Keep grain cool. Check your temperature probes every two weeks while grain is in storage. For best results, the temperature of grain should uniform and be less than 15°C. Aerating or turning grain helps keep grain cool and dry. Hot spots in grain may be indicators of the presence of insects.
Monitor moisture levels. Keep your grain at the appropriate moisture content to reduce the risk of spoilage. Moisture levels should be checked every two weeks.
Spot and identify insects. When you check grain moisture and temperature, take samples from the core of your grain to monitor for insect populations. Also check the top of the grain in the bin – this is where heat and moisture collect and insects may find this very attractive. If you find insects, determine what type they are to find the best control method.
Watch out for mould. Under warm, moist conditions, moulds can grow quickly and some fungi may produce poisonous mycotoxins, such as ochratoxin A. Mould may not be visible in dark grain bins or may form inside the grain bulk. A musty smell or grain clumping or caking may be signs of mould.
Contact the Canadian Grain Commission's Infestation Control and Sanitation Officer for further assistance.
Monitor stored grain regularly for hot spots and insect populations:
- insects are likely to be found in pockets of warm or moist grain
- sample the grain from the core at a depth of 30 to 50 centimetres (12 to 18 inches) from the surface
- sieve the samples or examine small portions carefully
- stored product insects are typically very small beetles (less than 3 millimetres or 1/8 inch) that may not be moving, so a magnifying glass can be helpful
- insects in your grain could be grain feeders, fungal feeders, or predators of these insects
- for advice on controlling grain-feeding insects, visit the Canadian Grain Commission's website
- Keep grain cool. Check your temperature probes every two weeks while grain is in storage. For best results, the temperature of grain should be less than 15 C. Aerating or turning grain helps keep grain cool and dry.
- Monitor moisture levels. Keep your grain at the appropriate moisture content to reduce the risk of spoilage. Moisture levels should be checked every two weeks.
- Spot and identify insects. When you check grain moisture and temperature, take samples from the core of your grain to monitor for insect populations. If you find insects, determine what type they are to find the best control method.
- Watch out for mould. Under warm, moist conditions, moulds can grow quickly and some fungi may produce poisonous mycotoxins, such as ochratoxin A. Mould may not be visible in dark grain bins or may form inside the grain bulk. A musty smell or grain clumping or caking may be signs of mould.
- Clean away old debris to ensure bins and storage sites are clean and free from grain residues that can harbour insects
- Treat your empty storage bins with a registered contact insecticide such as malathion, pyrethrin or a diatomaceous earth-based product if required - make sure you treat floor-wall joints, aeration plenums or floors and access points thoroughly
- Do not use malathion in bins intended for canola storage
- Monitor stored grain regularly for hot spots and insect populations: insects are likely to be found in pockets of warm or moist grain. Sample the grain from the core at a depth of 30 to 50 centimetres (12 to 18 inches) from the surface. Sieve the samples or examine small portions carefully. Stored product insects are typically very small beetles (less than 3 millimetres or 1/8 inch) that may not be moving, so a magnifying glass can be helpful
- Identify insects in your grain to determine the right control method - insects in your grain could be grain feeders, fungal feeders, or predators of these insects
Dec. 7, 2015 - Alberta soils could store significantly more carbon if trees and grassland are integrated into cropland areas, new research from University of Alberta reveals.
Scientists looked at the influence of shelterbelts, hedgerows and silvopastures to evaluate the role of trees and different land uses across the agricultural landscape in mitigating climate change, and to see which system is more conducive to carbon storage. They found that soils under trees stored 36 per cent more carbon.
"Trees had the greatest benefit in raising soil carbon levels in agroforestry systems where they were combined with neighbouring annual cropland subject to cultivation, while perennial grassland maintained soil carbon levels similar to that of the natural forest," said Edward Bork, a rangeland researcher.
Aeration. Chilled aeration. Natural air drying. Near-ambient air drying. Low temperature air drying. High temperature air drying. Dryeration. When did using forced air through a grain bin become so complicated?
Dr. Digvir Jayas, vice-president (research and international) and distinguished professor at the University of Manitoba, outlined how forced air ventilation can be used during a presentation made to the Brazilian Postharvest Conference in Maringa, Brazil in 2014. The results (Singh, C.B., D.S. Jayas and R. Larson. 2015. Assessment of fan control strategies for in-bin natural air drying of wheat in Western Canada. Canadian Biosystems Engineering, 56:3.25-3.36) are summarized here.
“Considerable research related to cooling and/or drying of grains by forcing air through bulk grains has been reported and continues to be reported in published literature. Although the process is simple and works well when properly designed and implemented, this simplicity also leads to a lot of misunderstandings about the process,” Jayas says. “Therefore, many systems get designed to force less than optimum amounts of air to complete the task.”
Aeration is the forcing of small amounts of air (1 to 3 L/s per m3 of grain) to typically cool grains after harvest using ambient air at temperatures below grain temperature during cooler hours of the day. The aeration can also be used to eliminate temperature gradients within bulk grains and thus to reduce moisture migration, remove spoilage odours from grains, remove fumigants from grains and remove small amounts of moisture from warm grains such as during dryeration (defined below). In colder climates such as in Canada, aeration could also be used to reduce grain temperature to below 10 C to reduce insect activity and population growth. Under Canadian conditions, aeration during winters (when temperatures are below -20 C) can be used to kill all life stages of insects in stored grain.
