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osunpk

osunpk

Since 2008 I have served as the Precision Nutrient Management Extension Specialist for Oklahoma State University. I work in Wheat, Corn, Sorghum, Cotton, Soybean, Canola, Sweet Sorghum, Sesame, Pasture/Hay. My work focuses on providing information and tools to producers that will lead to improved nutrient management practices and increased profitability of Oklahoma production agriculture

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Nitrogen rate and timing for a forage wheat crop. Year 1 Results.

Written by
Mr. Bronc Finch, PhD. Student, Precision Nutrient Management. 
Dr. Brian Arnall, Precision Nutrient Management Extension Specialist. 
In cooperation with Dr. James Rogers, Noble Research Institute. 

With the amount of wheat acreage in Oklahoma being utilized for grazing cattle, and much of that land grazed completely instead of harvested for grain, many questions have arose regarding the management of grazed cropland. A major question in the management of a graze-out wheat crop pertains to fertilizer management strategies. A study developed in co-operation with the Noble Research Institute is attempting to answer these questions among others. In 2019 the trial was established at three locations: near Lake Carl Blackwell in Stillwater, OSU South Central Research Station in Chickasha, and Noble Research Dupy farm in Gene Aurty, Oklahoma. Each of these three sites were setup with three nitrogen (N) treatments in Gallagher winter wheat, with 2 pre-plant applications of 60 and 120 pounds per acre, and a 60 pound pre-plant and 60 pound top-dress application. Grazing simulation harvests were taken at two times with the top-dress N being applied after regrowth was noticed following the winter season. The Dupy location was planted late and therefore only had a single harvest at the end of the season. Rising plate meter measurement were collected at feekes 7.5 and represented in the graphs below as Mid-season. The Chickasha location revealed unexpectedly high residual soil N levels, which resulted in no differences in dry matter biomass for the first harvest, which was delayed until early march due to excessive rains. The second harvest at Chickasha did show treatment differences with a 0.4 ton difference between the 60 and 120 lbs preplant N rates and increase of 0.8 ton increase over the 120 lb pre-plant when the additional 60 lbs of N was delayed. LCB had a timely first harvest in December resulting in the 120 lb N application outperforming the 60lb N applications by ≥0.33 tons. The second harvest further showed how the split application of N proves beneficial for biomass production. As the split application increased yields by 1.7 and 2.6 tons over the 120 lb and 60 lb preplant applications, respectively. The Dupy location revealed no significant difference in dry matter biomass yield between N treatments at the time of the rising plate meter measurements or for the final cutting.

Figure 1. Dry matter harvest results for each of the harvest dates from the graze out wheat trials from the Chickasha, Lake Carl Blackwell, and Dupy locations for three fertilizer treatments. 60: 60 lbs of nitrogen applied preplant, 120: 120 lbs of nitrogen applied preplant, 60/60: Split application 60 lbs of nitrogen preplant and 60 lbs applied top-dress. Dupy only had one harvest date, the Mid-season yield is estimated via rise-plate measurements taken at Feekes 7.5.

 

The Chickasha and Lake Carl Blackwell (LCB) locations produced an increase in total yield with both the increase of applied N and the split application of N. The 60 lb increase in applied N at preplant, 60 lbs vs 120 lbs, produced a 0.7 and 1.2 ton increase in total dry matter harvested at Chickasha and LCB, respectively. As expected an increase in N increased the yield of wheat biomass for grazing production. The top-dress application, which was made as a late season post Feekes 6 (hollow stem), produced more biomass for graze-out wheat production. The split application of 60 lbs of N preplant and 60 lbs of N top-dress increased dry matter by .8 and 1.3 tons over 120 lbs applied preplant at Chickasha and LCB, respectively. Chickasha yielded higher biomass production than the LCB location due to increased residual N.

