Mowing, conditioning and windrowing
If weather conditions are expected to be suitable, mow as early as practicable after the dew evaporates. In very hot or very cold dry weather, when no dew falls and the soil is dry, over-rapid drying can be a problem. To reduce moisture loss from the hay crop, mow when it is cooler, during the late afternoon or at night.
Most modern mowing machines combine mowing, conditioning and windrowing into the one operation to save on operating costs. After cutting, the lucerne crop is first conditioned and then laid back onto its stubble in a continuous heaped structure called a windrow. The width of the windrow may be adjusted to suit the prevailing haymaking weather.
Conditioning crushes or crimps the stem, opening it up to allow simultaneous air circulation over the inner and outer stem surfaces. This helps to even up the drying rate between stem and leaf, and reduces the drying time to half that of unconditioned hay. If separate mowing and conditioning units are used, the best time to condition is within 30 minutes of mowing.
Raking
Interlocking plant stems should be rigid enough to support the open structure of a windrow, allowing drying air to circulate over, and through, the windrowed crop. Because the stems of freshly windrowed crops are still flexible, those on the bottom of the windrow will bend under the weight of the green material above them, causing the windrow to settle or compact.
Turning a windrow with a hayrake will lift it up and maintain its open structure. Regular turning also helps to maintain an even drying rate between bottom and top, and prevents too much sunlight from concentrating on one area of the crop and bleaching away its green colour.
Frequency of turning depends on drying conditions. In hot, dry summer weather, a crop may be dry in 1 to 3 days; in cooler weather, it may take up to 15 days. In average haymaking weather, turn once a day before the dew evaporates, extending to every second or third day as the crop dries. Under rapid drying conditions, the turning frequency may increase to several times a day to maintain a suitable drying rate.
Before pressing small bales, it is common practice to combine two smaller windrows into one. For larger bales, dual rakes are used to combine four or more conventional-sized windrows into a large wide one that satisfies the intake capacity of the machines used to make large bales.
Baling
Field-dried lucerne hay is ready for baling when the moisture content is between 20-230/0. Moisture below 180/0 may result in heavy leaf loss, while moisture above 250/0 may cause heating of the bales in storage, especially in more humid storage environments. Such high-moisture hay can now be treated with a micro-organism inhibitor, applied to the hay at the time of baling, to reduce spoilage in the bale. Overdryness during raking and baling may be partially overcome by working the crop in the cool of the night, when dew may remoisten the leaf and restore its pliability.
Table 8.1 Moisture content (0/0) for baling hay
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Hay moisture tests
Most haymakers carry out simple tests to estimate the correct moisture level for baling. They test whether:
• a small sheaf containing, say, 8-10 stems taken from the centre of a windrow breaks cleanly and easily when cranked, or
• the skin on the stem does not readily peel when scratched with a thumbnail. The hay may then be safely baled and stacked.
If the stem fails to break cleanly, if free moisture is observed in the crank area, or the skin peels, the crop is too wet to bale.
The following test, using hay samples progressively dried in a microwave oven, is more accurate:
• Take samples of hay from throughout the windrows at random and cut into small pieces.
• Weigh 100 g from each sample and dry in a microwave oven (6 minutes at lowest setting, reheat for 2 minutes if necessary).
• When these 100 g samples are dry, reweigh them; the difference in the weight of each before, and after, drying is its moisture content, e.g. if a sample is 100 g on first weighing, and 80 g on second weighing, the difference is 20 g or 200/0 moisture.
• To average the moisture, add all the weight differences and divide the total by the number of samples.
Freshly made, small, rectangular bales should be moved to a hayshed or stacked in the field as soon as possible after baling to reduce the risk of damage by rain or bleaching, which is caused by overexposure to sunlight. Rain causes bales to go mouldy, while bleaching reduces their visual appeal by destroying their fresh green colour.
There is now a range of moisture meters available in Australia, some of which provide reliable accurate hay moisture readings. Hay producers intending to acquire such equipment are advised to consult reputable local dealers.
Bale size
Most lucerne hay is bought in small rectangular bales weighing about 25 kg each, with 40 bales/tonne. Density of hay can be altered on the baler, and increases with moisture content. Average density of lucerne hay (80-83% dry matter) is 130-170 kg/m3. The bales are made in a bale chamber of cross-sectional dimensions 35 x 45 cm and 40 x 45 cm. Their length varies (usually from 60-110 cm). These small rectangular bales are preferred by buyers and handlers alike, because:
• they are compact and easy to handle, both manually and mechanically;
• carriers can easily stack bales across the trays of their trucks;
• small quantities of hay are often sold by the bale and small bales have a lower individual price;
• buyers are better able to inspect the quality, colour, aroma, moisture content and texture of small bales.
Other bale size options are the large, rectangular bale and the round bale. A variety of large balers that can produce bales of different dimensions are available to suit individual haymaker, and user, requirements, but bales from both these systems, because of their size and weight, can only be handled mechanically.
A large rectangular bale is a giant higher-density version of the smaller rectangular bale and is made in several sizes. An average bale of 300-500 kg is 60 x 90 x 250 cm, while a very large bale up to 1000 kg is 120 x 120 x 260 cm. Density ranges from 160 to 230 kg/m3.
A round bale can weigh from 250 to 950 kg, with its dimensions ranging from 90 to 190 cm diameter and from 100 to 170 cm in width. Densities range from 110 to 180 kg/m3. Round bales were initially designed for short-term storage and use near the area where they were made. Improved methods of handling and transportation have greatly increased their competitiveness with rectangular bales.
Table 8.2 Typical weights of round baled hay
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