return on investment. With nitrogen, the higher the rate usually equates to higher yield. The same can be applied to apple production. There needs to be a calculation that leads to how much nitrogen can be applied to obtain a certain yield and receive a positive return on investment. To figure out what the best application rate will be, an end goal must be established.

Some growers prefer dessert apples, others culinary and sauce or cider. There are many different products produced using apples and this will be the leading variable to nitrogen rates. The cultivar can have a great influence on nutrient requirements. Seasonal changes and environmental factors, as well as soil test levels, play a key role in nutrient applications.

Nitrogen is one of the major drivers for vegetative growth in plants. Too much nitrogen uptake can lead to rapid vegetative growth and shoot elongation. This will lead to shading of fruiting areas, increased humidity in the canopy and a competitive fight for nutrients from the fruit. This is where apples can experience diseases, such as Bitter Pit, because the calcium is being used in cell construction of vegetative growth rather than fruit production. From a management perspective, it creates much more pruning to contain efficient harvest heights and open canopies.

For dessert apples, higher nitrogen rates can be used. The producer wants a large apple that is juicy. Using the term “juicy” does not necessarily mean better juice, perhaps just more of it. The higher the nitrogen, the higher the water content of the fruit juice. By pruning correctly, fruit size will increase but it is important to regulate nitrogen applications for higher sugar content. For cider and sauce uses, the amount of tannin, pectin and fruit size is mostly dictated by the cultivar. However, to have the highest sugar content, low nitrogen rates create smaller fruit. This leads to more fruit skin surface area resulting in much higher tannins and less water concentration creating a higher sugar content.

Precipitation amounts will play a large role in water content of an apple. A wet, rainy season during fruit growth stages will increase water uptake, carrying nitrogen with it, which will increase the fruit size and decrease sugar content. The type of soil, slope and location of trees can have a large impact as well. Soil with good drainage, will hold less water. Heavier soils with higher organic matter will mineralize more nitrogen and typically yield larger fruit with less sugar content.

Do Cover Crops Produce Nitrogen for Your Next Crop?

Cover crops provide many benefits to agricultural soil, increased organic matter, erosion reduction, weed suppression, moisture retention, improved soil structure, disrupting pest cycles, and the list goes on. However, a common question is, do they provide nitrogen to the next crop? The straightforward answer is yes, maybe, sometimes, and it depends…

The first thing to consider is the type of cover crop. Legumes such as clover and peas have the potential to provide nitrogen. Grass species such as rye and oats are not likely to provide any nitrogen to the next crop. It all comes down to the carbon to nitrogen ratio. The majority of nitrogen in plants is tied up in proteins. Legumes have more. The problem is that protein is not plant available and must be decomposed by soil microbes to be released as ammonium or nitrate for the plants to utilize. In order for the microbes to do their job, they need a C:N ratio of about 25:1. Grass species generally have a C:N around 30:1 to 50:1. This means that the microbes need to find another source of nitrogen to breakdown these cover crops leaving none to be released. On the other hand, legumes generally have C:N around 15:1 to 25:1. When there is more nitrogen in the cover crop than the microbes need, it can be released to the soil solution for the crop to utilize.

As with anything in agriculture, weather has the greatest impact on the potential for nitrogen release from cover crops. The microbes need warm soil temperatures and adequate moisture. Fortunately, when conditions are favorable for microbial activity, it is also favorable for plant growth which means there is a greater chance of utilizing the nitrogen.

So, how much nitrogen can you realistically expect from a legume cover crop? Some research has claimed that a clover cover crop can provide 70 to 90 pounds of nitrogen per acre. This is not entirely true. When testing the biomass of the cover crop, it is definitely possible for there to be that much nitrogen, but it does not, the crop will have access to all of it. Another misconception in some of the research is that all the yield gained following a legume cover crop is a result of a nitrogen contribution. As mentioned above, cover crops can provide many benefits that can improve yield. So, if you reduce a nitrogen application by all the nitrogen in the cover crop biomass, you may be under applying leaving missing out on potentially higher yields. A more realistic expectation following a well established legume cover crop is about 30 pounds of nitrogen per acre. Another thing to consider is tillage. A cover crop terminated through conventional tillage is more likely to decompose in a timely manner than one that is terminated with herbicide in a no-till situation due to the increased soil contact with the plant tissue.

