May 04, 2021

Not All Manure is the Same – Liquid Swine Manure

The nutrient characteristics of a manure is dependent the species of animal, the diet of the animals, and how the manure is handled. In recent years crop managers have been advancing the use of liquid swine manure from waste product to nutrient source. To efficiently utilize the nutritional benefit of liquid swine manure takes a bit of management.

The nutrient content of liquid swine manure is less concentrated than other manures which adds additional handling challenges handling large application volumes per acre. Effective manure management of liquid swine manure starts well before the day of application. The greatest variable in liquid swine manure is moisture content. The moisture content of liquid swine manure is mostly dependent on external water sources. Excess drinking water loss to barn manure pits, wash water from the barn, along with rainwater additions to open exterior pits increases water content of the manure resulting in a dilution of nutrient content. Reduction of external water making its way into storage pits and lagoons can help reduce dilution. In pits and lagoons, the solids settle to the bottom of the pit or lagoon creating a stratification of manure moisture content with depth.  As much agitation as can be safely achieved at application time can help reduce variability in the nutrient content of the applied manure.

Most of the nitrogen in liquid swine manure is in an ammonium form rather in organic forms. The amount of organic N is directly related to the solids content in the manure, which is usually low. The solid fraction separated from whole manure or cleaned from the bottom of a lagoon/pit after settling, can have more organic nitrogen than ammonium.  Any organic forms of nitrogen in manures need to be mineralized into inorganic ammonium before becoming plant available, this additional step in making organic nutrient forms plant available further slows the release to plant and help reduce potential losses. Especially in cold soils which are not conducive to microbial activity needed to break down the complex organic molecules. The ammonium form of nitrogen is held by the soil cation exchange capacity (CEC) and is directly available to plants for use and to soil microbes for conversion to nitrate. Ammonium is subject conversion to nitrate and possible loss in warm (over 50⁰F) and moist soils. For fall and early spring liquid swine manure applications, ammonium nitrogen stabilizers can be added to reduce/delay the conversion of ammonium to nitrate.

If liquid swine manure is applied in the fall before the soil temperature falls below 50⁰F, or if a period of warm temperatures occurs in the spring prior to planting allowing soils to warm up above 50⁰F for period of several days, non-stabilized ammonium nitrogen can rapidly convert to nitrate and become subject to loss. If these conditions occur when the manure was applied as a planned nitrogen source for corn, it is highly recommended to perform a presidedress soil nitrate test (PSNT) to evaluate soil nitrogen levels and the need for supplemental nitrogen. Given that most of the nitrogen in liquid swine manure is plant available at time of application makes liquid swine manure a good nutrient fit for side-dressing corn, and top-dressing winter wheat.

Most of the phosphorus in liquid swine manure is in an organic form so the concentration of phosphorus is directly related to the solid content of the manure. Liquid swine manure phosphorus content increases with increasing solids content. Potassium is water soluble in the liquid fraction and the concentration remains relatively constant regardless of manure solids content.

Ammonium nitrogen, soluble phosphates, and potassium contained in liquid swine manure are highly water soluble and contained within the liquid fraction of the manure. Off-site movement of liquid swine manure nutrients could occur rapidly if surface applied to the soil without incorporation, applied to areas of the field prone to concentrated surface flow, close to open drains/ditches, shortly before heavy rains, and to frozen or snow-covered fields. Incorporation of liquid swine manure greatly increases the retention of nutrients and reduces odor.

Nutrients targeted in feed rations can become elevated in the manure. High concentrations of zinc used in nursery feeding often leads to elevated zinc levels in manure. Repeated application of high zinc manures on the same field can lead to elevated zinc soil test levels. Some zinc is beneficial to crop growth, especially corn, however elevated zinc levels can lead to reduced plant growth.

Sources:

Chastain, J.P., J. J. Cambarato, J. E. Albrecht, and J. Adams. (1997). “Swine Manure Production and Nutrient Content. Swine Training Manual.” (pp 3-1:3-15). South Carolina Cooperative Extension.

