Grain and pulse storage – looking at the options for maintaining quality in storage
Author: Ben White (GRDC stored grain extension team) | Date: 14 Feb 2019
Take home messages
- Select a grain storage option that provides flexibility to meet market requirements.
- The only silos suitable for fumigation are gas-tight (meeting AS2628-2010), pressure tested.
- Hygiene and monitoring are keys to maintaining grain quality in storage.
- Aeration is an effective tool worthy of consideration – best paired with an automated controller.
Storing grain on-farm is increasing in popularity nationally, but growers need to select storage options carefully to ensure grain quality is maintained and market options are not limited.
When it comes to storage options, gas-tight pressure-tested silos offer simple fumigation in insect disinfestation. Aeration is a valuable tool used to cool the grain with carefully selected air.
Grain bags have a place for improved harvest logistics but are a short term (3-4 months) option. For best results, site selection and preparation are critical, as are regular weekly inspection and maintenance to maintaining bag integrity and preventing grain spoilage.
Top ten tips
- Start clean – hygiene is essential. Insects only need a handful of grain to survive and breed. Feed any spilt grain out or bury it away from the storage facility.
- Make sure the pressure relief valve has light hydraulic oil (ISO46) in it (wetter can be used as an alternative).
- To pressure test, pressurise the silo with an air compressor to 25mm water gauge (250Pa or 0.036psi). The pressure in the silo should not drop below 12.5mm (125Pa) over a three-minute period. Most silos have a marked semi-opaque or clear pressure relief valve to measure the 25mm and 12mm pressure lines, but if not, use a home-made u-tube manometer using a length of clear hose with some water in it.
- Fumigate within three weeks of the completion of harvest while grain is still warm and any insects that may have come into storage with the grain are most active.
- Silos must be gas-tight and seal-tested to meet a 3-minute half-life pressure test. Spread the tablets out – no more than 2-deep on a tray in the headspace or in the ground-level applicator. Do not mix tablets in with grain — there is nothing to be gained by doing this — phosphine is a very active gas.
- Keep your gas-tight sealable silos for untreated grain – fill these first and if using for seed, apply any treatments on outload.
- This also means you can sell this surplus pesticide residue free (PRF) grain if you do not use it at seeding.
- Use your unsealed silos for treated grain and make sure any seed treatment includes an insecticide for protection but check with potential buyers first. Do not use phosphine in silos that do not meet the seal pressure test in point 4.
- Follow the label — a fumigation cycle will take between 10 to 17 days including ventilation and withholding. Follow the GRDC fumigation flowchart.
- Phosphine is usually applied at two tablets per tonne of capacity of wheat (regardless how full the silo is) but check the label to be sure.
- Aeration cooling works well and is worth considering if purchasing new silos and there is power on site. Note that used properly, aeration will slow or even stop insect reproduction and activity by cooling the grain – but will not kill insects.
- Call the GRDC grain storage extension team on 1800 WEEVIL (1800 933 845) and go to www.storedgrain.com.au if you are unsure or just want to check on anything grain storage related.
The research undertaken as part of this project is made possible by the significant contributions of growers through both trial cooperation and the support of the GRDC — the author would like to thank them for their continued support.
GRDC Project code: PRB00001
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