458 



No advantage was ascribable to Thomas slag compared with the super- 

 l)hosphate. 



The determinations of nitrogen compounds iuchide those of the total 

 uitrogen, nicotine, nitric acid, and ammonia. The total nitrogen was 

 greater from the fall than from the spring applications of barn-yard 

 manure; and was unusually small in the product from the unfertilized 

 plat. Applications of nitrates increased not only the total yield of 

 tobacco, but also the percentage of total nitrogen in the leaf. In general 

 the largest per cent of nicotine occured where barn -yard manure had 

 been applied. In no instance was a high nicotine content found where 

 the supply of plant food had been insufficient ; the smallest percentage 

 was found in the product from the unfertilized plat. Ajiplications of 

 ammonia seemed the most favorable to the production of a high nico- 

 tine content. 



Where nitrogen was either entirely wanting in the fertilizer, or was 

 applied in the form of ammonia, a constant percentage of 0.04 nitrogen 

 as saltpeter was noticed in the product; this small amount seemed 

 necessary to the existence of the plant. 



The color seemed to be considerably influenced by fertilizers, a lux- 

 uriant growth inducing a darker color. In general the color was lighter 

 or darker in proportion as the nicotine content was higher or lower. 

 The author observed that often with application of Chili saltpeter a 

 spotted leaf was produced, evidently because plants thus fertilized 

 cured more slowly and unevenly. 



The following are among the practical conclusions drawn by the 

 author from this and previous observations. The use of artificial fertili- 

 zers alone, even on a soil rich in humus, is not advisable. A liberal 

 application of barn-yard manure must for the present remain the basis 

 of tobacco culture, at least in Europe. In cases where tobacco is grown 

 year after year green manuring with rye may be practiced, especially 

 in times of low prices. As supplements to insufiBcieut natural sui)plies 

 of manure, according to the needs, either Chili saltpeter, superphos- 

 phate, or potassium-magnesium sulphate, or a combination of these, 

 applied shortly before the setting of the plants, is recommended. 



With reference to the burning qualities of the leaf, it is recommended 

 that the first year a piece of land is used for tobacco the barn-yard 

 manure be applied several months previous to the setting of the 

 plants; and regarding the use of artificial fertilizing materials, to 

 use those containing no chlorides or sulphates and those which con- 

 tain an excess of incombustible basic constituents, that is, saltpeter 

 for the nitrogen source (not ammonium sulphate, treated Peruvian 

 guano, or gas water) ; double superphosphate, bicalcic phosphate and 

 Thomas phosphate (better than common superphosphate) for the phos- 

 phoric acid supply; and wood ashes or carbonate for the potassium. 



The color may be in a measure influenced by the nature and extent 

 of the fertilizers applied. Strong ai)plications of nitrogenous manures 



