A THIRTY-YEAR FERTILIZER TEST. 139 



a cultivated fallow, and in 1912 something which in its effect was prac- 

 tically a fallow. The 1913 corn crop therefore had the benefit of two 

 years of soil idleness. In 1914 a crop of soy beans failed to mature, and 

 hence presumably left more of value in the stubble than would have been 

 the case had the crop ripened its seed. In 1916 sweet clover was sown, 

 but the crop appeared to be mostly weeds. This was cut and removed 

 from the soil but not weighed. The corn crops of 1913, 1915 and 1917 

 therefore are not comparable with the earlier crops, although they may 

 indicate the fertility tendencies as brought about by this abnormal treat- 

 ment. 



The Hay Crops. 



There were six crops of grass and clover. One of the most marked 

 results in the whole history of the experiment was the character of the 

 vegetation produced by differential fertilizer treatment on uniform seed- 

 ing. Clovers failed to grow where potash was not apphed. The effect of 

 this is shown primarily in the rowen crop, which consisted largely of clover. 

 The number of haj^ crops was, however, too small and the crop too re- 

 sponsive to varying weather conditions to admit of any very satisfactory 

 interpretation of the data. The graphic presentation (Fig. 2) represents 

 the total yields for the six crops. 



Rov^en 



13 Plaster 



Fig. 2. — South Soil Test. Total yields per acre. Six hay crops. 



