ORGANIC COMPOUNDS OF SOILS IOI 



Phos- 

 phoric 

 acid com- Water- 

 bined holding 

 Weight Humus. Nitrogen, with capac- 

 per cu. Per Per humus. ity. 



Character of soil. ft. lbs. ceut. cent. Per cent. Percent. 



, Cultivated thirty-five years ; 

 rotation of crops and manure; 



high state of productiveness . 70 3.32 0.30 0.04 48 

 , Originally same as 1 ; con- 

 tinuous grain cropping for 

 thirty -five years ; low state of 

 productiveness 72 1.80 0.16 0.01 39 



Cultivated forty -two years ; 

 systematic rotation and ma- 

 nure ; good state of product- 

 iveness 70 3.46 0.26 0.03 59 



Originally same as 3 ; culti- 

 vated thirty -five years ; no 

 systematic rotation or ma- 

 nure ; medium state of pro- 

 ductiveness 67 2.45 0.21 0.03 57 



