NITROGENOUS FERTILIZERS FOR TOBACCO 7 



Table 3. — Mean burn in seconds of tobacco grown with different 

 nitrogen carriers supplying one-half the nitrogen, 1932-1934 



Carrier 



Nitrate of soda 



Sulfate of ammonia ... 



Calcium cyanamid .... 



Urea 



Standard mixture .... 



The possible relation of form of fertilizer nitrogen to degree of infestation 

 of brown root-rot of tobacco was studied. The percentage of infection was 

 determined by random sampling, and the results are given in Table 4. No 

 consistent differences due to treatment were noted. If, as has been suggested 

 by one of the authors, brown root-rot of tobacco is caused by the rapid ab- 

 sorption of unoxidized forms of nitrogen, it appears from the present experi- 

 ment that the form of fertilizer nitrogen used is in itself an unimportant factor. 

 The nature of the preceding crop and the amount and distribution of rainfall 

 appear to be the dominant factors affecting brown root-rot. 



Table 4. — Percentage of brown root-rot in tobacco grown with dif- 

 ferent NITROGEN CARRIERS SUPPLYING ONE-HALF THE NITROGEN, 1932-1935 



The fact that, according to these figures, sulfate of ammonia and urea did 

 not lower the reaction, suggests that because of a seasonal difference in time 

 of sampling, all the values in the second column are a little high. Long- 

 continued use of these fertilizer materials would no doubt accentuate differences 

 here indicated and possibly produce soil conditions unfavorable to the best 

 growth of tobacco. 



Ratio of Organic to Inorganic Nitrogen in Fertilizer 



As previously stated, good fertilizer practice in the growing of tobacco in 

 the Connecticut Valley has demanded a fertilizer containing a high percentage 

 of organic nitrogen. The organic nitrogen carrier in demand has been a seed 



