ABARES now forecasts Australia’s 2026-27 winter crop at 61 million tonnes. That is 12 per cent down on last season, but it would still be the fourth-largest crop on record and 16 per cent above the 10-year average (ABARES, September 2026). It is also a significant lift from June, when ABARES expected the crop to fall 21 per cent to 54.5 million tonnes (ABARES, June 2026). ABARES attributes the improvement to a wetter-than-expected winter in south-east Australia, and to high fertiliser prices having less impact on planted area and yields than first feared (Grain Central, September 2026).
By crop, ABARES forecasts 29.9 million tonnes of wheat, with barley lifted to 16.4 million tonnes from 14.1 million and canola to 7.27 million tonnes from 6.19 million (Grain Central, September 2026). If realised, the barley crop would be the second largest on record (ABARES, September 2026).
The crop is unevenly spread across the states.
South Australia is the standout, with winter crop production forecast to rise to 11.3 million tonnes from 9.1 million last season (ABARES, September 2026). Bunge and other major South Australian handlers are expecting a particularly strong harvest on the Eyre Peninsula. Victoria is the only other state expected to grow, with a forecast increase of 12 per cent (Eyre Peninsula Advocate, September 2026).
The north tells a different story. New South Wales winter crop production is forecast to fall 30 per cent to 13.1 million tonnes, and Queensland’s 44 per cent to 2.2 million tonnes. In both states, rainfall has been enough only for late crop establishment, and yields are expected to be below average (ABARES, September 2026).
In Western Australia, ABARES forecasts a 16 per cent fall to 22.8 million tonnes, down from 27.2 million tonnes in 2025-26 (ABARES, September 2026). The Grain Industry Association of Western Australia (GIWA) is slightly more optimistic. It lifted its estimate to 23.06 million tonnes in September, up from 21.01 million tonnes in mid-August, after a cut-off low in late August brought heavy rain to central regions. GIWA expects heat to be the biggest limit on yield, and harvest in the Esperance zone is expected to begin around 10 October (GIWA, September 2026).
The spring outlook adds some risk. ABARES expects much of eastern and southern Australia to be drier than average. However, winter crops in the south-east are well advanced and soil moisture stores are good, so this season’s crops should depend less on spring rain (Grain Central, September 2026).
Permanent storage is expanding.
In Western Australia, CBH is adding additional bunker storage at two receival sites ahead of harvest. At Mingenew, its largest up-country site in the Geraldton Zone, seven open bulkheads will add 270,000 tonnes of capacity, lifting the site’s total to 710,000 tonnes (CBH, June 2026). At Miling, four new open bulkheads, two new auger pits and conveyor loading systems, and two new weighbridges are being installed (World Grain, August 2026). Both projects follow a record 2025-26 season in which CBH received 24.2 million tonnes, exceeding its previous record of 22.9 million tonnes (Milling Middle East & Africa, June 2026).
Sources: ABARES | GIWA | CBH | Grain Central | World Grain | Eyre Peninsula Advocate | Milling Middle East & Africa
Grain is food. That makes plastics in the grain storage system part of the food supply chain, not only part of the storage infrastructure. The principle is set out plainly in the Australia New Zealand Food Standards Code: only packaging material that is fit for its intended use and is not likely to cause food contamination must be used (Food Standards Australia New Zealand (FSANZ), Standard 3.2.2). A separate standard, Standard 1.4.1, sets maximum levels for some contaminants that can enter food through contact with packaging material.
The food safety risks from grain bunker and grain bag plastics fall into two groups: physical contamination, where pieces of the material end up in the grain, and chemical contamination, where substances in the material migrate into it.
Physical Contamination
Physical contamination is the more familiar risk in grain storage. Before woven and coated ground sheets were adopted, fragments of cheap polyethylene film regularly found their way into grain during out-loading. Coated fabrics carry a related risk known as pilling, the formation and de-lamination of small balls of coating caused by front-end loader buckets pushing grain back and forth across the sheet. Both were covered in last month’s issue.
The defences are material quality and site practice. Good quality ground sheeting reduces pilling through strong coating adhesion and a well-formulated coating.
Chemical Contamination
Plastics are not pure polymer. Grain storage fabrics and films also contain ultraviolet stabilisers, pigments, coatings, fillers and processing aids. Food-contact rules control which of these substances may be used and how much of them may migrate into food. FSANZ has reviewed chemical migration of these substances and concluded that estimated dietary exposure is low and not of concern for human health (FSANZ, October 2017), which is why the emphasis falls on using materials made and documented for the purpose.
