At one time, in the not too distant past, most livestock producers looked at the manure their livestock produced as a nuisance that had to be disposed of. But lately, manure has experienced an elevated status and many actually now look as manure as a valuable resource.
“Manure is an integral part of any livestock operation – you put in feed and you get something out, and that something isn’t nothing, we can actually take advantage of it,” said John Breker, a soil scientist with Agvise Laboratories in Northwood, N.D.
Manure has value in two aspects, Breker noted – as a cost effective alternative to commercial fertilizer and its influence on improving soil quality. The most important component of manure is the nitrogen it contains – the major economic driver in the financial aspects of manure.
There are several steps that should be taken in a manure management program if the maximum results are going to be obtained:
Soil test the fields
This is the first step because it is necessary to determine how many nutrients are needed on the field where manure will be applied. In some fields we may have legal limitations on how much manure we can apply, while in other fields that won’t be a problem.
It also must be determined if a certain field will require additional fertilizer beyond the manure application. Are we going to apply excess nutrients, beyond what the crop will take up? Soil testing may indicate there is a better field in which to make the manure application.
In addition, it is recommended to keep track of the soil nutrient status over time.
“One of the biggest issues can be the accumulation of phosphorus up to a level where it causes an environmental concern and the field ends up with levels outside of regulation,” Breker said.
Manure is an inherently variable resource, both in terms of sampling and analysis, Breker noted. Values have ranged in tests Agvise has run from $4 per ton to over $80 per ton, based on the fertilizer nutrient value and that is why testing the manure is a useful tool from the get-go.
As far as time to sample, Breker said sampling the manure just before hauling is the best time. Sampling at this time is usually more accurate, because you have a sample of what is coming out of the manure stockpile and you can actually sample each load spread on the field, since manure piles are so variable.
“You won’t have the information available to determine the application rate, but you can actually back calculate and figure out how much will go on in the future,” he said.
In the case of a liquid manure, care must be taken to make sure the manure is mixed up and solids are carried into suspension. The liquid can then be put in a small, plastic sample jar.
Solid manure samples are a little more difficult to work with. If you are sampling before hauling from the pile, samples must be taken from several different areas and depths of the pile. Avoid taking samples close to the edge of the pile or from the top crust on the surface, since manure in those areas are either dried out or the nutrients leached out due to rain or melting snow. Sampling while hauling from the pile involves taking a several small sub-samples from each load that is applied to the field.
Once all the samples of dry manure are obtained, Breker recommends piling the samples on a clean area and to start chopping up the material and mixing it. You take half of the original pile and again chop and mix it and then take half of that pile and repeat. This continues until you end up with a sample size of about two cups.
Both liquid and dry samples should be submitted in a plastic jar, not a glass jar. Since the manure contains microbes they might produce enough gas during the transit time to the lab to cause the glass jar to explode, he cautioned. The samples should be stored in a cool place, such as a refrigerator, or freeze the samples if it will be a while before the samples are sent off.
An information sheet should accompany the sample, indicating what the sample is and also what you want it tested on.
Samples sent to Agvise should be sent early in the week, Breker stressed. They don’t want the samples to be in a heated warehouse of a shipping company over the weekend, since microbial activity is taking place, which would change the true analytic results.
Breker presented this program at the first annual Livestock Summit of the North Dakota Livestock Alliance in Fort Ransom, N.D. In our next issue, he will explain the reasons why manure nutrient tests can vary so greatly.