I’m a traditional guy. I wear my cap bill-forwards and take it off inside the house. I like lace-up shoes, making eye contact during conversations and listening to baseball during long summer nights on the tractor. So when SFC’s editor asked me to try out a handheld hay moisture tester, I wondered, what for? I’ve already got built-in testers. They’re called “hands”. They’ve been calibrated over decades, using settings passed down through generations. Best of all, they come at no additional cost.
Then again, you get what you pay for. A few years ago during a dry summer, I hopped off the tractor and left the round bale spinning in the chamber. When I turned around, there was so much dust or smoke flying around the machine I thought it was on fire. The good news: it wasn’t a fire. The bad news: I was literally watching the protein fly off my hay in a cloud of broken leaves.
Pasture is the focus of this column, but if you’re wintering livestock, you need high-quality forage to retain or extend gains through the cold season. A $300 hay moisture tester won’t guarantee good hay; (you need good weather, luck and hard work for that). But if it improves the odds, it’s a worthwhile investment. Here’s why:
1. It could prevent a barn fire
At 11 per cent, this hay is dry enough to lose leaves and nutrients when baled.
Hay is like beef jerky: the drying process preserves feed value and prevents spoilage. Grass in the field is probably 80 per cent moisture, and the haymaker’s challenge is to get this below 20 per cent at baling time.
“Hay that is baled too wet creates an environment where microbes can thrive,” says Christine O’Reilly, forage and grazing specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs. Above 20 per cent, there’s likely to be some loss in nutrients as plants continue to “sweat” or respire in the bale, temporarily continuing to burn sugars as if they were still rooted and growing. The result is dusty, mouldy hay, with reduced levels of protein and carbohydrates.
The situation is even more dire with really damp hay. At moisture levels above 25 per cent, microbial growth becomes more rapid, releasing more moisture and producing heat as the microscopic creatures gobble nutrients in the forage. Some spoilage will almost certainly result. If tightly-packed bales warm above 60 C, farmers risk extensive spoilage and a chain reaction that could trigger a hay fire.
Whether hay is tested the old way, by feel in the hands, or with a moisture tester, the point is put up good quality, cured grass with a moisture content that won’t lead to fire.
Sampling bales after baling and within the first few days of storage helps manage this risk. Be especially cautious of hay that appears dry, but has moisture locked up in stems. O’Reilly says ideal moisture levels are 15-18 per cent for small squares, 13-16 per cent for softcore round bales and 12-15 per cent for hardcore round bales and large square bales.
If hay is coming off the baler much above 20 per cent moisture, consider waiting until the hay is dryer. At the very least, leave those “tough” bales in an airy, dry location and monitor them until they cool off. Bales could take as long as three weeks to cool in the open air, but up to six weeks to heat and spoil if packed tightly into the barn.
2. It could help you bale better hay, and maybe save a few bucks
Because I’m persnickety about baling dry hay, I tend to bale too dry, shattering and losing leaves in the process. That’s partly because I’ve been relying on hand-testing for dryness and erring on the side of caution. As Idaho forage specialists Glenn Shewmaker and Ron Thaemert write, the “popular method of twisting and breaking the stem is useful if you wait until the stem actually breaks, however by then the forage is too dry and leaf retention is almost impossible to maintain until dew occurs.”
Losses can be considerable: alfalfa raked at about 15 per cent moisture can lose more than a quarter of its leaves. Some older round balers can shed up to 15 per cent of the crop’s nutrients, if the hay is overly dry.
The tester helped me rethink my haying system. By testing the first few bales during this past scorching-hot hay season, I discovered they were already too dry (often 10-12 per cent). Raking and baling earlier in the day led to moisture levels that were still okay to bale, but less prone to leaf loss. As a bonus, I was able to make denser, heavier, tighter square bales, with incremental savings in twine. By putting more pounds of hay in the same storage area, I also made more efficient use of the haymow.
3. It supplements your judgement (but doesn’t replace it)
There’s a range of hay testers out there, from highly accurate machines for researchers (as well as techniques using convection and microwave ovens to determine hay moisture,) to sensors mounted in baler chambers and handheld units. Handheld units are the cheapest. You can pick one up at a hardware or farm supply store for about $300. Baler-mounted sensors cost twice as much (and are typically coupled with a preservative system using propionic acid), but are considered more accurate. As a bonus, they track moisture in real time as you’re baling.
These basic testers determine moisture levels by “measuring the electrical conductivity of the hay,” says Joel Bagg, forage development specialist with Quality Seeds. “The more moisture, the more electrical flow, calibrated to certain levels of moisture by the manufacturer.”
“The bottom line is the tester is really a tool you need to use in conjunction with what you know. You can’t put 100 per cent confidence in what you read, because there’s natural variation within fields, and even within bales.”
Haying, of course, is a mix of art and science, and I found a modest investment in science helped improve my art. Besides, a hay tester will easily pay for itself if it reduces spoilage, or prevents a hay fire. If you’re a traditionalist, as I am, think of hay moisture testing as a tradition worth starting.
Hay testing by hand
Check the bottom of the heaviest windrows, including areas with a lot of legumes. (While you’re at it, check stems for evidence of crimping to ensure haybine rollers are correctly set.)
Moisture-testing techniques include grabbing a handful of stems and twisting, bending a few stems and examining how readily they snap, and scraping stems with a fingernail.
- 25-30 per cent moisture: hay rustles. Stems will bend but not break, or break with difficulty. (In other words, the hay is “tough.”) Thick stems release moisture when scraped.
- 20-25 percent: Hay snaps more easily when twisted. Stems, especially of legumes, may still be green and moist. Some leaves may bend rather than break.
- 15-20 per cent: Stems and leaves break readily when bent or twisted. Juice is difficult to squeeze or scrape out of stems.
Source: Michael Collins, University of Kentucky, “Saving those valuable leaves during haymaking.”
Using a hand-held hay tester
Be sure to read the instructions for using and calibrating your tester. If you’ve got a tester designed for bales, one way to check hay in the swath or windrow before baling is to pack it tightly into a container (mimicking the density of a bale) and test the sample. (For more information on making your own swath-testing tool, see this advice from the University of Idaho: https://www.cals.uidaho.edu/edcomm/pdf/CIS/Cis1107.pdf)
Test moisture and temperature by inserting probe at least 30 cms/one foot into a bale. (In square bales, test towards the bottom half, where damper hay accumulates during baling, and pushing the probe through rather than between the “flakes” of hay that make up the bale.)
Keep the sensors clean according to the manufacturer’s instructions.
Take lots of samples. Experts typically recommend 20 random samples per 200 tonnes of hay.
I usually take two samples per bale (square or round), testing the first few bales of each baling session, and randomly test bales before they go into the barn. When the bales are in the mow, I do a few random checks from week to week to keep tabs on moisture levels and temperature.
- Ray Ford