Chilled aeration is the forcing of chilled air (1 to 5 L/s per m3 of grain), conditioned using a chilling device (air conditioning unit), through bulk grains. The purpose of chilled aeration is to reduce the temperature of the grain below 10 C for slowing insect activity and population growth. Chilled aeration can also be used to store wet grain without deterioration for two to three weeks during which it can be dried to safe moisture contents for storage.
Natural air drying is the forcing of ambient air (10 to 25 L/s per m3 of grain) to decrease the moisture of grain to safe storage levels. The amount of air required increases if the initial moisture content or ambient relative humidity are high, or if ambient air temperature is low. The latter two are dependent on weather conditions following grain harvest.
Near-ambient air drying is similar to natural air drying but air temperature is a few degrees (up to 5 C) above ambient conditions which can be caused by frictional losses from the fan motor assembly when air is pulled over these.
Low-temperature air drying is similar to natural air drying but air temperature is 5 C to 10 C above ambient conditions which can be caused by adding supplemental heat from any source such as electricity, propane, natural gas, wood or solar panels.
High-temperature air drying is the forcing of air (15 to 30 L/s per m3 of grain) at 50 C to 250 C to remove moisture content from grain to safe storage levels. The air temperature and amount of airflow depend on mechanisms of dryers (e.g., concurrent, countercurrent, cross and mixed flow) as well as the initial moisture content of grain and grain type.
Dryeration, also known as combination drying, is the cooling of hot grain after high-temperature air drying by aeration and the removal of one to two percentage points of moisture. Thus, grain is dried to about two percentage points above desired safe moisture content using high-temperature drying, tempered for eight to 10 hours for redistribution of moisture within grain kernels and then cooled by aeration using ambient air. The main advantages of dryeration over high-temperature drying include increased drying capacity, use of higher air temperatures, energy savings, elimination of the cooling section in high-temperature dryers and reduced stress cracks in grains.
The main components of the forced air systems are: a flat-bottom storage bin containing a deep layer (more than one metre deep) of grain, a plenum to introduce air into the grain bulk, a fan and duct arrangement to force air through the bulk grain, and vents to exhaust the air once it has passed through the grain. A plenum with a fully perforated floor over concrete (or solid) foundation and levelled grain surface provides most uniform airflow distribution in the grain mass. Thus, fully perforated floors are commonly used but several partially perforated floors are also used in flat-bottom bins. (See Fig. 1 below.) Many farms also have hopper-bottom bins, which are equipped with different configurations of perforated plenums to introduce air into the grain.
The area of partially perforated flooring through which air can be introduced into the bulk grain should be sufficient to avoid formation of stagnant zones in the bulk grain. The size of perforations in the floors should be small enough to support the smallest-seeded grains to be stored in the bin and the number of perforations should be enough (equivalent to >10 per cent of the perforated floor area) to cause minimum pressure drop across the floor.
The fan should be sized properly to ensure sufficient airflow through grain at its maximum depth and for a grain which offers maximum static pressure at that airflow rate while taking into consideration a thorough understanding of type of fan and its characteristics, i.e., relationship between the airflow rate (L/s) supplied by the fan against different static pressures.
The amount of airflow from the fan decreases as the static pressure increases. Thus, a fan sized for shorter depth may not dry grain in the expected time if grain depth is increased. Similarly, a fan sized to provide a certain airflow rate, say for wheat, will not provide the same airflow rate for canola because pressure drop per unit length of canola is 2 to 2.5 times more than for wheat, and fan output would be lowered considerably at the increased pressure offered by grain for all fan types.
The vents should be enough in number and size to avoid stagnation of air in the bin and thus cause minimal back-pressure to be overcome by the fan.
The appropriate amount of airflow through grain ensures proper drying in the specified period. The excess amount of airflow will dry grain sooner but may also result in more non-uniformity in grain moisture content with continuous airflow. Grain mixed with fines (particles smaller in size than grains) offers more pressure drop per unit length than clean grain, and the moisture content of grain also affects pressure drop (Moses et al., 2013). Therefore, a good estimate of static pressure in order to properly size the fan should consider all of the factors that affect pressure drop across grain.
Also, measured fan characteristics, if available, should be used in sizing the fans because at times the values reported by the manufacturers give higher air flow rates than the measured on-site values for the same static pressure. If the difference between measured and reported values is large, then a fan sized using manufacturer’s data will be undersized for actual drying conditions.
In a system with air moving vertically upwards, the bottom layer dries first while the top layer stays close to initial moisture content. As drying progresses, more layers from bottom to top dry, but sometimes re-wet if air relative humidity of incoming air is greater than the equilibrium relative humidity of grain moisture in the layer.
Drying could be stopped based on many criteria, such as: top layer is at the target moisture content, but this may cause severe over-drying in the bottom layers; average grain moisture content is at the target moisture content but this may require grain mixing after drying is stopped; or, moisture in all layers is within certain percentage point of the target – producing the most uniform drying. These criteria could be applied using measured data or using mathematical models.
There are many control strategies which can be used for turning the fan on or off during drying, but the best strategy should be the one that requires the least energy for both the operation of fan and the supplemental energy if used; results in most uniform drying; minimizes over-drying and spoilage of grain; and, completes drying within the specified period.
