Fall Manure Application: Part 3 Manure sampling and testing

An important part of nutrient management is knowing the nutrient composition of the manure you’ll be applying to your fields. Manure sampling and testing provides this information but there are some tips and tricks when it comes to taking the sample. Learn more in this third episode of the Fall Manure Application podcast series.


Liz Binversie, Agriculture Educator, Brown County UW-Extension


Kevan Klingberg, Outreach Specialist, UW-Discovery Farms

Trisha Wagner, Agriculture Agent, Jackson County UW-Extension


Time: 9:43 minutes


Liz Binversie: Greetings. I’m Liz Binversie, Agriculture Educator for Brown County UW-Extension, and today we’re going to talk about the tools you can use for getting it right this fall with manure application. On the panel is Kevan Klingberg, Outreach Specialist with UW-Discovery Farms, and Trisha Wagner, Agriculture Agent for Jackson County UW-Extension. Kevan and Trisha, what kinds of tools can farmers use to help them make the most of this fall application?

Trisha Wagner: Well, Liz, as was mentioned in a previous podcast, manure is an excellent source of many essential plant nutrients. With proper management, it can meet nearly all the crop nutrient needs. Manure test results combined with soil test recommendations and manure spreader calibration are the basis for determining appropriate manure application rates to meet those crop needs. UW-Extension has a handy fact sheet that can walk you through these steps of calibration. You can contact your local extension office for this or the Nutrient & Pest Management Program website to obtain a copy. It is a great idea to do your own manure sampling so that you can have the most accurate information available. Unlike fertilizer, manure form and composition, and therefore the nutrient analysis, can vary widely. It’s essential that you take the sample properly. Only a small amount of manure is sent to the laboratory for analysis, so it’s imperative that the sample represents the average composition of the manure being applied. I’ll talk a little bit about sampling solid manure. When manure is stored in barns or bedded packs or litter or stored in a stack, it’s not typically affected as much by the weather. There can be significant variation in the nutrient content throughout the manure based on uneven mixing, bedding, or hay or spilled feed that may be in the manure. It’s important that you get a representative sample and that it’s mixed very well before it is actually sent to the lab. The best recommended times for solid manure sampling is while the manure is being loaded. During loading, you can take samples of the manure and place it in a 5-gallon bucket. You want to have a minimum of 5 samples, approximately the same size when you’re loading manure out of a storage space. You want to avoid large chunks of bedding or feed. After all of the five samples have been collected in a bucket, you should really mix them very well. If the manure is not too liquidy, a good idea would be to place all the samples on a clean open space—concrete surface—and mix it thoroughly. Then you’re going to take a subsample from those mixed composite samples and put them into a container for the lab. Another recommended time for sampling would be during spreading. One option there would be to spread a tarp or some sort of sheet of plastic in the field where the spreading is taking place. Pass the spreader over the tarp so that you can collect a sample. You would want to do that a minimum of five times out in the field. Again, collect those samples into one large composite sample and mix thoroughly again. Then take a sample of that and place into the lab manure sample container. You can also sample during daily haul by placing a 5-gallon bucket under the barn cleaner and do that 4-5 times while loading a spreader. After you’ve collected all the samples in that bucket, again, mix them very thoroughly and take a subsample from the mixed composite samples and fill the lab manure container. You want to probably repeat this several times throughout the year to determine the variability over time. Some people think that sampling stockpiles is a good idea, but actually it’s probably the least recommended method. It’s difficult to obtain a representative sample by sampling the stockpiles, and again it’s really not getting at the sample that’s being spread out into the field as is when you sample during loading, spreading, or daily haul.

Kevan Klingberg: Thank you Trisha for helping us understand how to sample the solid manure for nutrient analysis. I’m going to visit with you a little bit about doing the same thing for liquid manure. Just to refresh our memory, each of the animal groups are different. The different species, whether we’re talking about swine liquid manure or dairy liquid manure. There’s other species that have liquid manure but those are the two main ones in Wisconsin. Different age groups, different times within the life cycle of those animals, are going to have different nutrients mostly based on the diet that those animals are fed. There’s a couple of different time periods that we can collect the liquid manure. One would be just straight at the loading time period. We want to make sure that the manure is agitated. When we think about storage and liquid, just remember and know that there’s settling that’s involved. The solids are going to be on the bottom. The more liquid fraction is going to be on the top, and so we want to make sure that the sample we send in is agitated. Another thing that I want to make sure we talk at least a little bit about, especially in the dairy sector. We’re starting to see a lot more farmers that have different categories of manure. The solid and liquid separation concept is being used a lot out there. There’s very legitimate reasons why you might end up taking a manure sample out of two or three different pits—pits that have different solid contents. It’s not unheard of that different fields on the farm would get different kinds of manure—manure that’s more liquid or more solid. It makes sense to take samples and analyze the nutrient content of any of the different kinds of manure storage that you’ve got. Again, we want to make sure that the material that you gather is representative of the manure that’s actually in the storage. Put it in a plastic bottle. Glass has the potential to break so we want to make sure we put it in a plastic vessel. If you’re not going to get it to the lab yet that day, throw it in the freezer. Once it does get to the lab, they’ll thaw it out and you’ll end up with a report that really does give you something very specific about your farm, your animals, your feeding regime, and the nutrients that are contained in the manure with the livestock that you’re raising.

Trisha Wagner: One last point would be to make sure you check with the lab that you choose to send the samples to. They will have a submission form that they’ll want you to accompany with your sample. They’ll also have information about the minimum amount to send for your sample. Some labs might ask for a gallon bag and maybe filled halfway. Like Kevan mentioned, you can send jars but usually plastic containers would be recommended with a screw on top. Most labs do not want glass containers shipped in the mail. Again, a lot of labs like to have manure samples sent early in the week so that the sample doesn’t sit over the weekend in a post office, or over a holiday where it would take longer to get to the lab. Of course, most labs want it to be frozen before it’s sent, too. So, sampling manure for analysis is an essential and valuable nutrient management tool for determining the nutrients available in manure. It’s important to know the nutrient content of the manure being applied on your farm in order to maximize the economic benefits of the nutrients in achieving yields and reducing fertilizer costs. Also, knowing the nutrient content of manure is helpful in reducing the environmental impacts from an excess nutrient application.

Liz Binversie: Thank you Kevan and Trisha for being on the panel today, and if you’d like to reach them you can do so by email. Tune in next time to learn more about preventing nutrient loss from manure application after corn silage.