318 ILLINOIS STATE ACADEMY OF SCIENCE 



soil layers by themselves. Noticing the fact that the sub- 

 soil layer of the peat soil contained a considerable 

 amount of clay particles or mineral matter, it suggests 

 for itself that the mineral portion of the soil forces phos- 

 phorus to react in the way here observed. It would seem 

 probable that some double salts of phosphorus with iron 

 or aluminum or with both are formed that are less soluble 

 than the calcium, iron and aluminum phosphates. The 

 presence of silica in the form of silicic acid perhaps has 

 considerable influence on the formation of these complex 

 combinations. However, the presence of bases common- 

 ly found in the soil is evidently essential for their for- 

 mation. The silica of the quartz sand, which was rather 

 coarse in texture, prevented some phosphorus from re- 

 covery, as one notices from Figure 4, in which data of 

 another experiment are shown where different amounts 

 of phosphorus were added to 25 gms. of quartz sand and 

 later extracted with fifth normal nitric acid. The influ- 

 ence of silica (with or without certain bases) on the be- 

 havior of phosphorus is under further investigation. 



In conclusion, I wish to emphasize the fact that the 

 phosphorus, which fifth normal nitric acid fails to ex- 

 tract from a given soil, exists in the soil in such a com- 

 plex combination that even subsequent extractions with 

 fresh nitric acid of the same strength fail to bring the 

 phosphorus in solution. Two soils, brown silt loam and 

 brown gray silt loam, were treated with either Tennessee 

 rock phosphate or double acid phosphate. The extrac- 

 tions with nitric acid were filtered and washed four times 

 with warm distilled water. The residue was treated with 

 fresh nitric acid, and the procedure was repeated five 

 times. The results are presented in Table 5 and show 

 that but a relatively small amount of phosphorus was 

 extracted from those soils after the first extraction, and 

 the amount was decreasing with every subsequent extrac- 

 tion. 



The time at my disposal here precludes the possibility 

 of discussing the various factors that influence the be- 

 havior of phosphorus in soil. This will be published else- 

 where later in a report. The presented paper, being its 

 integral part, will be reproduced in its essential features. 



