SULFATE OF AMMONIA. 



93 



millet was cut for hay when the seed had formed but had not filled out. 

 The crop of 1916 was a catch crop. The land had produced an excellent 

 crop of clover the preceding j'ear, and the stubble had been plowed under. 

 Potatoes were planted early in the spring of 1916, but the stand proved 

 too uneven to be satisfactory for the experiment, and the land was plowed 

 and seeded to millet in the early summer. The crop was ripened and cut 

 for seed. 



In 1913 continuous tillage with corn for two years had used most of the 

 organic nitrogen in the soil, and the sulfate of ammonia plots yielded 60 

 per cent more than those without nitrogen. In 1916, when there was a 

 lot of organic nitrogen from the clover stubble, the no-nitrogen plots 

 produced almost as well as those with ammonia. 



Table VIII. — Average Yield of Japmiese Millet {Pounds per Acre). 



No nitrogen, 

 Sulfate of ammonia, . 

 Percentage increase, 



6,230 

 6,430 



Limed over half area. Crop harvested as haj-. 

 After clover. Crop ripened for seed. 



Summary of Results by Crops. 



Corn was benefited by the sulfate of ammonia in 1906, 1912 and 1918 

 where lime was present and the land had not recentlj'' been in sod. In 

 1911, following four j^ears of grass and clover, the ammonia was in- 

 effective. Without lime, on old ground, in 1889 and 1918, ammonia was 

 ineffective. 



Oats responded to sulfate of ammonia every year in which they were 

 grown. The crop was least responsive in 1893, which was a season of 

 favorable rainfall, and the plots without nitrogen gave a maximum yield. 



Soy beans were benefited by the sulfate of ammonia, but its effective- 

 ness grew less as natural inoculation of the soil developed. 



Potatoes received little benefit from the ammonia under the conditions 

 of the experiment. 



Clover was discouraged by sulfate of ammonia in the absence of lime. 

 Redtop was benefited by the ammonia without lime. Grasses in general 

 require lime with the sulfate of ammonia. 



Japanese millet was much increased by the sulfate of ammonia on old 

 ground; but following clover the ammonia had but little effect. 



