«/. //. Gi'lh-jrl— Pwnts i 



Dr. J. H. Gilbkb' 



i with Vegetation ; by 



[(Vmt 



n page 32.] 



Amount of nitrogen assimilated by plants.— Let us now recur 

 to the question of the various amounts of nitrogen assimilated 

 over a given area by plants of different natural orders, and call 

 attention to the facts bearing upon the point which these 

 experiments on the mixed herbage of grass land have supplied. 



Table IV". — Yiel 



of Pa; 



"~ 



ac 



V' r '~. 





'vsvzssr 





§ 



# # 



°S£ 



1SS? 



i:z: 



TJnmanured 



BfaL Manure, t 



Complex Min. Manure4 



l 



Zt 



1 



li 



■iii 





In Table IV. is i 

 of hay) in lbs., per 

 "3 of the gramin 



i the average produce (in the condition 

 per annum, over twenty years, of herb- 



family, of herbage of the l< _ 



family, and of herbage of other order.-, cm'.: 



-of each of these, determined in ?«• 

 at six pertods, namely, in 1862, 1867, 1871, 1872, 1874, and 

 1875, in samples of the produce of four of the plots \vh 

 received no nitrogenous manure from the commencement: 

 and there is also given, by the side of these results, the average 

 annual yield of nitrogen 'per acre over the first ten, the second 

 the total period of twenty years, in each case. 

 The quantities ot nitro n viebl 1 r. cnlculated from the 

 results of actual determinations of the nitrogen in the mixed 

 produce of the respective plots ; but the esth 

 tity of the produce referable to the different Natural Orders 

 must be taken as only giving a general indication or an 

 approximation to the truth; for, while the amount of tne 

 total mixed " f the twenty years, 



■ 



rations only, namely, 1! 



