Greenhouse Evaluation of the Agronomic Efficiency of Anhydrous Ammonia1

Abstract

AbstractThree greenhouse pot experiments were conducted with corn grown on Mountview loam and Hartsells fine sandy loam to (a) measure the relative agronomic effectiveness of direct applications of anhydrous NH3, as influenced by preplan incubation period and schedule of application, and (b) to determine the influence of soil moisture content at time of NH3 injection on crop response to anhydrous NH3.Response of corn to anhydrous NH3 tended to be less than to an ammonium N source with shorter incubation periods, but was generally as effective as a nitrate N source except when high N rates were applied at planting. In the latter case, yields were somewhat reduced.When anhydrous NH3 was injected into the soil‐root zone according to different application schedules, corn yields were considerably reduced at the higher N levels when compared to equivalent applications of urea and NH4NO3. Yield reduction in these cases was attributed in part to root damage due to NH3 toxicity, and possibly to temporary positional unavailability of the applied N. Soil‐cultured corn plants, however, appeared to be remarkably tolerant to high levels of anhydrous NH3 when applied directly into the root zone.A small but consistent decrease in yield was observed when high levels of anhydrous NH3 were applied to soils in an air‐dry rather than moist condition.