Recent heavy rainfall through parts of the southern cropping region is likely to result in growers having to deal with grain going into storage with high moisture content.
High-moisture stored grain can lead to mould and insect growth, so storage experts are advising growers to take prompt action to avoid damage.
Grain storage specialist for the southern cropping region, Peter Botta, says monitoring grain moisture and temperature daily will enable early detection of mould and insect development.
“Grain at typical harvest temperatures of 25-30°C and moisture content greater than 13-14 per cent provides ideal conditions for mould as well as insects,” Mr Botta says.
“Although many growers don’t have the equipment and infrastructure in place for drying grain, there are some other measures they can take to reduce the risk of grain being damaged in storage.”
Grain that is over the standard safe storage moisture content of 12.5 pc can be dealt with by:
- Blending – mixing high-moisture grain with low-moisture grain, then aerating.
- Aeration cooling – grain of moderate moisture, up to 15 pc moisture content, can be held for a short term under aeration cooling until drying equipment is available.
- Aeration drying – large volumes of air force a drying front through the grain in storage and slowly removes moisture. Supplementary heating can be added. Aeration drying requires airflow rates in excess of 15 litres per second per tonne.
- Continuous flow drying – grain is transferred through a dryer, which uses a high volume of heated air to pass through the continual flow of grain.
- Batch drying – usually a transportable trailer drying 10-20 tonnes of grain at a time with a high volume of heated air, which passes through the grain and out perforated walls.
Mr Botta says dedicated batch or continuous flow dryers are a more reliable way to dry grain than aeration drying in less-than-ideal ambient conditions.
A trial by the Queensland Department of Agriculture and Fisheries revealed that over-moist grain generates heat when put into a confined storage, such as a silo.
Wheat at 16.5 per cent moisture content at a temperature of 28°C was put into a silo with no aeration. Within hours, the grain temperature reached 39°C and within two days it reached 46°C, providing ideal conditions for mould growth and grain damage.
“Over-moist grain, which in most cases is grain above the 13-14 pc moisture content range, therefore needs to be dealt with promptly to avoid mould and insect issues,” Mr Botta says.