Points in the Composition of Soils. 145- 



account for a lanre proportion of the nitrogen estimated to be- 

 contained in the Vicia crops. 



Other experiments were quoted, which bear less directly on the 

 point, the results of which are, however, accordant ; and they at 

 the same time afford illustrations of the loss of nitrogen that the 

 land may sustain by fallow in a wet season, and therefore of the 

 benefits arising from the ground being covered with a crop which 

 takes np the nitrate as it is produced. To conclude on this part 

 of the subject, it may be considered as established that much, at 

 any rate, of the nitrogen of the crops is derived from the stores 

 within the soil, and that much, and in some cases the whole, of the 

 nitrogen so derived is taken up as nitrates. 



This leads the authors to the consideration of the second part 

 of their subject, namely, the sources of the fertility of some Mani- 

 toba prairie soils. 



Soils from Portage la Prairie, from the Saskatchewan district 

 and from near Fort Ellice, were first examined. They proved to 

 be about twice as rich in nitrogen as the average of arable soils 

 n Great Britain, and perhaps about as rich as the average of the. 

 surface soil of permanent pasture land. 



Four other Manitoba soils were examined in greater detail, one 

 was from Niverville, forty-four miles west of Winnipeg, the 

 second from Brandon, the third from Selkirk, and the fourth from 

 Winnipeg itself. These soils show a very high percentage e£ 

 nitrogen ; that from Niverville nearly twice as high a percen:. _ 

 as in the first six or nine inches of ordinary arable land,, 

 about as high as in the surface soil of pasture land in Great 

 Britain. The soil from Brandon is not so rich as that from 

 Niverville, still the first twelve inches of depth are as rich 

 as the first six or nine inches of good arable lands.. The soil- 

 from Selkirk shows an extremely high percentage of nitrogen, 

 in the first twelve inches, and in the second twelve iac^es as 

 high a percentage as in ordinary pasture surface soil. Lastly^ 

 both the first and second twelve inches of the soil from Winnipeg- 

 are shown to be very rich in nitrogen — richer than the average of. 

 old pasture surface soil. 



The question arises, how far the nitrogen in these soils is 

 susceptible of nitrification and so of becoming easily available fou- 

 vegetation ? The soils and subsoils are placed in shallow dishes.. 



10 



