If you read our article “How to make good quality hay” then you will know how important it is to keep your hay dry. When hay becomes wet a number of factors result in dry matter and quality losses. These include plant respiration, leaching, and possibly mould, microbial and yeast growth. So, rain damage should be avoided or minimised as much as possible.
“It is important to keep hay as dry as possible to ensure good quality feed for animals,” says Ruben Badenhorst, agricultural advisor at Overberg Agri. “Excess water in hay can lead to leaching of soluble nutrients, necessary for ensuring good animal health and to improve overall animal performance.”
Badenhorst recommends keeping the moisture content as low as possible before even starting to cut the hay. If there is too much moisture, plant respiration can lead to a decrease in the nutrient content.
“Hay with a high moisture content has a lower financial and nutritional value, because at the end of the day you are feeding your animals water instead of dry matter,” Badenhorst says.
“Hay should not contain more than 15% moisture,” Professor Robin Meeske, researcher at Outeniqua Experimental Farm in George and extraordinary professor at Stellenbosch University, says. This is to prevent growth of yeast and mould in the hay.
Another huge drawback with wet hay is the potential accumulation of mould.
“Mould makes hay less palatable, decreases intake or even [causes] refused intake and can lead to an overall decrease in growth performance as well as productivity,” says Badenhorst. And some fungi moulds can even produce mycotoxins that can be toxic to animals.
Luckily, according to Badenhorst mycotoxins are rarely present in hay and occur mostly in hay that contain weed seeds.
“[The] best is to stack bales under a roof to keep the quality for as long as possible,” says Dr Johan Strauss, directorate of plant sciences at the Western Cape department of agriculture. “The midden (heap) needs to be stacked with spaces for airflow.”
But if rain is on the way, your bails are on the field, and you won’t have all the bales in a shed or under a tarp before it arrives, what can you do?
First, avoid the worst damage. Then, after the rain, make sure you save the salvageable hay in the correct ways.
1. Avoiding the worst damage
The first step to avoiding the worst rain damage is to minimise the contact area that the rain has on the hay.
“Most people that produce hay that don’t have access to storage structures will stack hay bales on top of each other and place them on a level part of the field,” Badenhorst says. “Some prefer to stack the hay at a slight angle to ensure water runoff.”
Badenhorst recommends covering these stacked bales with plastic or any other durable and water-resistant material.
“It would also be wise to place the bales on a platform ± 1m above the ground to avoid water flow damage,” he says.
Farm Online proposes these following shapes to stack your hay in:
- Stand the bales on their ends in threes so that they resemble an upside-down V-shape.
- Lay two bales horizontally on their edge so that they lean into each other at the top edge. This will form a “V” into which the third bale is then placed.
The uncut side of the bales should be facing up since it tends to shed the water more effectively.
The second technique is the better method for shedding rain off small square bales.
Large square bales can be stacked in small stacks around the field which could be covered with tarps or plastic sheets. Although the outer edges of the bales will become wet, their internals should remain relatively dry.
Round bales, if balled tight or tied up, will shed most of the rain. According to Badenhorst round bales should be stacked in a pyramid form.
Due to the surface area of spheres, the outer parts of round hay bales contain the largest part of the volume of the bale. To avoid high losses, round bales of high-quality material should be put under cover in a shed as soon as possible or stacked and covered with plastic to minimise losses.
“The bales should be placed in rows (end-to-end) and orientated in a North-South orientation,” Badenhorst says. “The North-South orientation will prevent excess deterioration caused by the penetrating sunlight.”
He also says that it is important to leave a space between each row to ensure proper ventilation.
Badenhorst says that research shows that stacking bales over a 12 month period in enclosed shelters only leads to a 5% loss in dry matter, 8% under a roof or outside covered with plastic and elevated, 35% when exposed and elevated and exposed with no elevation can lead to up to 50% of loss in dry matter.
2. After the rain
After the rain, if better weather is on the horizon, it might be good to keep the bales in their stack so that a breeze can help to dry them out.
The most cost-effective way to dry your wet hay is to place the hay outside in the sun. Make sure the hay is completely dry before storing, since a small section of one bale containing moisture may be adequate to cause spontaneous combustion if stored before becoming sufficiently dry.
“By stacking the hay bales in the field, the outer parts of the haystack will get really wet while the insides may be dry but this can cause the midden to spontaneously ignite,” warns Dr Strauss.
“If you want to protect the hay from external conditions it can be placed in a barn (or any other structure with a roof) that is well ventilated to get rid of excess water,” says Badenhorst. “Ventilation is the key aspect that can help with drying wet bales.”
All bales which are rain affected will be much damper than normal, even after a period of drying, so regularly monitor the stack for signs of dangerous heating and do so for up to seven weeks.
Ugandan farmer Hamiisi Semanda explains the importance of storing hay, and how to bale your hay, in this video: