TRANSACTIONS OF SECTION B. 



687 



nitrogen 

 [nvh crops, 

 m tVdiu the 

 iwcver, no 

 iildgical 

 nil, results 

 after the 

 1 tri folium 

 took up 



nitropren as nitric acid ; and in the pxperiraents in question the deficiency of nitric 

 nit"ogen in the soil and subsoil of the vifia miira ])lot3, compared with the amount 

 ii, liiiose of the trifoUum ropcn.s plot tf> the depth examined, was sullicient to 

 account for a largo proportion of the nitrogen estimated to be contained in the 

 ririfi crops. 



Other experiments were quoted which bore less directly on the point, the 

 results of which were, however, accordant ; and tliey at the same time atlbrded 

 illustrations of tlie loss of nitro^^en that the land may sustain by fal'ow in a wet 

 season, and therefore of the benefits arising from the ground being covered with a 

 crop which tfikes up the nitric acid as it is produced. To conclude on this part of 

 ihe subject, it might be considered established that mucli, at any rate, of the 

 nitrogen of 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 led to the consideration of the second part of their subject, namely, the 

 sources of fertility of some Manitoba Prairie soils. 



Soils from I'ortage la Prairie, from the Saskatchewan district, and from u^-ar 

 Fort Illlice, were first examined. 'I'hey pro\ ed to be about twice as rich in nitiogeu 

 j\stlie average of arable soils in flreat liritain, and perhaps about as rich as the 

 average of the surface .soil of permanent pasture land. 



Four other ]Manito))a soils were examined in greater detail. One was from 

 Niverville, forty-four miles west of Winni])eg, the second from lirandon, the tJiird 

 from Selkirk, and the fourth from A\'innip;'g itself. Tliese soils sliowed a very 

 high ptM-centage of nitrogen; that from Xiverville nearly twice as In'gh apercentaffo 

 as in the first six or nine inches of ordinary arable land, and about Jis high as ia 

 the surface soil of pasture land, in Great Britain. 'J'he soil from JJrandon was not 

 so rich as that from Niverville; still tlie_fir.st twelve inches f)f depth was as rich as 

 the first six or nine inches of good old arable lands. 'J'h(^ soil from Selkirk 

 showed an extremely high percentage of nitrogen in thi> first twelve inches, and in 

 the second twelve inches as high a percentage as in ordinary pasture surface soil. 

 Lastly, both the first and second twelve inches of the soil from AN'innipeg were 

 shown to be very rich in nitrogen, richer than the average of old pasture surface 

 soil. 



The question arose — how far the nitrogen in these soils was susceptible of nitrifi- 

 cation, and so of becoming easily available to vegetation. The soils and subsoils 

 were placed in .shallow dishes, covered with plates of glass, kept under proper 

 conditions of temperature and moisture for .specified periods, extracted from time 

 to time, and the nitric acid determined in the extracts. 



The periods were never less than twenty-eight day.s, and sometimes more. The 

 rate of nitrification declined after tlie third and fourth periods. There was a very 

 marked increase in the rate of nitrification in the subsoils during the eighth period 

 compared with the seventh, there having been oidy as much as a tenth of a gram 

 of giirden soil containing nitrifying organisms added. This r(>3nlt was of much 

 interest, aflbrding confirmn'ion of the view that the nitrogen of subsoils is subject, 

 to nitrification, if only under suitable conditions, and that the growth of deep-rooted 

 plants may favour nitrification in the lower layers, 



liecords show that the rich prairie soils of the North-west are competent to 

 yield large crops: but under existing conditions they certainly do not, on the 

 average, yield amounts at all commensurate with tlicir richness C()ni])Mred with tiie 

 soils of Great liritain which have been under arable cultivation for centuries That tlie 

 rich prairie soils do not viehl more produce tbiin they do, isdue])artly to climate but 

 largely to scarcity of ia))Our, and consiviuent imperfect cultivation, iuid too luxuriant 

 a growth of weeds ; and until mixed agriculture, with stock fee( ling, can be had 

 recourse to, and loc;il demand nrises. the burning of the straw, and deficiency or 

 waste of manure, are nmre or less inevitnl)le, but still exhausting iiractices. So 

 lung as land is cheap and labour dear some sacrifice of fertility is miavoidable in the 

 process of bringing these virgin soils under prolitable cultivatio?i ; and the only 

 remedy is to be found in increase of population. Still the fact should not lie lost 

 .-iglil of. lluil such practices of early settl-'nient, however unavoidable, do involve 

 serious kiss of fertility. 



I. 