Lorimor, J., W. Powers, A. Sutton. (2004). “Manure Management System Series. MWPS-18, Section 1 - Manure Characteristics.” 2nd ed. Midwest Plan Service, Iowa State University.

 

April 29, 2021

What Tissue Test Will and Will Not Tell You

Tissue testing has long been utilized as a diagnostic tool but is increasingly being used as part of the overall crop fertility management. This concept is helping agronomists and growers find more effective and efficient ways to provide plant nutrition. It is easy to read too deeply into tissue test result, while missing basic issues. There are a couple of basics to keep in mind when reviewing plant tissue data. In many cases, observation of the crop leading up to sampling is key.

Less than 15% of the plant dry biomass is represented by tissue test data. Much of a plant dry biomass is carbohydrates comprised of carbon, hydrogen, and oxygen that is not reported in the tissue test data. As the carbohydrate content of the plant goes up, the percentage of the plant represented by the nutrients on the tissue test decrease.  A plant that is stunted or stressed due to environmental impacts that do not directly impact the update of nutrients can result in overall normal to high tissue test data values.

Plant growth patterns can impact tissue test data. Just prior to a rapid growth phases, plants accumulate nutrients in preparation. At this point tissue test results tend higher. Once the plant enters the period of rapid growth, the plant begins to accumulate carbohydrates very quickly. These additional carbohydrates effectively dilute the nutrient content of the plant biomass. These growth patterns can also shift the mobile nutrients in, and out, of the plant segment being sampled.

A tissue test is a snapshot in time. It is an evaluation of the nutritional status at the time of sampling. This will reflect the nutrients the plant was able to access in the past but does not give any indication at to predicting nutrient values into the future. This a key reason why management systems with a defined focus on tissue testing a part of an overall fertility plant promote repeated sampling of the same area through the growing season.

Repeated tissue testing of the same area can show how any seasonal patterns and plant development may impact the crops’ ability to access nutrients through the growing season. To make valid assessments of the tissue data, weather data, along with crop observations, are key. For example, periods of dry weather can reduce nutrient availably to the plant, soil water is essential in nutrient movement to and into the plant. Dry weather with normal growth, resulting in normal carbohydrate accumulation, will normally lead to slightly lower nutrient vales in tissue tests, especially nitrogen and potassium. If the dry weather is severe enough to effectively stop plant growth, resulting in reduced carbohydrate accumulation, the tissue test could come back normal to high.

A tissue test can tell you what nutrient is missing in the plant but cannot tell you why. Was the plant unable to access the nutrient, or was the soil void of the nutrient? Often the first instinct is to apply the nutrient that was low in the tissue test. In this situation it is recommended to retest later to see if the nutrient application corrected the issue. A second recommendation is to take a soil test from the same sample locations as the tissue samples to identify if the nutrient is low in the soil or could something like soil pH be impeding the availability of the nutrient.

Do not get too wrapped up in ratios of nutrients in the plant. If a nutrient included in the ratio is deficient, the ratio will be skewed towards the opposite value. This can be seen with or without a calculated ratio if target for normal levels for a given nutrient are included. Ratios do help bring attention to these variances. For example, if one of the nutrients in the ratio is very close to the bottom of a normal or target level, while the other is high the ratio may alert you to abnormality a bit sooner than looking only at the individual nutrient ratings. The reporting of a ratio does not specifically mean there is an interaction between the nutrients.  A good analogy is a brick wall. A brick wall has a defined ratio of mortar and bricks. If you have more bricks, you cannot build any taller of a wall, and the extra bricks don’t impact how much mortar it takes to build the wall.

Trying to predict yield or any future values from tissue testing is difficult. There are more factors than plant nutrition that can impact plant growth and the final yield. If you are looking to start plant tissue test monitoring this growing season, contact your ALGL regional agronomist for details on our plant monitoring program before the sampling season begins. Contact your ALGL regional agronomist with any other questions or tissue testing needs.