Figure 2. Total dry matter harvest results for the graze out wheat trials from the Chickasha, Lake Carl Blackwell (LCB), and Dupy locations for three fertilizer treatments. 60: 60 lbs of nitrogen applied preplant, 120: 120 lbs of nitrogen applied preplant, 60/60: Split application 60 lbs of nitrogen preplant and 60 lbs applied top-dress.

For the following discussion remember that protein is determined by N concentration, so that a increase in N uptake is the same as an increase in protein. Evaluation of the N uptake (% N in the biomass x amount of biomass harvested) over the season revealed treatment effects at all locations, which was not seen from biomass yield. Chickasha and LCB revealed a 20% or greater increase in N uptake with the 120 lb application over the 60 lb application of N at pre-plant. The late season top-dress application yielded a 3, 27, and 27 percent increase in uptake for Chickasha, LCB, and Dupy locations, respectively, over the 120 lb pre-plant application. Although, these results are expected from these results, there are a few things we did not expect. The 120 lb N application did not increase the N uptake above that of the 60 lb application. However, the split application of N resulted in an additional >40 lbs uptake, aka increased protein.

Figure 3. Total nitrogen uptake results for the graze out wheat trials from the Chickasha, Lake Carl Blackwell, and Dupy locations for three fertilizer treatments. 60: 60 lbs of nitrogen applied preplant, 120: 120 lbs of nitrogen applied preplant, 60/60: Split application 60 lbs of nitrogen preplant and 60 lbs applied top-dress.

This study also includes summer forages with and without additional fertilizer. The study will be continued for multiple years on the same locations to evaluate the impact of management on production and soil characteristics.  But one surprising note has already been made, in all three locations a greatly delay top-dress still increased N-uptake. In two location it significantly increase yield and protein. This data is falling in line with the grain only data (How late can you wait) showing that an application of N at Feekes 6 (Hollow stem) and even shortly after can provide positive return on investments.

 

For any questions for comments please contact
Brian Arnall
b.arnall@okstate.edu
405-744-1722

 

Watch Forage Nitrate Closely on Certain Crops

Nitrate is one of the major nitrogen (N) forms utilized by plants. Excessive nitrate accumulation can occur when the uptake of nitrate exceeds its utilization in plants for protein synthesis due to factors such as over N fertilization and stressful weather conditions. It can be toxic to livestock when too much nitrate is accumulated in the forage crops. Sorghum and millet have been noted as having a high potential for accumulating nitrate. Producers should watch their forage nitrate closely to avoid cattle fatality and to better manage their hay crop since we have seen many high nitrate forage samples every year. Normally, drought stress, cloudy weather and other climatic conditions will enhance nitrate accumulation in the plant. In addition, forage planted in failed wheat fields with high soil residual nitrogen unused by wheat can result in high forage nitrate problem too.

Figure 1. Summary of our laboratory nitrate test results in the past on two major warm season forage crops.

It is considered potentially toxic for all cattle when nitrate in the forage is greater than 10,000 ppm. Producers should avoid grazing or feeding with high nitrate hays. More detailed interpretation can be found from OSU Extension Fact PSS-2903 Nitrate Toxicity in Livestock. The most reliable way to find out nitrate in the hay is to collect a representative sample and have it tested by a laboratory. OSU Extension Fact PSS-2589 Collecting Forage Samples for Analysis highlights the proper techniques to collect forage samples. Samples can be submitted for nitrate and other forage quality analyses to the Soil, Water and Forage Analytical Laboratory in Stillwater through the local county extension office. We normally have the results ready within 24 hours form the time when sample is received by the lab. However, many samples we receive at the lab were not sampled properly. More attention should be paid on sampling standing forage, such as a haygrazer by following the right procedures:

Clip at least 20 representative plants at grazing or harvesting height from the suspected area. Cut the whole plants (include leaves and heads) into 2-3” long pieces, combine and mix well in a bucket.

Fill the cut sample into a forage bag. Use quartering to reduce the amount if there is too much sample to send to a lab.

Put the forage bag into a plastic bag will give you more accurate moisture content, but never put plastic bags inside our forage bags.