Did the 2025 Drought Impact Soil Test Results?

In short, yes—for those areas that experienced a D3 drought. For much of the region, D3 drought conditions developed partway through the fall harvest of 2025 and extended through the spring of 2026. Over the past few years, areas impacted by D3 drought have shown consistent effects on soil samples. Observations suggest that late D2 into D3 droughts can significantly influence soil test results.

Below are previous blog posts with additional information on how drought impacts soil samples:

• algreatlakes.com/blogs/news/impacts-of-the-dry-2024-fall
• algreatlakes.com/blogs/news/soil-testing-after-a-drought-originally-posted-2012

How can you tell if your data is impacted?
The clearest indicator is areas within fields showing very high soil pH. While not ideal to manage, these locations are best suited to assess drought impact. These areas typically have a soil pH of 8.1 to 8.2 and are often associated with free calcium carbonate in the soil—meaning there are more carbonates (lime) present than can chemically react.

High soil pH is usually accompanied by very high calcium (ppm) levels and calcium cation saturation of 80% or greater in mineral soils with a CEC of 10–20, and over 90% in sandy soils.

This situation is unique because the acid-neutralization reaction stalls when soil pH reaches 8.1 to 8.2 and cannot increase further. At that point, unreacted carbonates (lime) remain in the soil, available to neutralize future acid inputs. This reserve capacity keeps soil pH elevated for the foreseeable future. These conditions can result from excessive lime applications or naturally occurring carbonates.

However, in areas with free or excessive carbonates that are severely impacted by drought, soil pH may drop below 8.0. In parts of northwest Indiana and northwest Ohio from fall 2025 through early spring 2026, soil pH values of 7.5 to 7.6 were observed in areas that historically tested between 8.0 and 8.2 - representing an approximate 0.5-unit decrease.

Soil test potassium (K) declines are less predictable but tend to occur under similar conditions. Reports indicate estimated declines of 15–30% in soil test K levels compared to recent historical values. While soil pH typically recovers quickly with increased rainfall, potassium levels may remain depressed for several months.

Some notable phosphorus (P) declines have also been reported. However, these may be influenced by reduced phosphorus application rates over the past few years.

Soil pH Impact on Potassium Retention

Soil pH impacts potassium differently than other nutrients. For phosphorus, soil pH affects the chemical form of the nutrient and the cations it bonds to. For potassium, however, the impact of soil pH is entirely about finding a place on the Cation Exchange Capacity (CEC).

Not all cations (positively charged ions) are created equal. The affinity, or lyotropic series, defines how strongly cations are held by the CEC. Assuming all cations are present in equal amounts, aluminum and hydrogen will bind to the CEC first, and sodium last:

Al³⁺ > H⁺ > Ca²⁺ > Mg²⁺ > K⁺ = NH₄⁺ > Na⁺

Aluminum and hydrogen have a high affinity for the soil CEC. At a low soil pH (below 5.5), aluminum becomes soluble and exchangeable, and the hydrogen concentration in the soil increases. At these low pH levels, these cations dominate, leaving little space on the CEC for the retention of potassium, ammonium, and sodium. (Sodium’s inability to bond strongly to the CEC is actually a good thing, as it leaches away).

High soil pH levels are created by the presence or application of calcium- and magnesium-based carbonates and bicarbonates. Calcium and magnesium have very similar affinities for the CEC, and both are much stronger than potassium, ammonium, and sodium. At high soil pH, calcium and magnesium dominate the sites bound to the CEC, again leaving little space for potassium retention.

Additionally, the typically low CEC of sandy soils reduces the chance of potassium finding a binding site. The structure of organic matter CEC is also not conducive to the retention of potassium at any soil pH.

In summary, the impact of soil pH on potassium is not about changing the form of the nutrient to limit plant uptake; rather, soil pH impacts the soil’s ability to retain potassium and prevent it from leaching down through the soil profile.

Biologicals and Nutrient Use Efficiency

As crop fertility inputs increase, the need for using soilborne nutrients more efficiently increases as well. This is not a new concept and occurs naturally without prompt. The soil is full of biological processes and is continuously converting organic substances to inorganic, or plant available, forms. There are, however, products in the marketplace that try to add to the native soil biology with varying success.

