Mowers and Mower-Conditioners
Cut height affects forage yield and quality, as well as crop regrowth and persistence. A low cutting height creates a risk of scalping the field and throwing soil into the forage, which increases ash content and can contaminate the feed. Cutting is a stressor, and cutting crops too low can remove growth points and any above-ground energy stores that are needed for regrowth. As a general guide, do not cut forages lower than 5–7.5 cm (2–3 in.). Different crop species have different tolerances for cutting heights, so consult forage species characteristics to determine if the cut height should be higher. In general, legumes can be cut closer than grasses, and cool-season crops can be cut closer than warm-season crops.
Conditioning speeds drying time and synchronizes the drying of stems and leaves. Conditioners crimp or crack the stems of forage plants to allow stem moisture to escape more readily. The goal of conditioner maintenance and adjustment is to have adequate conditioning and optimize drying, while minimizing shattering and leaf loss. Underconditioning increases the risk of rain damage, while over-conditioning increases cutting, raking and baling losses. Ontario’s humid climate can result in heavy dews and prolonged drying time, so conditioning is especially important when making dry hay.
Adjust mower-conditioners according to the owner’s manual. The adjustments on roll conditioners 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 the hood.
Roll clearance should be slightly smaller than the alfalfa stems, which usually means setting the clearance at 1.5–2.5 mm (1/16–3/32 in.). 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 7.5–10 cm (3–4 in.) 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.
Increasing the swath width is often limited by the width of the conditioner on the mower. Wide swaths wilt faster than narrow ones, but if a producer must forgo conditioning to widen the swath, does that negate any advantage of having a wide swath? According to research from Cornell University, conditioning reduces wilting speed in wide swaths at haylage moisture levels by disrupting the capillary flow and evapotranspiration of moisture through the stems to the stomata (pores) in the leaves.
In a narrow dense windrow, the stomata close, so conditioning is an important drying mechanism. On the other hand, where there is a wide swath with sunlight to keep the stomata open, the Cornell research indicates producers could forgo conditioning in a haylage system.
This is in contrast to a field study by Dr. Kevin Shinners (Agricultural Engineering, University of Wisconsin) that showed a benefit to conditioning in all haylage swath width situations. He concluded that it may only be advantageous to give up conditioning in situations where swath width could be nearly doubled (i.e., 35% to 65%) by eliminating the conditioner. More research is being done to sort out these conflicting conclusions.
Conditioning is unquestionably essential when moistures fall below 60%–65% during dry hay making (see Moisture Content and the Hay Drying Curve later in this chapter). Conditioning stems is extremely important at lower moistures in making dry hay. Strategies for wilting silage are quite different from dry hay making, but wide swaths are advantageous for both.
Tedders
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.
Tedders can also be used to shake a heavy dew off a cut crop very early in the morning. This will speed up drying throughout the day. Tedding should be finished before the top of the swath is dry.
Rakes and Mergers
Raking is done to narrow the swath for the baler, and to move the wetter material at the bottom of the windrow to the outside. Every time hay is raked 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% and 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.
Ground-driven wheel rakes should not be used for baleage production. They are not designed to move a heavy, wet crop and because of this they incorporate more soil into the windrow than other types of rakes. The soil is more likely to stick to the wet forage and cause clostridium contamination. Wheel rakes were designed for dry hay production, where they are moving a dryer, and therefore lighter crop, and the lower moisture content reduces soil retention.