"WATER OF GRAVITATION IN THE SOIL 105 



The gravitational soil-water cannot long remain 

 in that condition ; for, necessarily, the pull of gravity 

 moves it downward through the soil pores and if 

 conditions are favorable, it finally reaches the stand- 

 ing water-table, whence it is carried to the great 

 rivers, and finally to the ocean. In humid soils, 

 under a large precipitation, gravitational water moves 

 down to the standing water-table after every rain. 

 In dry-farm soils the gravitational water seldom 

 reaches the standing water-table ; for, as it moves 

 downward, it wets the soil grains and remains in the 

 capillary condition as a thin film around the soil 

 grains. 



To the dry-farmer, the full water capacity is of 

 importance onlj- as it pertains to the upper foot of 

 soil. If, by proper plowing and cultivation, the 

 upper soil be loose and porous, the precipitation is 

 allowed to soak quickly into the soil, away from the 

 action of the wind and sun. From this temporary 

 reservoir, the water, in oljedience to the pull of 

 gravity, will move slowly ck)wnward to the greater 

 soil depths, where it will be stored permanently 

 until needed by plants. It is for this reason that 

 dry-farmers find it profitable to plow in the fall, as 

 soon 'as possible after harvesting. In fact, Camp- 

 bell advocates that the harvester be fcjllowed im- 

 mediately by the disk, later to be followed by the 

 plow. The essential thing is to keep the topsoil 

 open and receptive to a rain. 