April 06, 2021

How Quick Can I Expect Pelletized Lime to Change Soil pH?

Can I apply pelletized lime at planting and expect it to address my low soil pH rapidly in-season? While pelletized lime provides many benefits, such as quickly altering soil pH and possessing handling qualities that can make the application of the product more versatile, it has some limitations.  

A traditional pelletized lime is a uniformly finely ground lime that has been pelletized using a binding agent. The chemical makeup of the lime material, final grind, and the binding agent can impact the rate of soil acidity neutralization. All these factors influence the rate in which the carbonate material becomes water soluble, and reactive with hydrogen ions, to neutralize the acidity. Likewise, the rate of reaction is impacted by soil incorporation and soil moisture.

The figure below (Jones and Mallarino, 2018) shows the relative rate of acidity neutralization as impacted by the fineness of a calcitic ag lime. If only the finest ground particles were applied to the soil, the rate of soil pH adjustment would take place quicker than a blend of particle sizes. In addition, the pelletizing of the finely ground lime greatly increases the uniformity of spreading and handling characteristics in fertilizer systems designed to handle granular fertilizer.

 Effect of fineness on calcitic ag lime to control soil pH over time.

This data was generated from an experiment conducted in a laboratory to control the environmental factors/conditions so that the research is repeatable. Primarily maintaining a constant soil temperature and moisture at 80-90% of field capacity. If we were to move this study to a field, fluctuations in temperature and soil moisture would impact the data. Lower soil temperatures and drier soils would slow the rate of reaction, especially for the more finely ground fractions.

The figure below from the same study (Jones and Mallarino, 2018) shows the relative rate of acidity neutralization as impacted by the product used. The results of the pelletized lime closely follow the results from the 60-100 mesh grind. Faster than traditional ag limes, but still slower than pure calcium carbonate when applied at equal rates.

Both the pelletized lime and the calcitic lime has similar pH impacts for the first 21-35 day of this experiment as the finely ground portion of the calcitic lime reacted similar to the fine grind of the pelletized lime.

This figure also shows that while pelletized lime increases soil pH more than calcitic lime when applied at equal rates, it also takes pelletized lime in excess to 100 days to reach a maximum soil pH adjustment. That is a over 3 months, or slightly longer when taking field environmental factors into consideration. If the pelletized lime is applied at planting the first of May, maximum pH will be achieved the bringing of August at the earliest. By this point in the season altered nutrient uptake and growth may have already negatively impacted crop yield.

Effect of lime material to control soil pH over time.

If pelletized lime is routinely applied every year, timing is not critical. If this is a recue application of pelletized lime to make a quick pH adjustment to a neglected field to avoid yield loss, fall to late winter application of the pelletized lime prior to the growing season will have a bigger impact on in-season soil pH levels when compared to an at-planting application. While pelletized lime is a very useful tool in fertility management, it still takes time for pelletized lime to make meaningful soil pH adjustments.

 

Source: Jones, John D., and Antonio P. Mallarino. “Influence of Source and Particle Size on Agricultural Limestone Efficiency at Increasing Soil PH.” Soil Science Society of America Journal, vol. 82, no. 1, 2018, pp. 271–282., doi:10.2136/sssaj2017.06.0207.

March 25, 2021

Checking for Consistency from One Sampling Event to the Next

Most progressive precision soil sampling programs are sampling fields on a 2- or 3-year cycle. Often in the course of 2 to 3 years, there have been changes in the personnel or equipment used to collect those samples. There are a few clues in your soil test results that can be examined to validate if those samples were collected consistently.

