CHEMICAL ANALYSIS OF SOILS 



315 



based on dry soil or in pounds to the acre to any suitable 

 depth. This method gives only the total of any constituent 

 and tells nothing regarding its availability to crops, although 

 a marked deflciency in any element may thus be detected. A 

 rock will often show greater amounts of the mineral elements 

 than a fertile soiL^ 



167. Partial analysis of the soil for mineral constitu- 

 ents. — When it was realized that a bulk analysis of the soil, 

 especially for the mineral constituents, gave no information 

 as to the availability of certain elements or as to the fertilizer 

 needs of the soil, extraction methods were devised. Such 

 methods, of whatever character they may be, are designed to 



portion of organic and inorganic phosphorus in Ohio soils. The figures 

 are an average of twelve types. 



Soils 



Total 



Oeganic P2O5 



AS Pee Cent 



OF Total 



Total 



Cultivated 



0- 7 inches 



% 



.0433 

 ,0345 



.0587 

 .0381 



% 



34 



20 



24 

 21 



.14 



7-15 inches 



.07 



Virgin 



0- 7 inches 



.19 



7-15 inches 



.08 







Sehollenberger, C. J., Organic Phosphorus Content of Ohio Soils; 

 Son Sei., Yol. X. No. 2, pp. 127-141, 1920. 



Por methods of determining organic phosphorus, see Potter, R. S,, 

 The Orgamo Phosphorus of Soil; Soil Sei., Vol. II, No. 4, pp. 291- 

 298, 1916. 



Rost, C. 0., The Ifetermmation of Soil Phosphorus; Soil Sci., Vol. 

 IV, No. 4, pp. 295-311, 1917. 



Potter, E. S., and Snyder, B. S., The Orgamo Phosphorus of Soil; 

 Soil Sei., Vol VI, No. 5, pp. 321-332, 1918. 



Sehollenberger, C. J., Organic Phosphorus of Soil: Experimental Worlc 

 on Methods for Extraction and Determination ; Soil Sci., Vol. VI, No. 5, 

 pp. 365-395, 1918. 



* Sulfur is determined by a separate method. Official and Tentative 

 Methods of Analysis of the Assoc, of Official Agr. Chemists, p. 317, 1920, 



See also, Hart, E. B., and Peterson, W. H., Sulphur Requirements of 

 Farm Crops in Melation to the Soil and Air Supply; "Wis. Agr. Exp. 

 Sta., Ees, Bui. 14, 1911. 



