Tag: manure testing

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Manure & Soil Health: Roundtables to Advance our Understanding of the State of the Science

Farmers and ranchers are becoming increasingly aware of the importance of soil quality/health to the productivity and sustainability of their agricultural system. Research and field observations have demonstrated that carefully managed manure applications can contribute to improved soil quality with limited environmental and social risks. However, a comprehensive assemblage of outputs and conclusions from research studies, field trials, soil labs databases, and other sources has never been developed. Therefore, the purpose of the initiative, Manure & Soil Health: Understanding and Advancing the State of the Science, is to assemble current knowledge on this topic, make it available to those influencing manure and land management decisions, and use it to inform and facilitate future research and service needs. The intent of the roundtables is to improve our understanding of: current knowledge, critical and emerging issues for which there are knowledge gaps, and information needs of farmers and their advisors.

What’s A Roundtable?

The four, hour-long roundtables consisted of a panel discussion with experts who were asked to summarize their current understanding of topics. Each panel also included a practitioner who shared perspectives on critical information needs of farmers and advisors and field experiences relative to use of manure. Panels were moderated to encourage interaction with audience. Roundtable participants were invited to ask questions of panelists and share expertise and experience.

When Were The Roundtables Held?

Date/Time Topic Panel Experts

February 9, 2017

 Manure and Soil Health Testing Bianca Moebius-Clune
Donna Brandt
Russell Dresbach
Geoff Ruth

February 16, 2017

 Manure and Soil Biology Rhae Drijber
Michele Soupir
Dr. Jonathan Lundgren

February 23, 2017

 Manure and Soil Erosion, Runoff, and Losses Nathan Nelson
John Gilley
Mike Kucera
Andy Scholting

March 9, 2017

 Manure and Cover Crops Tim Harrigan
Barry Fisher
Heidi Johnson
Sarah Carlson
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Solid Manure Sampling Procedures

Developing a nutrient management plan depends on testing manure for nutrient content. Your manure test results are only as good as your sample. This page outlines recommended ways to sample solid manure from open feedlots.

Sample During Loading

The recommended sampling for solid manure is to sample while loading the spreader. Sampling the manure pack in a barn directly has been shown to result in very variable results and is not recommended. Take at least 5 samples during the process of loading several spreader loads and save them in a bucket. When all of the samples are collected, thoroughly mix the samples and take a subsample from this to fill the lab manure test container.

Sample Manure During Spreading

Spread a tarp or sheet of plastic in the field and spread manure over this with the manure spreader. Do this in several locations and with several loads of manure. Collect the manure from the tarp or plastic sheet in a bucket. Mix the manure collected from different locations and spreaders, and take a subsample from this to fill the lab manure test container. This procedure is usually only practical for more solid manures.

Photo courtesy USDA NRCS

Sampling Daily Haul Manure

Place a 5 gallon bucket under the barn cleaner 4 or 5 times while loading the spreader. When all of the samples are collected, thoroughly mix the samples and take a subsample from this to fill the lab manure test container. Repeat this several times throughout the year to determine variability over time.

Sampling Manure in a Poultry House

Collect 8-10 samples from throughout the house to the depth of the litter to be removed. Samples near feeders and waterers can be very different. Collect samples from these areas proportional to the space they occupy in the house. When all of the samples are collected, thoroughly mix the samples and take a subsample from this to fill the lab manure test container. A sample taken while loading the spreader or during spreading is likely to be a more representative sample.

Sampling Stockpiled Litter

Take 10 samples from different locations around the pile at least 18 inches below the surface. When all of the samples are collected, thoroughly mix the samples and take a subsample from this to fill the lab manure test container. Large diameter auger bit and portable drill or soil sampler can be used to access manure deep within pile.

Taking a sample from a manure stockpile Taking representative sample from all subsamples mixed together in a bucket

Sampling stockpiled manure. Picture Source: Manure Testing for Nutrient Content

Sampling Manure from an Open Lot

These videos were produced by the Iowa Learning Farms project.

