The problem may not be getting the tobacco to grow so much as not getting too much nutrient into it so that it has limited crop value for smoking. In my experience the stuff is too strong to smoke if it has too rich a soil after it is started (and transplanted). Transplants work great on the burned out podzols of Northern Florida which are generally acid, as are many low nutrient soils. 

Tobacco is very sensitive to the physical and chemical properties of the soil. The best soils are those which are open, well drained and properly aerated. The plant is highly susceptible to injury from flooding or inundation of the soil. The desirable soil pH is 5.0 to 6.0 . But, in many parts cultivation is successful where the pH is 8 or more. 

However FCV tobacco is grown on different types of soils ranging from sands to sandy loams. Typical characteristics of soils best suited to the production of high quality Flue-cured tobacco are (1) a sandy surface soil up to 15 to 25 cm depth (2) a yellowish or a reddish sandy clay subsoil extending up to a depth of 150 cm. (3) an acidic soil reaction of pH 5.5 to 6.5 (4) a low reserve of essential plant nutrients (5) a low organic matter content and (6) very low chloride content (less than 100 ppm). Cultivation of tobacco on inundated lands and low-lying basins are to be avoided as the leaf produced on these soils has been found to exhibit very poor burning properties, due to absorption of moisture and deteriorates in colour during storage. Similarly, saline soils whose soil chloride content is greater than 100 ppm should be excluded from virginia tobacco cultivation.

 I think these information is useful to you.

Djaafar Zemali

Soil pH for achieving higher quality tobacco is different under different climatic conditions. Best pH for tobacco growth in US 6.0-6.4, in INDIA 7.5-8.5, in China 5.0-7.0,

currently academic commity consider optimal pH  for QUALITY TOBACCO leaf production to be range pH soil 5.5-6.5

I hope it will helps

Mostly neutral to slightly acidic pH (5.0 to 7.0) is better for yield and quality of Tobacco.

Why grow tobacco when it is a known carcinogen?  Will you pay for the people you kill?

Tobacco plants need to be planted in moderately acidic soil, otherwise they won't flourish. The soil itself should have a pH of 5.8. Poor growth and some growth disorders may occur if the soil pH is 6.5 or higher.

Around 6.0 pH is suitable for tobacco cultivation.

Although I mostly agree with Paul Milham, there is an awkward problem in the US where a great deal of the leaf tobacco is grown by the very poor on tiny acreages, or fractional acreages. The soil will not support anything else that pays as much and the tobacco allotments are the only thing of value these farmers own. And yes I agree that Djaafar Zemal should reconsider before encouraging new plantings of this menace. 

Note :

. Absorption of Nicotine

The pH of smoke from flue-cured tobaccos, found in most cigarettes, is acidic (pH 5.5–6.0). At this pH, nicotine is primarily ionized.

As a consequence, there is little buccal absorption of nicotine from flue-cured tobacco smoke, even when it is held in the mouth (Gori et al. 1986). Smoke from air-cured tobaccos ,the predominant tobacco used in pipes, cigars, and some European cigarettes, is more alkaline (pH 6.5 or higher) and, considerable nicotine is unionized. Smoke from these products is well absorbed through the mouth . (Armitage et al. 1978 ) It has recently been proposed that the pH of cigarette smoke particulate matter is higher than previously thought, and thus, a larger portion of nicotine would be in the unionized form, facilitating rapid pulmonary absorption (Pankow 2001).

The soil pH for achieving higher quality tobacco varies with different soil and climatic conditions. For example, the best pH for tobacco growth in the United States is 6.0-6.4; while in India, the best pH is 7.5 - 8.5; and in China, the soil pH found in high-quality tobacco-growing areas is primarily in the range of 5.0 - 7.0. Currently, the academic community considers the optimal pH for quality tobacco leaf production to be in the range of 5.5 - 6.5

Ref: http://www.jocpr.com/articles/the-effects-of-soil-ph-on-tobacco-growth.pdf