THE SOIL SOLUTION 



283 



Table LXII 



THE AMOUNTS OF POTASSIUM, PHOSPHORUS, AND CALCIUM IN THE 



SOLUTION OF VARIOUS SOILS AS DETERMINED BY THE OIL 



PRESSURE METHOD. EXPRESSED IN PARTS PER MILLION 



BASED ON DRY SOIL. 



Morgan's data indicate that the least variation may be ex- 

 pected in the phosphorus (P0 4 ) content, which does not differ 

 greatly in different soil solutions nor does it vary to any great 

 extent in the same soil. Potassium (K) and especially cal- 

 cium (Ca) show considerable fluctuation, as does the nitrate 

 nitrogen (N0 3 ), as has already been emphasized. The figures 

 of Morgan correlate fairly well with the data obtained by the 

 Bureau of Soils x by means of centrifugal extraction. The 

 potassium (K) averaged about 28 parts per million based on 

 the solution, the calcium (Ca) 32, and the phosphorus (POJ 

 8 parts per million. 



148. Influence of season and crop on the soil solution. — 

 It has already been emphasized that the concentration and 

 the composition of the soil solution suffer wide fluctuations. 

 The principal causes of such variations are as interesting as 



1 Cameron, F. K., The Soil Solution; p. 40, Easton, Pa., 1911. 



