Pulse crop harvest and storage in 2007

Source: Saskatchewan Agriculture and Food

Very high temperatures this past summer have resulted in the rapid advancement of most pulse crops across the Prairies.

Ray McVicar, the Provincial Special Crop Specialist with Saskatchewan Agriculture and Food (SAF), says most pulse crops advanced rapidly throughout the Prairies due to the heat. "Harvest came on very quickly this year, which provides both benefits and drawbacks," he noted.

"Warm weather and, in some cases, no rainfall results in an early harvest, which reduces the risk of early frost problems; however, along with early maturity also comes lower yields and smaller seed size."

McVicar says that swathing green lentil at very high temperatures can sometimes lead to unexpected oxidation of the seed. "Seeds in the top of the swath can become discoloured quickly in temperatures over 35 degrees Celsius. Then, when the swath is run through the combine, the discoloured seeds are mixed throughout the sample."

Green peas can bleach if rain showers are followed by bright sunshine. "This year, there were numerous reports of yellow pea seed staying green at harvest as they reached maturity, due to the very high temperatures," he added.

McVicar says producers generally want to get some of their pulse crops off early in order to take advantage of possible marketing opportunities and to save storage space for later harvested crops. However, harvesting in late July and early August often means the crops are put into storage at high temperatures.

"We commonly think of increased storage problems due to high moisture, but pulses stored at high temperature can also be at risk," he stated.

McVicar says there were reports in 2006 of green lentils oxidizing within a few days in the bin when stored above 30 degrees Celsius. He advises growers to use aeration to cool the crop as soon as possible.

Due to their large size, stored chickpeas and peas need time for the moisture to equalize throughout the seed. Chickpeas harvested at high temperatures will most likely sweat in the bin. This occurs as the moisture migrates within the bin.

For prolonged safe storage, McVicar suggests that pulse crops should be cooled to less than 15 degrees Celsius and dried to less than 14 per cent moisture. Seed that is cooled to 10 degrees Celsius will store well for long periods.

The Saskatchewan Pulse Growers Pulse Production Manual offers a good guideline for the safe storage of peas at various temperatures and moisture content levels. It can be obtained online at www.saskpulse.com/media/pdfs/ppm-field-pea.pdf.

Especially helpful is the handy table found in the manual that takes a lot of the guesswork out of a producer's pea storage options. "For example, at 14 per cent moisture and 10 degrees Celsius, peas can be safely stored for approximately 95 weeks. If the temperature of the same grain was 25 degrees Celsius, the safe storage limit drops to 16 weeks," McVicar said.

"Most other pulse crops will be similar in nature. However, red lentils are considered to be dry at 13 per cent moisture content to match the needs of the splitting industry."

The hot weather earlier this summer means that many pulse crops were harvested dry, but controlling the temperature of the grain once in storage is an important step that producers can't overlook.

For more information, contact:
Ray McVicar, Provincial Special Crops Specialist
Saskatchewan Agriculture and Food
Phone: (306) 787-4665