jp/o] 



CARBON, PHOSPHORUS AND NITROGEN IN SOILS 



109 



TABLE 12. APPROXIMATE CARBON-PHOSPHORUS AND NITROGEN-PHOSPHORUS 

 RATIOS IN THE MORE COMMON HUMUS PRODUCING MATERIALS 



The ratios in the more* common humus producing 4 materials 

 calculated from the average of a number of analysis for nitrogen 

 and phosphorus (68), will be found in Table 12." In the coarser 

 material the phosphorus-carbon ratio varies from i 1417 to 1 1525 : 

 the phosphorus-nitrogen ratio is more constant being i :6.2 and l :8. 

 In the hays, the phosphorus-carbon ratio varies from i :i86 to 1 1283 

 while again the phosphorus-nitrogen ratio is more constant, the 

 variation being i :ii.i to i :8. In nuclein the ratios are I 13.7 and 

 i 11.4 respectively. 



In Table 13 will be found the phosphorus-carbon and phos- 

 phorus-nitrogen ratios obtained by calculation from the Minnesota 

 Soil Studies. The phosphorus determinations which were reported 

 as phosphoric anhydrid were first recalculated to the element basis. 

 Both ratios, it will be observed, are very narrow. 



In Table 14 will be found the phosphorus-carbon and phos- 

 phorus-nitrogen ratios in Illinois soils calculated from the data re- 

 ported by Hopkins and Pettit (68). The average of 7 calculations 

 of the gray silt loam on tight clay gave the phosphorus-carbon and 

 phosphorus-nitrogen ratios as i 142.6 and i 113.8 respectively. 



TABLE 13. MINNESOTA SOIL STUDIES: CARBON-PHOSPHORUS AND NITROGEN 



PHOSPHORUS RATIOS 



