Tobacco transplant seedlings were grown for 30 days in fumigated and non-fumigated Cecil and Appling soil material in growth chambers at either 13, 21, or 29°C temperatures. The plants were fertilized with either KNO₃, (NH₃)SO₄ or NH₄NO₃. No abnormal growth characteristics were observed on the non-fumigated soils with any of the nitrogen sources used. Stunted plants with leaf abnormalities developed on the fumigated soils when ammonium was the nitrogen source; the abnormalities were not observed when nitrate was the nitrogen source and only slight abnormalities were observed when ammonium nitrate was used. Plants recovered more quickly from growth inhibition and leaf abnormalities at the higher temperatures. Greater total nitrogen uptake occurred on the Cecil soil and more nitrogen uptake by the plants occurred on the fumigated treatments.

(Full article published with kind permission from "Tobacco International")