Australia’s own standard (AS 2070-1999 Plastics Materials for Food Contact Use) guides industry on the polymers, additives, colourants, inks and coatings suitable for food contact. The most widely used benchmark is European Regulation (EU) No 10/2011, the EU’s specific regulation for plastic food-contact materials. It lists the substances permitted in their manufacture, sets limits on how much of any listed substance may migrate into food, and caps total migration at 10 milligrams per square decimetre of contact surface. A second European regulation, REACH (EC No 1907/2006), takes a broader view: rather than food contact, it governs the chemicals used in the material itself. Under REACH, suppliers must tell customers if a product contains more than 0.1 per cent by weight of any substance on Europe’s list of ‘Substances of Very High Concern’. Together, the two give growers a practical test: a food-contact compliant material that is also REACH compliant is safe in contact with grain and free of the most hazardous chemicals.
Practical Steps for Grain Handlers
Ask for documentation – a declaration of compliance against a recognised food-contact standard, such as European Regulation (EU) No 10/2011.
Ask also for a ‘REACH’ statement confirming whether the material contains any ‘Substance of Very High Concern’ (such as PFAS, BPA & phthalates), above 0.1 per cent by weight. Reputable suppliers should be able to provide one without hesitation. A supplier who cannot is a reason to look elsewhere.
Use materials made for grain. The Grains Research and Development Corporation (GRDC) warns that bags designed for silage look similar to grain bags and can be confused, with serious consequences (GRDC, July 2014). The same principle applies to grain cover fabrics.
Keep grain covers & ground sheets for grain. A grain cover or ground sheet that has been used over fertiliser or chemicals should not return to grain service. The GRDC notes that dual-purpose storage requires impeccable hygiene practices to avoid contamination (GRDC, June 2020).
Clean and inspect reused sheets. Retired top covers are commonly repurposed as ground sheets (Kondinin Group, August 2024), which is sound practice provided the sheet is clean, intact and has only ever been in grain service.
Bunker plastics are usually specified on strength, ultraviolet life and price. For the months grain sits against them, they must also meet a simpler requirement – nothing from the material should end up in the grain.
Grain bunkers (bulkheads) and grain bags are both ground-level storages. In each case, grain is held on a prepared pad and protected from the ground water, weather, insects and vermin by plastic sheeting.
That is where the similarity ends. The two systems differ in scale, in how long they can safely hold grain, in how insects are controlled and in what they cost per tonne stored. Choosing between them is a decision about the storage plan for the season, cost, grain quantity, space and terrain.
Bulk handlers, who store the vast majority of Australia’s grain, rely on bunkers far more heavily, each holding 50,000 tonnes or more (Kondinin Group, August 2024). On Australian farms, grain bags make up around 7 per cent of on-farm storage facilities and bunkers or pits around 11 per cent, with fixed silos (grain bins) accounting for the balance (Grains Research & Development Corporation, June 2020).
Grain Bags
A grain bag, also known as a silo bag, is a sealed tube of three-layer polyethylene film. Two white outer layers reflect heat and protect against ultraviolet light, and a black inner layer blocks light from the grain (GRDC, July 2014). Bags generally run 40 to 90 metres long and hold 100 to 300 tonnes, depending on the grain and how far the bag is stretched during filling, which is typically about 10 per cent.
The major benefit of grain bags is speed and flexibility at harvest. They allow grain to be quickly stored, buying growers time to choose between despatching grain to a bulk handler after harvest (when transport costs are lower), or direct to port. A bag can be laid on prepared flat ground on-farm and filled from a chaser bin, which takes pressure off trucks and bulk receival sites in a big season.
Grain bags are best suited to short-term storage of around three months, beyond which the GRDC warns of considerable risk of grain losses and spoilage in many of Australia’s growing regions. Cereal grain should be stored below 12.5 per cent moisture, and storing of canola or high-value legumes in bags is not recommended by the GRDC.
Grain bags attract a unique set of challenges and demand close attention. Overfilling bags can lead to splitting, and bags are susceptible to attack by rabbits, foxes and mice. Inspection is recommended at least weekly, and as often as twice daily when mice are plentiful in wet weather. Creases attract mice, and every hole must be patched promptly to keep moisture out and the bags sealed. Keeping bags sealed is essential – a well-sealed bag limits oxygen, which slows insect and mould activity. However, dry grain produces little carbon dioxide, so bags can’t be relied on to control insects. Fumigation is possible only under specific protocols, which is one reason bags are best suited to short-term storage.
