Producers applying anhydrous ammonia this spring should guard against theft, a South Dakota State University Extension specialist said.

Brad Ruden, who is with SDSU Extension's project of the North Central Pest Management Center, said people making the illegal drug methamphetamine sometimes steal anhydrous ammonia to use in that process. On the meth makers' black market, anhydrous ammonia can bring as much as $300 a gallon.

Ruden said agribusiness suppliers are well aware of the issue of anhydrous ammonia theft and generally take precautions. But he added that producers, too, can take steps to stop theft, including:

- Use locks if possible. Some distributors have them installed on their fill tanks and nurse tanks.

- Have tanks delivered as close to the time of application as possible so that they are not left unattended in fields.

- Position tanks in open areas where they may be easily seen from roadways, putting would-be thieves at a disadvantage.

- If there will be a delay in using all of the anhydrous in a nurse tank, return the unused portion to the ag dealer and order a different tank when application can resume.

- If it can be done safely, relieve pressure in the hose with the bleed valve when a tank must be left in the field overnight. Producers may also consider removing hoses for longer-term storage of partially filled tanks.

- Check tanks at night and in the morning for any signs of tampering; also note whether the level of anhydrous ammonia has changed.

- Watch for vehicle tracks or footprints around the tank; note whether valves are not closed tightly, a possible sign of tampering; and note whether hoses are in a different position than when you left.

- Look for suspicious items near the tank such as duct tape, garden hose, bicycle inner tubes, buckets and coolers. Thieves will sometimes leave behind such items if they are scared off.

- Check for broken or missing wire ties or seals that you have placed on valve wheels as a marker.

Ruden cautioned that producers should not disturb the crime scene if they see signs of anhydrous ammonia theft, but instead contact local law enforcement.