Toxicity of Preplant Anhydrous Ammonia to Germination and Early Growth of Corn: I. Field Studies1

Abstract

AbstractField experiments were conducted to study the effects of preplant anhydrous ammonia on germination and early growth of corn (Zea mays L.). Corn was planted directly over and parallel to NH3 bands applied at different rates, depths, and times before planting. Injurious effects on corn observed with certain NH3 treatments were: reduced stand, stunted early growth, restricted seedling root development, and increased occurrence of P‐deficiency symptoms. These effects were generally most severe for NH3 applied 10 cm deep immediately before planting at 5 cm deep. Increasing the time interval to 1 or 2 weeks between application and planting generally reduced the toxic effects. Increasing the depth of application was more effective in reducing injury than was increasing the time interval between application and planting. Injury was largely prevented when application depth was 25 cm, for all times and rates of application. Injury generally increased as rate of NH3 application increased. Soil (NH3 + NH4+)‐N concentration near seeds in excess of approximately 1,000 ppm resulted in significant stand reductions.