92 SOILS 



of the tubes, which are now not on the surface but 

 eight inches, six inches or three inches below the 

 surface, according to the depth to which the soil 

 has been loosened. The practical application of 

 this fact, and other benefits of tillage, are fully 

 described in Chapter V. 



THE WATER-MOVING ABILITY OF DIFFERENT SOILS 



Since soils are so variable in composition and in 

 texture they naturally vary a great deal in their 

 "capillarity," or their ability to move film water. 

 This point is worth considering when selecting a 

 farm; a soil through which water moves slowly is 

 not apt to be very productive. The coarser a soil 

 is, the less water it can draw up. Fill one lamp 

 chimney with coarse sand and another with clay 

 loam, both packed hard. Set both of them 

 in a pan of water and note the difference in 

 the amount of water that they draw up and the 

 time it takes them to do it. For a while water will 

 rise rapidly through sand, but it will not be drawn 

 very high, because the spaces or tubes are so large. 

 In the finer soils, especially those containing some 

 clay, water rises more slowly, but it is drawn up 

 very much farther. Humus increases the water- 

 drawing power of a soil. 



The importance of securing a soil with high 

 capillary power lies in the relation this has to the 

 water supply of crops. Film water, on which 

 plants feed, is drawn largely from the reservoir 

 of free water below. It is important that a soil be 

 able to draw water freely and rapidly in order to 

 keep the roots constantly bathed in the life giving 

 fluid. A large crop makes a tremendous drain 

 upon the water in the upper part of the soil during 