The examples of different fan control strategies are:
- Fan running during certain number of hours (e.g., six hours on and six hours off cycle, fan running during daytime only or fan running during night time only, fan running continuously)
- Fan on when temperature of ambient air is above certain set point (thermostat)
- Fan on when humidity is below certain set point (humdistat)
- Fan on when there is a set temperature difference between grain temperature and ambient temperature
- Fan on when there is a set relative humidity difference between grain equilibrium relative humidity and ambient relative humidity
- Fan on when there is a set difference between grain moisture content and equilibrium moisture content based on air conditions
- Fan on when plenum EMC (equilibrium moisture content) and temperature are within a set target range (natural air drying - NAD)
- Fan and/or heater on using self-adapting variable heat (SAVH) with NAD control
The best strategy can be selected by running simulations using historical weather data for multiple years (> 25 years) for several locations based on different climatic zones of a region, with different initial harvest moisture contents, different harvest dates, different amounts of airflow rates through different grains, and for different control strategies.
*Concepts are synthesized from many documents and authors of those documents (too numerous to mention by name) are gratefully acknowledged. This paper also summarizes the work of many graduate students who were supervised by Dr. Jayas and were supported by research grants held by him from many funding agencies including the Natural Sciences and Engineering Research Council of Canada. Many students received funding as part of the University of Manitoba Graduate Fellowship.
Long, sausage-like rows of white grain bags have become common across the Prairies as not only a way to deal with bumper crops, but as a way to conveniently store grain in the field. However, little Canadian research has been done to look at the safety of storing canola at different moisture levels, and determining how long canola can be stored in the bags without losing grade.
“Silo bag storage is probably a cost-effective method compared to other temporary storage systems, but there are some concerns over seed spoilage, insect and mould damage, moisture migration and quality losses,” says Digvir Jayas, project leader and grain storage expert in Biosystems Engineering at the University of Manitoba.
In addition to Jayas, the team included Chelladurai Vellaichamy, a graduate student, and Fuji Jian, a research engineer, both in biosystems engineering at the University of Manitoba; and Noel White and Paul Fields of Agriculture and Agri-Food Canada at Winnipeg. They conducted two studies looking at grain bag storage in canola. The results of these studies have been submitted as two papers (full versions are available from Jayas) to the Journal of Stored Products Research for publication.
Canola best stored if dry
The research covered two periods. The first project looked at canola at three different moisture contents 8.9, 10.5 and 14.4 per cent (wet basis), representing dry, straight and damp grades, stored in silo bags for 40 weeks (from autumn 2010 to summer 2011) at Winnipeg, Man. For each moisture content, each bag was loaded with approximately 20 tonne canola seeds with greater than 90 per cent initial germination. Germination, free fatty acid value (FAV), and moisture content of canola seeds at seven locations of each silo bag were analyzed every two weeks along with carbon dioxide concentration of air and temperature between canola seeds.
For dry grade canola, the germination was maintained above 90 per cent, and FAV also stayed at safe storage level during the 40-week storage. The germination of straight grade canola maintained its initial value in most parts of the silo bags except at top layer.
Damp grade canola lost germination, dropping below 80 per cent, and FAV doubled within eight weeks of storage.
Moisture migration was evident with the top layer showing significantly higher moisture content than the middle and bottom layers over the first 28 weeks of storage of dry canola. By the end of the storage period, the middle and bottom layers had higher moisture content than the top layer for dry and straight moisture bags. Damp moisture bags experienced larger moisture gradients, especially after 28 weeks of storage.
“This trend shows the accumulation of moisture due to condensation at the periphery of bags caused by temperature and moisture gradients during autumn and winter seasons, and in the summer the top layer grain was dried due to the hot ambient temperature,” Jayas reports.
Temperature and CO2 concentrations were also measured. Temperatures fluctuated depending on season, and sampling location. In dry and straight grade canola bags, the bottom layers had higher temperatures during autumn and winter. In the spring and summer, temperature was hotter near the top. Jayas says the temperature of the top layer of the seeds followed the ambient temperature changes. For damp canola, temperature gradients were completely different.
“Hot spots developing inside the damp grade canola bags could be the reason for this change in temperature pattern. Even in mid-winter, the temperature of top layer of the damp grade canola bags stayed above freezing, and the middle layer of the canola seeds followed the ambient temperature during winter time,” Jayas says.
High levels of CO2 concentration in damp grade canola seeds indicated higher amounts of biological activity in high moisture seeds. Localized hot spots were also observed in the high moisture bags.
While the dry, straight and damp canola all graded Canada No. 1 when loading the bags at the start of the trial, there was degradation for the straight and damp canola after 40 weeks. The dry canola still graded No. 1, but small amounts of heated seeds in the top layer of straight canola bags reduced the grade to No. 2. After 40 weeks, the damp grade canola was caked and, because of the high moisture, the grain bag extractor could not unload the canola seeds from the bag. The damp canola graded Feed.
Refining storage time for damp canola
While the first project found that dry canola could be safely stored up to 40 weeks without loss of grade, the researchers wanted to find out if damp canola could be stored for shorter periods of time without losing grade. They conducted additional research for two storage years (2011-2012 and 2013-2014) to determine the changes in grain quality while storing 12.1 and 12.4 per cent moisture content canola in grain bags. The temperature during loading was 15.5 C and 16.2 C, respectively.
