PHYSICAL PROPERTIES OF SOILS 37 



It is possible, to a great extent, to vary the cultiva- 

 tion so as to conserve the moisture of the soil to meet 

 the requirements of crops. 



28. Shallow Surface Cultivation. When shallow sur- 

 face cultivation is practiced, the capillary spaces near 

 the surface are destroyed and the direct connection of 

 the subsoil water with 

 the upper layer is 

 broken, the ground is 

 covered with finely 

 pulverized earth, and 

 the soil particles have FlG - l6 ' Soil without Surface Cultivation - 

 been disturbed so there is not that close contact which 

 enables the water to pass from particle to particle. When 

 evaporation takes place there is a movement of the sub- 

 soil water to the surface, but if that is covered with a 

 layer of fine earth, the' subsoil water cannot readily pass 

 through such a medium, and evaporation is checked. 

 Hence shallow surface cultivation conserves the soil 

 moisture. 



The means by which surface cultivation is accom- 

 plished must, of necessity, vary with the nature of the 

 soil. If a harrow is used, the pulverization should be 

 complete, if a disk, the teeth should be set at an angle, 

 and not perpendicularly, so as to prevent, as suggested 

 by King, 13 the formation of hard ridges which hasten 

 evaporation. When the disk is set at an angle, a layer 

 of soil is completely cut off, and the capillary connec- 



