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.


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:

Sampling From the Manure Storage

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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

Slurry Manure Collection and Handling Systems

Slurry manure is typically generated in systems where little or no bedding is added to the excreted manure/urine. Slurry manure is typically between 5% and 15% solids. It is “thicker” than liquid manure, but cannot be stacked or handled the same way as solid manure. Some common system for handling and storage of slurry manure are described in this article.

Collecting Slurry Manure

Slotted Floor

The simplest manure collection arrangement for slurry manure is the slotted or perforated floor over a manure collection tank. In this scenario excreted manure simply falls through openings in the floor on which the animals stand and collects in a tank below.

Slotted floors above a manure tank are a simple means of collecting slurry manure.


Slurry manure can also be collected using scrapers. In this case the manure is usually confined in an alley (dairy freestall barn) or gutter under slats (swine confinement building). A scraper moves along the length of the alley or gutter and deposits the slurry manure in a reception pit or tank at the end.

Mechanical or tractor-mounted tire scrapers can be used to collect slurry manure in a dairy freestall barn.

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Another type of slurry manure collection device utilizes a vacuum to “suck” slurry manure from a concrete surface and deposit it into a tank. This approach eliminates the need to pump the slurry manure into a tank or wagon.

Labor is reduced when a suction or vacuum is used to collect slurry manure from a concrete alley.

Slurry Pumps

Slurry manure has fluid properties that allow it to be moved by pumps that are specially designed to handle thick fluids containing solids and stringy material. Slurry manure pumps are designed with open-type impellers and usually have cutting or chopping devices at the inlet to the impeller to minimize plugging problems. Low-pressure/high volume slurry pumps are used to fill tankwagons and move manure in other applications where higher pressures are not required. High-pressure slurry pumps are used to move manure through long pipelines and provide the needed pressure for land application in crop fields.

Slurry pumps have open impellers and cutter/chopper blades designed to handle manure with high solids content.

Low-pressure/high volume slurry manure pumps are used to quickly fill manure tankwagons.

High pressure slurry manure pumps can move manure long distances through pipelines to field application equipment.

Transporting Slurry Manure


Tankwagons can be used to transport or move slurry manure from one point to another, usually from a manure storage facility to a crop field. Tankwagons are available in a variety of sizes from small (1,000 gallons) to quite large (12,000 gallons). Tankwagons typically serve the dual function of transporting slurry manure to a crop field and spreading or injecting the manure into the soil for crop nutrient uptake.

Large tankwagons allow producers to empty manure storage facilities quickly with less labor.


Since slurry manure has fluid properties it can be pumped through pipelines from storage to crop field as an alternative to hauling with a tankwagon. Pumping is a “continuous flow” process whereas hauling is necessarily a “batch” process. Hence pumping can offer significant advantages over hauling in moving large amounts of manure in shorter lengths of time. Tankwagons are generally used to move manure over longer distances although pipelines have been used for distances up to five miles.

Rigid aluminum irrigation pipe has been used for pumping slurry manure in the past. However the labor advantages of using flexible “layflat” tubing for pumping make this type of pipeline more attractive in many cases. Long lengths of this tubing can be stored on reels and placed overland with much less labor than is required with rigid tubing.

Flexible hose or tubing requires less labor for a manure pipeline than rigid pipe.

Slurry Manure Land Application

Field or land application of slurry manure requires that the application devices place the manure in the proper location and at the proper rate for good nutrient management practices. Devices which inject or incorporate manure into the soil are generally preferred since the following advantages are associated with this practice.

  1. Odor is reduced
  2. More nutrients are retained
  3. Runoff potential is reduced

Injection units place manure into the soil to reduce odor, conserve nutrients and minimize runoff.

Some injection units are designed for sod with minimal surface disturbance.

Authors: Charles Fulhage and Joe Harner

Photos: CC 2.5 Charles Fulhage or Joe Harner

Role of Solid Liquid Separation in Manure Storage

There are benefits for manure storage systems in separating manure into solid and liquid components. Solid-liquid manure separation is also a desirable first step in many systems used for manure treatment (composting, anaerobic digestion, etc.)

