

illustrations and arguments we have confined attention almost ex- 

 clusively to the nitrogen in the soils, we in any way ignore the 

 importance of a liberal available supply of the mineral constituents, 

 so essential for the effective action of the nitrogen. There is abundant 

 evidence, however, that the failures that have been cited have not 

 been due to a deficiency of mineral constituents. 



If, then, the supply of mineral constituents not being defective, 

 the yield of our crops is in the main dependent on the amount of 

 nitrogen which is available to them within th„ period of their growth 

 from the soil itself, or from manure applied to it, surely the fertility of 

 a soil must be largely measured by the amount of nitrogen it contains, 

 and the degree in which it becomes available. And, if this be so, is 

 not the soil a *' mine," as well as a laboratory ? 



In this connection, speaking here in America, it will not be in- 

 appropriate to conclude with a brief reference, such as the limited 

 data at our command will permit, to what we believe must be a cha- 

 racteristic difference between a large proportion of the comparatively 

 recently, or even not yet, broken up soils of this continent, and those 

 which have been long under arable culture on the other side of the 

 Atlantic. 



A sample of Illinois Prairie soil, obtained some years ago by Mr. 

 (now Sir) James Caird, and submitted by him for analysis to Dr. 

 Voelcker, to whom we are indebted, not only for his own analytical 

 results, but also for a sample of the soil itself, shows, by almost 

 identical results in the two laboratories, very nearly 0*25 per cent, of 

 nitrogen. We have no special history of this soil, nor do we 1 low 

 the depth to which it was taken ; but Dr. Voelcker informs us that 

 the sample supplied to us was a mixture of both soil and subsoil as 

 supplied to him, and that in the separate surface soil he found 0"33 

 per cent, of nitrogen. 



During the present year (1882), between forty and fifty samples of 

 soil from the North-west Territory, taken at intervals between Win- 

 nipeg and the Rocky Mountains, were sent over to the High Com- 

 missioner in London, and exhibited at the recent show of the Royal 

 Agricultural Society of England, at Reading. The soils were exhi- 

 bited in glass tubes four feet in length, and are stated to represent 

 the core of soil and subsoil to that depth. Three samples of the 

 surface soils have kindly been supplied to us for the determination 

 of the nitrogen in them : — 



No. 1 is from Portage le Prairie, about 60 miles from Winnipeg, 

 and has probably been under cultivation for several years. The dry 

 mould contained 0"2471 per cent, of nitrogen. 





^MEm' 