There is also a quick screening test using diphenylamine at your county extension office. This video shows how to properly use the test kit: https://www.youtube.com/watch?v=vArUP6KFQFI&feature=youtu.be

 

Hailin Zhang

Department of Plant and Soil Sciences

Hailin.zhang@okstate.edu

Recent Weather Causing Corn (and Sorghum) Injury From Pre-emerge Herbicides

With the brief window of dry ground last week my crew went at full speed planting and applying pre-emergence. Today I am sitting at home with campus closed due to the potential to severe weather with a forecast of 4-6 inches of rain for the areas I planted. Combine the recent planting activities and limited windows for pre-emergence applications, I will not be surprised if we don’t start seeing injury in some of the sorghum that was just planted before the rains. I would also add the over the years I often see bleaching in sorghum, that looks similar to zinc and/or iron deficiency, caused by atrazine injury.  This typically occurs when atrazine is applied prior to a heavy rain. The atrazine is washed down slope and into the rows, the injury is almost always seen in low lying areas.  The crop usually grows out of it.

Atrazine injury in sorghum. Heavy rains followed application. Pic via Rick Kochenower.

Atrazine injury in sorghum. Heavy rains followed application. Pic via Rick Kochenower.

Brian A.

This article is written by Mr. Cody Daft, Field Agronomist Western Business Unit, Pioneer Hi-Bred

Have you noticed any corn leafing out underground prior to emergence? Have you seen tightly rolled leaves or plants that can’t seem to unfurl leaves and look buggy whipped? Almost all of the fields I have looked at recently have shown these symptoms in at least a portion of the field, and some fields this has been very widespread. The common denominator in all the fields I have viewed has been the herbicides applied were a metolachlor (Dual/Cinch type products) and the weather (cooler than normal, wetter than normal). Similar issues can be noted in grain sorghum to some extent.

The recent wet weather and water-logged soils have increased the possibility of corn injury from many popular soil applied herbicides. Corn growing in wet soils is not able to metabolize (degrade) herbicides as rapidly as corn growing in drier conditions. Plant absorption of herbicides occurs by diffusion. What this means is that the herbicide diffuses from locations of high concentration (application site on the soil) to low concentration (plant roots). The diffusion process continues regardless of how rapidly the corn is growing. In corn that is not growing rapidly (cool, wet conditions) corn plants can take up doses of herbicide high enough to show damage and a few differences in symptomology.

The unfortunate aspect of wet soil conditions is that additional stress is put on the plant not only to metabolize herbicide residues, but also to ward off diseases and insects. These additional stresses can impact a corn plant’s ability to metabolize herbicide.

The most common type of herbicide injury observed under these conditions is associated with chloroacetamide herbicides. These herbicides are used for control of grass and small seeded broadleaf weeds, and are seedling root and shoot inhibitors.

These products include the soil-applied grass herbicides such as:

  • Dual/Cinch/Medal II
  • Degree/Harness
  • Microtech/Lasso
  • Frontier/Outlook
  • Define/Axiom
  • And other atrazine premixes like Lumax (a premix of mesotrione (Callisto), s-metolachlor (Dual II Magnum), atrazine and a safener benoxacor).

What About The Injury Symptoms?

Before corn emergence:

  • Stunting of shoots that result in abnormal seedlings that do not emerge from soil.
  • Corkscrewing symptoms similar to cold/chilling injury.
  • Corn plants and grassy weeds may leaf out underground and leaves may not properly unfurl.

After corn emergence:

  • Buggy whipping – leaves may not unfurl properly.
buggy-whipping syndrom

Figure . Buggy-whipping symptom from carryover of PPO herbicides to corn.via https://www.pioneer.com/home/site/us/agronomy/library/herbicide-carryover/

 

 

What About Safeners?
Products like DUAL II Magnum herbicide contain the safener benoxacor which has been shown to enhance S- Metolachlor metabolism in corn. This enhanced metabolism can reduce the potential of S- Metolachlor injury to corn seedlings when grown under unfavorable weather conditions such as cool temperature or water stress. However, a safener is not the silver bullet, and slow plant growth may still have trouble metabolizing the herbicide even with a safener…but it does help the severity of damage/symptoms.

