Stirrer speeds up the drying process
Proper sampling builds representative picture
By Andrew Pearce
Good sampling technique, exercised regularly, is a cornerstone to knowing whats happening to your grain. "Too many farmers close the door on a dried crop and dont open it again until its time to sell," says Peter Grant of Protimeter.
Proper sampling builds a representative picture of a bigger mass of grain. And achieving this accurate snapshot is important both before and after drying – particularly if moisture content looks right for long-term storage straight off the field.
Trailer samples should be made up from taking at least three separate sub-samples, mixing them and only then measuring moisture content.
With milling or malting crops its sensible to retain one such mixed sample from each load, taking enough grain – around one litre -for a range of quality tests. Where the crop is destined for a deep bin or a floor store where grain depth will be more than 3m (14ft), these individual load samples build into a microcosm of the entire bin contents.
In store, either still drying or held prior to sale, its necessary to monitor bulk moisture content and temperature; primarily for the control of pests and mould. A comb-ined moisture content/temperature probe, speeds the job considerably.
Although moisture content of dried grain tends to be stable if the crop is stored properly, a local problem can escalate. So consistent monitoring, weekly for a start and then at least fortnightly, is both sensible and a requirement under ACCS.
Sampling from the same points and graphing the results will let trends be picked up. In stored grain, changes of more than 0.5% in samples taken at least 0.5m below the surface should be viewed with suspicion.
Where to sample depends on store type and layout.
• On-floor stores. In each bay (ie between stanchions), mark out a W-pattern with numbered canes Squarer areas suit the five-dot dice layout. If the store has been filled relatively evenly by loader, probe straight down. But where fixed-elevator filling has left cones at the surface, probe at an angle below the cone cap to miss warm grain. If you suspect a cone cap to be heating, take a separate sample from it.
• Bins and silos. Compared to a floor store, bins have a small surface area. Grain delivered from a conveyor tends to fill their volume fairly evenly without coning, so vertical spear sampling is OK. Given the limited surface available, its acceptable to spear at a different point or points each time a check is made. *
Stirrer speeds up the drying process
By Andy Moore
PUTTING 1000t of grain through a 9t batch drier during a wet harvest a few years ago proved time consuming for Fred and John Rowson of Manor House Farm, Thorpe St Peter, Lincs.
The solution came in the form of a Rekord DMC Stir-Dry (grain stirrer) which was fitted in one store to work in conjunction with an existing ambient air on-floor drier last year.
The Rowsons first impressions of the machine are high.
"Being in quite a wet area near the coast, it is very rare to harvest grain with the acceptable moisture contents at 15% or 16%, so drying is essential," says Fred. "Stirring immediately after tipping breaks up any moist patches so the grain does not fester. In about two days, the moisture content can be reduced by about 3.5% leaving the grain in a good condition."
The grain stirrer cost less than £11,000 with the electrical work costing about £1000 and a new grain store floor £5000.
Running costs have so far not been monitored and compared to the old batch drier. But even if they are higher, the Rowsons believe they can be offset by the increase in operation convenience and grain throughput.
Growers AA Needham and Son of Apley Manor Farm near Wragby, Lincs – about 15 miles from the Rowsons – run a similarly sized grain store and have been using the Stir-Dry for five years.
Like the Rowsons, grain drying was previously carried out by an on-floor ambient air drying system. The move to the grain stirrer was to improve grain quality and increase drying throughput.
With these targets fulfilled, the Needhams have also seen drying costs fall by about £1.30/t when compared with those attributed to the standard ambient air on-floor drier.
"We can now take about 5% moisture out of 1100t in a week compared to two months with the old system," claims David Needham.
"The grain stirrer can mix corn with moisture contents up to 22% with no problems and is especially useful for breaking up hot spots to reduce mould."
In addition, the grain stirrer is claimed to give a finer control over the Hagberg level within the grain. And moisture can be added back into over-dry grain by mist sprayed from a boom behind the auger carriages.
Although the grain stirrer is used mostly for mixing milling wheat at about 25C, on the Needhams farm it can also work with rape seed to help raise the oil content.
Giving a thorough and complete mixing action, the grain stirrer also offers the advantage of increasing store capacity. The Needhams have extended their stores retaining wall by 0.6m to 3m (10ft) with boards – boosting overall capacity from 1000 to 1100t. *
David Needham of Apley Manor Farm claims the Rekord grain stirrer can remove 5% moisture from 1100t of grain in a week.
Choose your weapon
Portable moisture meters work by one of two principles – capacitance or resistance.
Resistance meters give best results when the sample is ground up and compressed. Current flow though the material is measured; the more the flow, the wetter the sample. By crushing and mixing the sample, potential errors caused by the outer grain husk being wetter or drier than the inner kernel are avoided.
Capacitance meters use whole grains and the sample needs to be weighed. Crop at differing moisture content holds different levels of electrical charge, which can be measured from the ability to pass current once the sample hopper is filled. Fast and easy to use, capacitance meters are generally accurate. But where grains are not in moisture equilibrium – for example, coming from a dewy field or hot from a high-temperature drier – the inside will be at a different moisture level to the outside, and errors can occur.
Whichever meter type you use, its accuracy is only as good as its calibration. For reliable results, have your meter checked and calibrated annually!