Anhydrous ammonia
Low cost, high nitrogen concentration and safer application management has increased the use of anhydrous ammonia while seeding.
But using NH3 can be controversial, says Robert Maze, of the Alberta Farm Machinery Research Centre of Alberta Agriculture.
“One of the long running debates among farmers has been whether cold liquid or hot vapor flow of NH3 is better in terms of soil retention,” he said.
NH3 consists of 82 percent nitrogen and 18 percent hydrogen by weight. It occurs as a vapor and turns into a liquid at -3C (28 F). For use in agriculture, NH3 is maintained in liquid form under pressure in a nurse tank. As it is released from the tank into the distribution system of the fertilizer applicator, NH3 expands and begins to warm, converting it into a hot flow vapor.
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To turn the vapor back into liquid before it is put into the soil, cold flow converters are used, Maze said.
NH3 expands in the converter and freezes, separating the liquid ammonia from the vapor and greatly dropping the pressure. Only about 85 percent of the anhydrous ammonia turns liquid; the remainder stays in vapor form. The liquid flows by gravity through regular application equipment into the soil. Remaining vapor is normally injected using additional hose.
In 1996, the machinery research centre, Agrium, Bourgault Industries and Prairie Seeds completed a study at sites in Lethbridge and Edmonton to determine whether cold flow convertors offered any advantages over hot flow.
“Crop emergence and yield were measured after direct seeding wheat, barley and canola using four seeding systems, and three nitrogen fertilizer rates,” said Maze.
Nitrogen was applied as a cold flow liquid anhydrous ammonia, a hot flow vapor anhydrous ammonia and as granular urea.
“The trials showed the type and rate of nitrogen used in the study made no difference in plant counts and, in terms of final yield, cold flow convertors did not provide any benefit to wheat, barley and canola,” he said.
– Alberta Agriculture
