Manure has always been a valuable input to agricultural soils in our region. The value of manure has increased significantly in the last few years as the cost of commercial fertilizers has climbed to record highs. As such, manure is in high demand because it is a locally produced source of macro- and micro-nutrients, as well as organic matter which is greatly beneficial to Delaware’s sandy soils. Yet, the nutrient content of manure is highly variable from farm to farm. Getting a manure analysis close to the time it will be spread ensures you get the most out of your manure. However, it can be challenging to get a manure analysis near the time of spreading when the analysis also has to be incorporated into a nutrient management plan. 

Sampling

Annual manure sampling and analysis can eliminate timing issues for operations with a consistent source of manure. After a few years of annual sampling, growers will have average manure analysis values that can be used for planning purposes. Using average manure analysis data reduces the stress of waiting for a current laboratory analysis and gives the farmer a better view if the nutrient values of the manure are changing. It is always in the best interest of the farm receiving the manure to have it analyzed, even if an average manure analysis isn’t being established.

Analytical Testing

Analytical testing is a foundational component of crop production because so many nutrient management decisions are based on the results of soil and manure analysis. The most important step in the analytical testing process is sampling. The goal of manure sampling is to take a sample that will accurately represent the nutrient content of the manure that will be land applied. Prior to sampling manure, it’s a good idea to gather the necessary supplies and to identify how and where the manure sample will be stored until it can be shipped to the lab for analysis. Most laboratories recommend freezing the sample but check with the lab for sample holding procedures if the sample is not taken to the laboratory for analysis within an hour of sampling. 

Sampling Solid/dry Poultry Manure

The focus of this article will be on sampling solid/dry poultry manure because this represents the majority of the manure samples collected in Delaware. Sampling solid poultry manure can be sampled from a stockpile, manure shed/storage area, or inside a poultry house. Good sampling techniques will minimize analytical variability, but will not eliminate it. Knowing that manure can be highly variable from farm to farm, it’s a good idea to take several samples and have those samples analyzed, even if the manure originated from the same farm. 

Before taking a sample, it’s a good idea to check with the laboratory that will be analyzing the sample. The laboratory will provide information on the quantity of manure to collect, how to store and hold the sample, ship the sample, quantity of the sample needed for analysis and the paperwork that needs to accompany the sample. The Delaware Department of Agriculture has a manure testing laboratory that is free for Delaware farms. A link to the Delaware Department of Agriculture: Agriculture Compliance Laboratory can be found here. If the sample is not taken to the laboratory for analysis within an hour of sampling, most laboratories recommend freezing the sample but check with the lab for sample holding procedures.

We recommend securing the following basic manure sampling supplies:

• Clean plastic bucket

• Clean shovel or spade

• Sealable plastic bags for dry samples like poultry litter or bedded horse manure

• Permanent marker for labeling the sample container

• Freezer space for the sample

It’s best to avoid the following when sampling manure:

• Metals buckets

• Glass bottles for liquid samples 

Sampling Dry Manure from a Stockpile

When sampling a stockpile:

• Take 10 - 20 subsamples and place them into a clean plastic bucket.

• Begin each subsample 18” below the stockpile surface (avoiding the crusted surface)

• Mix subsamples thoroughly in a large bucket or on a clean, hard surface 

While sampling a stockpile, it’s best to avoid:

• Sampling manure on the outside of the stockpile that has been exposed to rain

• Taking soil with the manure subsamples

• Sampling areas of the stockpile that look different from the majority of the stockpile

Sampling Inside a Poultry House

Nutrient concentrations are highly variable within the poultry house. The area around feed lines, waterers and brooding chambers can have different nutrient concentrations than the rest of the house. When sampling litter in a poultry house:

• Visually divide the house into three areas, length-wise.

• Walk the length of the first area, in a zig-zag pattern, taking between 8 and 10 subsamples.

• With the spade, remove a small “trench “of litter above the soil floor (this is not the subsample)

• Once the area is clear, now take a 1” thick slice of litter for a subsample and add the slice to a clean bucket.

• Avoid taking soil with the subsample. 

• Repeat this in the other two areas.

• Thoroughly mix subsamples together.

• Fill a plastic bag 2/3 full with the composite sample. 

• Label bag and place in a cooler with ice.

Sampling from a Manure Shed/Storage Area 

Sampling from the manure shed or storage area can be tricky if the structure is full. It will be nearly impossible to sample in a fashion that allows for the collection of a representative sample. Most of the manure in a full shed or storage area will be inaccessible and the manure that can be sampled easily may be exposed to rain. Therefore, if sampling from a manure storage structure or area is the only option, it is best to wait for the shed or storage area to be cleaned out when all of the manure can be accessed for sampling. If different types of manure are stored in the same area (e.g., crust or cake with total clean out litter), it is best to sample those different manure types separately. If the majority of the manure in storage is accessible, follow the steps under “Sampling Dry Manure from a Stockpile” to obtain a representative sample.

Storing and Shipping Samples

It’s best to avoid shipping samples late in the week which can cause the sample to be held for many days before it is analyzed. When preparing a sample for shipment to the lab    

• Place a portion of the mixed subsamples into a quart size plastic bag 

• Label sample with contact information 

• Place sample bag inside another quart size plastic bag

• Store in a freezer or cool area until shipment

Manure is a valuable resource. Taking a representative sample for analysis will ensure that the true value of the manure will be utilized during the cropping season and to minimize environmental losses. 

For more resources and/or information about manure management, please contact your local county Cooperative Extension Office.

New Castle County Extension Office: 302-831-8965

Kent County Extension Office: 302-730-4000

Sussex County Extension Office: 302-856-7303

Additional Manure Sampling Resources

(including liquid manure sampling)

Delaware Department of Agriculture Manure Sample Submission Form

University of Maryland Extension Sampling Manure For Nutrient Content

Penn State University Manure Sampling for Nutrient Management Planning