Protecting Your Pulses

Who is minding the storage?

by Geoff Geddes

For Canadian pulse crops, quality is central to success for producers and industry. In large part, proper storage will determine how well those crops are preserved and, in the process, how well they perform in the marketplace.

“Quality is so important in realizing the highest price for your crop, maintaining market share, and trying to increase it,” says Dale Risula, Provincial Specialist, Special Crops, Saskatchewan Ministry of Agriculture. Because many countries do not have the same calibre of storage equipment and techniques as Canada, it is an area where we can gain a competitive edge. To do so, producers need to keep a few factors in mind.

Wetter is Better, to a Point

“At harvest time, crops are subject to deterioration mostly from weather, so harvesting them in a way that lets us gather most of the crop at the highest level of quality and put it safely into storage is crucial,” says Risula.

That means harvesting pulse crops at the right moisture content to prevent damage to the seed coats which could reduce grading and impede next year’s seeding.

Once the crop is harvested, the grains continue to respire, releasing CO2 and moisture into the bin. At that point, proper aeration — including the right fan strength and bin flooring — is important to ensure sufficient air flow through the grain mass, and sufficient time for movement of a drying front from bottom to top.

“The challenge with pulses is that they are harvested slightly tough to minimize damage from augering,” says Joy Agnew, Project Manager — Agricultural Research Services at Prairie Agricultural Machinery Institute.

“Peas typically dry at around 16 per cent moisture and lentils around 13 per cent, so they are usually harvested one to two per cent higher than that.”

Consequently, they must be managed carefully in the bin by blowing air or heated air through it.

Keeping Your Cool

Temperature is another key factor and one that helps with longevity of storage.

“Even if the moisture content is a bit high, cooling your pulses allows you to store them safely for a reasonable amount of time,” says Risula.

“We recommend trying to get the grain mass down to 15°C, or to 10°C if you have moisture. That should ensure a couple of weeks of secure storage.”

Match, Do Not Mix

With paint, mixing colors can have some intriguing results. With pulses though, it could put your business in the red. “Lentils must be stored separately from last year’s crop as they tend to oxidize and change color,” says Risula. “This can lead to a downgrade in the quality assessment of your crop.”
“Avoid mixing red and green lentils or green and yellow peas. Green peas generally have a market advantage which can be negated by such mingling unless they are being sold for livestock feed.”

Although the specific guidelines for pulse storage today are limited, that may be changing.

Filling the Gap is Full of Potential

“We are trying to fill that gap with a new project funded by the Saskatchewan Ministry of Agriculture aimed at defining storage practices for pulses,” says Agnew. For example, there is a shortage of information on the resistance to air flow produced by pulses, knowledge that is needed to understand fan air flow rates.

“We will also be validating other tools for storage like equilibrium moisture content charts,” says Agnew. “There are some charts out there from the 1980s, but we need to see if they are relevant today and help producers understand how they can be used to manage storage.”

Updating the charts will require a lot of data points. At the very least, Agnew hopes they can determine how close the existing charts are to reality.

“The biggest issue for pulses is damage during handling,” says Agnew. 

With crops like flax or canola, producers turn them frequently in the bin to break up hot spots. This practice is discouraged for pulses, as every time they pass through the auger there is the potential for damage and grade loss which can seriously impact revenue. Therefore, the primary method of
controlling conditions in the bin is to use air.

“To manage conditions in the bin for pulses, we must understand resistance to air flow and equilibrium moisture content or the effect of the air’s condition on the seed’s moisture content.”

Given the importance of proper pulse storage, producers would be well advised to review current guidelines and stay up to date on any changes.