Good preparation is key to ensure that quality is maintained while crops are in store, says Andrew Head
The old adage “prior planning prevents poor performance” (the five Ps) should not be overlooked when it comes to preparing for harvest and successful crop storage.
It sounds obvious, but it is important to start at the beginning. Ask yourself whether your storage facility is fit for purpose. There is a tendency that once last year’s crop has gone everything is turned off, the doors shut and that’s it for another year.
Ask too whether your crop handling equipment is ready to be fired into action. Have you checked since switching everything off at the end of last harvest? If so, it’s a good idea to make sure it is working and check any service requirements.
It is also important to treat the crop correctly when it comes in from the field. Is it dry and clean enough to go straight into storage? If not, how wet is it and how long are you going to have to dry it for?
Grain should be stored at 14.5% moisture content and oilseeds at 7.5-8.5%. And it almost goes without saying that you need to ensure that your chosen drying solution is capable of doing a good job.
Different drying methods
There are three main drying methods when it comes to crop storage.
- Continuous flow driers – can continually extract 10-12% moisture from the crop and are generally the quickest drying solution. Most have some wet storage facility and can keep up with the daily harvest throughput.
- Mobile batch driers – keep the crop inside the dryer until the target moisture content is reached and are often the choice for a mixed farm where a fixed installation isn’t justified.
- Floor store bulk drying – probably the slowest way to dry a crop, extracting up to 1% moisture per day.
When drying with a hot air drier, whether continuous flow or batch, the crop will generally come off the drier at 5-10oC above ambient temperature, so ventilation needs to start as soon as possible to prevent the risk of insect and mite infestations.
It is handy to keep the following target storage temperatures in mind:
- Within two weeks of harvest – below 15oC
- Within three-four months of harvest – below 12oC
- End of December – below 5oC
Below or above ground ventilation
Below floor ventilation, although perceived as expensive, is the easiest to use when loading and unloading stores. With fans on the outside of the store, the cold air is forced up through the crop, via laterals set in the floor.
There are three options for above floor ventilation:
- Airstacks/pedestals – vertical columns with a perforated/louvred bottom section. The ventilation fans are positioned on top of these columns and the air is drawn down through the crop, into the bottom section of the columns and then expelled by the fan.
- Pyramids/floor vents – positioned on the floor with below ground ducting to the outside of the building, floor vents suck warm air down through the crop whereas pyramids blow cold air up through the crop.
- Half round perforated pipes – sit on the floor with external fans blowing cold air up through the crop.
Manual or automatic temperature monitoring
Manual monitoring is time consuming as it means physically walking the crop, taking temperature readings and turning the fans on/off to get the temperature down.
Automatic monitoring uses temperature probes positioned in the crop. The probes are linked to a controller that automatically turns the fans on/off if the ambient temperature is 5oC lower than the crop temperature.
Andrew Head is managing director of BDC Systems. For details call 01672 810851 or visit www.bdcsystems.com