Will The Plants Recover?
Plants that have leafed out underground or show corkscrewed mesocotyl symptoms are likely to not recover or even emerge from below the soil. Larger plants that are already emerged that show tightly rolled leaves and are buggy whipped will most likely recover once the field sees drier conditions and we have warm weather and sun light to assist in better plant growth.

More Information Discussing Corn Injury From Pre-emerge Herbicides Here:

http://ipm.missouri.edu/IPCM/2009/4/Cool-Wet-Soils-Can-result-in-More-Corn-Injury-from-Preemergence-Residual-Herbicides/

 

Cody Daft
Pioneer Hi-Bred
cody.daft@pioneer.com

The challenge of collecting a representative soil sample

Guest Author, Dorivar Ruiz Diaz, Nutrient Management Specialist Kansas State University

At first glance, soil sampling would seem to be a relatively easy task. However, when you consider the variability that likely exists within a field because of inherent soil formation factors and past production practices, the collection of a representative soil sample becomes more of a challenge.

Before heading to the field to take the sample, be sure to have your objective clearly in mind. For instance, if all you want to learn is the average fertility level of a field to make a uniform maintenance application of P or K, then the sampling approach would be different than sampling for pH when establishing a new alfalfa seeding or sampling to develop a variable rate P application map.

In some cases, sampling procedures are predetermined and simply must be followed. For example, soil tests may be required for compliance with a nutrient management plan or environmental regulations associated with confined animal feeding operations. Sampling procedures for regulatory compliance are set by the regulatory agency and their sampling instructions must be followed exactly. Likewise, when collecting grid samples to use with a spatial statistics package for drawing nutrient maps, sampling procedures specific to that program should be followed.

 

Figure 1. The level of accuracy of the results of a soil test will depend, in part, on how many subsamples were taken to create the composite sample. In general, a composite sample should consist of 15 or more subsamples. For better accuracy, 20-30 cores, or subsamples, should be taken and combined into a representative sample. F

Regardless of the sampling objectives or requirements, some sampling practices should be followed:

  • A soil sample should be a composite of many cores to minimize the effects of soil variability. Take a minimum of 12 to 15 cores from a relatively small area (two to four acres). Taking 20-30 cores will provide results that are more accurate. Take a greater number of cores on larger fields than smaller fields, but not necessarily in direct proportion to the greater acreage. A single core is not an acceptable sample.
  • Use a consistent sampling depth for all cores because pH, organic matter, and nutrient levels often change with depth. Match sampling depth to sampling objectives. K-State recommendations call for a sampling depth of two feet for the mobile nutrients – nitrogen, sulfur, and chloride. A six-inch depth is suggested for routine tests of pH, organic matter, phosphorus (P), potassium (K), and zinc (Zn) (Figure 2).
  • When sampling a specific area, a zigzag pattern across the field is better than following planting/tillage pattern to minimize any past non-uniform fertilizer application/tillage effects. With a GPS system available, recording of core locations is possible. This allows future samples to be taken from the same locations in the field.
  • When sampling grid points for making variable rate nutrient application maps, collecting cores in a 5-10 foot radius around the center point of the grid is preferred for many spatial statistical software packages.
  • Avoid unusual spots obvious by plant growth and/or visual soil color/texture differences. If information on these unusual areas is desired, collect a separate composite sample from these spots.
  • If banded fertilizer has been used on the previous crop (such as strip tillage), then it is suggested that the number of cores taken should be increased to minimize the effect of an individual core on the composite sample results, and to obtain a better estimate of the average fertility for the field.
  • For permanent sod or long-term no-till fields where nitrogen fertilizer has been broadcast on the surface, a three- or four-inch sampling depth would be advisable to monitor surface soil pH

 

 

Figure 2. Consistency is sampling depth is particularly important for immobile nutrients like P. Stratification of nutrients and pH can be accentuated under reduced tillage.

