Pacific Northwest Division

Buried drip irrigation systems offer an efficient and cost-effective way to irrigate crops. They use less water than above-ground systems because they deliver water directly to the plant roots, so excess evaporation and agricultural diseases associated with moist leaves are avoided. Additionally, the drip irrigation systems can bring systemic insecticides to roots in slow, controlled doses.

Unfortunately, roots often clog drip emitters in buried drip irrigation systems, and this tendency severely limits the service life of a valuable irrigation technology.

Now, through a unique marriage of polymer and root-growth inhibitor, researchers at Battelle's Pacific Northwest Laboratories have created long-term, controlled-release devices that establish a barrier zone where plant roots cannot grow. Called "Biobarrier," the devices exclude plant roots for up to 100 years.

The Biobarrier for drip irrigation applications is engineered to exclude plant roots from drip emitters for up to 20 years. Buried drip irrigation systems protected with the Biobarrier offer all the benefits of the buried drip irrigation technology without the problem of root intrusions.

Battelle-Northwest's Biobarrier technology excludes plant roots from drip emitters for up to 20 years.

Combining Chemical and Carrier

The Biobarrier technology combines polymers or other synthetic rubbers with herbicides that inhibit root growth. The technology, originally developed for buried waste sites, releases the herbicide at a uniform rate, maintaining sufficient soil concentration to prevent root growth in the barrier zone The Biobarrier herbicide was selected for its effectiveness and minimal impact on the environment.

It is harmless to birds, mammals, and insects. It does not kill plant roots but does prevent longitudinal root growth. Also, the herbicide is not significantly water soluble and is not actively translocated into the aerial tissues of the plant. Furthermore, concentrations needed to inhibit root-growth are low, making the biobarrier herbicide an economical and ecologically sound choice.

Battelle-Northwest researchers have identified several polymers and synthetic rubbers as candidate carriers for the Biobarrier herbicide. These materials have proven effective as chemical carriers for controlled-release devices. They act as reservoirs for the chemical and provide a sustained and prescribed chemical release while protecting the herbicide from degradation. Stable and strong, these carriers are also relatively inexpensive to process.

Promising Applications

Battelle-Northwest researchers can tailor the Biobarrier technology to meet many needs. Varying the chemical concentration, polymer thickness, or polymer type creates an engineered obsolescence in the various devices of 2 to 100 years. Integrating the chemical with different polymers or synthetic rubbers, or changing the construction method allows the Biobarrier to assume many shapes and sizes. For example, Battelle-Northwest researchers designed and constructed a sewer gasket that prevents roots from growing through the barrier zone for up to 50 years.

The long-term, controlled-release technology could be used to prevent unwanted plant, animal or insect intrusions in many applications: driveway and highway expansion joints building and house foundations sidewalks, tennis courts, and swimming pools commercial and residential landscaping.

Battelle-Northwest researchers have identified other promising applications for the long- term, controlled-release technology. By incorporating chemicals into controlled-release carriers, researchers may solve problems such as biodegradation of telephone poles, fire ant and termite infestation, rodent and insect attack on buried wires, and tree growth under power lines.

Assistance from Battelle-Northwest

Each application of the Biobarrier concept requires individual study for design and engineering of a long-term, controlled-release device. Companies interested in more information about the Biobarrier technology are invited to contact Battelle-Northwest. The research staff will be pleased to discuss arrangements for feasibility analyses and technical assistance for this or other longterm, controlled-release technology.

For more information, contact:
Peter Van Voris
Battelle/Pacific Northwest Division
P.O. Box 999
Rich land, Washington 99352
(509) 375-2498

Pacific Northwest Division
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