58 



1917, the soil was leached as described above. As soon 

 as the first leaching was completed the containers were 

 replaced by others and a second leaching obtained. 

 The soil was then air dried and again leached. The 

 treatments and the analyses of the extracts are given 

 in Table XI. 



Table XL— The Effect of Dried Blood and Sulphate of 

 Ammonia on the Development of Salable Manga- 

 nese in Soils from the Pennsylvania Experi- 

 ment Station. Mn. and N0:> in p. p. m. 

 of Air Dry Soil. 



In the first teachings, the air dry soil from plot 31 

 gave up 17 p. p. m. and soil from plot 32, 33.5 p. p. m. 

 of manganese. Incubation of these soils with distilled 

 water for three months resulted in a decrease in the 

 soluble manganese in soil from plot 31, while there was 

 quite an increase in the amount recovered from soil 

 from plot 32. In each soil incubation with dried blood 

 produced approximately 2.5 as much soluble manga- 

 nese as was found in the dry checks; and very nota- 

 ble increases in the nitrate content. Soil from plot 31 

 nitrified ammonium sulphate to a certain extent, with 

 an increase in the soluble manganese equal to that pro- 

 duced by dried blood. On the other hand, ammonium 

 sulphate retarded nitrification in the soil from plot 32, 

 but caused an enormous increase in the solubilifv^ of 

 the manganese. Qualitative tests showed the presence 

 of traces of iron and small amounts of aluminum in 

 some of the extracts. However, the amount of alumi- 

 num present was not nearly as great as the manganese. 



The amount of chlorides found in the soil ex- 

 tracts was very small; and of those examined for sul- 

 phates, where dried blood was the source of nitrogen, 

 only minute quantities of sulphate were found. The 

 conclusion seems justified, therefore, that the man- 

 ganese recovered was in the form of nitrate, in the 

 dried blood treated soils; and as nitrate or sulphate 