Soil test results for organic matter, pH, and non-mobile nutrients (P, K, and Zn) change relatively slowly over time, making it possible to monitor changes if soil samples are collected from the same field following the same sampling procedures. However, there can be some seasonal variability and previous crop effects. Therefore, soil samples should be collected at the same time of year and after the same crop.

Soil test results for organic matter, pH, and non-mobile nutrients (P, K, and Zn) change relatively slowly over time, making it possible to monitor changes if soil samples are collected from the same field following the same sampling procedures. However, there can be some seasonal variability and previous crop effects. Therefore, soil samples should be collected at the same time of year and after the same crop.

Soil testing should be the first step for a good nutrient management program, but it all starts with the proper sample collection procedure. After harvest in the fall is good time for soil sampling for most limiting nutrients in Kansas.

For instructions on submitting soil samples to the K-State Soil Testing Lab, please see the accompanying article “Fall soil sampling: Sample collection and submission to K-State Soil Testing Lab” found in this eUpdate issue.

For any questions Contact.
Dorivar Ruiz Diaz, Nutrient Management Specialist
ruizdiaz@ksu.edu

 

Soil sampling for pH and liming in continuous no-till fields

Quest Author, Dorivar Ruiz Diaz, Nutrient Management Specialist Kansas State University

One question that commonly comes up with continuous no-till operations is: “How deep should I sample soils for pH?” Another common question is: “How should the lime be applied if the soil is acidic and the field needs lime?”.

Sampling depth in continuous no-till

Our standard recommendation for pH is to take one set of samples to a 0-6 inch depth. On continuous no-till fields where most or all of the nitrogen (N) is surface applied, we recommend taking a second sample to a 0-3-inch depth. We make the same recommendation for long-term pasture or grass hayfields, such as a bromegrass field that has been fertilized with urea annually for several years.

Nitrogen fertilizer is the primary driving force in lowering soil pH levels, so N application rates and methods must be considered when determining how deep to sample for pH. In no-till, the effects of N fertilizer on lowering pH are most pronounced in the area where the fertilizer is actually applied. In a tilled system, the applied N or acid produced through nitrification is mixed in through the action of tillage and distributed throughout the tilled area.

Where N sources such as urea or liquid UAN solutions are broadcast on the surface in no-till system, the pH effects of the acid formed by nitrification of the ammonium will be confined to the surface few inches of soil. Initially this may be just the top 1 to 2 inches but over time, and as N rates increase, the effect of acidity become more pronounced, and the pH drops at deeper depths (Figure 1). How deep and how quickly the acidity develops over time is primarily a function of N rate and soil CEC (cation exchange capacity), or buffering capacity.

Where anhydrous ammonia is applied, or liquid UAN banded with the strip-till below the surface, an acid zone will develop deeper in the soil. As with long-term surface applications, these bands will expand over time as more and more N fertilizer is placed in the same general area. The graphic below (Figure 1) illustrates the effect of repeated nitrogen and phosphorus application with strip-till in the same area in the row middle on a high CEC soil for more than 12 years.

Figure 1. Soil pH stratification after 25 years of no-till and surface nitrogen fertilizer application, and the effect of repeated fertilizer application with strip-till in the same area after 12 years.

Liming application methods in continuous no-till

Where do you place the lime in continuous no-till?

If you surface apply N, then surface apply the lime. That’s a simple but effective rule. But remember that surface-applied lime will likely only neutralize the acidity in the top 2-3 inches of soil. So if a producer hasn’t limed for 20 years of continuous no-till and has applied 100 to 150 pounds of N per year, there will probably be a 4-5 inch thick acid zone, and the bottom half of that zone may not be neutralized from surface-applied lime. So, if a producer is only able to neutralize the top 3 inches of a 5-inch deep surface zone of acid soil, would that suggest he needs to incorporate lime? Not really. Research has shown that as long as the surface is in an appropriate range and the remainder of the acid soil is above pH 5, crops will do fine.

