PLASTIC wrap is not a silver bullet for hay that was rain affected before baling or for hay that is too wet or for silage that is too dry.
Recent hay seasons have resulted in the above scenarios, leaving farmers and contractors with quandaries such as "it's about half to one day off being OK to bale but now $##*#& rain is threatening" or "the hay was cured enough and being baled when it started to drizzle".
A response by many these days seems to be to wrap it in stretch wrap plastic and turn it into silage or at least use plastic to stop it going mouldy.As much as I hate to say this, there is no cut-and-dried right answer. I must also say that sometimes wrapping hay might prevent mould but more often than not it will not.
Let's look at two scenarios.
First scenario: Since it's probably mid to late November/early December when making hay, most pastures will have a lot of stem with seed heads prominent. This means the quality of the forage on the ground will be well down, probably under 9.5 megajoules of metabolisable energy per kilogram of dry matter (MJ ME/kg DM), about 9-11 per cent crude protein (% CP) and more than 50 per cent neutral detergent fibre (% NDF). However, a leafier crop and or one with higher clover content might be higher quality (more than 10 ME, over 14% CP and under 45% NDF).
The dry matter (DM) content may be about 70-80 per cent, i.e. moisture content 20-30 per cent so the forage will be too wet for hay but generally too dry for silage. I call this the 'danger zone' and the result is often mouldy and/or foul-smelling fodder. This is because there is not enough moisture to allow a satisfactory lactic-acid type fermentation, which converts plant sugars to acids, which preserves the crop.
Another issue is that if bales of late maturity forage have been wrapped in stretch wrap plastic their high proportion of stems to leaves allows a lot of air to be trapped between and even within the hollow stems. Same result as above, often mouldy and less-than- pleasant to horrible-smelling silage with reduced palatability. Let's not even think of the consequences if these bales are punctured/holed and how quick and far air will enter the bale and rapidly head towards compost.
Another issue caused by rain is that soil is often splashed onto the forage or inadvertently picked up by further tedding or raking. This soil contains undesirable soil organisms that can contribute toward a poor fermentation and plastic won't prevent this.
Sometimes, the farmer will get a win. To increase their chances they will need to individually or continuously in-line wrap the rounds or squares. Do not even think about saving money by stacking 'danger zone' large squares under sheets of plastic as I have heard too many farmers who have tried this being disappointed with the outcome.
If considering it with round bales, just stick them straight into a compost heap, at least the garden and worms will benefit.
At about $10 to $18/bale to wrap small rounds to large square bales plus the cost of plastic, and the added hassle of handling wrapped bales if not equipped to this, even if the plastic did work, is its quality worth the extra cost of wrapping?
If the moisture content is only 3 to 5 or 6 per cent above the ideal baling moisture content, the best outcome might be to stick to baling it as hay, but use a reliable hay preservative. Use hay preservatives at the correct rate, remembering wet hay is heavier than cured hay, and ensure the preservative covers as much forage as possible.
Second Scenario: If the crop is pasture or lucerne and is medium to high quality, that is more leaf and less stem, or thinner stems for the lucerne, the same story still applies as in the first scenario. However, there will be less air trapped in these more tightly packed bales and this time it starts with a higher quality base with plants containing more sugars on which the bacteria can work.
The closer this forage is to silage dry matter, and although there will still be a drop off in quality, the chances of a positive outcome are somewhat higher. With this scenario, still individually wrap and/or use a preservative but there's still no guarantee of success.
There is no magic answer to 'is it worth wrapping that' and unfortunately Mother Nature has not been on the hay/silage maker's side in recent years. But, if the raw product was crappy to start with, then the end product will be too.D
*Senior dairy extension officer, Agriculture Victoria, Victoria
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