134 



been the same as above, with the exception that all the 

 cultural-method plats received a uniform application of 

 fertilizer in 1911. This fertilizer was made up on a 6-10-5 

 basis and applied at the rate of about 600 pounds to the 

 acre. The frost also injured the crop quite severely on 

 most of the fertilized portion of this experiment in 1913, 

 while that on the cultural-method plats was scarcely 

 touched. "Whatever experimental advantages have arisen 

 therefore have been distinctly on the side of the cultural 

 methods rather than otherwise. The results up to date are 

 given in Table VI. 



TABLE VI. 

 Relative Influence of Cultural Methods and Fertilization on Yield. 



(Annual yields per acre, during five years, 1909-'13, in Expt. 338) 

 An. Yields An. gain An. gains 3 yrs. before 



Treatment per acre over sod fertiliz'n of Cult Methods 



(a) Cultural Methds. bu. bu. bu. 



Sod 204.9 



Sod Mulch 293.2 88.3 22.0 



Tillage and covercrop 356.0 151.1 100.0 



(b) Fertilization 



te 



123.0 



451.0 

 390.0 



The results here are self-explanatory. Through a 5-. 

 year period, the addition of a mulch alone has increased the 

 annual yields by 88 bushels per acre over sod, and the sub- 

 stitution of tillage and covercrops have increased this gain 

 to as much as 151 bushels. These are both important gains 

 and they are the maximum thus far shown by either treat- 

 ment in any of our experiments. 



When we add certain kinds of fertilization to this same 

 sod, however, still more important increases are secured. 

 These have not been obtained by the orchard fertilizer com- 

 monly recommended, viz., phosphorus and potash. This 

 combination has here given an increase of only 46 bushel?,, 

 per acre, and that incidentally is a fairly characteristic 

 showing for this particular application. But when nitrogen 

 and phosphorus are added, either in commercial form or in 

 manure, the annual gains are more than twice as great as 