Grain Bunkers
A bunker (bulkhead) is a stack of grain built on a drained and compacted pad, usually inside low walls, and protected by heavy-duty grain covers. Ground sheets beneath the stack are required to prevent ingress of ground water, thereby mitigating spoilage. Fumigation can be achieved once the top covers and ground sheets are sealed, by a licensed fumigator applying and monitoring the gas (Kondinin Group, August 2024).
Scale is where the bunker storage system is unmatched.
The bunker’s key advantage is its capacity for long-term, high-volume storage. It allows for effective fumigation, grain quality monitoring, superior temperature control and efficient loading/unloading in large grain quantities. This makes bulk handling possible, allowing growers to transfer responsibility of the storage and quality control from themselves to bulk handlers.
Bunkers, however, do require enough grain volume to justify heavier expenditure on labour and equipment. Deploying a large cover takes a team, and building and emptying the stack needs a stacking elevator or drive over hopper stacker and a loader.
Bunkers range from a few hundred tonnes to more than 50,000 tonnes, and the cost per tonne falls as the stack grows. Earthen, steel or concrete bunker walls add capacity without increasing the footprint of the bunker.
Financial Analysis
The biggest difference between the two systems is where the money is outlaid. With bags, most of the cost is up front in the machinery: around $30,000 to $50,000 for each of the loading and unloading machines. Every tonne then carries a further $4 to $5 for a single-use bag (GRDC, June 2020). With bunkers, the up front is in levelling and grading the pad (with or without a walling system), after which most of the cost is in the covers, which are reused. A nominal $6 to $10 per tonne for a 500 to 1,000 tonne bunker falls considerably once spread over three or more seasons, and retired top covers commonly go on to a second life as ground sheets. The GRDC’s worked example puts a bunker tarp at around $1.50 per tonne per year, against around $3.70 per tonne for a bag (GRDC, June 2020). Bags can still be the cheaper option at smaller scale. An independent analysis of on-farm storage found that grain bags returned more than silos, sheds or warehousing when 1,500 tonnes was stored, because once the machinery is owned, extra capacity needs only extra bags rather than new capital (Holmes Sackett & Associates, July 2006). The same analysis found that owning the machinery lost its advantage at 500 tonnes, where contracting the bagging became the better option. In practice, bags favour growers storing moderate tonnages for a few months, while bunkers reward volume and repeated use.
Choosing Between Them
In addition to financial consideration, the choice between bunkers and bags comes down to: how much grain, for how long, how insects will be controlled, and who will manage the store.
Volume: grain bags suit smaller, segregated parcels and harvest overflow, while the cost per tonne of a bunker falls as tonnage rises.
Duration: around three months is the practical limit for grain bags. A bunker can be set up for a single season or run as a permanent store, with covers replaced every few years.
Insect control: both are harder to fumigate than a gas-tight sealable silo. A bunker sealed top and bottom can be fumigated by a licensed fumigator; a bag can only be fumigated under specific protocols.
Labour and reuse: grain bags need frequent inspection and are single-use, leaving a disposal task every season and no residual value beyond the machinery. Bunker covers are reused over several seasons but need a crew to deploy.
Neither system tolerates a poorly prepared site. Both depend on a firm, elevated pad that sheds water, and matching the wrong format to the storage plan ends the same way in either case: spoiled grain and lost value.
Both systems also keep grain in direct contact with plastic for the whole storage period, which raises a question that is easily overlooked: whether those materials are fit to be in contact with food. We turn to that in our next article.
Two developments this month are reshaping the infrastructure landscape behind Western Australia’s grain export chain, and grain handlers in the Great Southern should take note of both.
A new terminal enters the market. Western Australia’s Port of Albany is set to have a third grain bulk handler in operation following Qube’s completion of its initial upgrade, which has made the former Albany Bulk Handling facility a multi-commodity site. The upgrade is stage one of a $13 million redevelopment of the facility. Infrastructure works have broadened the port’s export capabilities beyond woodchips, enabling it to handle grain, mineral sands and critical minerals. Completed works included strengthening the hardstand and ship loader, along with installing a new grid to support a wider range of commodities. Qube bought the Albany site for $25 million in 2025. Second-stage works are being considered, including fixed grain storage, covered multi-commodity shed space and improved open stockpile segregation. The upgraded facility is intended to provide additional capacity for all port users, helping to ease congestion, improve vessel scheduling and reduce delays during peak export periods, including seasonal grain exports.
