66 



seriously injured in the field. Each crop fertilized 

 with dried blood sutTered very seriously from some 

 cause. The damage on the dried blood sections was 

 much greater on the ends that had been in fallow for 

 several years, than on the ends that had been continu- 

 ously cropped, with the exception of the plot in cotton, 

 in which case the entire plot failed. The condition of 

 each crop on the end of the plots previously fallowed 

 and previously cropped, is clearly shown in the photo- 

 graphs on Plates VII, VIII and IX. A possible explana- 

 tion of the different yielding powers of the fallowed and 

 the cropped ends of the plots is that toxic salts accumu- 

 lated in the fallowed section. At times during previous 

 seasons, the fallowed plots frequently accumulated 

 more than 100 p. p. m. of nitrates, while the other end 

 of the same plot, carrying a crop, usually had less than 

 10 p. p. m. at the same time. It should be stated, how- 

 ever, that such differences usually disappeared with 

 the coming of heavy winter rains. Even in such in- 

 stances, it is possible that the readily soluble salts may 

 have been, in part at least, brought back to the surface 

 soil in the capillary water during the dry weather of 

 spring. 



It is difficult to explain the much greater injury to 

 crops on the plots fertilized with dried blood than on 

 those where cotton seed meal is the source of nitrogen. 

 The nitrate content of the plots to which cotton seed 

 meal is added has been, usually, slightly higher than in 

 the dried blood treated plots. It has been suggested 

 that a part of the nitric acid developed through the 

 nitrification of the cotton seed meal may be neutralized 

 by the calcium and potassium compounds in the meal 

 itself, and hence less manganese is rendered soluble. 



Examination of the roots of plants which were mak- 

 ing poor growth showed that the roots were brown or 

 nearly black, and in many cases, practically dead. Cot- 

 ton plants shed most of their leaves, and finally most of 

 them died outright. The leaves of sorghum and corn 

 seemed to be affected alike.. The tips and margins of 

 the leaves turned yellow and usually died. So many 

 of the sorghum plants died that by summer, the stand 

 was very poor. The corn plants had a purplish color, 

 similar to that described by Kelley (19). 



In the fall of 1917 the first tier of plots in this sec- 

 tion was prepared as usual and planted on October 20. 

 One or two rows of the following crops were planted 



