Topdressing Winter Wheat with Anhydrous Ammonia.

Anhydrous ammonia (NH₃) has proven to be a reliable and economical source of N for fall preplant application on winter wheat. However due to the risks associated with wheat production, many Kansas producers prefer an N management system that consists of a “starter” application at planting with the balance of N fertilizer applied in the spring. This approach makes sure the crop survives the winter before the investment in N is made and reduces loss potential over the winter months. It has not been feasible to use NH₃ for topdressing in the past due to the damage to the growing crop from application with traditional knife style applicators. With the development of the John Deere 2510 high speed, low disturbance NH₃ applicator, topdressing may be feasible. This low disturbance is achieved using a coulter type opener instead of the conventional knife apparatus. A two year experiment was conducted looking at application speed, N application rate, and spring application timing of topdress NH₃ for wheat, and to compare the NH₃ application system to traditional topdressing with urea.  The initial 2010 study was promising, showing no significant yield loss comparing topdressing with NH₃ to urea. The experiment was repeated at two locations in 2011.  Results were mixed, showing soil conditions and the plants ability to recover from the NH₃ application injury was important for the success of topdressing with NH₃.