SOUTH AFRICAN TOBACCOS. 189 



ton to the acre not being an exceptional quantity. The a])pHca- 

 tion should contain: 



Phosphoric Acid 4 per cent. 



Nitrogen 5 „ 



Potash .• .... 9 ,. 



The potash should be applied in the form of high-grade 

 sulphate, sulphate of potash-magnesia, or silicate of potash, and 

 the nitrogen preferably from nitrate of soda, cotton-seed meal 

 or the hnest grade of old and partially decomposed Sea Island 

 guanos. The phosphoric acid is most economically obtained in 

 the shape of acid phosphate, although cotton-seed ^meal and 

 guano contain small quantities of this essential. 



2. Climatic Conditions. — With reference to the climate, the 

 tobacco grown in a damp climate does not lose so much water 

 by evaporation from the large surface of the leaves as in a dry 

 climate with continuous sunshine. In a dry climate the plant 

 draws in by the roots much more water than in a damp climate, 

 and with the water taken up by the roots a larger amount of 

 saline matter enters into the system of the tobacco and increases 

 the percentage of ash. In many cases the cause of an exorbitant 

 amount of chlorine compounds in the tobacco is to be traced 

 to peculiar methods of irrigation. The soil not being loose 

 enough, the fine fibrous roots of the tobacco plant cannot pene- 

 trate sufficiently deeply into the soil. The water in many 

 instances is led directly on to the plant, and this retards the 

 development of the roots, because the principal roots, which 

 provide the tobacco plant with food, are near the surface, and 

 the plants can thus satisfy their requirements of moisture without 

 developing long roots. In this surface soil are the largest 

 amounts of chlorine compounds, which show themselves in dry 

 weather as a white efflorescence on the surface. The solubility 

 of these salts in water is much greater than that of lime or 

 potash compounds, and since the water is led directly on to the 

 plant, it dissolves the surface salts first and supplies the chlorine 

 compounds to the plant. This can be prevented to a considerable 

 degree by loosening the soil to a greater depth and leading the 

 water in between the rows of tobacco plants, thus compelling the 

 plants to extend their roots and live on a larger portion of soil. 

 Tobacco grown under these conditions does not burn so readily as 

 tobacco grown in a humid atmosphere. 



It is also known that the same variety of tobacco contains 

 less nicotin when grown in a damp climate than in a sunny 

 climate. Some of the districts where tobacco is grown are dis- 

 tinguished by a tine sunny climate, but the tobacco contains such 

 an excessive quantity of nicotin that it is more suitable for the 

 manufacture of sheep-dip than for the manufacture of cigar or 

 pipe tobacco. 



The writer has continued the researches made by Mr. 

 Schenck and Dr. Juritz in 1886, and has examined a number of 