Ownership changes hands. On 14 August 2026, Macquarie Asset Management (MAM), together with its managed funds and co-investors including UniSuper and Pontegadea, completed their investment in Qube Holdings by way of Scheme of Arrangement, valuing Qube at approximately $A11.7 billion. The scheme was backed by 98.11 per cent of shareholders present and voting, and 86.72 per cent of votes cast, and Qube was removed from the ASX Official List on 17 August 2026. MAM has indicated the investment is underpinned by long-term structural trends including demographics, rising demand for goods and services, and a growing focus on sovereign capability.
For grain handlers, the practical question is whether private ownership accelerates or moderates Qube’s stated capital commitment to Albany. Qube is described as Australia’s largest provider of ports and terminal infrastructure assets, with a 10,000-strong workforce, and MAM has indicated it will focus on investing across Qube’s existing network while pursuing new opportunities across the Asia Pacific region. The second stage at Albany, if it proceeds, would add fixed grain storage capacity to a port that currently has none – a development likely to change the competitive dynamics for grain handling in the Great Southern.
Yarn is the building block of woven & coated textiles. It is woven to form the base fabrics which make up the foundation of grain storage materials.
Yarn can be created from almost any type of polymer. Base fabrics used in the grain industry are generally made from polypropylene, polyester or polyethylene. Yarn matters because it is the key element in giving coated fabrics their strength. Without a high quality yarn, tear strength, dimensional stability and burst strength can all suffer, leading to premature fabric failure in the field.
Two distinct yarn types are used in grain storage fabrics: multifilament spun yarn and tape yarn. Each has different physical characteristics and is suited to different applications within the bunker storage system.
Multifilament Spun Yarn
Multifilament spun yarn is formed by drawing and twisting together many fine continuous filaments.
A close up image of multifilament spun yarn.
The performance of a spun yarn is measured by four principal properties:
Fibre tenacity, the breaking strength of the fibre relative to its linear density, expressed in centinewtons per decitex (cN/dtex). Higher tenacity means greater load-bearing capacity for a given yarn weight.
Fibre length, for staple-spun constructions, longer fibres produce a more uniform, cohesive yarn with better tensile consistency.
Twists per metre (tpm), the number of times the filaments are twisted along a given length. Twist consolidates the yarn structure, balancing tensile strength against flexibility. Too few twists and the yarn is weak; too many and it becomes stiff and prone to fatigue.
Yarn weight, expressed as denier (grams per 9,000 metres) or decitex (grams per 10,000 metres). Heavier yarns contribute more mass and generally more strength to the finished fabric.
In grain storage applications, multifilament spun yarn is typically polyester (PET) or polypropylene (PP) and is used for grain (top) covers. It forms the base cloth of the cover before coating is applied.
Tape Yarn
A close up image of tape yarn.
Tape yarn is produced by slitting a flat polymer film into narrow strips and stretching them under heat, in a process called drawing, to align the polymer chains. This substantially increases the tensile strength of the tape. Drawn tape is then annealed: held at a slightly lower temperature without further stretching, which relieves the internal stress created by drawing and stabilises the tape against later shrinkage. Tenacity, length, twists per metre and linear weight are all also properties measured in tape yarns. However, twists per metre (tpm) of the tape is not measured, as the yarn relies on the film extrusion and stretching process for it’s tensile strength, rather than any twisting.
A further process, fibrillation, can be applied to tape yarn. Controlled fibrillation splits the tape’s surface into a network of fine fibres, giving the yarn an appearance similar to multifilament spun yarn. More importantly, fibrillation increases yarn density and contact area within the weave, which raises the fabric’s overall strength without requiring a heavier yarn.
In grain storage applications, tape yarn is predominantly polyethylene (PE) and is used in ground sheets and wall liner rather than in the grain cover base cloth.
The importance of yarn UV stabilisation
Regardless of type, yarns used in grain storage fabrics require ultraviolet stabilisation. Ground sheets are exposed to reflected and direct solar radiation during deployment and storage. Without UV treatment the polymer chains degrade, leading to premature embrittlement and loss of mechanical strength. This requirement is essential across all yarn types and all applications in the bunker system.
Once yarn is woven into a base fabric, the weave construction itself further determines the material’s properties, an important subject that will be covered in a future article.
