6 MASS. EXPERIMENT STATION BULLETIN 346 



was supplied by these forms and the other half by cottonseed meal. Nitrogen 

 was used at the rate of 175 pounds to the acre. The phosphoric acid and 

 potash were from the same sources and at the same rates as those used in the 

 first experiment, except that high grade sulfate of potash was used instead of 

 nitrate of potash. The standard mixture, also, was of the same composition 

 as in the first experiment except that the amount of nitrogen was uniformly 

 at the rate of 175 pounds. This experiment, as were the others reported in 

 this bulletin, was run with quadruplicated plot treatments, and plots were 

 also one fortieth acre in size. The mean of the yield, grade index, and crop 

 index for four years is given in Table 2. 



Table 2. — Mean yield and grade of tobacco grown with different 

 nitrogen carriers supplying one-half the nitrogen, 1932-1935 



Carrier Yield, Lbs. 'A Grade Index Crop Index 



The differences shown are not considered significant, although a strong trend 

 is indicated in favor of tobacco supplied with nitrate of soda over that grown 

 with other forms of nitrogen. Little superiority is shown by the treatment 

 containing nitrate of soda over the standard mixture, as reflected in the crop 

 index. The difference is due to the grade index, not the yield, which is slightly 

 higher from the standard mixture. It should be noted, however, that the 

 standard mixture contained considerable nitrate nitrogen both in nitrate of 

 soda and nitrate of potash. 



Calcium cyanamid produced the highest yield and best grade of tobacco 

 the first year. In the following years nitrate of soda produced the best grade 

 and highest yield, except for one year when it was exceeded by the standard 

 mixture. The grading quality of tobacco fertilized with sulfate of ammonia 

 sulered more than did the yield. Calcium cyanamid and urea were erratic in 

 their eTects. However, all treatments produced tobacco of better than aver- 

 age yield and grade throughout the experiment as a whole. 



The effect of fertilizer treatment on burning quality of the tobacco is shown 

 in Table 3. The comparatively poor fire-holding capacity of tobacco fertilized 

 with sulfate of ammonia conforms with results of experiments conducted else- 

 where and with practical experience. Nitrate of soda showed marked superi- 

 ority in its effect on burn, and most likely the nitrate content of the standard 

 mixture contributed to the good effect of that fertilizer. It is not known from 

 the present experiment whether the beneficial effect of the nitrate was direct, 

 in the sense that it increased the nitrate content of the leaf, or whether its 

 beneficial action was primarily indirect. Experiments conducted at the 

 Connecticut Experiment Station (1 showed that tobacco leaves containing 

 potassium nitrate gave perfect fire-holding capacity, but high concentrations 

 produced a black ash and an undesirable sputtering and sparkling. 