Sampling Stockpiled and Composted Manure

Related Web Pages

Overview of Manure Testing

Page Authors: Douglas Beegle, Penn State University and John Peters, University of Wisconsin

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Estimating Manure Density

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Procedure for Estimating Manure Density

Manure density varies with moisture content primarily depending on the amount of bedding. To calculate a more accurate estimate of manure density, use the procedure below:

  1. Weigh an empty 5-gallon bucket. Record the weight in pounds.
  2. Fill the 5-gallon bucket with a typical sample of the manure and weigh the bucket and manure. Record the weight in pounds.
  3. Subtract the weight of the empty bucket (step 1) from the weight of the bucket with manure (step 2). Record the weight of the manure in pounds.
  4. Repeat steps 2 and 3 at least 5 times and calculate an average weight. Record the average weight in pounds.
  5. Divide the average weight by 5 to determine the density in pounds per gallon. OR
  6. Multiply the average weight by 1.5 to determine the density in pounds per cubic foot.

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Liquid Manure Sampling Procedures

When testing manure, your nutrient management plan is only as good as your ability to obtain a representative sample. In liquid manure storage, agitation is critical to spreading uniform manure and to getting a representative sample. Agitating for 2-4 hours is the minimum. Depending on the type of storage longer agitation times may be required. The agitation for sampling should be similar to the agitation done when the storage is emptied. For this reason the most practical time to sample is when the storage is being emptied for field application.

If the storage is not adequately agitated there will likely be stratification. The figure below illustrates how manure analysis can vary within a storage without adequate agitation. In this example manure in the last 15 loads spread from this storage has 2 to 3 times more phosphorus than in the first 45 loads spread. If the storage is known to be stratified, separate samples should be taken as the manure consistency changes during emptying.

diagram

cc2.5 Les Lanyon

Sampling As Manure Storage Is Emptied

Agitate the storage thoroughly before sampling. Use a bucket to collect at least 5 samples during the process of loading several spreader loads and save them in the bucket. When all of the samples are collected, thoroughly mix the samples and take a subsample from this to fill the lab manure test container. When filling containers with liquid manure never fill the container more than ¾ full. If samples are collected over a several hour period, the bucket with manure sample should be stored on ice to limit ammonia losses.

Sample Manure When Pumping From Storage. Photo courtesy of Ontario Ministry of Agriculture, Food and Rural Affairs. Photo Source: http://www.thecattlesite.com/articles/1307/sampling-liquid-manure-for-analysis


Sampling From the Manure Storage

Picture Source: http://www.extension.iastate.edu/pages/communications/epc/Winter02/manure.html

Sampling a storage directly is much more difficult and likely to result in more variable results than sampling as the manure is loaded into the spreader. Agitate the storage thoroughly before sampling. Use a small bucket or tube to collect at least 5 samples from different locations in the storage. Combine these samples in a bucket and thoroughly mix the samples and take a subsample from this to fill the lab manure test container. When filling containers with liquid manure never fill the container more than ¾ full.

Liquid Manure Sampling Video

This video from the Iowa Learning Farms Project shows two sampling techniques for liquid manure storage prior to agitation. As indicated above, samples of agitated liquid manure should be obtained when possible, but in cases where the information from the lab analysis (which can take several days) is needed before manure can be applied to crop land.

Part 2: Sampling Liquid Manure

Sampling Manure During Application

This method is good for irrigated manure. Place buckets around the field to catch manure from the spreader or irrigation equipment. Place these to collect manure from more than one spreader load. Combine and mix the manure collected from different locations, and take a subsample from this to fill the lab manure test container. This method may give you “crop available ammonia nitrogen” as any ammonia losses may have already occurred prior to reaching bucket. What reaches the bucket is likely to soak into the soil and be available to the crop.

Related Web Pages

Overview of Manure Testing

Page Authors: Douglas Beegle, Penn State University and John Peters, University of Wisconsin

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Total and Available Nutrients In Manure

Standard manure analysis procedures determine the total N, P, K, and other nutrient content in the manure. Some special analyses such as ammonium-N and water extractable P determine the concentration of specific forms of nutrients in manure. These special tests should be clearly labeled as such on the manure test report.

