94 HATCH EXPERIMENT STATION. [Jan. 



100 ; barnyard manure, 90 ; sulfate of ammonia, 89 ; dried 

 blood, 86 ; the plots receiving no nitrogen, 68. 



It should be [)ointed out : («) That the figure for l)arn- 

 yard manure is probal)ly not a correct indication of the rela- 

 tive efliciency of the nitrogen it contains, because barnyard 

 manure su})plics humus and considerable quantities of lime, 

 magnesia and other minerals which are not supplied by the 

 fertilizers used on the other plots. These constituents of the 

 barnyard manure are in almost all cases useful. The crops 

 where manure is used, therefore, stand relatively higher than 

 the availability of the nitrogen alone would warrant. (6) It 

 is ini})ortant to point out, further, that the relative standing 

 of the sulfite of ammonia is lower than it undoubtedly would 

 have been had lime been more largely used. Before these 

 plots were limed the crops in some years were almost an 

 absolute failure. Comparing the yields on the sulfate of 

 ammonia with those on the nitrate plots for the years only 

 wliich immediately follow the application of lime, we find, 

 representing the yield on the nitrate of soda as 100, that the 

 yield of the sulfate of ammonia is 101. The conclusion is 

 inevitable, that, if we are to depend upon sulfate of ammonia 

 as a source of nitrogen, we shall be obliged upon many of 

 our soils to occasionally use considerable quantities of lime 

 in connection with it. Since, however, a given quantity of 

 nitrogen in the form of sulfate of ammonia costs more than 

 the same quantity in the form of nitrate of soda, it is evident 

 that the latter should usually be preferred. The nitrate of 

 soda, however, is not so readily used in mixture with other 

 fertilizers, on account of its tendency to become moist. 

 Such materials as sulfate of ammonia and dried blood are far 

 more likely to remain dry, and can therefore l)e more readily 

 incorporated with other materials in manufacturing fertilizers 

 or in making home mixtures. 



II. — Crops of the Clover Family (Legumes) as Ni- 

 trogen Gatherers. 

 This experiment is carried out in connection with the 

 experiments to determine the relative value of different ma- 

 terials furnishing nitrogen on Field A . Both soy beans and 



