Effect of Tillage and Anhydrous Ammonia Application on Nitrogen Use Efficiency of Hard Red Winter Wheat

Nitrogen use efficiency (NUE) in cereal grain production is estimated to be 33% throughout the world, and can be lower when N is applied in single, pre-plant applications compared with split N applications. This study was conducted to evaluate tillage system and anhydrous ammonia (AA) application methods on yield, N uptake, and NUE in hard red winter wheat (Triticum aestivum L.), using a narrow (10 cm) nozzle spacing on a V-blade (Noble or sweep blade) applicator and wide (46 cm) nozzle spacing on a knife applicator. Over the four-year period evaluated, conventional tillage was significantly higher in grain yield in five of eight site years over no-till. However, no-till was significantly higher in grain yield at Lahoma in 2003 where the highest overall grain yield was observed. Mixed results were evaluated in NUE for tillage; four site years of no significant differences between tillage systems and the other four site years split evenly between conventional-till and no-till. The V-blade improved...