Availability of Manure Nutrients

However, the total amount of nutrients in manure may not all be available or may become available only over a period of time. States and regions have developed “availability factors” that are applied to the manure analysis results to estimate the availability of the manure nutrients to the immediate crop and to future crops. This availability is usually a fertilizer equivalent availability. This is important because soil test recommendations are made on the basis of applying fertilizer nutrients. This means that by using the availability factors you can substitute “available” manure nutrients for recommended fertilizer nutrients on a 1 to 1 basis.

Because availability is influenced by local climate and soil conditions and may be customized for local management practices, it is very important that availability factors developed for the area where the manure is applied are used. Most state land grant universities have published availability factors for manure nutrients. Check with your local cooperative extension service for the appropriate factors for your area or State Specific Manure Nutrient Management Information

diagram

cc2.5 Doug Beegle

Some labs will apply availability factors to the analysis results and show “Available Nutrients” on the manure test report in addition to the analyzed total nutrient concentrations. It is very important to check to see if these factors are appropriate for the area where the manure will be spread. Some labs serve a large geographic area and while their analytical results may be excellent, availability factors may not be appropriate for all areas that they cover. It is always a good practice to check with the local cooperative extension service to make sure the availability factors a lab is using are appropriate for that area. Even if the availability factors use by a lab are not appropriate, the analytical results for total nutrients can be used with local availability factors to get valid estimates of available nutrients.

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Page Authors: Douglas Beegle, Pennsylvania State University and John Peters, University of Wisconsin

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Manure Test Record Keeping

Manure nutrient analysis will vary from sample to sample on a farm even with consistent management and careful sampling. Generally, a running average of manure analyses will better reflect what is in the manure than any one sample result. Also, most of the sampling methods outlined here recommend sampling at the time the manure is being spread. This means that manure analysis results will not be available until after the manure is already spread. Therefore, nutrient management plans should be based on previous test results.

Creating a Baseline For Your Manure Analysis Records

It is recommended to test manure annually for at least 3 years to establish a running average manure analysis that is used in the following year to develop the nutrient management plan. If there is significant variation within this time frame the 3-year period should be extended. Determine what might cause the variation. Can management changes be made to reduce the variation (eg. better sampling, better agitation, etc.)? Can management changes be made to react to the differences from year to year (eg. increasing rates in a year when above average rainfall dilutes the manure, or adjusting rates based on changes in animal feeding, etc.)

Once a baseline is established, less frequent manure testing may be acceptable. When a new manure test is run, it should be compared to the running average. If the new analysis is consistent with the average it can be added to the running average. If there is a trend, for example manure analyses are slowly and consistently increasing or decreasing over time, the oldest value in the running average should probably be dropped when the new value is added.

What If You Receive an Abnormal Manure Test Result?

If the new manure test result is very different from the running average, immediately try to determine the cause. Evaluate the sampling procedures, especially if there were no obvious management changes. Consider having the sample rerun or submitting a new sample if possible to confirm or correct the analysis. Look for management changes such as major changes in animal feeding; changes in dilution water in liquid manure (more or less rainfall, changes in washwater added, etc.); or changes in manure handling (manure scraped from barn floors more or less frequently, different bedding management, etc.).

If the change was a one-time occurrence do not add this value to the running average. If a permanent management change was made a new round of more intensive sampling should be initiated to establish a new baseline for future planning.

Also, management adjustments may have to be made after manure application, such as applying more or less supplemental fertilizer to fields where the manure was spread. Plan to apply supplemental fertilizer after manure application is complete and actual manure nutrient application is known based upon a current manure sample.

The data below from a PA dairy farm illustrates how records are used to develop a useful manure analysis program. Only the N and solids analysis are shown here but all test results would be analyzed similarly.

