Dates and locations are set for the 2022 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. For more details, please visit our website.
February 3, 2022 - Fort Wayne, IN
February 10, 2022—Rockford, IL
February 15, 2022 - Frankenmuth, MI
February 23, 2022 - Perrysburg, OH
February 24, 2022 - Grand Rapids, MI
March 1, 2022 - Fort Wayne, IN
A corn stalk nitrate test (CSNT) can be a useful tool in assessing the effectiveness of a nitrogen program. However, the test results often generate more questions than answers. This has been very true of this season so far. The general interpretation of a CSNT is that if the result is less than 700 ppm, nitrogen may have limited your yield, from 700 to 2,000 ppm, nitrogen use was optimal, and greater than 2,000 ppm indicates excess nitrogen. This season it has been very common to have results greater than 10,000 ppm from all over the Great Lakes region. What can possibly explain the excessively high numbers? Here we will discuss a few possible explanations.
The most obvious explanation is that too much fertilizer was applied. No, this does not indicate that growers are carelessly over applying fertilizer. It simply means that for the current growing season, a lower amount of applied nitrogen would likely have generated the same yield for reasons that are impossible to predict at the time the nitrogen was applied.
Drought stress is one of the leading causes of high CSNT results. Most growers are applying about 1 pound of nitrogen per bushel of projected yield. So, if 200 pounds of nitrogen is applied between a starter and sidedress application expecting to harvest 180-200 bushels, but a late summer drought cuts that yield down to 100-120 bushels, the excess nitrogen will accumulate in the lower stalk since there is not enough grain to utilize the applied nitrogen.
Another potential explanation is another nutrient deficiency. For example, if the crop was supplied with enough nitrogen to grow 200 bushels, but the plants are experiencing a severe sulfur or potassium deficiency reducing the yield, there will be excess nitrogen in the plants.
Generally high CSNT results indicate that some other factor than nitrogen reduced the yield. What has been unique this season is that many of these high CSNT’s are coming from fields that did not have excessive nitrogen applied, the overall soil fertility is good, they were not drought stressed, and they are expecting excellent yields. Where is this extra nitrogen coming from? Most likely the soil. There is a huge bank of nitrogen in the soil organic matter that can possibly be mineralized if the soil has adequate moisture, heat, and microbial community. If or when this will happen is nearly impossible to predict. For much of the region, the spring started off fairly cold with descent moisture and then in late June the temperature skyrocketed and we got some sizeable rain events. These conditions likely spurred a rapid microbial release of nitrate more than what the crop needed since the nitrogen fertilizer was likely applied a month prior to these conditions.
For more information about sampling corn stalks for nitrates, please see our fact sheet or contact your ALGL agronomist.
Conversations about soil carbon are becoming rather common at grower meetings, but what exactly is soil carbon? Soil organic carbon is the carbon fraction in the soil that originated from plant material, the source of the carbon within the parent plant material was CO2 from the atmosphere. The basic goal of the carbon market is to convert CO2 from the atmosphere into plant biomass, and then keep it sequestered in the stable humus and/or resistant organic matter to avoid the release of carbon back into the atmosphere .
Many simply equate soil carbon to soil organic matter. While soil organic matter does contain carbon, soil organic matter is more than carbon. The percent of carbon can vary depending on the soil organic matter parent material, how stable the soil organic matter is, and depth within the soil profile. While the Van Bemmelen factor from 1890, based on the assumption that soil organic matter is 58% carbon, is commonly used to calculate soil organic carbon from soil organic matter values on a soil test. Since 1890 a wide range of studies have shown soil organic matter to be from 52% to 40% carbon. While it is correct that increasing soil organic matter results in more organic carbon in the soil, exact determination of organic carbon volume from soil organic matter data alone is challenging.
Testing for total carbon in soil via combustion is a laboratory method performed at ALGL. However, there is both organic and inorganic carbon in the soil. The primary inorganic carbon in soil are calcium carbonate (CaCO3) and magnesium carbonate (MgCO3), the two main components of ag lime. Because past management (lime applications) vary by field, estimations of lime-based carbon content is not practical. ALGL also offers the Walkey Black, a wet chemistry test specifically for organic carbon. The difference between the two can identify the inorganic soil carbon content. Unfortunately, these tests are slower and more costly than basic soil fertility test that most producers are accustomed to.
