AVAILABILITY OF PLANT NUTRIJENTS 



341 



applied to a clay soil and to a sandy loam soil at the rate 

 of 640 pounds to the acre. Analyses of aqueous extracts 

 some ninety days later showed the following : — 



Kind op Soil 



Fertilizee 



Nitrates in Soil 

 (Parts per million) 



Clay 



Clay 



Sandy loam 



Sandy loam 



Sodium nitrate 

 No fertilizer 

 Sodium nitrate 

 No fertilizer 



7.8 



1.8 



150.0 



29.7 



There was apparently a much greater retention of 

 nitrate by the clay soil, as shown by a comparison of the 

 fertilized and the unfertilized plats on both soils. 



Schulze ^ extracted a rich soil by slowly leaching 1000 

 grams with pure water, so that one liter passed through 

 in twenty-four hours. The extract for each tw^enty-four 

 hours was analyzed every day for a period of six days. 

 The total amounts dissolved during each period were as 

 follows : — 



Successive Extractions 



Total Matter 

 Dissolved 



Volatile 



Inorganic 





(Grams) 



(Grams) 



(Grams) 



First ...... 



0.535 



0.340 



0.195 



Second ...... 



0.120 



0.057 



0.063 



Third 



0.261 



0-101 



0.160 



Fourth 



0.203 



0.083 



0,120 



Fifth 



0.260 



0.082 



0.178 



Sixth 



0.200 



0.077 



0.123 



1 Schulze, F. Ueber'derL Phosphorsaure-Gehalt des Wasser- 

 Auszugs der Aokererde. Landw. Vers. Stat., Band 6, Seite 

 409HH2, 1864. 



