ISSUE 3 May 17, 2001
AMMONIA APPLICATION AT SEEDING
By the book, seeding following an anhydrous ammonia application should wait about five to seven days. However, I have seen anhydrous application made in the fall of the year have effects on the following spring seeded wheat and sugarbeet crop. So when is it safe to seed? My rule is that it is never safe, so manage the application and seeding accordingly. When applying anhydrous ammonia prior to seeding, apply it at an angle to the proposed planting direction. When seeding, increase the seeding rate about 10% to compensate for the seed that will not germinate, or die shortly after germination when it is seeding into or close to the ammonia band. Some stand loss will result, but it will be the few plants seeded over the band at intervals, and not large gaps if the field had been seeded in the same direction as the ammonia application.
Understanding this, how do many growers seed and apply ammonia at the same time? Because the application boot is designed to always have distance between the outlet (usually 3-4 inches) from the seed. Only seed that scatters into the ammonia band zone will have germination problems in the one-pass scenario.
Because of the flurry of seeding, sometimes urea application has to be delayed until after seeding so that the seeder does not have to wait until the fertilizer applicator finishes their job. With recent temperatures in the 80's and above, ammonia volatilization following surface application will be very fast. This application needs to be incorporated in some manner or rained in by at least 1/4 inch of rain on bare soil or at least ˝ inch of rain or more on no-till residue (more if there is significant residue covering the soil surface), or losses of up to 50% in a week are possible. Impregnating the urea pellets with Agrotain® has been shown effective in many University trials in the US and Canada in delaying the breakdown of urea for about 10 days longer than normal. Cost of the product depends on the rate of urea used. Impregnation rate is based on a 5 qt/ton urea at maximum rates. At the rates of urea normally used in the region for small grains, cost would be somewhere around $6-8/acre. If you don’t have a 100% chance of rain in the next 48 hours, this product could reap many times its cost if N is lost through urea volatilization.
Dr. Dave Franzen,
NDSU Extension Soil Specialist