FERTILIZERS. 



387 



nitric iiitrogiMi originally present is (leterniined by e()mpariii«^- tlie tint 

 obtained with that of a type solution of picrate ot ammonia, (1 mg. per 

 liter). 



For the determination of ammoniacal nitrogen grind 10 gm. of the 

 fresh i)lant in a mortar and i)la('e it in a Ihisk with 50 cc. of water, 0.5 

 gm. of magnesia, a few pieces of pnmice stone, and a small cpiantity of 

 paraffin. Connect the flask with a condenser an<l distill off about three- 

 fourths of its contents into a flask containing a few drops of very dilute 

 snlphuric acid. Make up the distillate to 50 cc. and test with Kessler 

 solution. 



Vegetation experiments on the availability of nitrogen in cer- 

 tain nitrogenous materials, S. W. Johnson, W, E. Britton, and 

 E. 11. Jenkins {CoimtrUcut iState H^ta. Ept. 1895, p}). 99-116). — Work of 

 previous years in this line (E. S. E., 7, p. 191) was continued during 

 1805. To the soils (in pots) used the previous year additional fertiliz- 

 ing materials were added and a crop of oats was grown, followed by a 

 crop of corn. The nitrogenous fertilizers tested and the method pur- 

 sued were practically the same as in 1894. 



The oat plants receiving organic nitrogen were sickly in appearance 

 and some of those receiving the heavier applications died. The corn 

 crop was also very irregular. 



"Our own experiments illtistrate wliat has been abiiudantly demonstrated by 

 others, that the weight of dry matter harvested (water-free crop) is uo certain 

 measure of the nitrogen assimilated bj- the crop; . . . but the determination of 

 the nitrogen actually taken up by the crops from the fertilizer makes the results 

 intelligible." 



Consequently this basis is adopted for the calculation of the availa- 

 bility of the different forms of nitrogen. The details are tabulated and 

 discussed in full. 



Summarizing this data, the relative efficiency of the A'^arious fertilizers 

 as sources of nitrogen to the corn and oat crops in 1891 and 1805 may 

 be stated (in round numbers) as follows : 



Rclatice effickncij of different forma of nltroyeii on corn and oats, 1SD4, 1805. 



N itrate ol' soda 



Castor pomace A 



Castor pomace l{ 



AverageT)t' castor pomace A and B 



Cotton-seed meal 



Linseed meal 



Dried blood 



Dry fish 



Dissolved leatlier 



Horn and liooC 



Tankane 



Steamed leather 



Roasted leather 



Kaw leather 



