As more growers and grower groups consider on-farm storage as a way of
protecting harvested grain quality, or for holding grain to exploit market
opportunities, the need to fully understand the range of storage technologies
is becoming essential.
One of the more attractive technologies for onfarm storage, in terms
of cost, is aeration - aeration cooling and high flow rate aeration
drying. However, successful use of high flow rate aeration drying requires
a thorough understanding of how the technology works. There are risks
to growers who store over-moist grain and either have a system that is
not designed for the purpose for which it is being used, or who do not
know how to manage the system.
This said, GRDC-funded studies do show that the time spent putting the
right system in place and learning how to drive it can pay off significantly
through higher grain quality and a significant reduction in harvest weather
In recent Northern Region Grains Research Updates, consultant John Cameron
and QDPI extension specialist Peter Hughes reiterated that aeration is
an effective, low-cost way to maintain grain quality in storage. Low flow
rates of about two litres per second per tonne (l/s/t) will cool grain
and suppress moulds and insects. If used correctly, flow rates of two
to six l/s/t can also enable the safe storage of grain for weeks to months
at moisture levels a little above receival standards.
This can then be dried, back blended with drier grain or sold into a
market that accepts higher moisture grain. However, it is critical to
realise that aeration cooling alone will not reliably dry grain and, if
used for this purpose, places the grain at risk.
Drying requires a well-designed, purpose-built high flow rate aeration
silo with flow rates of about 20 l/s/t and higher.
When drying is not the issue, aeration for cooling alone can be a highly
profitable addition to on-farm storage. Low flow rate aeration cools grain
and slows most quality deterioration processes affecting:
Experience has shown that being able to harvest early maximises yield
and quality and reduces the risk of weather damage.
If a purpose-built high flow rate aeration dryer is also used, harvesting
can potentially start at even higher grain moisture levels. Some growers
are reportedly harvesting and drying cereals at up to 20 percent moisture.
Harvesting higher moisture grain closer to physiological maturity lowers
the risk of downgrading or quality losses due to rain. Also, as moist
grain is less prone to pre- and post-harvest shatter losses and splitting,
yield in the bin and sample quality are usually better than if left to
dry naturally in the field. However, growers are cautioned to be careful
about immature grain that may not mature properly if harvested too early.
It has been shown that yield losses due to shattering from the head,
pod deterioration in seed size, weight and colour, and increases in splitting,
can be large. Trials from Esperance, WA, showed yield losses of 0.25 to
0.75 percent, averaging 0.5 percent a day for barley and 0.18 to 0.53
percent a day for wheat. In Queensland, losses of 0.3 to 2.5 percent a
day for wheat were reported. The table shows the potential impact of different
levels of grain loss.
The value of harvest loss in cereals ($/ha) at a yield of 2.5
and 4t/ha at $200/t on-farm.
The other issue for on-farm storage is insect control. Chemical control
options for grain protection on most farms are limited to phosphine and
an ever-decreasing number of protectants. Insect resistance to low doses
of phosphine is becoming widespread. To control resistant populations,
phosphine must be used in a sealed silo.
However, aeration suppresses the speed of insect development by cooling
the grain and slowing insect life cycles.
For more information:
under ‘grain storage")
Kotzur Silos: www.kotzur.com.au
AgriDry Rimik: www.agridry.com.au
Agriculture WA: www.agric.wa.gov.au
USA websites: bru.usgmrl.ksu.edu/flinn/
QLD - Peter Hughes 07 4688 1564
QLD - Philip Burrill 07 4661 2944
VIC - Peter Botta 03 5761 1647
SA - Peter Fulwood 08 8568 642
WA - Chris Newman 08 9366 2309
NSW - John Cameron 02 9482 4930
GRDC RESEARCH CODE DAQ00028, program 5
North, South, West