Recommended principles for proper hay sampling
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- Published on Thursday, October 25, 2012
myWestman.ca
Proper sampling of hay and forage is of tremendous importance to assure an accurate forage test. Remember, a lab test is only as good as the sample provided to the lab.
Hundreds of thousands of pounds of highly variable plant material must be represented in a single, tiny, thumbnail-sized sample!
Often, the sample actually analyzed by the lab is often only half a gram.
The first step is to identify a single lot of hay. The lot could be a single cutting, a single field and variety and generally be less than 200 tons. Combinations of different lots of hay cannot be represented adequately by a forage sampling method.
It is important to sample the hay either as close to feeding, or as close to point of sale as possible. Dry matter measurements are especially subject to changes after harvest and during storage, but other measurements may also change. After hay has equilibrated to the range of 90 per cent DM (10 per cent moisture, depending upon humidity), it is typically quite stable.
‘As received’ dry matter measurements should be used to adjust quantity (tonnage, yield), not quality parameters, which should be compared on 100 per cent DM basis.
Choose a sharp, well-designed coring device. Never send in flakes or grab samples. It is nearly impossible for these samples to represent a hay lot. Check with your local MAFRI office to borrow a probe if you don’t have your own.
Take samples by walking around the stack as much as possible, and sample bales at random. For example, the sampler may walk 15 steps, sample, walk 20 steps, sample, walk 5 steps, sample, trying to represent all areas of the stack.
The recommendation is to take a minimum of 20 core samples to represent a hay lot.
Sampling should be done so that about half a pound of sample is produced. Too-small samples don’t fairly represent the full range of variation in the hay lot. Very big samples (common with large length or diameter probes) are excellent at representing the hay but have practical disadvantages.
Seal composite 20-core sample in a well-sealed plastic bag and protect from heat. Do not allow samples to be exposed to excess sun (e.g. in the cab of a pickup truck). Refrigeration of hay samples is helpful, however, dry hay samples (about 90 per cent DM) are considered fairly stable.
Contact your local MAFRI office for more information.
MAFRI
