1897.] PUBLIC DOCUMENT — No. 33. 183 



For details I have to refer to previous annual reports. 



The foUowiiiir local observations are worth mentioning 

 again on this occasion : — 



(a) Alfalfa (^Medicago saliva) and crimson clover {Tri- 

 folium vicarnatum)y in repeated trials, sufl'ered seriously 

 from winter-killing. This result has to be ascribed more to 

 late frosts early in spring, when the ground is filled with 

 water, than to the severity of mid-winter. 



(6) Mixed crops of peas, vetch and horse bean, and 

 vetch and oats or barley have given, as a rule, ver\^ satisfac- 

 tory returns as far as quality and quantity are concerned. 



(c) Soy beans, early and late varieties, have yielded, as 

 a rule, daring average seasons large crops ; yet they have 

 failed to enrich the soil they were raised upon sufficiently 

 in available nitrogen plant food to secure under otherwise 

 corresponding conditions, as far as the supply of available 

 potash and phosphoric acid is concerned, as high a yield of 

 a succeeding crop of rye, oats, barley and even soy bean, 

 as Avhere from forty to fifty pounds per acre of an available 

 form of nitrogen were added. The liberal addition of nitrates 

 to the soil interfered with a liberal development of root 

 tubercles, in case of soj' bean, in a well-infected soil. 



Similar results are reported by other investigators in 

 regard to lupines followed by oats or potatoes ; an addition 

 of nitrates in connection with a potash and phosphoric acid 

 containing fertilizer increased the yield. The infection of 

 the soil by lupine bacterium did not benefit the growth of 

 other leguminous crops. 



The belief that each variety of leguminous crop is associ- 

 ated with a root bacterium of its own finds support in the 

 circumstance that the root tubercles of different varieties of 

 these crops quite frequently vary, not only in size and shape 

 but in their mode of distribution over the main roots or root- 

 lets. Illustrations of this feature have been furnished by the 

 writer in form of photographs from nature in case of soy 

 bean, horse bean, lupines, etc., (see State station report for 

 1894). 



Much has been learned regarding the symbiotic or com- 

 bined life of root bacteria and leguminous plants, yet much 

 further investijration in the vea'ctation house and the field 