Solids Accumulation

Waste solids, particularly those from dairy freestall housing bedding, can accumulate quickly in waste storage ponds. Solids accumulation requires longer, more thorough agitation at pump out time to re-suspend settled solids and special manure solids handling “chopper” pumps for transfer to tanker wagons or waste slurry irrigation systems.

Solids can cause pumping problems, and over time can greatly reduce usable storage pond volume. Serious consideration is usually given to the installation of solids separation equipment between animal housing, particularly dairy freestall barns, and the waste storage pond.

Mechanical separators are typically either rotating or stationary screens and generally remove 20 to 30 percent of the waste solids. These separators require little attention although operation in freezing weather requires special considerations. They produce manure solids that may be easily recycled as bedding or land applied off-farm with solid manure spreaders.

vibrating screen separator conveyor inclined screen separator typical two-cell settling basin

Settling Basins

Properly designed gravity settling basins can remove up to 50 percent of the waste solids but need enough elevation between the barn collection channel bottom and the maximum storage pond liquid surface height for installation of the settling basin and associated minimum 1% slope gravity in/out transfer lines. Gravity settling basins require periodic cleaning out with a tractor front end loader and work best when at least two are constructed side by side to allow alternating use and some manure solids drying out before cleaning.

Separated solids can be handled by conventional manure solids handling equipment. These nutrient-rich solids can be spread on distant fields and pastures as fertilizer and soil amendments, or sold for horticultural uses, with or without composting. Removing solids that retain their nutrients can help reduce nutrient loading on nearby fields, which are often irrigated from storage ponds or lagoons during the periodic pump outs required for proper management.

Related Web Pages

Page Managers: Ted Tyson, Auburn University, and Saqib Mukhtar, Texas A&M University, .

Costs of Slurry Manure Application and Transport

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Manure Value and Economics

Livestock such as dairy and swine often have slurry type manure. The manure is liquid but does not flow easily. It is either stored directly below the animal pens, or scraped or pumped periodically into a holding pen outside of the building.

Loading Slurry Manure

Loading slurry manure is accomplished with a pump powered by a tractor or stationary engine. The slurry can be loaded into tractor-pulled or truck-mounted tankers, or pumped through a hose attached to a tractor that applies it as it is being pumped from the pit. The cost of loading slurry is usually low because the pump can do it quickly and the volume per animal is not usually high.

Slurry Manure Transport

Transportation of slurry by tanker can be expensive because a lot of water is being transported and the same equipment that is hauling the slurry is usually land applying the slurry. When tankers are used, the number of hours spent transporting the slurry is frequently the limiting cost. The land may become unavailable to receive the slurry, due to crop planting times or soil conditions, before all of the slurry can be land applied. Often, the distance transported is limited so that the time constraints can be met.

If the slurry is pumped through a hose to the field, the transport time is negligible. As the slurry is pumped, it is simultaneously injected or surface applied to the land. The important cost becomes the cost of purchasing pipe and hose that is sufficient for this method of land application.

Land Application of Slurry Manure

The cost of land application of slurry varies with the type of equipment used. Tankers can be expensive to own unless they are used for many animals on many acres. There is a definite economy of scale with tankers. Additionally, the tankers usually require fairly large tractors or trucks. If the livestock owner does not have a cropping enterprise that requires the large tractor, ownership of the tractor for manure distribution alone becomes expensive.

Tankers are economical for large-scale operations with slurry manure.

When slurries are applied via hoses (called dragline hoses), a tractor pulled distributor is used to move the hose around the field so that the slurry is evenly distributed. The cost of the equipment can be very expensive, but the amount of time is decreased considerably compared to using tankers because most of the time is spent in applying the slurry. Very little time is spent getting into and out of the field, as is the case when using tankers.

Authors: Ray Massey, University of Missouri and Josh Payne, Oklahoma State University