218 SOILS : PROPERTIES AND MANAGEMENT 



figures have been obtained by Buckingham 1 in his study of 

 loose and compact soils. The following curves repre- 

 sent the general trend of his results : 



FIG. 35. Diagram showing the effect of a compaction upon the distri- 

 bution of moisture in capillary columns. (L), loose sandy loam; 

 (Z/), compact sandy loam ; (C), compact clay ; (C'), loose clay. 



While it is evident that the mean water content of the 

 compact sandy loam is greater than that of the less com- 

 pact, the latter showed a higher percentage of moisture 

 up to about the tenth inch. The clay shows a more 

 marked effect from compacting, dropping in the compact 

 sample almost as low as the sand, on the average, and 

 showing at about ten inches from the end of the column 

 a percentage of moisture considerably below that of either 

 the loose or the compact sand. It is obvious that the 

 farmer may do much in the control of capillary water by 

 promoting a proper physical condition of his soil. 



146. Organic matter and the amount of capillary mois- 

 ture. Organic matter, especially when it has been 

 reduced to the form of humus, has great capillary capac- 

 ity, far excelling in this regard the mineral constituents of 

 the soil. Its porosity affords an enormous internal sur- 



1 Buckingham, E. Studies on the Movement of Soil Mois- 

 ture. U. S. D. A., Bur. Soils, Bui. 38, pp. 34-35. 1907. 



