Ti-l EXPEEIMENT STATION RECORD. 



soil and the weight and surface area of the leaves, nor is there a con- 

 stant relation between surface area and weight of a scjuare meter; and, 

 consequently, no relation between surface area and the number of 

 square meters of leaf surface in 1 kg. of leaves. It also appears that 

 the texture and weight of leaves vary as much on similar soils with the 

 same treatment as the}' do on different soils or with different treatment. 



The results of chemical aiiah'sis are shown in 6 tables and discussed 

 at length, and the methods of analysis employed are described. 



The most common cause of failure of the crop or of unsatisfactory 

 quality is drought. It is held that the soils on which tobacco is grown 

 to-day have not as great power to retain moisture as they once had. 

 Ten years ago the crop was not ruined until ■iO days had passed with- 

 out rain; a few years later 24 days of drought brought failure; and at 

 present planters complain of the extremely dry weather when but 15 

 dsijs haye passed without rain. The decrease in the power of soils to 

 hold water is attributed to a change in their texture and in the humus 

 content brought about by continuous tobacco growing and frequent 

 burning. Tobacco grown on virgin soil oi' on low land where the 

 ground water is near the surface can successfullj" withstand a drought 

 that will prove disastrous to plants grown on an old field. The author 

 points out that it is more important to know the number of da3"s of 

 continuous drought than to know the number of inches of rain that 

 have fallen in a given time. 



Success in tobacco growing depends primarily upon the suppl}" of 

 fresh water. The weather and the texture of the soil are important 

 only as thej affect the water supply and the formation and movement 

 of salts. That the size of the soil particles is of little importance is 

 shown b}^ the fact that tobacco differing but slightly can be raised on 

 white clay or on coarse sand. 



Good tobacco can be grown in the neighborhood of the sea if the 

 location is sheltered from the sea breeze so that the salt particles are 

 not carried to the land. Good tobacco can not, however, be produced 

 on soil which contains salt, and the presence of salt-loving wild plants 

 indicates a soil unfit for tobacco growing. 



The quality of the leaf is injured when it contains large proportions 

 of lime, chlorids, sulphates, or nitrates. Potash is desirable since it 

 adds to the burning qualities of the leaf. Guano is a frequent source 

 of injur}^ because it affords such a ready suppl}' of nitrates. This is 

 particularly true during periods of drought, when the nitrifying bac- 

 teria are especially active and the nitrates are not washed out of the 

 soil b}^ the rains. During such dry periods the plants do not make a 

 vigorous root development and consequently they reach only a small 

 quantity of the potash which is fixed, while the mobile salts and the 

 lime arc carried up l)y the ascending water current and brought within 

 reach of the plant. The nitrates are absorbed by the plant and stored 

 in the leaf and injure the quality of the tobacco. — H. m. tieteks. 



