Several chemical and organic products are available that, when sprayed uniformly onto lucerne hay, either assist the drying process, or enable the crop to be baled when its moisture content is higher than normal. Any practice that hastens the time from mowing to baling is potentially useful, especially when the drying conditions are slow, e.g. during winter, or if rainfall is expected.
Drying agents
K-Hay
K-hay is the name given to lucerne hay treated with a solution of potassium carbonate (K2CO3), rather than simply conditioned. K-hay dries faster than conditioned hay. The improvement in drying rate depends on the environment and the amount of potassium carbonate solution applied. In Queensland, at least one day is saved during summer, and up to five days in winter. Overseas results claim increases in the drying rate of between 30% and 50%.
Because potassium carbonate has a greater effect on stem drying than on leaf drying, reduced leaf loss can be expected. Reduced field exposure time reduces the risk of loss due to rain, and damage to regrowth. A 70/0 yield increase has been demonstrated in one case, and there have been several other reports of improved yields.
Potassium carbonate costs around $2/kg, which is about 15c/bale, depending on application rate. The application equipment varies with the system used, but simple systems have been put together for less than $200; more elaborate systems could cost in excess of $1500.
Potassium carbonate is applied as a 20/o solution in water. Increasing the concentration is less effective than increasing the amount applied to each hectare; the aim is to get it onto the stems. It is normally applied at the rate of 4-8 kg/ha in 200-400 L of water.
The leaves and stems of lucerne have a waxy surface that is normally impermeable to water. The potassium carbonate breaks down the waxes, and the surface then behaves like wet blotting paper, allowing rapid moisture loss. The effect is more noticeable on stems than on leaves.
Hay quality is almost certainly better because there is less leaf loss, but this has not yet been proved in research. The hay is often greener because it has spent less time in the field, and is generally less fragile than conditioned hay with the same moisture content.
Because K-hay dries faster than conditioned lucerne it often feels cooler and wetter. It is extremely difficult to judge the moisture content of K-hay by ‘feel’, and misjudgment of moisture content results in over-drying. Over-drying reduces bale weight and can result in fragile, dusty hay. It only takes a few minutes to check hay moisture content using a moisture meter or a microwave oven and good kitchen balance. This is worth doing until growers get used to the different feel of K-hay. Tests have shown that the moisture content of K-hay is the same as that of conditioned hay after long-term storage. K-hay simply gets to its final moisture content faster.
Potassium carbonate is a mild soapy alkali, and not dangerous to handle. If the solution comes in contact with the skin, it causes stinging of any wounds and drying of the skin.
Potassium carbonate solution left on machines encourages corrosion, so machines should be hosed down after use. If potassium carbonate is mixed with poor quality water, nozzles and filters can become blocked. A small amount of wetting agent or detergent will usually solve the problem. Undetected nozzle blockage can leave untreated strips of hay, which can lead to damp patches in bales.
Equipment can be bought from any supplier having experience with K-hay. Any sort of pump can be used, as spraying pressures are generally less than 350 kPa. Roller vane pumps should be washed out and lubricated after use. Fan nozzles have been used satisfactorily, but US reports suggest that cone nozzles might be better. It is important that nozzles can be easily seen by the operator so that blockages can be detected and rectified quickly. A nozzle providing an output of 1.5 L/min at 305 mm spacing applies almost 400 L/ha at 8 km/h.
Mould inhibitors
Hay 2000®
Hay 2000 is buffered ammonium propionate, which has similar properties to a number of naturally occurring organic acids. At normal strength, it allows lucerne hay to be baled with a moisture content of up to 250/o or, at double normal rate, up to 300/o. It is a mould-inhibiting agent, which prevents the growth and activity of fungal organisms that cause the spoilage and heating of hay. It is produced and marketed by Cobbett Pty Ltd, Hornsby, NSW.
Hay 2000 is applied to hay through one, or two, flat fan nozzles. These are directed at the hay as it is fed into the bale chamber during the baling operation. The chemical is applied at a rate of 1 Lit of hay at 20-250/0 moisture content, or 2 Lit for hay being baled at 25-300/o moisture content. It is not recommended for use on hay with over 300/0 moisture content. Baling at these higher moisture contents means that hay can be baled a day earlier than under the normal moisture requirements of 15-20010. This results in one less raking, less leaf loss and, consequently, higher quality hay.
Hay 2000 is available in 25 L drums, and costs approximately $6/L, which is about 15c/bale when applying 1 L/t. Application equipment can be made up on farm, but a kit is available from Hay 2000 suppliers.
Anhydrous ammonia and urea
Anhydrous ammonia is an effective fungicide that has been used as an additive to high-moisture hay. It sterilises hay, killing the organisms that cause mould.
Urea is a common nitrogenous feed ingredient that has been used as an alternative to anhydrous ammonia. Urea offers advantages in reduced corrosiveness and volatility.
Neither of the anhydrous ammonia or urea treatments are in common use due to the temporary nature of their benefits, and occasional losses of cattle due to subsequent development of toxic substances.
Lucerne hay inoculant
Hay Inoculant, produced by Pioneer Hi-Bred Australia, is a bacterial inoculant that contains a special strain of Bacillus pumilus selected specifically for moist lucerne hay. These natural bacteria prevent heating of the hay by competing with the spoilage organisms.
The inoculant is applied at the pick-up point on the baler to material with up to 25% moisture content. The application rate is 4 L mixture per tonne of lucerne hay. The inoculant consists of 8 g product plus 4 L water. The cost is around 25c per bale when there are 40 bales/t (ie. $10/t). A granular formulation of this product is now available in 10 kg bags. Application rate for granules is 1 kg/t of baled lucerne hay. For optimum distribution throughout the hay, use any suitably calibrated granule applicator.
The inoculant is not an acid, is non-corrosive and will not damage baling machinery. It is non-toxic, and will not reduce palatability.
Caution:
• Regardless of what product is used to prevent hay damage caused by overheating, hay baled at over 200/0 moisture content needs to be stacked so that bales are well ventilated to allow moisture to escape. Avoid fully enclosed sheds. Allow for a breezeway between stacks. Do not stack higher moisture hay in direct contact with dry hay until the newly preserved hay has lost its moisture.
• When considering use of such hay additives, it is wise to check with potential buyers. From time to time, some buyers reject hays treated and baled at higher-than-normal moisture content regardless of their state of preservation. This has been experienced especially by growers who supply hay to clients in more humid coastal environments, who have had spoilage of hay due to bale moisture in storage in such environments. Some clients report that stock refuse hays with ‘off’ odours remaining in treated hay.
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