He's Using Anhydrous To Kill Weeds

He's Using Anhydrous To Kill Weeds CROPS Weed Control 27-6-17 Can anhydrous ammonia be used as a herbicide to kill weeds? Yes, and in the process it can also be used to supply the crop with foliar fertilizer, says Gary Martens with the Department of Plant Science, University of Manitoba. The last two years he has used a specially designed 3-pt. mounted sprayer to test the idea on small grains. "This idea is in the early stages of testing and there are still a lot of things to work out, but I think it holds promise," says Martens. Initial testing has been on an oat crop in the 3 to 4-leaf stage and infested with red root pigweed and volunteer canola. The sprayer is equipped with a 6-ft. wide shroud that contains two booms - one to apply ammonia gas and one behind it to apply water. The ammonia gas completely covers all plants inside the shroud and the water converts it to liquid nitrogen fertilizer - in effect, providing the crop with a 20-0-0 foliar fertilizer. Application rates range from a low of 1 gal. per acre (5 lbs. of 82-0-0 or about 4 lbs. of nitrogen per acre) to a high of 16 gal. per acre (80 lbs. of 82-0-0 per acre or 65 lbs. of nitrogen per acre) with about 3 seconds of exposure time. Weeds were controlled and oats in the ammonia strips yielded significantly more than the untreated strips - 140 bu./acre in the ammonia-treated strips to 113 bu./acre in the untreated strips. "With the yield increase, it's almost like having zero cost weed control," says Martens. "The ammonia acted as a contact broadleaf herbicide because broadleaf plants are more susceptible to damage from ammonia than grass. But we were surprised at how well the oats grew back. All the oats leaves were burned brown within 24 hours, but they grew back and looked completely green again within 10 days. Apparently the ammonia acts as a contact burnoff, allowing the growing point in the oats to keep on growing. The plants matured about one week later than normal. "Of course, this idea won't work on grass weeds or wild oats." Martens says he got the idea from observing a row crop cultivator that was applying anhydrous ammonia into the ground to add late season nitrogen. "Whenever the cultivator was lifted at the end of the row, any ammonia that escaped would kill all the broadleaf weeds but just burn back the corn plants. I think the same idea would work on row crops if you used a shroud between each row to protect the corn plants. Even if you were to broadcast ammonia over the emerged corn, the corn leaves would burn off like frost and then come back. " The ammonia under pressure, was released via a controller. An electric pump was used to spray the water. "I used an expensive controller because I was applying ammonia at very low rates of 5 to 10 lbs. per acre. Farmers typically apply 70 to 100 lbs. per acre," says Martens. The sprayer was designed and built by Rob McClement of R-Tech Industries, Homewood, Manitoba. Martens plans to continue tests next year using a much bigger sprayer. Contact: FARM SHOW Followup, Gary Martens, Room 222, Agricultural Building, University of Manitoba, Winnipeg, Canada R3T 2N2 (ph 204 474-8227; email: gary_martens@umanitoba.ca).

To read the rest of this story, download this issue below or click here to register with your account number.