Once again, canola was stored in grain bags in the fall, but in these years, the bags were unloaded at three different times at 20 weeks (middle of winter), 28 weeks, (end of winter) and 40 weeks (summer). Again, germination, FAV, moisture content, temperature and CO2 levels were monitored.
The results of both storage years showed that there were significant changes in moisture content with an accumulation of moisture in the top layer of grain. In both the years the FAV values remained at safe levels until 20 weeks of storage, but increased at 28 weeks and was more than double at 40 weeks. This was an indication of quality loss. (See Fig. 1.)
In 2011-2012, after 20 weeks of storage, the canola still graded No. 1. At 28 weeks, it had dropped to No. 2, and by 40 weeks was downgraded to Feed. In the second year, grade remained at No. 1 in the first two unloading periods, and dropped to No. 2 at 40 weeks.
“Canola seeds with 12 per cent moisture content could be stored up to five months, into the late winter, without any quality deterioration under the western Canadian conditions,” Jayas says.
The results of the two projects indicated that dry canola loaded into grain bags at ambient temperatures of around 15 C could be stored up to 40 weeks without loss of grade. Canola at 12 per cent might be safely stored up to 20 weeks. If canola is above 12 per cent moisture, growers should consider drying the grain first before storing in grain bags, or only use grain bags for temporary storage of a few weeks.
Oct. 19, 2015 - Due to the speed at which damage can occur, producers need to watch for potential canola storage problems as fall transitions into early winter.
"Canola seed's high oil content makes it very susceptible to deterioration in storage. As such, canola is stored at a lower seed moisture level to prevent spoilage," says Neil Whatley, crop specialist, Alberta Agriculture and Forestry. "Safe, long-term canola storage is at or below eight per cent moisture content and cooler than 15 degrees Celsius., Declining outside air temperatures also need to be properly dealt with to ensure safe storage."
Canola respires or goes through a "sweat" period for up to six weeks after being binned. "Even if it's initially binned dry, canola should continue to be monitored. Respiring canola generates additional heat and moisture, creating an unstable condition. This instability can potentially result in hot spots or mould growth, and when mould begins to form, it creates more heat that accelerates the spread of more mould growth. Therefore, aerating stored canola during its respiration period is important. Spoilage can be eliminated if the canola is sufficiently conditioned to the point where the aeration cooling front moves entirely through to the top of the grain mass."
Changing outside air temperatures in the spring and fall causes repeated moisture cycles in a bin, permitting moisture to concentrate in certain bin areas, and potentially leading to spoilage and heating. As outside air temperatures decline during October and November, the grain nearest to the outside bin edges cools first. This cooling system then migrates downward along the bin edge, and then upward through the central core.
"As this cooling system migrates, it gathers moisture and warmth that creates a pocket of humid and warmer air at the top of the central grain core where spoilage and heating can begin," says Whatley. "So, as outside air temperatures decline, aeration fans should be operated again until canola at the top of the bin is cooled to the average daily temperature. Due to continuously declining outside air temperatures, it is wise to aerate repeatedly until the whole bin of canola is between zero and five degrees C. November is an important month to check canola bins again to see if they are stable going into winter as temperatures drop below zero degrees C and stay there."
Producers may also consider turning one third of the canola bulk out of a full bin by truck in November.
"This would be the method used if aeration is not possible, but may be an important task to complete in November even if aeration isn't used. Moving the grain disrupts the moisture cycle created by declining outside temperatures, cooling the grain mass and reducing the risk of spoilage. Even if bin temperature is being monitored with sensors, this may not provide a complete reading of the whole bin as problems may emerge in pockets away from the sensors. So, turning the grain ensures cooling as well as allowing producers to smell the grain as they are moving it to let them know if any grain is in the first stages of spoilage. If green counts, moisture, weeds or dockage are high, turning the whole bin may be safest."
Extra caution is required in unique circumstances, adds Whatley. "Canola that was stored with a higher green seed count has higher moisture content than your average mature canola seed, potentially increasing spoilage risk. Such canola should be delivered as soon as possible to prevent spoilage, which could result in further price reduction. Extra attentiveness is also required when canola is stored in large bins, especially tall and narrow bin types that can reduce aeration air flow due to increased compaction."
How to handle many aspects of farming depends on the individual nature of each unique farm, as well as the farming systems used. Grain drying certainly falls under this category, but while there are many different ways to accomplish it, universal rules still apply.
“In general, the capability of a producer to dry, condition and store their own grain can provide flexibility and open up some marketing options,” notes James Dyck, Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) engineer for crop systems and environment. “If you do it yourself, you avoid elevator drying charges, and you can dry and condition the grain to your own requirements. It also allows growers to market their harvests at their preferred time.”
Grain dryers and storage systems come with the same questions that apply to any new on-farm equipment. There are capital installation costs to consider, as well as ongoing maintenance and repairs, operational differences, benefits and risks.
In grain drying, both natural and heated moving air can be used. Dyck says that choice depends on the crop to be dried, incoming moisture level, desired final moisture content and ambient air conditions. “Numerous systems are available, including bin aeration, batch-in-bin, elevated-batch-in-bin (drying section on top of bin, with stored dry grain below the drying section), auto-feed, continuous flow and portable dryers,” he says. “There are also multiple fan technologies, including backward-curved centrifugal and axial flow. Each technology has different requirements, options and efficiencies, and the merits and drawbacks of each must be considered when determining the best fit.”