The role of ground sheeting in bunker storages is to exclude ground water and contaminants from gaining access to the grain stockpile, and also to prevent any escape of the fumigation gas which is of critical importance protecting the stored grain from insect attack.
The evolution of ground sheeting materials and systems has been a central element of the success of the grain bunker storage system. Without this, it is doubtful that the bunker system would have become as widely adopted as has occurred throughout Australia and increasingly in other parts of the world.
The bunker (bulkhead) grain storage system had its origins as a temporary ‘overflow’ solution in the event fixed storages had reached full-capacity during ‘bin-buster’ harvests. Often this Australian invention involved holding overflow grain on the local cricket ground. In Western Australia bunker storages are still sometimes referred to as TS’s (temporary storages) despite little grain now being stored any other way.
In the early years of the evolution of grain storage bunkers very few of growers co-operatives (one per state) had the necessary funds to invest in asphalt hard-stands on which bunkers could then be constructed. Although CBH in Western Australia invested heavily over many decades in asphalt hard-stands for its bunkers, for most grain handlers, bunkers were built on compacted gravel sites. These sites therefore needed plastic sheeting underneath the grain to protect it from ground water, contaminants and the risk of escaping gas. At the time, the most suitable ground sheeting material available was extrusion-blown black or clear polyethelyne (PE) film having a thickness of 200 microns and a maximum available width just 4.0 metres. . Cargill operations manager, Richard Shields, recently recalled that at SACBH (now Bunge) and at AWB GrainFlow (now Cargill) … “we were forced to use 50 metre length rolls of black builder’s film taped together … it was a nightmare in windy conditions”.
The situation changed dramatically about 25 years ago when a Queensland AWB GrainFlow site manager, Jim Moran, suggested that the rolls of narrow width PE ground sheeting film should be replaced with large dimension ground sheets fabricated from woven/coated PE fabric. A typical ground sheet was 42.0m x 30.0m, and had a folding pattern which enabled progressive and quick deployment even in windy conditions. A fabric weight of 120 gsm was adopted, although in more recent years there has been a move to a more study 180 gsm. A major West Australian fabricator specialising in supplying the Grain Industry materials took-up the suggestion and this ‘new’ approach to the ground sheeting system was adopted for AWB. It was quickly also adopted Australia-wide. The only exceptions were the sites lucky enough to have asphalt hand-stands, and also a major operator in South Australia which maintained the use of rolls of PE ground sheeting film.
Grain stored on a polyethylene ground sheet prior to covering.
The woven/coated ground sheets overcame the contamination of grain in bunkers during out-loading activities – when fragments of cheap PE film found their way in the grain.
The use of large-dimension prefabricated woven/coated ground sheeting accelerated the acceptance of grain bunkers by replacing almost entirely the use of unmanageable narrow-width rolls of black and clear PE films. This is turn added motivation for grain handlers, traders and growers to convert from fixed storages to bunkers which are now the dominant grain storage system in Australia due to their flexibility and low cost.
Ironically, over the past 30 years progress has been made in the development of wider-width blown PE films, first to 6 metres, than 8 metres and then 10 metres. Today widths of up to 20 metres are available. The other important development was in the film itself, by adding metallocine to the PE formulation. This ‘new’ film mPE is very much tougher than the standard PE’s. Wide-width and more sturdy mPE films has led to ground sheeting film making something of a comeback in some quarters as a ‘back-to-the-future’ option for ground sheeting at a very similar square metre price.
One unwanted feature of woven/coated ground sheets is the risk of ‘pilling’ during out-loading activities. Pilling is the formation and de-lamination of tiny balls of coating material caused by the pushing of grain back and forth by the buckets on front-end loaders. Although good qualtity ground sheeting material minimises the risk of pilling through better coating adhesion strength and the chemical formulation of the coating itself. However, pilling can still be encountered if cheap ground sheets are used.
Another key aspect of ground sheeting, whether film or fabric, is ensuring generous over-laps between sheets when deploying. Overlaps should be 1.5 metres minimum and should run with down-hill lapping to minimise the risk of ingress of ground water. Stitching of laps is preferable over lapping alone. The fins created when stitching should preferably face down rather than up into the grain pile. Being water tight fabric, if these procedures are closely followed, very rarely can the root cause of water ingress into bunkers be blamed on ground sheeting.
As can be appreciated, ground sheeting is a core element of the grain bunker storage system. The progressive improvements in ground sheeting films and fabrics has been central in enabling the adoption of the bunker system as Australia’s preferred system for low-cost flexible grain storage.
