Influence of Certain Soil Fumigation Treatments on the Response of Tobacco to Ammonium and Nitrate Forms of Nitrogen

Abstract

AbstractFertilizer mixtures in which the nitrogen was allammonium, all‐nitrate or equal parts ammonium and nitrate were applied in conjunction with the following soil fumigation treatments: not‐fumigated, Dowfume W‐85 (ethylene dibromide), Shell DD (dichloropropene and dichloropropane), and methyl bromide. Data were obtained on the effect of fumigation and N treatments on (1) the relative levels of ammonium and nitrate N in the soil during the growing season, (2) the ammonium and halogen content in the tobacco leaf at certain stages of growth, and (3) the yield and certain properties of the cured tobacco leaf.Methyl bromide and Shell DD reduced nitrification to a greater degree than did Dowfume W‐85. Three weeks after transplanting, the ammonium N and halogen contents in tobacco leaves from the ammonium N treatment were higher than from the nitrate N treatment on soil fumigated with Shell DD or methyl bromide, but no different for the Dowfume W‐85 or not‐fumigated treatments.The yield and quality index of tobacco from the Shell DD and methyl bromide fumigation treatments increased with increasing percentage of the total N applied in the nitrate form. With Dowfume W‐85, the highest yield was from the mixture of ammonium and nitrate N. There were no differences in yield or quality among N treatments on soil not‐fumigated. For all fumigation treatments, the percentage N and percentage nicotine in the cured leaf were higher where ammonium N than where nitrate N was applied.