A good moisture tester is an important tool for producers planning to store their own grain. Dyck says many commercially-available testers allow for easy recalibration, and can be readily checked against an elevator tester. “Some newer testers also have the ability to link to a computer via USB and an online connection, and can be quickly and easily calibrated or updated in this way,” he says. “Remember that periodic calibration is prudent to ensure consistent results.” Dyck adds that proper care and storage of the tester is also key. Leaving a tester exposed in freezing temperatures or in high-moisture conditions such as dew or rain may be detrimental to the device’s operation and lifespan.
Hybrid selection may have some bearing on drying and storage in Dyck’s view, and a primary consideration in choosing varieties is ensuring they will have time to mature before harvest. The local climate and the planting date will have significant impact on this, he notes, and each hybrid will pollinate, mature and dry differently. Given that weather is always unknown at the start of a growing season, planting a range of hybrids can allow a producer to spread this risk.
Whether or not to use a pre-cleaner to remove fines is another consideration. “It can be beneficial, but similarly to dryers, pre-cleaners present another source of costs, maintenance and repair,” Dyck explains. “I think that for control of fines in stored grain, coring bins are very important. Fines tend to collect in the centre of a bin as it is filled. Coring removes grain with the highest concentration of fines and also establishes the flow funnel through the bin. This all results in better airflow patterns.” Coring should be done within a few days of filling the bin, to prevent fines from setting up, he notes. Cored material can be sold or cleaned and put back into the top of the bin.
Once grain is dried, maintaining grain condition is all about aeration. Aeration accomplishes many important things, such as removing heat, equalizing bin temperature, helping to eliminate hot spots and preventing convective air movement within the grain. For long-term storage, Dyck says grain mass temperature should be maintained within a few degrees of ambient air (and in winter, this means the grain is frozen), and aeration is key to accomplishing that. “It will maintain uniform grain temperature profiles and prevent spoilage as ambient air temperatures change,” he says.
Spot monitoring of stored grain can be used to check for temperature differences, but Dyck points out that inserting sensors more than a few inches into dense grain in a bin can be difficult. “And even with sensors, it’s important that growers remember that hot spots can be missed,” he states.
Grain producers deal with many uncontrollable variables, chief among them the weather, but also including market conditions, fuel prices, disease and pest pressure, and maintenance issues. But once the harvest is complete, it’s all about looking after it. “In drying your grain, there is no ‘magic bullet’ best system or strategy or equipment to consistently achieve the best results,” Dyck says. “I advise growers to study the issue thoroughly. There are many resources available to producers to assist with these decisions, including industry publications, manufacturers’ information and also OMAFRA resources, to name a few.”
Oct. 2, 2015 - Safe storage of a crop depends on both the temperature of the grain and the moisture level it is stored at.
"Harvest has been difficult this fall - frequent showers have slowed the harvest and grain quality is suffering," says Harry Brook, crop specialist, Alberta Ag-Info Centre, Stettler. "No one has yet managed to control weather and that is the greatest risk of all. There might be a temptation to harvest damp or wet grain just to get it in the bin. This can work in the short term but the issue of wet grain has to be dealt with fairly quickly. Once it is in the bin is no time forget about it."
Here is a list of crops and the maximum moisture content they are considered to be "dry" at and safe to store.
- barley (feed)-14.8
- barley (malt)-13.5
- domestic mustard seed-10
- triticale -14
"This chart shows approximately how long damp grain can be stored safely in the bin," says Brook. "Be warned that deterioration can start to occur before the time expires. It still has to be either dried or aerated. Aeration requires warmer temperatures and low humidity, which is what we are currently lacking. Going into fall, temperatures will continue to decline, lengthening the time it takes to bring moisture levels down. Even dry, hot grain placed in a bin creates moisture migration. It takes time for grain to stop respiring and moisture to equalize in the bin."
The hot grain or oilseed creates circulation in the bin. Cold air outside will cool the grain against the bin sides and moisture will move down the outside of the bin, and then come up the middle.
"If there is any place for the moisture to accumulate, it will be in the middle of the bin, just below the top," explains Brook. "Green seed or immature seed in the bin may also contain more moisture and add to the problem. This is why it is imperative when harvesting hot grain to cool it quickly. Aeration under hot harvest temperatures is important to get the grain or oilseed temperature down to a safe storage level."
In addition to the condition of the crop, hot grain in the bin acts as a beacon to cereal grain insects. Rusty grain beetles are good fliers and they home in on hot grain, infiltrating the bin and starting to breed in the high moisture zone.
"Warm conditions at harvest and multi-staged crops are potential ingredients for storage problems," adds Brook. "You've spent a lot of money and time getting the harvest in the bin. Take the time to monitor the stored grain condition and cool those bins down. Don't get an unpleasant surprise when selling the grain with discounts for heated grain or insect problems."
Accessing and using fumigants for grain beetle control in stored grain has become more complex, says an Alberta Agriculture and Rural Development (ARD) specialist.
"Obtaining the fumigant, whether Phostoxin, Gastoxin or Weevilcide, is only half the job, as requirements for application and record keeping have changed," says Harry Brook, crop specialist, ARD, Stettler. "Products containing phosphine are highly toxic and rules have been recently updated to reduce the risk to both the applicators and the public."
