THE FARMER'S MAGAZINE. 



191 



In class 3rd, where the yield is not only steadiest but 

 greatest, the proportion of nitrogen is /en*^. 



Arranged according to the several amounts of mineral 

 ingredient, the table may be abstracted thus : 

 Table IX. 



Putting aside the Experiment No. 12, as being in its 

 results too anomalous to be associated with any of the 

 other instances, here are presented three classes, ar- 

 ranged according to the several degrees of secular de" 

 crease exhibited by the experiments, and comprising all 

 the trials with substances composed wholly or in part of 

 nitrogenous salts ; and from this arrangement, it clearly 

 appears that — 



In class 1st, where the secular decrease is ike great- 

 e»t (and hence the progressive exhaustion of the soil 

 most strongly evinced), the mean proportioti of nitrogen, 

 in the three instances comprised in it, is the highest. 



In class 2nd, where the secular decrease is smaller, so 

 also is the mean amount of nitrogenous element. 



From this, the true conclusion seems to be the very 

 reverse of that deduced by the e.xperimentalists them- 

 selves, for here it would seem that if the mineral ele- 

 ments be applied in plenty to the soil, an abundant and 

 sustained yield will be procured, albeit the quantities of 

 nitrogen in the manure be proportionally very incon- 

 siderable. 



From these last tabulations, the experiments with 

 rape-cake have purposely been omitted, because com- 

 posed as that fertilizer is of substances in a state of 

 organic union, there is no rational analogy between 

 them and the crude salts forming the components of 

 factitious experimental matters. But even in this 

 organic manure, when supplemented with mineral in- 

 gredients, the same consequence of an increase of pro- 

 duce coincident with a decrease of the proportion of 

 nitrogen, exhibited itself. The following calculations 

 (but only approximate as regards the composition 

 rape-cake), are very conclusive on this point : 



X 



