As featured in Arable Farming Magazine
Managing damp grain to avoid spoilage in stores
by Arable Farming
Many farmers are facing tricky decisions on how to get grain into long-term storage after a prolonged, stop-start harvest. Jonathan Wheeler reports.
After yet another rainy August, a key issue facing many growers is how to safely store batches of grain that may have come in at widely differing moisture levels.
Harry Henderson, knowledge exchange manager for AHDB, says: “The key is making sure that grain with a raised moisture content is dealt with before it goes into long-term storage.
“The danger is that any packet of grain with higher than 15% moisture put into a store where the moisture level is lower could cause a hotspot.
“There is a risk of that causing spoilage in that patch, which could then spread through the other grain.
You can end up with a lot of issues.
“As a priority, all grain needs to be dried and brought down to below 15% moisture.”
Risky strategy Blending higher moisture grain with other samples is a possibility, but one he says farmers should think about carefully.
“Blending grain with a higher moisture content into drier grain can work well, but it is a risky strategy.
“If you only have a couple of trailers full, then it is manageable.
But trying to work a larger quantity – such as a whole day’s harvest – into the store would be a real risk.
“And there is the danger that if you don’t blend it into the drier grain really efficiently, the higher moisture grain will pose a threat to the whole store.”
He suggests damper grain is stored under cover and separately until it can be dried sufficiently to mix with the grain already in store.
“You should aim to store all grain under cover unless you are totally confident it is not going to rain.
“But it can be surprising how much dew falls every night, especially as we go deeper into autumn.
It can burn off during the day, but we know how unpredictable the weather is.”
Providing the moisture level is not too high, there is still time to make plans and take deci sions, he says.
But as a general rule, the higher the moisture content, the faster decisions and drying should be completed, because the risk of spoilage is greater and the onset sooner.
“Grain can be stored under cover without the risk of spoilage for a number of weeks, provided the moisture content is not too high,” says Mr Henderson.
AHDB has an interactive tool on its website (ahdb.org.uk/ safe-storage-time-calculator) which enables how quickly any sample of grain might be expected to spoil to be assessed.
Germination By entering a number of relevant details about the crop – including harvest date and moisture content – the key dates when mould, germination, mites and insects might be expected to become problematic can be obtained As an example, Mr Henderson gives the following figures for two crops harvested on the same day but at different moisture levels.
One was harvested at 17%, which has been commonplace this harvest, and the other at 24%, a level that Scottish farmers encounter quite regularly.
“The calculator suggests cereals harvested at 21degC and 17% moisture had a safe storage period of 16 days before they need to be placed in store.
“After that, mite infestation could have been expected to become an issue.
And from 17 days after harvest, germination might also cause problems too.”
Mould would have been the next issue with the potential to damage quality, being expected to set in 29 days after harvest.
The fourth and final difficulty – insect infestation – would be expected to set in from 50 days after harvest.
If the harvest date and temperature remain the same but the moisture level is raised to 24%, the damage can be expected to start faster and in a different order.
“At those levels the germination risk starts in just two days and the potential for damaging moulds just another day after that.
“Mites could be expected to become an issue after 10 days.”
The only consistent threat is that from insects, which could still be expected to become a problem from 50 days after harvest.
“In that scenario, by the time you got to 50 days after harvest it is questionable whether you would still have a saleable product.”
He suggests using the tool to prioritise which grain to prepare for storage first.
“Some crops can clearly be left for longer than others.
The tool will indicate how long farmers have to complete the job.
“That will enable them to decide whether it can wait a week, or whether they need to stop harvesting, cultivating or drilling and get it done right now.”
Speedy maintenance Farmers who have had trouble with grain drying and storage this autumn should consider maintaining their equipment in the same way they do tractors and combines.
So says Andrew Head, managing director of BDC Systems, who also warns that delaying ordering new equipment could be a false economy “Things like tractors and combines may get changed every three or five years.
But too many farmers do not look at grain drying facilities in the same way.
“We have had lots of calls over the past few weeks from people who have realised – while trying to handle this year’s tricky harvest – that their facilities are no longer up to the job.
“These issues need to be thought about now for next year and if you have had problems then get them fixed now, not next spring.
“Steel prices are very unstable, as is availability, while delivery periods are getting longer and longer.
“Those considering doing repairs, modifications or upgrades need to address it now to make sure it gets done as soon as possible.”
Stores under stress This autumn’s damp harvest has stressed UK farmers’ grain handling and storage facilities.
But some simple forward planning and preparation could help avoid problems, suggests Joel Capper, national sales manager at Martin Lishman.
“Maintaining the highest quality grain relies on more than just good ventilation.
“Before the season, farmers need to make sure the store is fit for purpose and carry out regular assessments to identify potential problems and correct them before the first load of grain arrives.”
And they should deploy the full range of tools to help them – including insect traps, sampling spears, ambient air measurement devices and accurate moisture meters.
The company’s flagship product is the Barn Owl Wireless system,which enables store operators to monitor their stores remotely.
The system can also send alerts to suitable devices to warn when temperatures fall outside a preset range or if there is any malfunction.
It also enables fans to be controlled automatically, to take best advantage of ambient air.
The company claims this can save ‘at least 40%’ of energy costs.
In stores using a pedestal cooling system, Mr Swinn suggests having a fan for every pedestal.
Moving fans between pedestals slows down the cooling process and raises the risk of areas not being treated, while also raising the requirement for more frequent temperature checks.
Where a localised problem does occur between pedestals, the advice is to use a hotspot spear, which can be screwed into the location and fitted with a fan to extract the heat.