Phostoxin was reviewed by the federal Pest Management Regulatory Agency (PMRA) in 2004 with changes recommended for its use and handling. Phostoxin is used extensively in agriculture to control grain beetles found in stored grain, both on farm and at the grain elevator. The PMRA has been inspecting users of Phostoxin to ensure they are complying with the new requirements for its use.
"If you have to use phostoxin either for stored grain pests or rodent control, you must have a valid Farmer Pesticide Certificate with the proper endorsement to purchase and use phostoxin. These certificates can be obtained by studying and taking the Farmer Pesticide Certificate exams. Any certificates without an expiry date are no longer valid as they were issued prior to 2008. There is one for the base course, then endorsements for stored grain pests and vertebrate pests (gopher control). Most producers can contact their local agriculture fieldman in the county office for details. These certificates are good for five years; after that, producers have to attend a refresher course to renew for an additional five years."
Once you have your endorsement to use phostoxin, and have the beetle in your grain bins or have Richardson ground squirrel problems (registered for control only in Alberta), you must have the right equipment, says Brook.
"Under PMRA rules you must use an approved air purifying, full face, gas mask with a chin style, front or back mounted canister approved for phosphine whenever handling this pesticide. Contact a local safety store for equipment."
There are also some major restrictions for use of phostoxin. A main one prohibits its use within 500 meters of a residential area.
"As well, treated bins should be aerated prior to re-entry," says Brook. "Treated areas must have posted placards. Warning placards must be placed on every possible entrance to the fumigation site. It is not legal to move treated products in trucks, trailers, containers, vans, etc., over public roads or highways until they have been aerated and the warning placards removed."
In addition to this, the user of phostoxin must have a fumigation management plan in place. "This is to ensure a safe and effective fumigation. The plan must address characterization of the site, appropriate monitoring and notification requirements. It outlines the steps you will be taking before and during application of phostoxin as well as when aerating. Phostoxin can only be used where bin temperatures are 5 C or warmer or it will fail to activate. The colder it is, the longer it will take the pellets to gas off and the longer the bin must be sealed before being aerated."
"As you can see, it is getting more complicated to fumigate stored grain. There are, however, easier solutions to the problem of grain beetles in the grain. You can condition the grain immediately after harvest to bring its temperature down below 20 C so the hot grain doesn't attract the beetles. This is the easiest answer. You can also aerate a bin interior down to minus 20 C for two weeks to kill off the beetles."
"As it gets more complex and onerous to fumigate grain, it is a good idea to look at some other, simpler methods to either avoid the problem or treat it. Phostoxin, Gastoxin and Weevilcide are very dangerous products that need to be handled properly. If you must use them then you'll have to abide by the increased oversight and care required to use it. Improper use can result in death or injury."
Nov. 28, 2014 - Canola delivery points report a spike in heated canola over the past couple of weeks. Crushers have capacity to accommodate a certain amount of mildly heated canola, but some locations are maxed out and have pushed back delivery of heated canola well into the new year — given the sudden increase in volume.
Growers are encouraged to check all canola bins as soon as possible. Heating can start small and go unnoticed for days and perhaps weeks. Cooling the bin and stopping this early heating now can save a lot of money in lost grade and lost delivery options.
Heated canola, the brown burned seeds, mean an immediate downgrade. Photo courtesy CCC.
Reasons for the increase in heated canola so far this year are wide ranging. They include hot harvest in August, high moisture at binning, green weed seeds and green canola seeds. Cool temperatures, rainfall and high humidity conditions experienced at harvest for a lot of later-seeded canola this year increased many of these risk factors (see Top 10 risky situations for canola storage).
What to do? Temperature cables are a good way to monitor whole bins. They may not always detect initial hot spots, but they will show temperature increases that suggest a whole bin is at risk. Without cables, accurate assessment requires a physical transfer of canola from one bin to another. Hand probing through doors or roof hatches is unreliable for finding hot spots near the core of the bin. When transferring, move at least one third of the canola out of a bin. If green counts, moisture, weeds or dockage are high (in short, anything that may increase the storage risk), transferring the whole bin may be safest.
Feel and smell the canola as it comes out of the bin. If canola has started to spoil, start looking for delivery options. Many of the companies on this list will buy heated canola.
Does your storage measure up? Cool conditions in the fall make it difficult to dry canola using aeration alone. Is it time for a heated air system, or a dryer? For more on storage considerations, the Canola Council of Canada has archived videos on floors, fans, bins and storage safety.
Spores can be present in storage bins, but the fungus will never generate without the right conditions, so best management practices are key.
As a child, the scariest thing about the Boogeyman was that he was hiding so close by that he could attack at any minute but couldn’t be seen. Until recent discoveries by researchers, some mycotoxins had escalated to the same mythical proportions for almost the exact same reasons.
Playing the role of the monster-under-the-bed in this case is a mycotoxin known as ochratoxin A, and any farm with grain storage could be producing it, according to Dr. Art Schaafsma, a researcher at the University of Guelph’s Ridgetown Campus. Schaafsma is working with Victor Limay-Rios to complete a four-year study of the known carcinogen in Ontario grain storage, which has had him analyzing 30 to 40 grain bins a year in the province. He says that when he started looking for spores, indicating the presence of the penicillin relative that produces the toxin, he found spoilage fungus in abundance.
