28 a EXPERIMENT STATION. [Jan. 



bility of producing splendid crops of clover on a soil physically 

 well adapted to the crop and liberally supplied with materials 

 furnishing phosphoric acid and potash without any application 

 whatever of nitrogen fertilizers during the long period of time 

 that the experiment has continued. On the limed portions of 

 the different plots, the no-nitrogen plots in 1915 gave yields 

 practically identical with those produced on plots where dried 

 blood as a source of nitrogen has been applied in liberal amounts 

 annually. The yield on the limed portion of the no-nitrogen 

 plots was only slightly inferior to the yields obtained where 

 nitrate of soda and sulfate of ammonia have been annually 

 applied, and the plots which have received no applied nitrogen 

 in any form during twenty-six years gave a yield of clover at 

 the rate of 253 pounds per acre greater than that produced 

 where manure has been applied annually. If we include both 

 the limed and unlimed portions of all the plots, the yield on 

 the plots to which no nitrogen has been applied for twenty-six 

 years was last year substantially equal to the yield on any of 

 the plots, and was at the rate of slightly over four tons per 

 acre. These results indicate clearly that the highest economy 

 in the production of clover is not possible when manure is 

 applied to the land; manure should certainly be reserved for 

 other crops. 



The report presents extensive averages which show in a 

 striking way the relative adaptation to different crops of the 

 two leading potash salts, muriate and high-grade sulfate. 

 Among crops for which the former is the best, as shown in 

 most cases by results extending over a considerable number of 

 years, are asparagus, currants, sugar beets, ensilage corn, 

 squashes, carrots and onions, while the muriate also has in- 

 variably given a heavier yield of corn stover than the sulfate. 

 Among crops for which the sulfate is clearly best adapted, this 

 statement also in most cases depending upon results extending 

 over a considerable number of years, may be mentioned black- 

 berries, raspberries, strawberries, rhubarb, potatoes, cabbages, 

 soy beans, alfalfa and clovers, while the yield of grain of the 

 corn crop has been slightly greater on sulfate than on muriate. 



The report on the results of top-dressing permanent mowings 

 brings out in a striking way the possibilities in the direction of 



