DISTRIBUTION OF APPLIED ANHYDROUS AMMONIA IN SOILS AND GERMINATION HAZARD TO WINTER-WHEAT

Current changes in residue management systems for winter wheat (Triticum aestivum L. ) include anhydrous NH//3 injection combined with herbicide application, planting, and other field operations. The feasibility of NH//3 application during planting is dependent upon potential NH//3 toxicity to germinating seeds. A laboratory experiment was conducted to study anhydrous NH//3 movement in soils. Soil samples were taken 1, 7, and 14 d afte N application. Soil NH//4** plus -N and calculated NH//3(aq) concentrations following NH//3 A injection generated a normal distribution curve with N concentrations highest near the injection point and decreasing with increasing distance. Calculated NH//4** plus diffusion coefficients decreased with time and water content and were soil dependent. Field studies were conducted in 1983 to determine the potential germination hazard from NH//3. In the 1984 experiment, increasing NH//3 rates did not decrease seedling stand, even though analysis of soil samples reflected increased soil pH and soil NH//4** plus -N concentration. Anhydrous NH//3 placement at a sufficient distance from newly seeded rows will ensure the success of systems which include NH//3 injection in conjunction with other field operations in residue management systems.