How to Test Hay Moisture Levels to Prepare for Safe Storage
Tips about moisture measurement in hay
How to use a hay moisture meter in the windrow, in bales, in the bale chamber or
during storage
Every farmer knows that proper storage of hay protects property and revenues as hay stored at excessive moisture levels can create a fire hazard. Testing moisture levels of hay prior to and after storing is the key to preventing property, crop and revenue loss. Baling hay at proper moisture levels and storing hay in a manner to reduce mold development can also preserve leaves, color and feed value.
Hay that contains too much moisture is fertile ground for fungus. As those micro-organisms accumulate during storage, they can raise the temperature of the hay. When the temperature rises, protein begins to degrade and the hay may be become indigestible. When temperatures reach 80° Celsius (180° F), there is a risk of spontaneous combustion.
Unfortunately, moisture levels can be difficult to judge, as hay may look and feel dryer than it actually is. Fortunately, a moisture tester specifically designed for testing hay in the bale, or the windrow – a row of hay raked up to dry before being baled or stored - can help you obtain accurate moisture readings to protect your valuable hay crop.
Appropriate Moisture Levels for Hay
Moisture measurement in hay should be measured in terms of ranges and not specific points. Generally, round bales requires a slightly lower moisture level than square bales. The challenge in either form is the variability of both the electrical properties of hay, as well as its non-uniformity, making it difficult to accurately represent anything but an “average” moisture level for one or more hay varieties.
Traditionally, the recommended moisture content for baling hay without a preservative is between 18-20%.
If using a preservative, follow the instructions provided by each particular preservative manufacturer. Smart use of a moisture tester in combination with preservatives and drying agents allows hay to be baled at higher than traditionally recommended moisture levels.
In either case, do not attempt to bale hay before it is at an acceptable moisture level, even when using a preservative.
Using a Moisture Tester for Hay in the Windrow
For moisture testing, hay should be removed from the windrow and placed in a five or ten gallon bucket or other container. Moisture testers with a multi-pin prod will yield the most accurate readings with high density around and between the contacts, so hay should be packed down as tightly as possible before inserting the prod.
As with baled hay, multiple tests are required in order to obtain an accurate reading. After taking the first reading, the operator should mix the hay, re-pack it and test again several times, then average the readings. A secondary test involves choosing several large, slow-drying stems from the same area of the windrow and lying them one at a time across two adjacent points on a multi-prong electrode. These readings will typically be a few points higher than the actual moisture level.
Repeat these steps in different parts of the field and pay special attention to the areas where the hay is heaviest. Your decision to start baling should consider the amount of variation found among windrow readings as well as the average stem moisture.
Using a Moisture Tester for Hay in Bales
When hay has been baled, the interior density and stem-to-leaf ratio are generally inconsistent throughout the bale. Therefore, it’s necessary to test a bale in several locations and average the readings, taking particular note of the high readings. It’s also important to test several bales in different locations, since field conditions may impact moisture levels and spoilage too.
A firm, uniform contact will yield more accurate results, so the prod should be driven across bale slices.
Random spoilage of baled hay can occur due to fluctuating field conditions, i.e. windrow size, soil moisture, density, low spots, and shade. Therefore, it is also important to check bales at several locations in the field.
On-the-Go Moisture Testing in the Bale Chamber
The hay producer can install a micro-controller based moisture meter in the tractor cab and connect it to a sensor in the bale chamber to produce on the go moisture monitoring while baling, without leaving the cab. The microcomputer collects and processes eight readings that are accumulated every four seconds. The meter then displays the average and highest reading. This cycle is repeated every four seconds.
A microprocessor-based continuous monitor is an easy and reliable way to give the operator clear guidelines and a little less to worry about. Even though this method provides reliable information, we recommend that you take readings in several bales, especially at the beginning of baling, and as you see conditions change. The FX-2000 can be used for on-the-go moisture monitoring or as a portable meter.
Additional Safety Precautions - Temperature
Whether hay in the windrow or bale is tested, the number of tests made should be increased whenever the initial readings show considerable variations.
Ensuring that hay is not baled at moisture levels above 20% is a significant step toward safe storage. However, moisture may be inconsistent and readings may be impacted by humidity levels in the air and other factors. Checking the temperature of stored hay, whether stored indoor or out and—especially during the risky period that lasts from two to six weeks after storage—is an important additional safeguard.
Hay is considered stable at 52°C (125°F), but when internal temperatures rise to 65°C (150°F) close monitoring is required. From there, the danger increases rapidly. At 80°C (175°), hot spots or fire pockets are likely and the local fire department should be notified.