To better understand how biological organisms use, convert, neutralize and upcycle nutrients they must be categorized and uses described. According to Cornell University, the different types of biologicals, or microorganisms, are best described as living and non-living. The living microbes may include nitrogen fixing bacteria and decomposers. Nitrogen fixing bacteria are microorganisms that can convert dinitrogen from the air using an enzyme called nitrogenase. Nitrogenase is very sensitive to oxygen exposure and needs an anaerobic environment to convert dinitrogen to ammonia. Decomposers simply break down organic matter and residue into available forms of nutrients. The microbes that consume organic matter and residues consist of bacteria, fungi and actinomycetes.

Each type serves a purpose in the process. Bacteria need warm soils and nitrogen to consume simple forms. Fungi and actinomycetes break down cellulose and lignin which take the longest to recycle. This is why residue worked in with tillage tools too deep may not break down for several seasons because fungi need oxygen to work. To make residue cycling quicker, it just needs more soil to surface contact. This can be done by utilizing chopping corn heads/aggressive knife rollers, crimpers/rollers, and tillage practices to name a few.

The non-living section of microbes are derived from living organisms and used as bio-stimulants. Humic and fulvic acids and sugars aid in the processes of residue and organic matter conversion. Living organisms need a multitude of factors to align to reach their full potential. Certain requirements must be met depending on the type of microorganism they are. Perhaps this is why research and yield data has been inconsistent, across the marketplace, for biological additives for cropping systems.

 As mentioned above, some microbes prefer oxygen and cool temperatures to perform their best. So, when introducing a live, or dormant, biological to the soil and/or plant what precautions are being taken? This may require climate cooled storage facilities with aerators for long-term shelf life and quick application windows. Others prefer no oxygen and warmer temperatures. In this instance, knifing (or subsurface application) of a bacterial application may be necessary. Most soils already contain necessary biological life. They may just need better fundamentals like moisture, air, organic matter and nitrogen.

Cornell University Nutrient Management Spear Program. (n.d.). Nutrient release from organic materials (Agronomy Fact Sheet #127). Cornell University College of Agriculture and Life Sciences.

The ALGL Customer Photo Calendar is Back!

The ALGL customer photo calendar is back! Once again, we are reaching out to the best customers a business can ask for.

 Do You have photos to share?  Please share with us pictures of those things in life sciences that speak to you and show how amazing the world around us truly is. We want to see pictures that illustrate what fuels your passion for life sciences and customer service. When you get that picture captured, send it to news@algreatlakes.com along with your name, address, and brief note about the picture(s). Please submit your pictures in the highest resolution possible before September 15th. Then we will select our favorite pictures, then we will be letting our followers on Facebook vote on their favorite, to be on the cover of the 2027 calendar. Follow us on Facebook for voting details.

 Photo criteria 

• Landscape oriented photos preferred but not required.
• Please do not crop the pictures before submission.
• Please share the highest possible resolution photo.
• Please try to avoid company logos and easily identifiable faces.
• No dangerous or illegal activities.

Rules 

• Photo submission deadline is September 15, 2026
• One entry per person, however you may submit more than one photo.
• Must be 18 years or older to enter.
• Need not be present to win.
• No purchase necessary.
• Submitting a photo gives A&L Great Lakes permission to use the photo for promotional use.
• Employees of A&L Great Lakes Laboratories, Inc. and their immediate families are not eligible for prizes but may submit photos for consideration in the calendar.
• Use of images in promotional items does not increase your odds of winning a prize.
• Contest decisions and/or judgements by A&L Great Lakes Laboratories, Inc. are final.

What’s the Difference Between Lawn & Garden and Routine Soil Test Packages?

As the weather begins to warm up, people start getting antsy about their outdoor hobbies such as gardening and lawn care. Many home landscape enthusiasts start each growing season with a soil test. While anyone is welcome to send samples to us directly, many samples often come through our traditional agricultural clients as people want their samples shipped in by the company that they plan to buy fertilizer from. This situation frequently raises the question as to what is the difference between our Lawn & Garden packages and the routine packages used for agricultural samples?

