Manitoba farmers struggling with fertilizer applications because it’s too wet have options, says provincial soil fertility specialist John Heard.
Ideally nitrogen should be banded ahead, or at the time of seeding, but that’s not always possible, he said. For example, a farmer might have a supply problem or fields too wet to support a loaded fertilizer tank.
Nitrogen can be banded soon after a crop has been seeded. It’s even possible to apply anhydrous ammonia immediately after a crop is seeded, Heard said. Use narrow knives to avoid soil disturbance and apply before the crop germinates.
“Limited research has indicated that post-seeding banding of anhydrous ammonia may have some advantages over top dressing in terms of cost and efficiency,” says Manitoba Agriculture, Food and Rural Initiative’s website (http://www.gov.mb.ca/agriculture/soilwater/nutrient/fnm03s01.html).
“Also, ensure that the anhydrous ammonia is applied at the recommended depth (at least four inches deep) to minimize the potential for seedling damage.”
Solid or liquid forms of nitrogen can be broadcast and harrowed in immediately after seeding.
“Harrowing can provide some incorporation and reduce the risk of volatilization or gassing off,” the website states.
Top dressing allows for quick seeding. It’s also an efficient method if it rains soon after application, which is common in the spring in the Red River Valley, the website says.
“However, if conditions favour volatilization (dry, warm and windy weather), loss of urea N or UAN solution N may be very high.”
That’s when farmers should apply nitrogen treated with Agrotain, Heard said. Volatilization occurs when urea comes in contact with moisture and urease, a naturally occurring enzyme in the soil and crop residue that breaks down urea and releases it as ammonia into the air. Agrotain delays losses from volatilization by blocking the urease enzyme. UAN solution should be applied as a dribble band or using streamer nozzles to further minimize losses.