130 EXPERIMENTAL FARMS 



5-6 EDWARD Vil., A. 1906 



The data fumish further evidence of a very satisfactory character concerning the 

 manurial value of clover. In one set of trials, two seasons of clover had enriched the 

 soil with nitrogen to the amount of 179 lbs. per acre, calculated to a depth of 9 inches ; 

 in the other, calculated to a depth of 4 inches, the increase was 1Y5 lbs. per acre. This 

 nitrogen, although not present in an immediately available condition, is associated 

 with readily decomposable organic matter and would be set free for the use of succeed- 

 ing crops.* 



INOCULATION FOE THE GROWTH OF LEGUMES. 



A statement regarding the results of work carried on in this investigation since 

 1896, by the Experimental Farms, was given in the report of this Division for last year 

 (1904). After briefly recounting the resvilts we had obtained from the use of German 

 and American cultures, the opinion was expressed that the necessity for inoculation was 

 by no means so great as was supposed by many; in other v/ords, that the soil bacteria 

 that serve to fix the nitrogen in the legumes had been found to be widely distributed 

 over the Dominion. Our experience this year confirms this view. During the past sea- 

 son, clover plants have been received from several districts in Manitoba, all bearing 

 nodules on their roots. Observation has gone to show that in the majority of cases in 

 which there has been failure to obtain a good catch of clover that one or more of the 

 following causes have been to blame rather than the absence of the necessary bacteria : 

 Deficiency of moistvire ; unsuitable mechanical condition of the soil, due to lack of 

 humus, inadequate drainage, or improper working of the soil; acidity or sourness of 

 the soil ; poor seed ; or, if the crop failed the second season, the severity of the winter. 



Last season (1904) we experimented with the new cultures for clover and alfalfa 

 supplied by the Bureau of Plant Industry, Washington, D.C. The results were, on the 

 whole, unsatisfactory, and we were consequently not in a position to report very favour- 

 ably. This season we have continued the investigation with the Washington cultures, 

 and also have experimented with those supplied by the Ontario Agricultural College, 

 Guelph, the latter being kindly furnished by Prof. Harrison, Bacteriologist. The trials 

 were conducted in pots and plots. 



POT EXPERIJilENTS. 



These were made in clean, new flowers pots, with a diameter at the top of 11 inches 

 and a depth of 13 inches. The soil was a light sandy loam of poor quality. After sow- 

 ing, the pots were plunged, the rim (2 inches) only being above the surface of the soil. 

 This was done in order to avoid as far as possible sudden changes in temperature and 

 moisture content. 



The inoculating fluids were prepared in accordance with instructions received with 

 the cultures. In the case of the ' seed inoculated,' the seed was immersed in the cul- 

 tural preparation for a few minutes and then allowed to dry by exposure to the air; 

 with the ' soil inoculated ' the inoculating fluid was used to moisten the soil to a depth, 

 approximately, of one inch. The same number of seeds were sown in each pot. 



Note. — The relatively larger increase in nitrogen obtained in the plot experiment may 

 be accounted for by the fact, often observed, that the greater part of the root system of the 

 clover lies in the first or upper six inches of soil. It is also possible that there had been 

 a more complete decomposition of the clover in the plot than in the pots. 



