jp/o] CARBON, PHOSPHORUS AND NITROGEN IN SOILS 105 



(B) EXPERIMENTAL PART 



The starting point of such an investigation consists of a con- 

 sideration from a mathematical point of view of the existing data 

 regarding the relationships of carbon, phosphorus and nitrogen of 

 the soil. 



i. MATHEMATICAL 



(a) INFlyUENClv OF AGE UPON THE NITROGEN-CARBON RATIO 



From the data available in the literature it is possible to deter- 

 mine within certain limits the influence of age upon the nitrogen- 

 carbon ratio in soils. From the average results of a number of 

 nitrogen determinations (68) and the carbon content obtained by 

 calculation from the proximate analysis, it is possible to determine 

 the approximate nitrogen-carbon ratio in the more common humus 

 producing materials. The results obtained in this way will be 

 found in Table 6. The materials naturally fall into two groups : 

 in the first group the ratio_ varies from i 152.2 for corn stover to 

 1 184.1 for wheat straw; in the second group the variation is from 

 i :i6.7 for alfalfa hay to i 135.4 for timothy hay. 



TABIE 6. APPROXIMATE NITROGEN-CARBON RATIO IN THE MORE COMMON 

 HUMUS PRODUCING MATERIALS 



In Table 6 will also be found the nitrogen-carbon ratio in some 

 of the compounds which might be expected to be found in humus. 

 The ratio is very narrow and does not vary much from i 13. 



The next step in the study in the influence of age upon the 

 nitrogen-carbon ratio would be to determine the ratio in as fresh 

 humus as possible from known materials. Snyder (35) in his 

 study of the production of humus from known materials placed a 

 weighed quantity of the material together with a weighed quantity 