Manure Test N Running Average N1 Solids
Year lb/1000gal lb/1000gal %
1 28 28 6.8
2 25 27 7.8
3 26 26 7.4
4 352 26 10.4
5 26 26 6.2
6 26 26 6.1
7 29 27 7.5
8 363 36 8.8
9 34 35 8.1
10 35 35 8.3

1Used to develop the nutrient management plan
2Value does not fit the trend. A review of the situation indicated that this was an abnormally dry year, thus there was less dilution from rainfall. Notice that the % solids were higher than they had been, which is more evidence that the dry year was the culprit. This value was not included in the running average. The farmer reduced his sidedress nitrogen (N) rate slightly that year to account for the higher N analysis and also lower yield potential because of the drought.
3The N analysis changed dramatically in this test. However, the farmer had a made a major change in his feeding program, replacing corn with distillers grains. This would be consistent with the increased N in the manure. Since this was likely a permanent change, a new running average was started. Since the change in feeding management was known, some educated guesses about how this would affect the manure analysis were used to make adjustments in the nutrient management plan for year 8 rather than using the existing running average.

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Page Authors: Douglas Beegle, Pennsylvania State University and John Peters, University of Wisconsin Reviewers: Jerry Martin, Pennsylvania State University and Rick Koelsch, University of Nebraska

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Manure Test Results

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Which Tests Do I Need?

Most labs have a basic manure test with the option to add other tests for an additional fee. Make sure the tests or the package you select includes at least the following analyses for nutrient management planning:

  • % Moisture or % Solids,
  • Total N,
  • Ammonium-N (NH4-N),
  • Total P, and
  • Total K.

Other analysis that may be useful in some situations include: pH, Carbon:Nitrogen ratio (C:N), water extractable P, calcium carbonate equivalent, secondary nutrients (Ca, Mg, & S), and micronutrients.

Manure Test Results Can Be Reported Differently

Dry Matter or As-Sampled?

Manure analysis results can be reported in several different ways. It is important that you clearly understand how your results are reported. The first consideration is whether the results are reported on an as-sampled basis or on a dry-weight (dwt) basis. Most agricultural labs that do manure testing report the results on an as-sampled basis. If the results are reported on a dry-weight basis the analyses will have to be converted back to as-sampled to be practical for use in a nutrient management plan. Example calculations for converting analyses results from % dry-weight (% dwt) or ppm to “as-is” results (lb/ton or lb/1000 gal are at Common Manure Test Results Conversions.

Reporting Units

Another, issue with reporting manure test results in the units used. When results are reported on an as-sampled basis the most common units used are lb/ton for more solid samples and lb/1000 gal for liquid samples. However, carefully check the units on the manure test because other units are sometimes used. For example, some labs report liquid manure test results in lb/100 gal. Lb/acre-inch may be preferred by producers using irrigation systems. Also, particularly when results are reported on a dry-weight basis, percent (%) and parts per million (ppm) may be used. Example calculations for converting analyses results from % dry-weight (% dwt) or ppm to “as-is” results (lb/ton or lb/1000 gal) are at Common Manure Test Results Conversions.

Elemental or Oxide?

Results may be reported as the elemental form for example P and K, or in the oxide form as P2O5 and K2O. Most agricultural labs that do manure testing report the results in the oxide form since this is how fertilizer recommendations are made. If the results are reported in the elemental form, they will have to be converted to the oxide form for use in nutrient management planning. Example calculations for converting analysis results from elemental to oxide are at Common Manure Test Results Conversions.

Solid or Liquid?

Finally, there may be situations where the results are reported for a liquid ie. lb/1000 gal but the manure is spread on a ton basis ie. tons/acre. The density of the manure can be used to convert from liquid to solid analysis. Example calculations for converting analysis results from liquid to solid or solid to liquid at Common Manure Test Results Conversions.

For more information see Reporting Manure Analysis Results taken from the publication “Recommended Methods of Manure Analysis”.

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Page Authors: Douglas Beegle, Pennsylvania State University and John Peters, University of Wisconsin

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