[SHUTT & charron] NITROGEN-ENRICHMENT OF SOILS S7 



been shown, also performs a valuable function in liberating plant food 

 and in storing moisture for 'the crop of the succeeding year, but there 

 is no gainsaying the statement that it at the same time is most wasteful 

 of those stores of humus and nitrogen which for centuries have been 

 accumulating and which constitute mainly the factors — physical and 

 chemical — that give those ISTorth-west soils their great 'productiveness. 

 The practice of fallowing every 'third year — now very common in many 

 districts "of Manitoba and the Territories — would not lead to the same 

 loss of nitrogen as indicated in the soil under discussion, for it was 

 fallowed every other 5"ear; but we must conclude that this operation is 

 impoverishing the soil, perhaps slowly, but nevertheless very surely, 

 in spite of the fact that increased yields 'may immediately follow 

 its use. The remedy will lie in the adoption of some system of rotation 

 which "will lead to the periodical replenishing of the soil's humus and 

 nitrogen. 



"Whenever climatic conditions vrill allow, this restoration, mainten- 

 ance, and indeed increase, of fertility may be most readily and economic- 

 ally accomplished through the growth of one or other of the legumes — 

 a family of plants possessing the unique' and valuable property of appro- 

 priating the free nitrogen of the atmosphere. We need not stay now to 

 discuss the 'agencies by which this is brought about, further than to 

 say that the necessary bacteria for this useful work are widely present 

 in the soil, and that by their assistance considerable amounts of nitro- 

 gen may thus be captured. This nitrogen may be easily made available 

 for succeeding crops, simply through the natural decomposition of the 

 clover or other legume on turning the crop under. 



In the study of the 'manurial value of clover and other legumes 

 we have endeavoured to secure evidence (a) by analysis of the legume, 

 (h) by 'analysis of the soil, before sowing and after the decomposition 

 of the legume, and, (c) by determining the yields of various farm crops 

 follo"«'ing this use of the 'legumes. 



Nitrogen-Content of Various Legumes. 



Of the legumes examined from the standpoint of soil-enrichers, we 

 shall bring forward data respecting seven that have been more commonly 

 advised: — Common Eed 'Clover, Mammoth Bed Clover, Crimson Clover, 

 Alfalfa, Hairy 'Vetch, Soja Bean, and English Horse Bean. In the 

 subjoined table data are given respecting the weight and nitrogen- 

 content of the stems 'and leaves and of the roots (to a depth of 9 inches) 

 per acre from these crops during one season's growth. It is impos- 

 sible to say A.-hat proportion of the nitrogen here recorded has been 

 appropriated from the atmosphere, but since all the crops were well 

 provided with nodules on their roots we may rest assured that the 



