CHAPTER II 

 PHYSICAL INTER-RELATIONS IN SOILS 



A VERY intimate relation exists between each of the 

 four fundamental physical soil conditions and all the 

 others, and between gravitational water and all four con- 

 ditions. So important are these relations that they should 

 be very thoroughly understood. A brief description of 

 them follows in the order of sequence as they appear to 

 the writer. 



INFLUENCE OF CAPILLARY WATER ON OTHER PHYSICAL 

 CONDITIONS 



45. Capillary water and soil structure. The physical 

 structure of a cultivated soil depends on four things, 

 the method of cropping, the organic matter present, the 

 use of tools on the soil, and the moisture content through- 

 out the year. This discussion permits the consideration 

 of but one of these four categories, and but one phase of 

 this the function of capillary water. 



46. Capillary water and plowing. One of the uses of 

 the plow is to mellow the soil. If a clay or a loam soil 

 is plowed when over-wet, the earth is puddled or packed by 

 the pressure of the mold-board upon it. The effect is 

 much the same as if an over-wet piece of the same soil 

 were squeezed in one's hand, or were rolled between the 

 two hands. In either case, the soil so puddled is com- 



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