As far as the laboratory processes being used, there is no difference. There are 2 options for Lawn & Garden packages, a basic and a complete package. The basic package is the same as our S1 package. The complete package is the same as our S2 and S3 packages. The difference is the level of fertilizer recommendations included. For Lawn & Gardens, the recommendations are given in pounds of nutrient per 100 and 1000 square feet and product specific recommendations are written by one of the ALGL staff agronomists, i.e. “Use 20 pounds of 21-0-0-24, ammonium sulfate, per 1000 square foot of garden.” These test packages are intended for homeowners who may not have knowledge of calculating fertilizer rates.

What many of our more traditional agricultural clients don’t realize is that we can provide the provide the same recommendations for lawns, gardens, flowers, etc. Using our routine test packages. The difference is that it only includes the calculated nutrient requirements, and not the product specific recommendations. This allows the retailer to choose the most appropriate fertilizer that they offer to meet their needs. When the products are being made by the lab agronomist, we often use very generic products so the homeowner has a better chance of finding them at a big box store or at a specialty garden store.

When using our routine soil test packages for lawn and garden type samples we will change the format to a graphical representation of the soil test ratings to help give the end customer a better understanding of the results. Below are examples of the different report formats.

Lawn and Garden report with product recommendations. 

The Role of Soil pH in Phosphorus Dynamics

Soil pH dictates various aspects of soil fertility. For phosphorus, soil pH impacts the chemical form present in the soil. As soil pH increases, the concentration of hydrogen ions decreases; likewise, the number of hydrogens associated with phosphate decreases.

Iron Fixation in Highly Acidic Soils

At soil pH levels below 3.0–4.0, the predominant form of phosphate in the soil is H₃PO₄. This form is not plant-available and has a high chemical reactivity with iron. This low pH also greatly increases the water-soluble of iron, which creates ideal conditions for the two to bond.

·        Oxidized Iron Soils (Red Clay): If the iron is in an oxidized state, the bond is very strong. This creates an insoluble mineral that has extremely low solubility and plant availability. Soil pH adjustments have little to no effect on releasing phosphorus bonded to oxidized iron.

·        Reduced Iron Soils (Grey Clay): If the iron is in a reduced state, the bond is also very strong but maintains a low level of water-solubility.

Aluminum Interactions and H₂PO₄^- Availability

As soil pH increases, the predominance of H₂PO₄^- increases, which is plant-available. The concentration of H₂PO₄^-starts at a soil pH of 3.5–4.0, peaks at a soil pH of 5.5–6.0, and ends at pH levels above 6.5–7.0. This form has limited reactivity with iron but is reactive with aluminum. Aluminum water-soluble occurs at soil pH levels below 5.0–5.5. The peaks of availability/ water-soluble between H₂PO₄^- and aluminum do not quite align. Additionally, as aluminum is included with iron, or replaces iron in the reaction, the water-soluble and plant availability of the resulting mineral increases slightly.

The "Sweet Spot" for Phosphorus Availability

Between pH 6.0–7.5, phosphorus exists as either H₂PO₄^- or HPO₄^2- _, both of which are plant-available, and the reactive partners of iron and aluminum are not water-soluble. This results in the optimal pH for plant-available phosphorus, with the lowest rate and severity of fixation due to the formation of insoluble minerals.

Alkaline Soils and Calcium Fixation

It is not until soil pH levels rise above 7.5 that HPO₄^2- is the prevalent form and excessive calcium drives the reaction of phosphorus with calcium. High soil pH is caused by the over-application of lime or naturally high calcium carbonate content in the soil. Because high soil pH and high calcium levels are strongly correlated, calcium is often confused with soil pH. The mineral formed in this environment between calcium and phosphorus closely resembles the rock phosphate mined for fertilizer production, which has low water-solubility. The amount of phosphorus participating in this reaction continues to increase as soil pH increases.  However, calcium phosphate minerals are more water-soluble than the minerals formed at a low soil pH. Like the mined mineral, the bond between calcium and phosphate can be broken by acidifying the material, leading to a significant increase in water-solubility. Acidic root exudates are effective at breaking this bond, leading to increased plant availability.