Liming benefits crop production in large part by reducing toxic aluminum, supplying calcium and magnesium, and enhancing the activity of some herbicides. Aluminum toxicity doesn’t occur until the soil pH is normally below about 5.2 to 5.5 and KCl-extractable (free aluminum) levels are greater than 25 parts per million (ppm). At that pH the Al in soil solution begins to increase dramatically as pH declines further. Aluminum is toxic to plant roots, and at worse the roots would not grow well in the remaining acid zone.

This implies that the acid zones from ammonia or banded UAN are probably not a major problem. We have monitored ammonia bands in the row middles of long-term no-till for many years and while the pH dropped very low, we never saw any adverse impacts on the crop that would justify liming and using tillage to incorporate the lime. In fact, some nutrients such as zinc, manganese, and iron can become more available at low pH, which can be an advantage at times.

Yield enhancement is not the only concern with low-pH soils, however. Herbicide effectiveness must also be considered. The most commonly used soil-applied herbicide impacted by pH is atrazine. As pH goes down, activity and performance goes down. So in acidic soils, weed control may be impacted. We do see that happen in corn and sorghum production.

Liming products for no-till

When choosing a liming product, is there any value to using dolomitic lime (which contains a large percentage of magnesium in addition to calcium) over a purely calcium-based lime product?

Most Kansas soils have high magnesium content. So as long as we maintain a reasonable soil pH, there normally is enough magnesium present to supply the needs of a crop. Calcium content is normally significantly higher than magnesium, so calcium deficiency is very, very rare in Kansas. The soil pH would need to be below 4.5 before calcium deficiency would become an issue. Before calcium deficiency would occur, aluminum toxicity or manganese toxicity would be severely impacting crop growth. So producers really don’t have to worry about a deficiency of calcium or magnesium on most Kansas soils.

What about the use of pelletized lime as a pH management tool on no-till fields?

The idea has been around for a while to use pel-lime in low doses to neutralize the acidity created from nitrogen and prevent acid zones from developing. . Pel-lime is a very high-quality product, normally having 1800 to 2000 pounds of effective calcium carbonate (ECC) per ton, and can be blended with fertilizers such as MAP or DAP or potash easily. Therefore, if you apply enough product this can be an excellent source of lime. Lime can be from various sources and with different qualities. Consecutively, to ensure a standardized unit of soil-acidity neutralizing potential, we use units of ECC.

Summary

Applying N fertilizer to soil will cause the soil to become acidic over time. Placement of the applied N and the level of soil mixing done through tillage determine where the acid zones will develop. Make sure your soil testing program is focused on the area in the soil becoming acidic, and apply the lime accordingly.

 

For any questions Contact.
Dorivar Ruiz Diaz, Nutrient Management Specialist
ruizdiaz@ksu.edu

PELLETIZED LIME – HOW QUICKLY DOES IT REACT

Each year the question comes in about lime source and rate.  To help provide some answers I along with several county educators will be establishing both large scale strip demonstrations and small plot trails on producers fields across Oklahoma.  Data collected from these project over the next four to six years will provide a great basis for future recommendations. But until we have more data I would like to share this article written by Dr. Lloyd Murdock. Dr. Murdock does a fantastic job describing the impact of source and rate on soil pH. Below Dr. Murdock contact is a list of relevant fact sheets and publications produced by Oklahoma State University.

Article written by: Lloyd W. Murdock, Retired Extension Soils Specialist 

Pelletized lime is made by granulating finely ground agricultural (ag) lime. It may be dolomitic or calcitic depending on the nature of the original limestone. The fine lime particles are bonded together with lignosulfonates during the pelletizing process. In general, the pelletized lime contains about 9% lignosulfonates. Pelletized limestone is a product that has been on the market for many years. The price of the material on a per ton basis is considerably higher than bulk ag lime, so its use has mainly been confined to specialty markets, with little use in production agriculture. However, the product is becoming more commonly used in production agriculture. Some questions have been raised about recommended rates of this material and the speed at which it reacts compared to standard ag lime.