These tests generate a value that represents the concentration of the total or organic carbon in the soil sample. To determine a carbon ton/acre value a soil bulk density is needed. Soil Bulk densities are most accurate when determined on a non-disturbed soil sample.
Methods of Soil Analysis, Part 3 – Chemical Methods, Soil Science Society of America, Madison, WI, 1996.
Hoyle, FC 2013, Managing soil organic matter: A practical guide, Grains Research and Development Corporation, Kingston, viewed 15 October 2018, https://grdc.com.au/resources-and-publications/all-publications/publications/2013/07/grdc-guide-managingsoilorganicmatter.
Over the last several years there has been a steady increase in the number of soil samples being submitted to the laboratory requesting recommendations for wildlife food plots. This increase has been driven by changes in deer baiting laws in some of the states in our region. As a result, many of our agricultural retail and cooperative customers have been tasked with servicing this new customer segment. While the fundamentals of soil fertility management in food plots is no different than in production agriculture, the application of the management practices can be more challenging. The goal of this article is to provide some tips to better advise customers in this situation.
To begin, what recommendations do you request from the lab? If the food plot is going to only be one type of plant, such as corn, soybeans, or clover, request recommendations for that specific crop, but with a low yield goal. There is no reason to fertilize a food plot for 250-bushel corn or 75-bushel soybeans if the crop is not going to be harvested for grain. More commonly, food plots are established with a mix of plants containing legumes, brassicas, rape, radishes, and small grains. For this type of food plot, we have developed a “wildlife forage” recommendation set. These recommendations target a higher pH to accommodate the legumes and a relatively low rate of nitrogen to help establish the non-legume plants and not to inhibit the legume establishment.
One of the challenges with food plots is that they are generally established on forest soils that are naturally low in soil fertility. Often fertility recommendations will call for very high rates of phosphorus and potassium to build the soil test to a more desirable level. Do not try to do this in a single application. Split the recommended fertilizer rates into 2 or 3 applications throughout the growing season to avoid loss of the nutrients and to avoid potential salt injury to the seeds.
Another property of forest soils is that they often have an acidic pH. It is not uncommon for our recommendations to call for 4 or more tons of ag lime per acre. The challenge here is that most food plots are not accessible to spreading equipment capable of handling that volume of material. Utilizing pelletized lime in these situations is the best option. Pelletized lime provides 2 benefits as compared to traditional ag lime. First, you can use much less and second, it can be spread with a small conical fertilizer spreader. Since pelletized lime reacts much faster than ag lime, it should only be spread at rates up to 500 pounds per acre. However, pelletized lime will have to be spread more frequently. For soils with a very low pH, it may take annual applications of pelletized lime for 4 or 5 years to get the pH to the desired level.
If you have questions about adjusting fertilizer and lime rates based on the products and equipment that you have available, contact your ALGL agronomist. Happy Hunting!
Often the number of turf soil samples and related phone calls to the lab increase in late August into September. Many of them with similar concerns as the turf growth slows and, in many cases, turns brown. Most are looking for what fertilizer or product to spray or apply to correct the issue. This is a simple fix, repeated liberal applications of dihydrogen monoxide… water. Applying more fertilizer is not always the answer.
We can see the same in crop production fields when the weather turns dry leading to reduced nutrient availability manifesting as visual deficiency symptomology, and possibly lower nutrient levels in tissue tests. While often the goal of crop fertility is seen as maximizing yields, additionally the goal of soil fertility is to reduce the risk of negative impacts to plant growth in challenging growing environments.
In either situation, being prepared ahead of time with adequate N for a strong and healthy plants, proper phosphorus levels to promote root development and sufficient potassium to aid in water management within the plant. Good fertility management aims to reduce the risk from uncontrollable factors, like droughty weather patterns, that can negatively impact crop nutrition. Keep in mind that controllable factors, such as soil compaction and poor drainage, can also manifest themselves as a nutrient deficiency.
When a plant is struggling, the immediate application of fertilizer is often not the answer. Could it be an underlying related agronomic issue? Could it be bad luck presenting you with an uncontrollable factor? Can the risk of a negative yield impact from this uncontrollable factor be mitigated in the future? The first step is using soil testing to ensure the foundational soil fertility in place in advance of the challenges of the growing season, and then use tissue test to verify at that the plants can access the soil fertility you have provided.
