Evaluation of Midseason Application Depth of Urea Ammonium Nitrate (UAN) Fertilizer in Winter Wheat (TRITICUM AESTIVUM L.).

Global Nitrogen Use Efficiency (NUE) is estimated to be 33%. Providing producers with efficient methods to increase the effectiveness of their Nitrogen (N) applications is integral to agricultural sustainability and environmental quality. This study is being conducted to evaluate various depths of urea ammonium nitrate (UAN) placement on overall grain yield and plant N uptake in winter wheat. The UAN was applied in bands at depths of 5.1 and 10.2 cm, along with surface applications, all at various N rates at Feekes growth stage 5. Fields under conservation tillage will likely receive the greatest benefit from subsurface applications when weather favors heightened microbial activity and low rates of N mineralization. No-till soils experience a shift in the active microbial zone compared to conventionally tilled fields, resulting in greater rates of N immobilization from N applied in the upper 6-7 cm of the soil profile. Conventional tillage generally benefits from subsurface applications when weather and environmental conditions are present that promote ammonia volatilization following fertilizer application. Nitrogen rates that provide the greatest economic returns are dependent on the environment, as yearly environmental variability is impossible to predict. Early estimates indicate differences to be seen between subsurface and surface applications of N. Due to above average temperatures throughout the fall and winter months, potential exists for heightened plant N demand, allowing for clear differences among the N rates. Trials located under conservation tillage will likely show differences when comparing subsurface and surface treatments.