The first clue to check is the organic matter level. The organic matter has the least potential to change significantly over the course of a few years. Even under intensive management to increase organic matter, such as no till, cover crops, and residue management, it is unlikely to see the soil test level increase by more than 0.1% per year on average. Any drastic change in organic matter levels likely indicate inconsistent sample depth, contamination of the sample with crop residue or manure, or an inadequate number of soil cores being collected to make up the sample.

The cation exchange capacity (CEC) should remain relatively consistent from sampling event to sampling event. The CEC is a measurement of the negative charge in a soil which comes from the clay mineralogy and organic matter that make up the soil. These 2 factors do not noticeably change in just a few years. On a routine soil analysis, the CEC is calculated from the extractable levels of calcium, magnesium, potassium, and hydrogen. Calcium and magnesium are generally the greatest contributors to the CEC. Unless extremely high rates of lime or gypsum have been applied, these 2 nutrient levels generally stay consistent resulting in a consistent CEC calculation.

Surprisingly, one of the numbers on your soil test that should not drastically change from sampling one sampling event to the next is phosphorus (P). Assuming your soil test P is at an agronomically desirable level, a high yielding corn or soybean crop are not likely to lower your soil test level more than 4 or 5 ppm in a single growing season. If the soil test P level changes more than 10—15 ppm between routine sampling events, it may be the result of inconsistent soil sampling procedure.

To truly compare soil test results from one sampling to the next, it is critical to minimize the variability. To do so soil needs to be sampled to the same depth, following the same crop, at the same time of year, and consist of at least 8 cores.

If you have any questions regarding irregular soil test results, please contact your ALGL agronomist.

March 25, 2021

Fertilizers and Plant “Availability”

Over the last few months, the ALGL agronomy staff have received many questions regarding different fertilizer products and whether the nutrients are plant available or how long it takes them to “release” the nutrients. The simple answer is that most fertilizer products are highly water soluble, and once they dissolve, the nutrients are in a plant-available form. However, this does not necessarily mean that the nutrients will be taken up by the plants right away. Below we will discuss the potential fate of the nutrients in a few common fertilizer materials if it is not taken up by the plant.

Most questions regarding nutrient availability are concerning phosphorus (P), MAP and DAP. Both products are more than 90% water soluble and are immediately in a plant available if there is adequate soil moisture. However, the P must be near an actively growing plant root to be taken up. So, what happens to the rest of the P if it is not taken up immediately? Much of the applied P will be loosely bound to the clay minerals through a process called adsorption. This fraction of the P can be released back to the soil solution as P concentrations are reduced through plant uptake. However different soil types can bind the P more tightly than others. Soils that are likely to bind P rendering it unavailable are soils with high clay content, high pH, and low soil test P.

Potassium (K) fertilizers such as potassium chloride and potassium sulfate also dissolve rapidly into the soil solution and are immediately in a plant available form that can be utilized by actively growing plants. A portion of the K will be held by the cation exchange capacity (CEC) of the soil and will be released as the K dissolved in the soil solution becomes depleted. The potential exists for the K to be lost to leaching or runoff if the K was applied in excess of the soils capacity to hold it or if there is no actively growing crop to utilize it. Soils most prone to K losses are high sand/low clay content soils, and soils with high organic matter.

The two most common dry nitrogen (N) fertilizers are ammonium sulfate and urea. Ammonium sulfate delivers nitrogen in a form that is immediately plant available. Since ammonium has a positive charge and can be held by the soils CEC, just like K, ammonium is generally considered the more stable form of plant available N. Urea, though it dissolves rapidly, is not in a plant available form initially. Urea requires an enzymatic reaction with urease to become ammonia, which quickly converts to ammonium to become plant available. If the N stays in the ammonium form, losses of N are minimized. Nitrogen losses occur when soils are warm enough for microbial activity to start converting the ammonium to nitrate. While nitrate is also plant available, it is a negatively charged so it is prone to leaching as it is repelled by the soil CEC.

