THE use of bulk grain bags for on-farm storage can be cost-effective, provide flexibility in harvesting logistics and allow growers to take advantage of grain marketing opportunities.
Bulk bags – also known as silo bags – can be a handy option for collecting grain direct from the chaser bin and storing it at a central site on the farm.
The Grains Research and Development Corporation (GRDC) estimates only about 9 per cent of the national grain harvest is stored in bulk bags, but indications are their popularity is growing.
Many Western Australian grain growers in south coastal and south eastern areas have adopted this storage option to improve harvesting logistics and work with marketers for out-loading priorities.
Good preparation is the key to success, according to GRDC Grain storage extension project specialist for WA, Ben White.
He says, typically, bulk bags are best suited to short-term, high-volume grain storage for a maximum of a few months.
But, Mr White warns there are some potential pitfalls and the risks of storing grain in bulk bags can be higher than using on-farm silos.
He says storing grain in bulk bags requires:
– Well prepared sites
– Safe moisture content and a method of regular sampling to monitor quality
– Regular inspections to repair any damage to bags (at least weekly).
Bulk bags are used in various parts of Australia for wheat, barley and sorghum crops – typically to provide additional short-term storage in high-yielding seasons.
Cereal grain quality is best maintained when grain moisture content in storage is below 12.5pc. Anything above this can increase risks of grain quality damage and mould development.
Storing oilseeds, such as canola, or pulse seeds, such as chickpea, in bulk bags is typically not recommended due to higher risks of seed quality damage.
Grain held for planting seed or other cereal grains, such as malt barley where maintaining good seed germination levels is critical, are usually best stored in standard silos with aeration cooling fans.
What equipment do I need to get started?
Bulk bags for grain (don’t use those designed for silage) can be bought with storage capacity ranging from 100 to 300 tonnes, but are typically about 240t.
The bags are single-use and cost about $5 per tonne of grain stored, or $1000 plus for a 240t bag.
Bag material varies, but is most commonly a three-layer polyethylene that protects against ultraviolet (UV) rays, heat and light. It is advised to check that bags are UV stable for 12 months and meet ISO 90001 quality standards.
Using poor quality bags can rapidly become a very expensive mistake.
Two separate machines are required to load and unload grain in storage bags. Each can cost about $25,000 to $35,000. Hiring opportunities may be available in some areas.
Typically, filling machines are power-take-off (PTO)-driven to carefully pack grain into the expandable bag.
There have been recent developments in gravity-filling systems that do not rely on power or tractors to operate.
Tips for filling bulk bags that will make emptying easier:
– Fill evenly and straight to avoid creases
– Adjust direction often and in small increments (making a line on the ground may help)
– Avoid over-filling
– Allow for stretching in hot weather
– Heat seal, use a clamp or role up on a pipe to close the bag
– Minimise folds at the finish end (mice can shelter there and make holes)
– A small amount of dirt over the sealed/clamped finish end may be useful for vermin control.
Preparing the storage site
It may be quick and easy at harvest to just fill bags next to each paddock. But leaving bags spread all over the property makes them difficult to inspect for damage every week.
Birds and wildlife soon find grain spills from damaged bags when holes are not promptly repaired and grain losses and water damage can be high.
An often-overlooked aspect is also accessibility to grain after harvest. Unless the bulk bags are placed on (or near) an all-weather access site, grain will be difficult to unload and sell when wet weather conditions prevail.
A central bulk bag storage area for the whole farm is ideal, according to Mr White, as this helps with site preparation, inspections, any necessary storage pest control and out-loading of grain.
He suggests a hard (or firmly rolled), smooth, elevated site where water can drain away and there are no nearby trees, rocks, sticks, sand hills or long grass where vermin shelter.
The site should be big enough for trucks and machinery to undertake bag unloading and be accessible in wet conditions.
Ambient temperature can be an issue in some areas, with temperatures above 30°C favouring stored grain insect pest reproduction rates that require extra vigilance and control.
It is advised to clean up around the bulk bag storage site after harvest and to set up mice control measures (such as baits in covered bait stations) in susceptible regions.
GRDC advises that fumigation with phosphine in bulk bags has recently been found to work in Australia as an option for stored grain pest control – if the correct method of application and venting is followed.
Alternatively, fumigation of grain-storage bags can also be performed using registered gases, such as sulfuryl fluoride. But this is only available for use by licensed fumigators and the cost is typically considerably higher than phosphine, according to the GRDC.
Economics of bulk bag use
An analysis of the economics of using bulk bags for on-farm grain storage – and comparisons with other grain storage options – are outlined in the GRDC ‘Grain Storage’ GrowNotes.
This resource includes a cost-benefit analysis template for use by growers and advisers to assess costs and returns on investment for individual properties and situations.
The GRDC has produced a comprehensive guide to ‘Successful storage in grain bags’ in a Fact Sheet.