Division of Agricultural Sciences and Natural Resources / Oklahoma State University
Closing the loop
on stored grain insects
By Don Stotts
Closed loop fumigation has become a success story for Oklahoma State University, thanks in part to two specialists who found that their ideas potentially could provide benefits not only for grain elevator operators everywhere, but also to consumers of cereal grain products.
OSU Biosystems and Agricultural Engineering professor Ron Noyes seals
ductwork on a closed loop fumigation system while Wheeler Bros.
Grain Co. employee Brian Krittenbrink prepares the
centrifugal blower for operation
Better performance, improved levels of worker safety, and reduced costs associated with both daily operation and regulatory compliance are possible for many grain elevators that are adapted to closed loop fumigation systems, says Ron Noyes, OSU agricultural engineer.
"CLF systems can reduce the amount of phosphine required by 50 percent or more in many cases and that can result in significant savings," Noyes says. "At the same time, CLF systems also improve the efficacy in the kill of insects, thereby reducing the insects' ability to build resistance to phosphine, which has been an ongoing problem for the past 10 years."
For the past few years, Noyes and Phil Kenkel, OSU agricultural economist, have worked to provide new design and economic analysis elements on CLF systems installation and operation.
Their work was based on James S. Cook's patented closed loop fumigation process that used low-volume centrifugal blowers and duct systems operating at low pressures.
Cook's system was adapted from systems developed and used in the early 1920s for methyl bromide fumigation in the United States and other major grain-producing areas of the world.
Now, Oklahoma has become a central point for the spread of new CLF technology.
"We have designed five closed loop fumigation systems for concrete elevators that interconnect from three to 17 concrete silos so phosphine can be recirculated through all silos as a group. Thus, groups of silos connected by recirculation piping manifilds can operate as one unit volume with capacities between 60,000 and 300,000 bushels, making them cost competitive with large steel tanks," Noyes says.
Kenkel says this Elevator CLF Systems Cooperative Project was funded by Region 6 EPA funds provided through the Oklahoma Department of Agriculture in 1995 and is being finished in 1997.
"This project was designed to improve efficiency while reducing pesticide inputs in the food supply chain," Kenkel says. "Part of the project is to collect installation and operating cost data that can be used to help other elevator operators as they consider installing CLF systems."
The ability to handle 60,000 or more bushels of grain puts these systems into the category of large steel grain bins, a prerequisite to making CLF systems economical for concrete grain elevators.
"Hopefully, within the next year we will have five operational concrete-based CLF systems that can serve as models for other grain elevator operations with comparable silos," Noyes says.
Currently, concrete silos adapted to CLF systems include grain elevators at Booker, Texas, which have been completely refitted; at Hobart and Ponca City, with refits that have been nearly completed; and at Corn and Frederick, which are in the early stages of putting in CLF technology.
"There is also a grain elevator operator at Ft. Worth, Texas, who is putting in a CLF system," Noyes says. "He and I designed that one over the phone."
CLF systems also are being adapted to grain operations that use steel tanks. Noyes traveled to 17 sites in a cooperative group project, accumulated data, designed the appropriate systems, and shipped the plumbing list and plumbing to them.
Biosystems and Agricultural Engineering professor Ron Noyes
uses a bit of mechanical help to move the centrifugal blower
to its installation site at an elevator in Kingfisher.
"Several are already up and running, including sites at Alva, Okarche, and Minco," Noyes says. "One at Omega was completed, then one of our famous Oklahoma wind storms came along and uncompleted it. They’ve since reworked it and put it back together."
The managers of other grain elevator operations for which CLF systems have been designed have told Noyes they are waiting for mill rights or improved economic conditions before starting new construction.
During the Pacific Northwest Grain and Feed Association meeting in February at Coeur d'Alene, Idaho, Noyes designed a CLF system for a 1.75 million bushel flat storage for a Washington elevator.
"This storage building is extremely tight and should work very well with CLF," Noyes explains. "It will save that elevator a great deal of money on fumigation labor and compliance costs, while doing a better job of insect management."
Noyes and Kenkel say technology transfer of this type is very important to Oklahoma and to the agricultural industry.
"Technology transfer helps to develop systems; the new systems help to improve quality and worker safety, which, in turn, enhance marketability,' Kenkel says.
A particularly noteworthy benefit to cereal grain marketability is that there are no detectable chemical residues associated with CLF systems when managed properly.
"Phosphine gas dissipates during the aeration process," Noyes says. "If you don't put phosphine pellets directly in the product, there is not even an ash residue. Even if you do and an ash residue is present, the amount is a very, very minute percent of the total mass."
Noyes says OSU's efforts in working with concepts designed to reduce chemical residues in food should be something in which everyone involved can take pride.
"Cereal grains are an important part of our food supply. Most people eat them every morning for breakfast, as well as in baked goods, breads, pasta, and a great many things."
Nor are the OSU's stored grain specialists standing pat on past or current successes. The Stored Grain Group has submitted a proposal with the Pesticide Impact Assessment Program to develop a means of releasing phosphine outside bins into a specially designed transportable unit, which then can be trucked from one grain elevator to another.
"We're also involved with an Australian corporation in the development of a liquid form of phosphine," Noyes says. "This has a lot of potential. Liquid phosphine can be used with regulated systems to trickle phosphine at much lower rates than is possible currently, and this can be done in bins that are not tlly sealed and still do an effective job."
Agriculture at OSU Spring / Summer 1997
Agriculture at OSU Home Page
Agriculture at OSU is provided for online viewing by the Department of Agricultural Education, Communications, and 4-H Youth Development, Division of Agricultural Science and Natural Resources at Oklahoma State University.