How Much Can the Rates be Reduced for Pelletized Lime?

The recommended rates and the effect on soil pH of any agriculture lime product is related to the neutralizing value of the lime, which is a combination of the purity (calcium carbonate equivalent) and the fineness of grind (particle size). As these two properties of lime change, so does the recommended rate of lime and its effect on soil pH. The finer the lime particles and the higher the calcium carbonate equivalent, the more effective the lime and the lower the rate of lime needed to make the desired pH change.

Bulk ag lime sold in Kentucky has an average neutralizing value of 67% when averaged for all quarries. All lime recommendations in Kentucky are based on this value. Therefore, if the neutralizing value of pelletized lime is substantially higher than 67%, then the recommendation should be lower. The information to calculate the neutralizing value should be on the pelletized lime bag, and the method to calculate the neutralizing value can be found in publication AGR-106,University of Kentucky College of Agriculture. For example, a high quality pelletized lime source may have a neutralizing value of 85. If this is the case, the lime rate can be reduced to 78% of what would be recommended for bulk ag lime. This is calculated by dividing the average neutralizing value of ag lime by the neutralizing value of the pelletized lime being used (67 ”85= 0.78). In this case, 1560 lbs/ac of pelletized would be required to equal one ton of ag lime. If less than this amount of pelletized lime is used, the expected soil pH change will probably not be obtained. As can be seen from this example, the recommended rates of pelletized lime cannot be greatly reduced as compared to bulk ag lime.

How Fast Will Pelletized Lime React?

The speed of reaction (rate at which the lime will change the soil pH) is mainly a function of surface area of the lime particles and their contact with the soil. The finer the grind of lime, the more the surface area, and the faster the reaction. Since pelletized lime is pelleted from finely ground lime, it is easy to assume that it will be faster reacting than bulk spread ag lime which has some larger, non-reactive particles as a part of its composition. However, this is not true. Based on research from several states, it appears that the pelletized lime reacts no faster to raise the soil pH than good quality ag lime applied at recommended rates. In fact, incubation studies at Michigan State University found the pelletized lime to have a slower rate of reaction. Field research from other states indicate the rate of reaction is about equal to ag lime.

The slower than expected reaction of pelletized lime is probably due to two things: 1) the lignosulfonate binding, and 2) the distribution pattern. The lignosulfonate binding must break down by solubilization or microbial action before the lime is released to neutralize the soil acidity, which would delay the speed of reaction. When the pelletized lime is spread, it is distributed on the soil in pellets and results in small concentrated zones (spots) of lime after the binder dissolves. The fine, reactive particles of ag lime, in contrast, are spread as more of a dust so that the lime is better distributed and not in concentrated spots. The bulk spreading method will allow the ag lime to contact a larger amount of the soil.

Summary

Pelletized lime is an excellent source of high quality lime. Its use in agriculture has been limited due to the price. The recommended rate of pelletized lime should be based on the neutralizing value of the lime and will probably be about 75 to 80% of that for average-quality bulk ag lime. Contrary to popular belief, the speed of reaction of pelletized lime is no faster than that of bulk ag lime. Thus, when comparing the two materials, less pelletized lime is needed to raise the soil pH to the desired level, but the increase in pH is no faster than with ag lime if both are applied on the basis of their neutralizing values.

 

Lloyd Murdock
Professor Emeritus

lmurdock@uky.edu
Phone (859) 257-9503 x207
Fax (270) 365-2667

Princeton Research & Education Center
1205 Hopkinsville St.,
Princeton, KY 42445-0469

 

OkState FactSheets.

