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ROYAL SOCIETY OF CANADA 



that might be considered as part and parcel of the soil, derived from 

 the growth of clover. 



The work was carried on in experimental pots and in small plots, 

 soil poor in nitrogen being purposely selected for the investigation 

 The plan in outline was to 'determine as accurately as possible the soil's 

 nitrogen content at the outset, to sow it with clover, to return the 

 crop to the soil and after its decay to again determine the soil's nitrogen. 



Pot Experiments: — Twenty-one pots, each having a diameter of 8 

 inches and a depth of 13 inches, were filled to a height of 9 inches 

 with a soil containing 00392 per cent nitrogen. These were sown 

 with Mammoth Eed clover on May 13th, 1902. On the 13th October 

 of the same year (1902) the crop (including the roots) was taken up, 

 cut very fine and returned to the soil, the cut clover and the soil being 

 thoroughly mixed. Throughout the following winter the pots were 

 kept in the laboratory building and the soil maintained in a moist con- 

 dition 'so that the decay of the clover might be as complete as possible. 

 On the 13th June, 1903, the pots were again sown with Mammoth Eed 

 clover, and the growth returned to the soil in the autumn as in the 

 pre\dous year. In the spring of 1904 (May 14th) the soils were again 

 thoroughly mixed 'and sampled, the undecomposed root fibre separated 

 by sieves, and again analyzed. The result was 0-0457 per cent nitrogen. 



Plot Experiment: — Similarly, and simultaneous with the Pot 

 experiments, a trial was made on a plot covering ^/ggo of an acre, soil 

 of a uniform character being used to cover it to a depth of 8 inches. 

 This plot was sown with Mammoth Eed clover seed on May 13th, 1902. 

 During the season's growth the clover was cut twice and allowed to 

 decay on the soil. At the close of the season the crop was turned 

 under, 'the soil being stirred to a depth of 4 inches. In the following 

 spring (1903) the plot was again sown with clover which made a very 

 fair growth. This was cut twice and finally turned under as during 

 the previous year. On May 14th, 1904, the soil of the plot was again 

 sampled to a depth of 4 inches and its nitrogen-content determined. 

 As in the case of the pots, there was a marked increase in the nitro- 

 gen, as the following tabulated statement will show : — ' 



