Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/4/2005
Publication Date: 12/1/2005
Citation: Arthur, F.H., Siebenmorgen, T.J. 2005. Historical weather data and predicted aeration cooling periods for stored rice in Arkansas. Applied Engineering in Agriculture 21: 1017-1020.
Interpretive Summary: Rice is an important commodity in Arkansas, and insect control during storage of rough rice is often necessary to limit economic damage. Controlled aeration is a non-chemical control strategy currently used for other crops, but there are concerns regarding the effective use of aeration in Arkansas. Historical weather data were summarized to determine if temperatures were cool enough in Arkansas to use aeration as a management strategy. Results show that controlled aeration in stored rice would be beneficial and storage bins could be cooled to temperatures that limit insect development. Efficient use of aeration may also reduce the need for chemical treatments to control insects in stored rice.
Technical Abstract: Aeration as a management strategy for stored commodities is often underutilized in the Southern United States, because of the perception that temperatures are too warm to effectively cool the commodity through aeration. In Arkansas, rice is harvested and stored in autumn, and can be infested by stored-product insects. Historical weather data were used to partition Arkansas into southern, central, and northern zones, based on the number of hours that ambient air temperatures were below 15°C in September and October from each year during 1990-1999. Data from one site from each zone were analyzed to predict how quickly rice could be cooled in early autumn to 15°C, the lower limit of development for most stored-product insects, using airflow rates of 0.08, 0.4, and 0.8 m3/min/m3 (0.1, 0.5, and 1.0 cubic feet per minute, CFM, per bushel), and different initial storage dates. The durations required for cooling decreased as the airflow rate increased, and fewer cooling days were required with later initial storage dates. Predicted durations required to cool rice to 15°C, using the lowest airflow rate of 0.08 m3/min/m3, ranged from 15 to 35 days, 6 to 20 days, and 5 to 18 days, in the weather stations chosen to represent the southern, central, and northern zones, respectively, depending on the initial storage date. Increasing the airflow from 0.08 to 0.4 m3/min/m3 yielded a predicted decrease in cooling durations of about 7 to 14 days. However, increasing the airflow rate from 0.4 to 0.8 m3/min/m3 gave only a one- or two-day decrease in predicted cooling durations to reach 15°C. Aeration was simulated using all three airflow rates for a second cooling cycle at all three sites, beginning November 1 and cooling to 7.2°C. In these simulations, the airflow rate of 0.4 m3/min/m3 was the optimal rate for the southern site, based on the time required to cool rice to 15°C. In the central and northern zones, 0.08 m3/min/m3 was the optimal rate. Results of these simulations show the potential for the expanded use of aeration to control insects in stored rice in Arkansas.