166 MASS. EXPERIMENT STATION BULLETIN 193. 



years by the gradual decline in the jaeld of tobacco. The table below 

 shows this decline, not steady from year to year, but an actual decline. 

 The average yield for the five-year period from 1905 to 1909 was 1,675 

 pounds in Massachusetts and 1,660 in Connecticut; from 1910 to 1914 it 

 was 1,676 in Massachusetts and 1,675 in Connecticut; while for the four 

 years succeeding, the average was 1,382 poimds in Massachusetts and 

 1,445 in Connecticut. The average for the whole period, however, was 

 1,592 for Massachusetts and 1,604 for Connecticut, both still well above 

 the average for the period from 1870 to 1910. Of course the decrease 

 from 1913 to 1918 is largely due to the poor growing season of 1915, to the 

 ^vind storms of 1916 and 1917, and to the excessive hail and the late frost 

 of 1917. 



Table 17. — Yields per Acre (Poiinds).^ 



Year. 



1880, 



1890, 



1900, 



1905, 



1906, 



1907, 



1908, 



1909, 



1910, 



1911, 



1912, 



1913, 



1914, 



1915, 



1916,2 



1917,2 



1918, 



1 Figures from United States Department of Agriculture, Bureau of Crop Estimates. 



2 1916 and 1917 are revised estimates made by the Massachusetts Agricultural College and 

 tobacco packers. 



This decrease has been attributed to many causes, such as a hurtful 

 accumulation of saline matters soluble in water, nitrates, sulfates and 

 chlorides of potash, soda, lime and magnesia, in the surface soil; or an 

 alkaUne condition of the soil, resulting from the use of tobacco ash elements, 

 cotton hull ash or carbonate of potash. However, the experiment stations 

 have questioned the truth of these two assumptions. Some attribute the 

 short crop of the last few years to the unnoticed prevalence of root rot in 



