Out With the Old Crop and In With the New - PulsePoint
August 17, 2018
Transitioning into new crop storage
By Bruce Barker
By this time of the year, bins are usually empty and the new crop is moving into storage. However India’s tariffs on peas, lentils, and chickpeas have growers holding onto the old crop longer than normal. With some of the old crop still sitting on farm, what is the best strategy for moving new pulse crops into storage?
“Peas are of the least concern for carryover. They seem to have the best ability to be stored longer if they are at the correct temperature and moisture content,” says Dale Risula, Provincial Specialist, Special Crops, with the Saskatchewan Ministry of Agriculture.
A major consideration in deciding which crop to move to market first is oxidization and darkening of the seed coat of some pulse crops. Pulses that contain tannins in their seed coats oxidize over time, and lose colour and grade. These include maple and dun varieties of peas, Desi chickpeas, normal tannin faba beans, and some lentil varieties.
Since discoloration is caused by oxidation and light degradation, storing pulses with tannin seed coats in cool, dry, and dark storage conditions may help lengthen the time before any discolouration occurs.
“With green lentils, you do not want to store over a second summer,” says Risula. “Move the old crop out as soon as possible and do not mix the old crop with the new crop.”
When handling the old crop (and new crop), moving should be done as gently as possible to reduce chipping and splits. Use belt conveyors instead of augers if possible. If augers are used, run them full but at a reduced speed. Chickpeas have irregular shaped seed and require special care to keep from breaking the exposed beak area, and to ensure seed coat integrity is not damaged says Risula.
New Crop Storage
Dry and cool is the mantra for grain storage, and that includes pulses. Follow the Canadian Grain Commission’s (CGC) seed moisture content specifications. At CGC dry grade, most pulses will be dry enough for safe storage.
However, even if the crop went into the bin dry, safer storage can be achieved if the bin is cooled with aeration. The target temperature for all grains, provided they are dry, is 15°C or lower.
For example, using the safe storage charts (Tables 2 and 3), peas at 14 per cent moisture content and at 20°C temperature could be safely stored for about 28 weeks. If the temperature was cooled to 10°C, peas could theoretically be safely stored for 95 weeks.
At the Prairie Agriculture Machinery Institute (PAMI) at Humboldt, Saskatchewan, Dr. Joy Agnew, project manager, is working to fill a knowledge gap in managing pulse crops once they go in the bin.
“There has been some baseline work done over the years to establish drying and wetting characteristics of pulses, but it has never been validated or widely adopted,” says Agnew.
The first of two years of research was completed in 2017. The goal is to validate equilibrium moisture content (EMC) charts for peas and lentils, to assess airflow rates on natural air drying, and to determine resistance to airflow in pulses. EMC charts can be used to predict how the ambient air used for natural air drying will affect the moisture content of grain. It takes into account the air temperature and relative humidity of the air. PAMI currently has EMC charts posted on their website for peas, lentils, and soybeans.
The PAMI research will help producers store pulses safely, but also minimize the risk of over-drying by having updated EMC charts. Agnew says over-drying can cost producers as much as 20 cents per bushel in lost bushel weight. An additional goal is to collect baseline data on how repeated wetting and drying cycles affect seed quality over long-term storage.
In 2017, various airflow rates in benchscale bins for peas and lentils were tested, and eight on-farm trials also collected information on static pressure across the fan, grain depth and volume, and moisture content. In 2018, the bench-scale research will be conducted along with expanded on‑farm trials.
Agnew says preliminary data from the first year indicates that, “Airflow rate definitely affected drying rate. Kernels from the middle of the bin had a poorer germination rate than those near the plenum.”
Monitor the Bin
After pulse crops are dried and cooled to recommended storage conditions, monitoring for moisture build-up, heating, or spoilage should be conducted frequently. Risula says pulse crops have a tendency to sweat after being placed in storage. The seeds continue to respire after going into storage and release water as a vapour that can migrate and accumulate in concentrations high enough to cause spoilage.
Monitoring is especially important for large Kabuli chickpeas because seed testing dry can sometimes hide seed with higher moisture levels internally in the grain mass.
“Peas, lentils, and chickpeas are usually off the field early enough in the fall that the air is warm and dry, which can help with natural air drying if the crop was taken off tough,” says Risula. “The important thing this fall is to get the new crop cooled down as quickly as possible.”