What Moisture Should Hay Be? A Haymaking Masterclass

The ideal moisture content for hay varies depending on the type of hay and intended storage method, but generally ranges from 12% to 18% for small square bales. Higher moisture levels risk spontaneous combustion and mold growth, while lower levels can result in excessive leaf shatter and nutrient loss.

The Importance of Hay Moisture: A Balancing Act

Haymaking is an ancient art, but modern science has refined our understanding of the crucial role moisture content plays in its success. Too much moisture, and you risk disaster. Too little, and you sacrifice quality. Achieving the right balance is paramount for producing nutritious, palatable, and safe feed for livestock.

The primary danger of excessive moisture is spontaneous combustion. As damp hay is stored, microbial activity generates heat. If this heat cannot dissipate, temperatures can rise to the point where the hay ignites. This is a significant fire hazard and represents a devastating loss of valuable feed.

Conversely, hay that is too dry suffers from excessive leaf shatter. Leaves are the most nutritious part of the hay plant, containing a disproportionately high concentration of protein and energy. When hay becomes overly dry, these leaves become brittle and easily break off during baling and handling, leaving behind less nutritious stems.

Therefore, understanding and accurately measuring hay moisture is essential for successful haymaking.

Moisture Levels and Hay Types: A Specific Guide

While the 12-18% range is a good general guideline for small square bales, specific types of hay have slightly different optimal moisture levels. Let’s examine some common examples:

• Grass Hay (e.g., Timothy, Orchardgrass): 12-18% for small square bales. Higher moisture levels can be tolerated with preservatives.

• Legume Hay (e.g., Alfalfa, Clover): 12-15% for small square bales. Legumes are more susceptible to leaf shatter, so drying them slightly faster is beneficial.

• Large Round Bales: 14-18%. The larger size of these bales makes them more prone to heating, so a slightly lower moisture content is often recommended.

• Wrapped Baleage (Haylage): 40-60%. This fermentation process relies on high moisture to create anaerobic conditions that preserve the forage.

Measuring Moisture: Tools and Techniques

Accurately measuring hay moisture is critical. Several tools and techniques are available:

Moisture Meters: The Technological Approach

Electronic moisture meters are the most common and convenient method for assessing hay moisture. These meters use probes that are inserted into the bale to measure electrical resistance, which correlates to moisture content. There are two main types:

• Probe-type meters: These are typically used for small square bales and offer quick, spot readings.

• Bale-averaging meters: These use longer probes that penetrate deeper into the bale, providing a more representative average moisture reading.

The Hand Twist Test: The Traditional Method

The hand twist test is a more subjective method, but with practice, it can provide a reasonable estimate of hay moisture. Here’s how it works:

1. Grab a handful of hay from the center of the bale.

2. Twist the hay tightly.

3. Observe the following:

   • Very Dry (Leaf Shatter): Hay crumbles easily, and leaves fall off. Moisture is likely below 12%.
   • Dry (Ready to Bale): Hay feels slightly stiff but doesn’t crumble excessively. Moisture is likely between 12-18%.
   • Damp (Too Wet): Hay feels cool and damp to the touch, and the twist leaves moisture on your hand. Moisture is likely above 18%.

Laboratory Analysis: The Definitive Test

For the most accurate determination of hay moisture, laboratory analysis is the gold standard. A hay sample is sent to a lab where it is dried in an oven, and the moisture content is calculated based on the weight loss.

Frequently Asked Questions (FAQs)

FAQ 1: What happens if hay is baled too wet?

Spoilage and potentially spontaneous combustion are the main risks. Excessive moisture promotes the growth of mold and bacteria, which can degrade the hay’s nutritional value and palatability. The heat generated by microbial activity can also lead to a fire.

FAQ 2: What are the signs of mold in hay?

Visible mold growth (often white or grayish), a musty or moldy odor, and heat within the bale are all signs of mold contamination. Avoid feeding moldy hay to livestock, as it can cause respiratory problems, digestive upset, and even death.

FAQ 3: Can I save wet hay?

While prevention is always better, there are some options for salvaging slightly damp hay. Proper aeration can help dry the hay, but this is only effective if the moisture content is only slightly elevated. Preservatives like propionic acid can also inhibit mold growth. However, severely wet hay should be discarded.

FAQ 4: How do preservatives work?

Hay preservatives, typically propionic acid-based products, inhibit the growth of mold and bacteria by lowering the pH of the hay. This allows you to bale hay at slightly higher moisture levels without the risk of spoilage.

FAQ 5: What are the advantages and disadvantages of using preservatives?

Advantages include allowing you to bale hay earlier in the day or in slightly damp conditions, reducing leaf shatter and preserving more nutrients. Disadvantages include the cost of the preservative and the need for specialized application equipment.

FAQ 6: How do I calibrate a hay moisture meter?

Calibration is crucial for accurate readings. Follow the manufacturer’s instructions. Generally, this involves checking the meter against a known standard or adjusting the settings based on laboratory analysis results.

FAQ 7: Is it better to err on the side of caution and bale hay too dry?

While avoiding overly wet hay is critical, baling it too dry also has drawbacks. Excessive leaf shatter leads to nutrient loss and reduced palatability. Aim for the optimal moisture range, not an extreme.

FAQ 8: How does weather affect hay moisture?

Sunlight, temperature, humidity, and wind all play a significant role in hay drying. Hot, sunny, and windy conditions promote rapid drying, while cloudy, humid, and still conditions slow down the process.

FAQ 9: What is “dew point” and how does it relate to haymaking?

The dew point is the temperature at which air becomes saturated with moisture and condensation begins to form. Baling hay when the dew point is high increases the risk of dampness and mold growth.

FAQ 10: How long does it typically take hay to dry?

The drying time depends on various factors, including the type of hay, weather conditions, and cutting height. Typically, it takes 3-7 days of good drying weather to reach the optimal moisture content.

FAQ 11: Can I use a tedder or rake to speed up the drying process?

Yes, tedding and raking can significantly accelerate drying. Tedding spreads the hay out to expose more surface area to sunlight and wind, while raking flips the hay and helps aerate the bottom layers.

FAQ 12: What is the best time of day to bale hay?

Afternoon, after the dew has evaporated but before the evening humidity rises, is generally the best time to bale hay. This allows for optimal moisture levels and minimizes the risk of spoilage. Monitoring the hay moisture throughout the day and adjusting your baling schedule accordingly is crucial for successful haymaking.