58 Thf. Ottawa Naturalist. iJu'y 



and, therefore, the turned-under clover crops can be considered 

 as adding largely to the mineral supply of the superficial soil 

 layer. But the feature specially worthy of note in this connec- 

 tion is that this mineral food now offered as humates for the use 

 of succeeding crops, is much more available than before the 

 clover appropriated it ; it is, as it were, already digested and, 

 therefore, the more easy of assimilation. To these benefits must 

 be added the good work that clover does as a "catch" crop, pre- 

 venting the loss of soluble nitrates and olher plant food through 

 the leaching action of autumn rains. 



Though it has oeen long known in a vague and indefinite way 

 that clover, unlike other crops, benefited rather than impoverished 

 the soil, that the yield of grain after a crop of clover was greater 

 than it would have been without such a previous seeding of clover, 

 there has not been until lately any intelligent appreciation or appli- 

 cation of the truth involved. The practice ot soil enrichment by 

 means of clover has only received anything like general attention 

 on the part of our farmers in Canada during the last few years, 

 though since the announcement of Hellriegel and Wilfarth in 1886, 

 furnishing proof that the legumes appropriated the uncombined 

 nitrogen of the air, there has been more or less interest evinced in 

 the subject by those who were keeping abreast of the times. 



Since the spring of 1893 systematic investigatory work to 

 determine the fertilizing value of the clover crop has been prose- 

 cuted on the Central Experimental Farm, Ottawa. Experiments 

 on the branch experimental farms commenced in 1896. 



In most of our trials the clover has been sown with grain, 

 wheat or barley, in the spring. This has always resulted in a good 

 stand of clover before the close of the season, as it grows rapidly 

 after the grain is harvested. If the land is intended for grain, the 

 ploughing under of the clover is done late in the autumn; if a crop 

 of potatoes or Indian corn is to be grown the next season, the 

 clover is left till the following spring, when about the second or 

 third week of May the clover will be quite heavy and furnish a 

 large amount of material for turning under. Our first experiment, 

 the clover having been sown in the spring with grain and the 

 estimations made in the following May, showed the nitrogen con- 

 tained in the crop ot one year's growth, including the roots taken 



