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Effective Grain Storage Critical to Ensure Quality

03 January 2011
The Australian Bureau of Agricultural and Resource Economics and Sciences

Preserving grain quality through effective on-farm storage will be critical following this year's rain-affected harvest.

Grain storage expert Peter Botta, from PCB Consulting, says with recent rains and flooding impacting on this year's crop in many parts of the southern region, any further reductions in grain quality will be unwelcome.

Mr Botta says as a rule, grain going into on-farm storage should have a maximum of 12 per cent moisture.

"Over the past decade people have probably often been harvesting at 9 to 10 per cent moisture but this year growers face the prospect of harvesting some grain with moisture levels higher than 12 per cent," according to Mr Botta, whose work is supported by growers and the Australian Government through the Grains Research and Development Corporation (GRDC).

"This means that growers storing grain on farm will need to measure moisture levels as grain is put into storage and then monitor stored grain moisture, temperature and insect activity regularly. Grain stored at too high a moisture level can be affected by mould and fungal growth and will be at a higher risk of insect attack.

"Aerated silos will help with these issues but may not provide all the answers, especially in humid conditions.

"It's important not to expect aeration to dry grain to any great degree â€" typical aeration on-farm is for cooling, aeration drying is a whole different practice. If growers are considering aeration to dry grain then it is important they seek correct advice and use equipment which can do the job."

Mr Botta says grain quality can steadily deteriorate if the storage environment is not managed correctly.

"Three key factors â€" farm hygiene, aeration cooling and storage choice â€" can provide significant gains for both grain quality and control of storage pests.

"Generally, the combination of good farm hygiene plus well-managed aeration cooling can overcome storage pest problems," Mr Botta advises.

When managing stored grain, prevention is better than cure and a number of basic steps can be taken to minimise problems that can result in reduced grain quality. including:

  • Maintaining good farm hygiene. Clean up grain residues in empty storage facilities and all grain handling and carriage equipment before new grain is stored and equipment used. Clean up spillages in areas around silos and destroy all residues to prevent re-infestation.
  • Ensuring insect pests or weeds are not carried onto properties on farm equipment such as harvesters. All equipment should be thoroughly cleaned down after use. The first grain through the header is often at the greatest risk of early infestation.
  • Once storages and equipment have been cleaned, treat them with a diatomaceous earth treatment.
  • Check the seals on gas-tight sealed silos before each filling and replace them if they are worn or damaged. Carry out a pressure test to be sure the silo is gas-tight before fumigating.
  • Install aeration cooling fans in storages to cool grain, and for best results install an aeration controller. Freshly harvested grain usually has a temperature around 30°C which is an ideal breeding temperature for many storage pests. Aeration fitted to stores can rapidly reduce grain temperature which reduces insect breeding and assists in maintaining grain quality.
  • Monitor grain monthly for insects, moulds, grain temperature and moisture.
  • Generally, grain stored for more than six weeks should be treated for insect pests. Fumigation must be done in pressure-tested sealable gas-tight silos.
Mr Botta says it is imperative that growers are aware of phosphine resistance in stored grain insects.

"Phosphine fumigation for control of stored grain insects is very effective but must be conducted correctly, under gas-tight conditions held at lethal concentrations for 7-10 days (depending on temperature) to ensure effective control of all life stages of the insects.

"Poor fumigation often results in a partial kill (usually only adults), selecting for resistance by leaving immature insects, eggs, pupae and more resistant individuals in the population to survive and breed."

The GRDC has established a dedicated on-line Stored Grain Information Hub, accessible via www.storedgrain.com.au, for growers seeking information.

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