Burley tobacco transplant producers using the float system, have had numerous problems with soluble fertilizers containing a significant proportion of the total nitrogen in the urea or ammonium forms. The objective of this study was to determine the effect of nitrogen sources on the growth and development of Burley tobacco transplants growing in the float system. An experiment was set up in which individual beds were fertilized with liquid fertilizers having an N-P-K ratio of 2-1-2. The proportion of total N from nitrate varied from 0 to 60%, with the remaining N supplied in the ammonium form. Two urea containing solutions were also tested, in which N from urea was either 20 or 100% of total N. Primed TN-90 was seeded in 200 count trays and floated on the fertilizer solutions. A check treatment with 100% ammonium-N but no plants was also prepared. Water samples were taken weekly, and analyzed for nitrate-N and ammonium-N. At six weeks after seeding, 10 plants from each tray were harvested. Soil solution was extracted from the soil plug of each harvested plant. During the first three weeks of the experiment there was little change in the N content of the water or the distribution of N sources. Four weeks after seeding there was a significant decrease in the total N in the water due to plant uptake, but there was little evidence of nitrification in the float water. Soil solution extracted from the no-plant treatment revealed an accumulation of nitrate, suggesting that nitrification was occurring in the media. Plants grown on ammonium or urea based fertilizers grew normally at first, but showed signs of slower growth four weeks after seeding. Dry matter production was significantly higher for fertilizers containing nitrate-N. Fertilizers intended for use in tobacco float systems should contain at least 50 % of the total N as nitrate.