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Cooling and Drying The Canadian Grain Commission has published guidelines on preferred temperatures and moisture content (MC) to minimize spoilage. The target MC is 16% for peas and 13% for red len ls; the ideal temperature is 15°C or lower for all grains. Blowing ambient air through grain can result in both cooling (aera on) and drying (natural air drying, or NAD). The key difference between aera on and NAD is airflow rate; higher airflow rates are required for NAD. The effect of airflow rate on drying are shown below from Year One of PAMI's trials. "How long should I run my fans to dry len ls or peas?" There is no simple answer but it depends on three variables – airflow rate, star ng MC and ambient condi ons. In the len l trial, only the high airflow rate achieved a safe-to- store MC level around the sixth day of the 12-day trial but the lower airflow rates likely would have dried the len ls eventually given a longer period with stable ambient condi ons. The pea trial began with a MC 3% above the safe-to-store condi ons of 16%. Both the high and medium airflow rates achieved 16% MC within the 32-day trial (on days four and nine, respec vely) but the low airflow rate did not. When the ambient air temperature dropped a er day 18, the air's capacity for drying was reduced. In fact, the high airflow rate resulted in rewe ng due to the dry condi on of the peas when cool air passed through it. Grain Quality Theore cally, excessively high airflow rates may result in repeated shrinking/swelling cycles (par cularly near the plenum) as ambient condi ons change throughout the day. However, preliminary tes ng on seed germina on in year one suggest that airflow rate and loca on in the bin did not have a consistent impact on germina on rate. More robust tes ng of these effects on seed quality will be conducted in year two to validate these findings. Resistance to Airflow Airflow resistance (i.e. sta c pressure) was measured for both peas and len ls. In both bench-scale and bin-scale trials, the values were higher than predicted based on a mathema cal model. This result was understandable because resistance to airflow models only account for the Unloading peas into the 15 bu test bins at PAMI's Humboldt facility. Fan and transi on duct used for one of the bin-scale airflow assessments with a partner producer. Figure 2. Average moisture content and ambient temperature throughout the pea drying trial (Aug. 26 to Sept. 27, 2017). Figure 3. Len l airflow resistance at various grain depths. F A L L 2 0 1 8 | 2 5 P U L S E C R O P N E W S

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