“You can find that inoculum everywhere, but originally, it came from the soil so there are places where we find more of it,” Schaafsma explains. “Manholes, doors, openings where there are air leaks and water getting in – that’s where the spore load is higher.” He says they also found that grain that has not touched the soil and was standing at harvest did not the have inoculum on it. “We did find a lot more inoculum on grain coming from heads in lodged crops or when the wheat field had been sprayed during heading and crop was tramped,” he adds. Basically, any wheat that has touched the ground will be loaded with spores.
Fortunately, Schaafsma has also found out that although spores can be present, the fungus will never generate without the right conditions. “Oddly enough, we’ve found ochratoxin in two of the many bins we’ve looked in, in the last three years,” he says. “So we’ve had six hits in three years . . . out of a whole pile of bins.”
With such sparse results, a budget-conscious researcher like Schaafsma ought to have concluded his study years ago. To understand why the study is still ongoing, he says, consider what instigated the research in the first place.
The ochratoxin hazard
In December 2009, Heinz Canada voluntarily recalled a baby cereal product after the Canadian Food Inspection Agency found elevated levels of ochratoxin A. Parents were simultaneously urged to inspect their pantry carefully, discard product lots immediately, and not worry if the cereal had already been fed to their child. As confusing as that may have been for consumers, it was downright bewildering to the food processing industry. “Raw cereal grains in Ontario were fingered,” Schaafsma recalls, “but most of the grain in this infant food production is coming from the west.” Wheat suppliers faced accusations but Schaafsma says that made little sense when oats posed the biggest ochratoxin concerns, by far.
Academics and international regulators, like Dr. David Miller, couldn’t find much common ground amongst themselves either, Schaafsma adds. Miller is a toxicologist who works at Carleton University in Ottawa and is one of those individuals that world health associations call on for expertise when it comes to mycotoxins. He says the problem with ochratoxin, unlike a mycotoxin like deoxynivalenol (DON), is twofold. “Ergot, vomitoxin, aflatoxin and zeralanone were all discovered because they made humans sick,” he says. “But ochratoxin suffers from the fact that we don’t know as much about it as we would like.”
Currently, risk assessment evidence can only suggest the toxin has carcinogenic potential rather than confirm whether it is a known or even probable cancer-causing agent. Some countries, particularly those in Europe, have decided to treat the mycotoxin with extreme caution anyway and have established import restrictions Schaafsma says can get as low as 0.5-1 part per billion (ppb). Following the Heinz recall, Health Canada made the unpopular decision to venture into discussions about implementing similar regulations. “The European approach to regulating ochratoxin is not universally accepted,” he says. “This would be the first time a toxin is regulated that we don’t have any sure link to human disease.”
Miller adds that the logistics of finding it present the other side of the ochratoxin hazard. “It’s a one-in-5,000-kernel problem,” he says – not to mention the fact that one kernel is visibly undetectable. But he says the good news, as Schaafsma is confirming, is that all surveillance efforts across the country have been proving that Canada produces really great grain on the whole. Which has put an end to regulation discussions for now. “The question is though, are there little failures here and there that really need to be prevented on the farm? The answer is yes,” says Miller, “and that’s what Art’s work is about.”
Establishing best management practices
Miller believes the great opportunity that has emerged from Schaafsma’s research is a much better understanding of the details farmers can take care of in their storage that will improve the already extremely good quality of the grain that exists in Canada. Schaafsma says this is because they’ve been able to correlate physical indicators directly with the presence of the toxin. “Basically we’re very confident it has to do with moisture during storage,” he says. “It doesn’t have to be in a warm period, most often it’s a freeze-thaw thing.”
During a cold snap of -10 C temperatures over several days, for example, a farmer will ventilate like crazy to cool a grain pile down. Since the pile cools from the bottom up, this creates warm, moist air that has to get out somewhere. Schaafsma says he has found bin downspouts act like a chimney at the top of the bin, and the wet grain he’s finding toxin in is coming from where water condenses then drips down into the centre of the pile.
Alternatively, if there’s a bolt missing in the bin where a lot of snow and ice can get in, these can form hot spots too. Schaafsma says if farmers eliminate these hot spots, they eliminate the chances ochratoxin ever forms in the first place.
“Sampling and analysis is already bad enough for vomitoxin, which you’re trying to manage at a one parts per million,” he says, adding that much like the Boogeyman, once rational thinking, best management practices and good science shed light on this situation, the worry becomes manageable.
Sept. 18, 2014 – Large amounts of last year's grain are still in storage and this year's grain is beginning to be delivered into the handling system. How you can protect all of your grain from spoiling or becoming infested?
The Canadian Grain Commission offers tips to help manage the quality of grain already in storage, and steps to take before filling bins to keep stored grain in good condition.
To protect the quality of grain currently in storage, the Canadian Grain Commission recommends you:
- Sample the grain from the core at a depth of 30 to 50 centimetres (12 to 18 inches) from the surface. Insects are likely to be found in pockets of warm or moist grain. Sieve the samples or examine small portions carefully. Typically, stored product insects are very small beetles (less than three millimetres or 1/8 inch) that may not be moving. A magnifying glass can be helpful.
- Monitor your grain in storage, if you can. Try to establish the temperature and moisture content of your grain as this will help you make decisions before insect or mould problems begin. For best results, your grain's temperature should be less than 15 C. As well, you should keep your grain at the appropriate moisture content, depending on its type (for example, wheat should be at or lower than 14.5 per cent moisture content). Grain temperature and moisture content should be as uniform as possible.
