28 Transactions of the Canadian Institute, [vol. x 



equal the net gain, so that we may conclude the clover added to the 

 soil in the neighbourhood of lOO lbs. per acre per annum. 



And lastly, in this connection I have to speak of our work with 

 bacterial cultures for inoculating the soil with those nitrogen-fixing or- 

 ganisms that permit the legume to draw upon the store of free nitrogen 

 in the atmosphere. The details of this investigation are very volumi- 

 nous, for the merits of many European, American and Canadian cultures 

 have been tested in pots and, on a larger scale, in half -acre plots. It 

 must suffice now to say that while some proved effective in promoting the 

 growth of the legumes, many proved worthless, no doubt due largely 

 to the susceptibility of the organisms in the cultures to light and heat. 

 Their vitality becomes seriously impaired with the keeping of the pre- 

 paration. Cultures, therefore, unless fresh cannot be depended upon, and 

 experience has taught us that the best inoculating material for clover 

 or alfalfa is the surface soil from a field that has recently grown clover 

 or alfalfa. 



About 300 lbs. of soil are required per acre, broadcasted and har- 

 rowed in. This is the surest and most direct method of inoculation. 

 Such soil can be obtained from nearly all the Experimental Farms on 

 payment of a small fee to cover the necessary freight charges. 



Though it has been conclusively shown that there are districts in 

 which inoculation is useful, it should be noted that inoculation is not 

 generally necessary. The nitrogen-fixing bacteria are not restricted to 

 a few small or isolated areas — our observations have proved that — and 

 we have reason to believe that many failures with clover have been due 

 to lack of moisture, poverty in humus, sourness or an unfavourable me- 

 chanical condition of the soil, rather than to absence of these valuable 

 organisms. 



Perhaps at this juncture I should say something of the use of the 

 so-called chemical or commercial fertilisers. Have they a place in a 

 rational, economic farming system? We Delieve they have, but it must 

 be secondary to the means I have outlined for the up-keep of fertility. 

 Fertilisers are no substitute for farm manures, though they can fre- 

 quently be used profitably as supplemental to manures. They furnish 

 plant food in available forms, but they do not add humus-forming ma- 

 terial, so necessary to the formation of a comfortable habitat for plants 

 and the retention of a due proportion of moisture. They are frequently 

 a snare to the poor farmer who depends solely upon them, but they 

 may be employed with great profit at times by one who conducts his 

 operations on rational lines. The farmer who would use them with 

 profit must keep up the organic content of his soil and be prepared to 

 do some experimental work. In general farming they have not as yet 