Comparison of Phosphorus Fixation by Soil Environment

How to Dial in a Nitrogen Rate for the Upcoming Corn Crop

The current economic conditions for corn producers require making wise decisions when it comes to crop inputs. One of the higher costs associated with a corn crop is nitrogen (N) fertilizer. Knowing exactly how much you need to purchase can help lock in better prices with early purchase options before the prices are likely to go up as the growing season approaches. Here is a list of things to consider when determining an appropriate N application rate.

Potential Yield – Determine a realistic yield for your operation. This is probably not the year to aim for record yields. Use the average of the last 5 to 10 years of actual yield averages, not just the average you hope for. Consult your seed company agronomist to see how different varieties have yielded in local plot trials.

Nitrogen Use Efficiency – This is the amount of N it takes to produce 1 bushel of corn. Every bushel of corn contains approximately 0.67 pounds of N. However, a corn crop takes up approximately 1.0 pounds of N for every bushel produced. If N can only be applied before planting, generally 1.2 to 1.4 pounds of N per bushel should be applied to account for the greater risk of loss. In a typical system with starter N and sidedress, aim for 1.0 to 1.1 pounds per bushel. If you have the option for late season applications (VT and later), it is possible to reduce rates to 0.7 to 0.9 pounds per bushel.

Maximum Return to Nitrogen (MRTN) – This is a model developed by multiple universities using N response data to calculate the economic optimum N rate for your situation. You begin by selecting your region then entering your expected price per bushel and your cost per pound of N. This model is accessible at https://www.cornnratecalc.org/.

Estimated Nitrogen Release (ENR) – You can use the organic matter from your routine soil tests to help reduce your N application rate. For every 1% organic matter, you can estimate that approximately 20-40 pounds of N will be mineralized or naturally released by the microbes in the soil. However, this is heavily dependent on the weather. So, it is advisable to stay on the lower end of the range.

Presidedress Soil Nitrate Test (PSNT) – Collect a soil test prior to a sidedress application to see how much nitrate has been mineralized by the organic matter. For sampling instructions and data interpretations please see our fact sheet, PSNT for Corn.

Soil Compaction Fundamentals

Soil compaction is often associated with its physical properties. It is when soil particles are pressed together and pore space is decreased. Pore space can account for fifty percent depending on soil type. This can be physically altered through natural and mechanical influences.

In the pore spaces of soil, water and air are in a constant back and forth balance. As soil solution increases due to precipitation weather events or capillary action, there is less air present in pore space. Contradicting this, the soil dries from lack of precipitation and more air is present. Water infiltration and capillary action are affected by soil type and soil compaction.

There are soil types that naturally are more resistant to compaction. The higher the sand content, usually, the less compaction occurs. Soils with more clay tend to compact more and further in depth. They have a higher water holding capacity, smaller pore space and tighter particle bonds.

Compaction can occur at various levels in the soil profile. Tillage practices can influence many compaction points, but on the soil surface it experiences multiple situations. How can some no-till fields have such a hard top layer? Heavy rain events cause lots of surface compaction. What can make this worse is a seedbed preparation tillage pass before such event. This will cause crusting of the soil surface with little pore spacing for germinated seedlings to emerge.

Each pass in the field, whether it be from machine or foot, compresses the soil limiting pore space and compacting as well. A tool to help measure these actions is a penetrometer. It is a solid probe with an indicator dial on top that is pressed into the soil. As it travels through the profile, the needle on the dial will show what the PSI is at the probe tip ranging from 0-300+. Using a ¾ inch tip, 0-200 is considered optimal, 200-300 roots are restricted and anything over 300 is very compacted.

Plow layers, or subsurface compaction, is caused by smearing of the soil and done on a routine basis. These can usually be found around 7-9” deep depending on the region and tools used. These are also mistaken for soil horizon changes. Such as Topsoil A Horizon, to Subsoil B Horizon as soil changes from higher organic matter to structureless massive soils with an anerobic environment.

To manage compaction, it starts with limiting soil surface exposure. Leaving residue or practicing minimal tillage. Not applying too much down pressure with the planter gauge wheels, proper tire inflation or the use of tracks, and not disturbing the soil when field conditions are marginal to saturated.