THE FARMER'S MAGAZINE. 



189 



Hence, then, not only does this experiment possess 

 the significant characteristic of secular permanency of 

 yield, but also this other striking peculiarity, of ex- 

 hibiting a higher rate of productiveness than any other 

 of the entire list ; and in every respect, therefore, it is 

 entitled to receive very special consideration; and to 

 this end we present the following comparative table : 



? S5 



E, =»■ =r 





oo eo w 



lO C,3 U» 



i? ro oj CO 05 I — 



en , 



Ul^ItOI-'pCOJOps cog 

 OOOiDOOOOO* 



8 B 



M-3 It 



S S " 





2 o 



to ;v3 o <i CO CO o en 

 'o> io --J to OS CO CO io 



il a- 

 b •" 



S'WS 



p o s 





— 2. 3' 



o P 



- ■" p, 

 « o 2. 



^ O O 



! O^ 3 



o „ c 



P 3 3 



rJ -J o 



From this table, then, is seen how coincident in 

 quality in every respect, save in silica, are the several 

 chemical ingredients of the manure and of the produce 

 raised by it j and probably the silicious element of vege- 

 tation is seldom otherwise than naturally superabundant 

 in all soils containing a moderate proportion of clay. 



In trial 17th, therefore, is presented a manure theo- 

 retically Tperlect, since it embraces in its conr position 

 every one of the mineral constituents of vegetative fer- 

 tility, and no less practically an effective one, since not 

 only did its use very largely enhance the yearly crop to 

 which it was applied, but maintained an unflagging pro- 

 ductiveness throughout the entire period of six succes- 

 sive years during which its use was repeated. Here, 

 then, are found all the elements required to constitute 



a valuable test ; and, thus, with the aid of this experi- 

 ment No. 17, as a gauge or standard of comparison, it 

 may now be possible to discover how well or ill-founded 

 are certain general conclusions deduced by the experi- 

 menters themselves from the experimental data, and 

 txpretsed at p. 492 of their report — 



" From a review," they there write, "of the whole 

 of the results relating to the action of special manures 

 upon the barley crop," &c., "we learn that exclusively 

 mineral manures, and especially those containing phos- 

 phoric acitl, annually increased the produce of barley, 

 even doing so in the first year of their application on the 

 land in the condition described." 



The following figures give the experimental parti- 

 culars falling within the scope of this proposition— 



Exp. 



Table III. 

 -Superphosphate of Lime. 



Produce 



Mean of second period of three years 

 True gauge mean 



Comparative deficiency 21 2f 



E.xp. 4. — Mixed Alkaiies, 



b. p. 



Mean of second period of three years 27 3 



Gauge mean £0 2| 



Comparative deficiency 22 3| 



Exp. 6. — Superphosphate of Lime and Mixed Alkalies. 



b. p. 



Mean of second period of three years 32 1 



Gauge mean 50 2 J 



Comparative deficiency 18 IJ 



(The mean of the second period is here and subse- 

 quently adopted in comparison, as being of more ap- 

 proximate accuracy than thatof the first period, whether 

 in decreasing or increasing instances.) 



Of these three experimental manures, it must further 

 be remarked, that although relatively inefficient when 

 compared with the true gauge, they certainly exhibit 

 some fertilizing influence when tested by the unmanured 

 experiment Nos. 1 and 2 ; No. 5, in this point of view, 

 showing an increase of 3 b. 2i p. per annum. No. 4 of 

 3|p., and No. 6 of 6 b. 2 p. But this manifestation of 

 fertile power, relatively small as it is, is no less a com- 

 plete exemplification of Liebig's teaching, which assigns 

 to every seemingly successful special manure, whether 

 nitrogenous, phosphatic, or alkaline, an exhaustive 

 character. This is demonstrated by the following 

 figures — 



Table IV. 



Ex. 5. Ex. 4. Ex. 6 



Produce of these three experi- 

 ments severally in the first 

 period of three years 34 



Produce of these three experi- 

 ments severally in the second 

 period of three years 29 



b. p. 



b. p. b. p. 



30 36 3 



27 3 



1 



Secular decrease per acre 

 per aunum 5 2 1 4 2 



Here it is plainly seen that the greatest yields at first 

 fell off most latterly. 



The second conclusion deduced by the experimenters 

 is as follows — 



" That with barley grown continuously on the Earn 

 land (as was the case with wheat), nitrogenous manure 

 had a much more striking effect than mineral manures." 



