AVAILABILITY OF PLANT NUTRIENTS 



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 : — 



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 x 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 twenty-four 

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

 The total amounts dissolved during each period were as 

 follows : — 



1 Schulze, F. Ueber den Phosphorsaure-Gehalt des Wasser- 

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

 409-412. 1864. 