The bottom line is that the best way to ensure adequate nutrient availability for your crops is to maintain good soil test nutrient levels and a desirable pH for and follow the 4R’s of nutrient management. Application of nutrients just prior to crop uptake reduces the potential for nutrient tie up and possible loss. If you have any questions about your specific crop and fertilizer situation, contact your ALGL agronomist.

February 26, 2021

Winter Wheat Nutrient Management Update

Winter wheat in southern Indiana and Illinois is beginning to break dormancy and  enter the spring regrowth phase and, as growth rates increase, so do nutrient demands of the developing crop. While a limited number of top-dress applications have taken place in southern parts of the Great Lakes region, recent rains and wet soils are limiting the opportunities for planned field operations. This has many wheat growers considering the best time for making a top-dress application to maximize benefit to the crop.

Information published by Charles Mansfield and Stephen Hawkins with Purdue University Extension suggests that nitrogen top-dress applications should be targeted for the early green up period as wheat comes out of dormancy when making a single application.  On sandy soils, a split application may be beneficial to wheat development, with the second application planned near boot stage.  When conditions prevent timely operations, nitrogen can be applied as late as heading, but yield will likely be limited due to nitrogen deficiency during vegetative growth stages.

Table 1. These recommendations are for mineral soils with adequate drainage and 1 to 5% organic matter, with wheat planted within 7 days after fly-free date last fall.

The Ohio State University Agronomy Guide Wheat Nitrogen Recommendations

Wheat nutrient uptake demands in early spring are increasing at a time when temperatures are normally low, microbial activity is suppressed, and the soil has a limited capability for supplying nitrogen, sulfur and other key nutrients.  Timely plant tissue analysis can be used to monitor the status of the crop and fine tune management decisions to maximize yields.

February 26, 2021

Consistent Soil Sampling

Most progressive precision soil sampling programs are sampling fields on a 2- or 3-year cycle. Often in the course of 2 to 3 years, there have been changes in the personnel or equipment used to collect those samples. There are a few clues in your soil test results that can be examined to validate if those samples were collected consistently.

The first clue to check is the organic matter level. The organic matter has the least potential to change significantly over the course of a few years. Even under intensive management to increase organic matter, such as no till, cover crops, and residue management, it is unlikely to see the soil test level increase by more than 0.1% per year. Any drastic change in organic matter levels likely indicate inconsistent sample depth, contamination of the sample with crop residue or manure, or an inadequate number of soil cores being collected to make up the sample.

The cation exchange capacity (CEC) should remain relatively consistent from sampling event to sampling event. The CEC is a measurement of the negative charge in a soil which comes from the clay mineralogy and organic matter that make up the soil. These 2 factors do not noticeably change in just a few years. On a routine soil analysis, the CEC is calculated from the extractable levels of calcium, magnesium, potassium, and hydrogen. Calcium and magnesium are generally the greatest contributors to the CEC. Unless extremely high rates of lime or gypsum have been applied, these 2 nutrient levels generally stay consistent resulting in a consistent CEC calculation.

Surprisingly, one of the numbers on your soil test that should not drastically change from sampling one sampling event to the next is phosphorus (P). Assuming your soil test P is at an agronomically desirable level, a high yielding corn or soybean crop are not likely to lower your soil test level more than 4 or 5 ppm in a single growing season. If the soil test P level changes more than 10—15 ppm between routine sampling events, it may be the result of inconsistent soil sampling procedure.

To truly compare soil test results from one sampling to the next, it is critical to minimize the variability. To do so soil needs to be sampled to the same depth, following the same crop, at the same time of year, and consist of at least 8 cores.

If you have any questions regarding irregular soil test results, please contact your ALGL agronomist.

February 24, 2021

It's Calendar Time Again!

Have you enjoyed our customer photography calendars the past few years? Do You have photos to share? We are excited to announce that we are launching our fifth year of the customer photo calendar!  We want to see pictures that illustrate what fuels your passion for agriculture 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. We will select our favorite pictures and invite our followers on Facebook vote on their favorite to be on the cover of the 2022 calendar. Follow us on Facebook for voting details.