Beginning August 1, 2021, the updated Tri-State Fertilizer Recommendations will be available from ALGL. This includes both recommendations requested on soil submittal forms and through SoilTrak.
Listed below are the details for the new recommendations. If you have any questions, feel free to contact your ALGL agronomy representative.
While fertilizer prices continue to increase, the rate of increase is slowing. It appears that the fertilizer prices are starting to stabilize. The price spike was largely due to supply shortages, supply chain disruptions, and higher producer demand following increasing commodity prices leading to more favorable farm income. While the prices are stabilizing at a higher level, many growers are looking to retain some of the increased revenues from improved grain prices. This is driving producers to evaluate fertilizer cost reduction strategies.
The second, and maybe bigger issue is the fact that the supply side of the equation has not changed and maybe growing tighter. While making plans to reduce fertilizer cost, producers also need to be making contingency plans if they cannot source enough fertilizer to meet their needs.
The strategies used in this situation will be very similar to those used when commodity prices are low but having a “Plan B” in the event that fertilizer is limited will be a new concept to look at. The first goal is to ensure that yield is not put at risk if possible, and the strategy will vary by nutrient.
All forms of nitrogen have about doubled in price in the last year. Concerns over anhydrous ammonium supplies have been minor, however dramatic increases in urea and UAN demand have greatly reduced the stock of these products in the field. The positive is that the high prices are delaying inventory purchasing to allow the supply chain inventory to refill. Flexibility in nitrogen source maybe key in the event one of the main materials supply declines.
Look for greater nitrogen use efficiency:
One of the greatest challenges in building phosphorus soil test levels is that it takes several pounds of phosphorus to raise a soil test 1 ppm, this is also an advantage in that it takes quite bit of crop removal to decline soil test levels. First separate your maintenance (crop removal) fertilizer rate from your build rates. The build rates can be reduced or eliminated if needed. Maybe prioritize the build on those fields with the lowest soil test values to make sure the build process continues.
If you’re not taking advantage of a precision ag based fertility program, know is the time to start. Putting the fertilizer where it is needed will pay in these challenging times. If you are in a program, take it the next level and add yield monitor crop removal. Replace only what the crop removes. In the events of very tight supply/cost and with good phosphorus levels, this technology could be used to apply less than crop removal on a percentage basis for a growing season or two with less negative impact than other nutrients.
Potassium soil test levels can change quickly, and it is not recommended to apply less then crop removal if the soil test levels are at or below targeted levels. Like phosphorus, build portions of fertilizer recommendations could be omitted. This again is a key advantage of a precision ag fertility programs with more frequent sampling cycle to keep current on soil test potassium levels.
Some research suggests that annual application of potassium fertilizers can increase yield. This reduces the volume needed to complete the fertility plan and reduces the price risk of buying fertilizer at the highest price for an extended crop rotation. If you traditionally apply your fertilizer in the fall, you many look into the logistics of spreading some or all of your potash in the spring in the event fall supplies are short.
If you have any questions on how various management decisions may impact soil and plant fertility, be sure to reach out to your ALGL agronomist sales representative.
2021 has been another unique growing season to date. Some areas receiving more rain than needed, while other less than needed. This had led to either a highly variable crop or an outstanding crop, either way you can benefit from incorporating yield map crop removal into your fertility recommendations.
Soil fertility recommendations have two key parts that are added together to arrive at a final nutrient application rate. Part one is crop removal. How much fertilizer do I need to apply to account for or replace the nutrients removed by harvesting a crop? The second part is how much fertilizer above crop removal do I need to apply to increase soil test levels from where they are to a target level over a given period of time. Most recommendation sets are built to move from the current soil test level to a target in 4 years, that time frame could also be extended to reduce application rates. Likewise, how much less than crop removal do I apply to reduce soil test levels to target levels over a given period of time.
Traditional soil fertility recommendations take the approach of predicting or forecasting crop yields for the coming year or two. That may be as accurate as forecasting the weather. When it comes to determining the amount of fertilizer needed to replace the nutrients removed by harvesting a crop, yield records are often more accurate than yield projections.
Rather than forecasting yield using a 10-year average or a yield goal for future yield, and applying fertilizer in advance, shift your mindset to replace the nutrients that past crops have removed. For example, you may have forecasted a 200 bu/ac corn crop for 2021 sometime before planting the 2021 crop, spread fertilizer, and now due a good growing season the yields may look more like 220-225 bu/ac. So effectively this leads to a 10-12% under application of fertilizer in 2021 by incorrect forecasting. The use of yield monitor data, storage structure estimates, and scale tickets of past yield values are significantly more accurate than forecasting future yields.
