During the spring of 1996, many tobacco producers used a water soluble 20-10-20 fertilizer in their float beds, only to have to throw out the stunted sickly plants that resulted, and start over. The fertilizer that caused the problems turned out to have 100% of the nitrogen (N) as urea-N. It was hypothesized that the poor growth was related to with the conversion of the urea-N to other forms of N. There have been numerous other cases where producers using fertilizers high in urea-N or ammonium-N (NH4-N) have had problems with stunted plant growth. Further study of nitrogen transformations is warranted to determine what caused the poor growth, and to improve nitrogen management in tobacco float systems.
Pearce, Robert C. and Palmer, Gary K., "Nitrogen Source Effects on the Growth and Development of Burley Tobacco Transplants in the Float System" (1997). Agronomy Notes. 28.