Fast drying is a key to successful haymaking. "Make hay when the sun is shining" is a well founded expression. In this part of the world, good haymaking periods without rain are frequently very narrow. We often struggle between getting the hay dry enough to bale before the next rain, or baling before the hay is quite dry enough and getting mouldy, dusty hay. Conditioning and raking has to be balanced against excessive leaf loss. Successful haymaking is a "learned art". We can't control the weather, but there are a few management practices that can improve your odds against rain damaged hay.

Adjust the Mower-Conditioner

The goal of conditioner maintenance and adjustment is to have adequate conditioning and optimize drying, while minimizing shattering and leaf loss. Conditioning speeds drying time and synchronizes the drying of stems and leaves. Under-conditioning increases the risk of rain damage, while over-conditioning increases cutting, raking and baling losses.

Unfortunately, many conditioners never get checked or adjusted again after they are purchased and brought home. Adjust mower-conditioners according to the owner's manual. On roll conditioners, the adjustments include roll clearance and roll pressure. Adjustments on impeller conditioners, designed for grasses rather than alfalfa, include impeller speed and clearance between the impeller and hood.

Roll clearance should be slightly smaller than the alfalfa stems, which usually means setting the clearance at 1.6 - 2.4 mm (1/16 - 3/32 inch). Too big a gap results in under-conditioning. Rolls that touch wear prematurely and cause excessive leaf loss. Heavier crops, such as first-cut, require more roll pressure (spring tension). Too much pressure can cause excessive leaf loss. Alfalfa stems should be crimped or broken every 3 - 4 inches to allow moisture to escape. At least 90% of the stems should be cracked or crimped, with less than 5% of legume leaves bruised or blackened.

Make a Wide Windrow

Swath width is an easy adjustment that has a big impact on drying time. Lay the crop as wide as practical. Do not cut hay into a tight windrow. A wider swath will dry faster, because more drying area of the hay is exposed to sun and wind. Solar radiation cannot penetrate very deep into the swath. University of Wisconsin research indicates that a 12 foot haybine laid into a 9 foot swath will reduce drying time by 35% versus a 6 foot swath. Wind speed and humidity are the most influential weather factors affecting drying time.

A higher cutting height (3-4 inches) comes at the compromise of some yield loss, but allows air to move underneath the swath and speeds drying. If the ground is wet and in contact with the windrow, the hay will absorb moisture.

Cut Early or Late in the Day?

Cutting hay in the morning, after the dew is off, maximizes daylight hours for drying and minimizes respiration losses. Research that suggests delaying cutting until late in the day to maximize sugar content, is based on the dry environment of the American west, and does not typically apply to the high humidity conditions of the Great Lakes area.

Rake Strategically

Raking is done to narrow the swath for the baler, and also to move the wetter material at the bottom of the windrow to the outside. Every time you rake hay there is some leaf loss, so rake strategically. The drier the hay is at raking, the greater the leaf loss. If possible, raking alfalfa at moistures between 30 - 40% is often a good compromise between low leaf loss and good drying. Leaf loss can be extremely high if raking at 20% moisture. Hay that is almost dry is less likely to shatter when raked in the early morning when the dew is still on.

Some rake designs are more aggressive and do a better job of fluffing, but are also more prone to leaf loss, particularly at lower moistures. Uniform, consistent raking without bunching is required to avoid wet bales.

If a partially dried hay field does receive a heavy rain, tedders or rotary rakes can break up a windrow that has clumped and matted into the stubble. Moving a windrow onto a drier surface, or fluffing onto stubble can speed drying. Tedders are better suited to grasses than alfalfa. Avoid using a tedder on alfalfa at moistures less than 50%. Avoid driving with tractor tires on the swath and causing leaf loss.

Propionic Acid

Inevitably, there will be situations when the storm clouds are moving in, but the hay isn't quite ready to bale. Rain on almost-dry raked hay is much more damaging than rain on hay that has just been cut. In situations where getting that last increment of drying is difficult, consider using a buffered propionic acid product. The use of propionic acid over a wide range of moistures to avoid mouldy dry hay is well researched and effective. This is particularly the case with higher density bales, such as large squares, that need to be drier at baling to avoid mould growth.

While there are certainly no guarantees in haymaking, the maintenance and adjustment of conditioners, windrow management and strategic raking can improve the odds of avoiding hay with rain-damage or mould.