PSS-2225 Soil Test Interpretations

PSS-2239 Causes and Effects of Soil Acidity

PSS-2240 Managing Acid Soils for Wheat Production

PT 2000-10 Liming Raises Soil pH and Increases Winter Wheat Forage Yields

PT 2002-15 The Risk of Not Liming

PT 2003-8   Lime Acid Soils: What You Should and Should not Expect

 

Poly versus Ortho another year of data from Iowa

Guest Author, Dr. Jake Vossenkemper; OkState Grad and Agronomy Lead, Liquid Grow Fertilizer

Updated Research Comparing Ortho/Poly-Phosphate Ratios for In-Furrow Seed Safe Starter Fertilizers. Last years post Link

Article Summary

  • Ortho-phosphates are 100% plant available, but a high percentage of poly-phosphates in starter fertilizers convert to ortho-phosphate within just two days of application.
  • This quick conversion from poly- to ortho-phosphate suggests expensive “high” ortho starter fertilizers are not likely to result in increased corn yields compared to seed-safe fluid starters containing a higher percentage of poly-phosphate.
  • On-farm field studies conducted near Traer, IA in the 2016 and 2017 growing season found no statistical difference (Pr > 0.05) in corn yield between conventional and high ortho-phosphate starters in either year.
  • High ortho starters cost more per acer than 50/50 ortho:poly starters, but do not increase corn grain yields.

Polyphosphates Rapidly Convert to Plant available Orthophosphates

Given polyphosphates are not immediately plant available and orthophosphates are immediately plant available, this gives the promoters of “high” orthophosphate starters ample opportunity to muddy the waters. Nevertheless, the facts are, polyphosphates are rather rapidly hydrolyzed (converted to) into orthophosphates once applied to soils, and this hydrolysis process generally takes just 48 hours or so to complete.

In September of 2015, we posted a blog discussing some of the more technical reasons why the ratio of ortho to polyphosphates in starter fertilizers should have no impact on corn yields. For those that are interested in the more technical details, we encourage you to follow this link to the September 2015 blog post.

While we was relatively certain that the ratio of ortho to polyphosphates in liquid starters should have no effect on corn yields, we decided to “test” this idea with on-farm field trials located near Traer, IA in the 2016 and 2017 growing seasons.

How the Field Trial Was Conducted

In these field trials, we used two starters applied in-furrow at 6 gal/ac. Each starter had an NPK nutrient analysis of 6-24-6. The only difference between these two starters was the ratio of ortho to polyphosphates. One of these starters contained 80% orthophosphate and the other contained just 50% orthophosphate. With the remainder of the phosphorus source in each of these two starters being polyphosphate. Each plot was planted with a 24-row planter (Picture 1) and was nearly 2400 ft long. In both the 2016 and 2017 growing seasons the experimental design used was a randomized complete block with 4 or 5 replications.

Field Trial Results

Averaged over the side-by-side replications there was less than 1 bu/ac difference in corn grain yield between the high ortho and low ortho polyphosphate starters in both the 2016 and 2017 growing seasons. In addition to finding no differences in grain yield between these two starters, the high ortho starters generally cost about $1 more per/gal (so the $6/ac difference in price at a 6 gal/ac rate) than the low ortho starters. So the more expensive high ortho starter clearly did not “pay” its way in our multi-year field trials.

More Trials Planned for 2018

While our findings agree with other research-comparing ortho and polyphosphate starter fertilizers (Frazen and Gerwing. 1997), we want to be absolutely certain that our fertilizer offerings are the most economically viable products on the market. Therefore, we have decided to run this same field trial at one location in northern, IL in 2018, and at one location in central, IA in 2018. Stay tuned for those research results next fall.

References
Franzen D. and J. Gerwing. 2007. Effectiveness of using low rates of plant nutrients. North Central regional research publication No. 341. http://www.extension.umn.edu/agriculture/nutrient-management/fertilizer-management/docs/Feb-97-1.pdf (accessed 8 of Sept 2015).

A big Thank You to Dr. Vossenkemper for sharing this article with us.
The original article and his contact can be found at Link