When forecasting yields these overages are often not accounted for in the subsequent years. In years when yield is higher than expected we can actually short for the following crops. While routine soil sampling can catch these variances, there maybe an economic or agronomic impact until the next sampling cycle, or longer.
The main questions. So, what’s in it for the producer? And what’s in for the fertilizer retailer? The producer’s key to future stability will be through better management. This process allows a producer to follow a low yielding year with an input reduction and hopefully be able to effectively maintain strong soil fertility after an exceptional yield year. The ag retailer that takes the effort to work through this transition building a stronger partnership with the producer in these tighter times will differentiate themselves in the marketplace. Better management is often the key to better profitability for both parties. Contact your ALGL agronomy representative with any questions you may have on this topic.
Tissue samples are submitted to the lab with the sample ID ‘s of “good” and “bad”, and often the tissue test data results are very similar. Sometimes the “bad” sample will have higher nutrient concentrations than the “good” sample.
Tissue test data is a concentration of a given nutrient within the plant biomass. The concentration is the relative amount of a given nutrient within a defined volume of plant biomass.
Impact of nutrient uptake and plant size on tissue test results.
If nutrient availability in the soil is not limiting, there is no reason to expect the tissue test data between a “good” and “bad” sample to be significantly different. if a plant is limited by physical or environmental factors leading to reduced plant growth, the biomass volume of the impacted plant will be less. Equally decreased nutrient uptake by the impacted plant will lead to a less total nutrient in the plant tissue tested. Often the decrease in plant biomass is correlated to the relative decrease in nutrient uptake. This leads to a very similar sample nutrient concentration. If the plant biomass is severely impacted while nutrient uptake continues the impacted plant could result in elevated nutrient levels. Observation notes and pictures taken at the time of sampling can be very valuable in interpreting plant tissue data.
Getting a tissue test report back form the lab showing that both the “good” sample and “bad” sample have adequate nutrient concentrations to support plant growth does not mean the tissue test did not tell you anything. It means the issue affecting the growth of the “bad” sample is most likely not nutrient related. Contact your ALG agronomy representative for support using plant tissue data in diagnosis situations.
Over the last few weeks, we have received many soil samples for nitrate analysis to help determine what rate of nitrogen to sidedress in corn. Several of the samples have generated questions for our agronomy staff regarding unusually high nitrate results. Upon further investigation we have found that many of these fields with high nitrate levels have one thing in common, they had manure applied since the previous crop was harvested. This is the exact scenario that the pre-sidedress soil nitrate test (PSNT) was developed to assess. Each university extension program in the Great Lakes region have developed interpretations for determining what rate of nitrogen to apply based on the soil nitrate level, and they all basically agree that if it is above 25 ppm, no additional nitrogen is needed. This year it has not been unusual to see 50 to 100 ppm.
Where is all this nitrogen coming from? Simply stated, we can thank the fall, winter, and spring weather. Last fall was dry, which allowed for timely manure applications. The winter was relatively dry and cold. This kept the microbial activity to minimum reducing the chance for nitrification and mineralization to occur that could lead to nitrogen losses. The early spring was cold through most of May, again minimizing nitrogen losses. Then early June got hot with some rain, and it kicked the microbes into high gear converting ammonium and organic nitrogen sources into nitrate.
So, what do we do with these high numbers? Most growers who use manure as part of their nitrogen program know that even an aggressive fall manure application will likely run short on nitrogen and generally require a supplemental source to get through the whole season. Even though the university interpretations say there is more than enough, you need to consider each situation on its own. Irrigated ground with a 300+ bushel potential is certainly going to require much more nitrogen than dry ground with 150 bushel potential. Is there an option for late season applications, such as fertigation or a high clearance spreader? If you are in a situation where your current soil test nitrate levels do not justify a sidedress application, your best bet is to monitor the crop. At tasseling, a corn crop should have taken up 60 to 70% of the nitrogen it needs for the season. Collecting a plant tissue sample at this time can potentially identify a nitrogen deficiency before any visual symptoms appear.
If you have any questions or want to discuss your own situation, contact your ALGL representative.