- If you find insects, identifying them will help you decide what to do. The Canadian Grain Commission has insect identification keys online that can help you. If you cannot identify an insect using these keys, call an infestation control and sanitation officer.
- Insects in your grain could be grain feeders, fungal feeders, or predators of these insects. By accurately identifying insects, you can determine the appropriate control method.
- The Canadian Grain Commission's website has advice on controlling grain feeding insects. You can also contact the infestation control and sanitation officer for further assistance.
Before harvest, insects may be attracted by grain residue around bins and storage areas.
- Make sure storage areas are clean and free from grain residues that can harbour or attract insects.
- If required, treat your empty storage bins with a registered contact insecticide such as malathion, pyrethrin or a diatomaceous earth-based product. Make sure you treat floor-wall joints, aeration plenums or floors and access points thoroughly. Note: Do not use malathion in bins intended for canola storage.
Sept. 9, 2014 - Producers can minimize potential pest problems by cleaning up in and around grain bins prior to harvest. Most empty grain bins will have some form of insects or mites surviving on dust or grain. Before binning new grain, these bins need to be swept, or preferably vacuumed, out and debris either buried or burned.
"The best time to minimize the potential for stored grain insects is before the grain is in the bin," says Jim Broatch, pest management specialist, Alberta Agriculture and Rural Development, Lacombe. "A thorough cleaning of the bin prior to filling is the best method to reduce any small populations of stored grain insects that may become a problem later in the year. Storage bins, especially if there's a history of infestation, can be sprayed or dusted with a recommended insecticide before grain storage."
Producers can help prevent problems by cleaning up any spilled grain around the bin. Spilt grain, exposed to environmental moisture, can easily build up populations of insects that could migrate into the bin later in the year. Cleaning up and removing any outside grain can minimize future problems within the bins.
"Warm, moist or weedy crops are most susceptible to damage," says Broatch. "Warm or moist grain will contribute to moisture migration within a bin. These conditions can cause locations within the bin where grain will spoil and result in insect infestation, mite and mould development. Therefore, clean out foreign matter prior to storage, and store the grain dry. Ensure appropriate aeration is applied to adequately cool the grain temperature below 15 C, or continuously turn the grain as the outside air temperature decreases, which prevents insects from further developing or laying eggs. Turning involves removing about one-third of the grain from the bin every two to four weeks and putting it back in the bin until the grain temperature reaches 15 C. Check the temperature of the grain in the bin at least every two weeks for the first 60 days of storage. Measure temperature by using temperature sensing cables that are permanently installed, or by probing the grain with a hand probe or an electronic sensor device."
If a stored grain insect problem is anticipated, products can be added while augering or moving grain. "Products with diatomaceous earth such as Protect-It can keep potential insect problems in check," says Broatch. "Addition of these products at recommended rates while augering grain will provide protection against stored grain pests. Other products are also registered for control of stored grain insects."
An Alberta Agriculture and Rural Development specialist says proper storage techniques are a must to maintain the quality of stored grain.
Producers typically manage grain by hauling directly to a grain buyer or putting the product into storage on the farm. If cereal grain is stored on the farm it is important to maintain the quality of the grain.
"The temperature and moisture content of the grain are two important factors that influence the length of time grain can be stored without a change in quality," says Mark Cutts, crop specialist, Alberta Agriculture and Rural Development. "In general, as grain temperature and moisture content increase, the allowable storage time decreases."
For example, grain stored at 18 per cent moisture and 18C can be stored for 20 to 30 days, while grain stored at 15 per cent moisture and 15C can be stored 160 to 240 days before spoilage becomes a concern.
For long-term safe storage (more than 240 days), grain entering the bin at 14 per cent moisture needs to be cooler than 13C. "There may be pockets of higher moisture grain present within a bin that is testing an average of 13 per cent," says Cutts. "These pockets of higher moisture can be a source of spoilage at isolated areas within a bin.
"Grain intended for long-term storage with a higher than desired moisture content should be put through a grain dryer," says Cutts. "Aeration can then be used to keep the dry grain cool and to ensure a uniform grain temperature throughout the bin."
If drying or aeration are not options, the grain should be monitored for heating. Permanent temperature sensing cables can be installed and used to evaluate temperatures throughout the bin. Another option is inserting a metal rod into the bin, leaving it for approximately 30 minutes, then removing the rod and checking it for warmth. "Another condition that must be carefully monitored in stored grain is the presence of stored grain insects," says Cutts. "Under the Canada Grains Act there is zero tolerance for the presence of live insects that feed on grain. As such, checking for the presence of insects is critical to maintaining crop quality. Warm, moist and weedy crops are particularly susceptible and should be closely monitored."
A monitoring program for insects should include checking bins on a weekly basis during the early stages of storage. Visible insects or feeding damage are signs of an infestation. Visual observations, however, are not always guaranteed to detect an infestation. The use of probe traps, which are placed into the bulk grain to capture the insects as they move through the grain, have proven to be an effective tool for detecting stored grain insects.
"In summary, cereal grains that are stored dry and cool (less than 15C) will minimize risks associated with grain spoilage and insect infestations," adds Cutts. "If a crop has the potential to be at risk, regular monitoring of the stored grain is critical to ensure the grain quality is not affected."
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