 Photo criteria 

  • Landscape oriented photos preferred, but not required.
  • 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, 2021
  • 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.
January 29, 2021

What is ENR?

In some nutrient recommendation strategies and on some soil test reports, there is a column labeled “ENR”. What is ENR?

ENR stands for Estimated Nitrogen Release. This is a calculated estimation of how much potential nitrogen may be released from soil organic matter (SOM) in one year. The actual amount and time of nitrogen release is dependent on the composition of the organic matter, soil moisture, and weather.

ENR is a calculation from the soil organic matter value on a soil test. Soil organic matter is reported as the percent of organic matter by weight. ENR is a calculation that is based on a couple of basic concepts regarding soil and the composition of soil organic matter. While these concepts are rooted in scientific research, they can vary.

The first concept explains that an acre of soil weighs approximately 2 million pounds. This is a rough estimation of the soil weight that is tilled/turned when an acre is plowed to the depth of a “standard” moldboard plow, which is assumed to be 6 2/3 inches. Using this standard value of 2,000,000 pounds per acre, we can approximate the amount of soil organic matter in an acre of soil, based on the percent of organic matter found through a soil test. For example, if a soil has an organic matter level of 3%, we can use the 2,000,000 pounds per acre value for the weight of the soil to calculate the total amount of soil organic matter per acre:

2,000,000 x (3/100) = 60,000 pounds of soil organic matter

The second concept states OM is approximately 5% nitrogen by weight. This may vary slightly based on several factors including soil type, management, and composition of the soil organic matter. From our previous example using soil with a 3% organic matter level:

2,000,000 x (3/100) = 60,000 pounds of soil organic matter (SOM)

60,000 pounds SOM x (5/100) =  3,000 pounds of N/acre

While this seems like an impressive value, unfortunately not all the nitrogen is available to the growing crop in a given year. The release of nitrogen from soil organic matter, a process referred to as mineralization, is a biological process that is facilitated by microorganisms within the soil. These microorganisms break down soil organic matter and, in the process, release nitrogen (along with other nutrients) into the soil solution where they can be utilized by the crop. However, the rate of mineralization is not particularly fast, and is governed by many factors. This makes it quite variable year to year. Therefore, it is assumed that only 2 to 4% of the nitrogen in OM will become available in any given year. From our previous example:

2,000,000 x (3/100) = 60,000 pounds of soil organic matter (SOM)

60,000 pounds SOM x (5/100) =  3,000 pounds of N/acre

3,000 pounds N/acre x (2/100) = 60 pounds available N

3,000 pounds N/acre x (4/100) = 120 pounds available N

60-120 pounds available N / acre

 

Weather conditions that promote strong plant growth, such as warm temperatures and adequate soil moisture, are also beneficial in the conversion of SOM to plant available nitrogen. Therefore, in those cropping years where weather conditions favor strong yields, they also tend to favor higher mineralization rates. These factors cause greater releases of N from soil organic matter. This greater rate of N release can therefore serve as a kind of buffer, supplying more N to a crop that could essentially benefit from higher nitrogen rates.

Determining a nitrogen application rate that is economically and agronomically optimum can be challenging when the soil has a higher OM content. For example, the nitrogen release from organic matter in a field with 6% OM can range from 120 pounds/acre to 240 pounds/acre. The variation of the nitrogen released is often weather dependent during the growing season and causes challenge when determining nitrogen application rates.

* Update - Organic soils, those with greater than 20% SOM, were able to develop over time due to reduced SOM decomposition. Saturated soil conditions for a portion of the year slows SOM decomposition in organic soils, thus reducing the mineralization of nitrogen. Those organic soils that have artificial drainage may experience a higher ENR than those that are not drained, but at a level less than determined by the ENR calculation.

January 29, 2021

Are You Putting Enough Soil in Your Sample Bags?

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 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.

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