57 



An inspection of Table X shows clearly that the addi- 

 tion of dried blood caused an increase in the soluble 

 manganese in each of the soils, with the exception of 

 No. 45. The amounts made soluble in soils No. 21, 41, 

 48, 51, 53, 62, and 76 are probably sufficient to cause 

 serious injury to most plants. Calculating the manga- 

 nese as nitrate, and assuming the acre foot of soil 6 

 inches deep to weigh two million pounds, the manga- 

 nese recovered from several of these soils is equivalent 

 to more than 200 pounds per acre, an amount that has 

 been found by a number of investigators, to be great 

 enough to injure crops. In the unfertilized soils, only 

 the Marshall silt loam from Wisconsin gave any man- 

 ganese in the extract. The evidence here given seems to 

 warrant the conclusion that the acids developed in the 

 nitrification of dried blood may dissolve manganese in 

 large quantities in the absence of active bases. Fur- 

 ther, it appears that sulphate of ammonia may increase 

 the solubility of manganese without increasing the 

 amount of nitrates in a soil. On the other hand, the 

 data show that a very considerable degree of nitrifi- 

 cation of the organic matter occurring in soils, does not 

 bring manganese into solution, as indicated by the 

 methods used. Again, when rapid nitrification causes 

 the solution of some manganese, not more than 20 per 

 cent of the nitrates recovered were in the form of man- 

 ganese nitrate, assuming all of the manganese to be 

 in nitrate form. 



Studies on Son.s from Plots 31 and 32, Tier 4, of the 

 Pennsylvania Experiment Station 



Through the courtesy of Prof. J. W. White, a small 

 quantity of soil was obtained from plots 31 and 32, tier 

 4, of the rotation experiments at the Pennsjdvania Ex- 

 periment Station. Plot 31 receives 48 pounds of nitro- 

 gen and plot 32 receives 72 pounds, in the form of sul- 

 phate of ammonia. The acidity of these two soils ac- 

 cording to White (21) is roughly proportional to the 

 amount of sulphate of ammonia that has been applied. 

 The soil on plot 32 has become so acid that crops have 

 begun to fail in recent years. To show^ whetlier or not 

 soluble manganese would be developed in tliese two 

 soils, the same method described above was employed, 

 using 100 grams of soil and .1 gram of dried blood and 

 sulphate of ammonia, respectively, per tumbler. 



After incubation from August 13 to November 23, 



