No. 4.] CHEMICAL AND FARM MANURES. 147 



Owing to these losses and transformations, it is now gener- 

 ally considered that the efficiency of nitrogen in the form 

 of sulfate of ammonia is only about nine-tenths as great as 

 that in the form of nitrates ; so that, for all purposes where 

 the nitrate suits the peculiar needs, sulfate of ammonia 

 would not be substituted for it until the price of nitrogen in 

 that substance has dropped to a point somewhat l^elow the 

 price of nitrate of soda. In using the two compounds, it 

 should be borne in mind that commercial nitrate of soda con- 

 tains about 15.5 pounds of nitrogen per 100 pounds, while 

 sulfate of ammonia contains 20.5 pounds. For this reason, 

 76 pounds of sulfate of ammonia may be used in the place 

 of 100 pounds of nitrate of soda, or 132 pounds of nitrate 

 of soda may take the place of 100 pounds of the sulfate of 

 ammonia, without materially changing the quantities of 

 nitrogen employed. 



In choosing between sulfate of ammonia and nitrate of 

 soda as a source of nitrogen for our crops, there are still 

 other factors to be considered. If one employs sulfate of 

 ammonia, continuously, on soils which are somewhat acid 

 and consequently deficient in carbonate (jf lime, the condi- 

 tions become more and more aggravated, until the material, 

 instead of serving as a valuable manure, becomes a veritable 

 poison. An instance of this kind was recorded by Professor 

 Sanborn in the early history of the New Hampshire station, 

 then at Hanover. At Abbott Run, R. I., upon the third 

 annual application of sulfate of ammonia the crop began to 

 fall off noticeably. At Hope Valley, R. I., the crop fell off 

 materially the second year, while a positive poisonous action 

 was noticed the third year. At Kingston, R. I., the sulfate 

 of ammonia exerted a poisonous action the first season. 

 Certain European experience points also to a marked inef- 

 ficienc}'^ of sulfate of ammonia upon certain soils, and an 

 instance of this kind is also on record near at home, the 

 same having been observed at North Hadley, in your own 

 State. The value of lime as a corrector of such conditions 

 was brought out simultaneously by Wagner and Dorsch in 

 Germany, and at the Rhode Island station in the former 

 instance in a trial of a single variety of plants, and at 

 Rhode Island with thirty-eight different varieties. Professor 



