CAMPBELL'S SOIL rui/rumo MANUAL 76 



experiments been made with a three inch layer of loose 

 soil mulch above the packed portion, they would have 

 shown a much greater increase of moisture at -the point 

 of two to eighteen inches. 



EFFECT OF THE SUB-PACKING. 



All these facts in connection with the movement of 

 moisture in the soil, under different conditions of the soil, 

 as indicated in the experiments noted and the teachings 

 of the most eminent students of soil physics, give us the 

 valuable lesson that the packing of the sub-soil, or what 

 may be properly termed the root-bed, aids us in these 

 important points; increasing the water holding capacity 

 of the soil facilitates the movement of the water from 

 below up to this point when it is needed. 



The last but by no means least of the advantages de- 

 rived from this sub-packing outside of what has been 

 already mentioned, is that by the increased upward move- 

 ment of moisture previously explained, we are able to keep 

 up the supply of moisture about the roots to that degree 

 that nitrification and the development of fertility continues 

 though the weather be hot and parching, and the plant 

 is growing rapidly, and yet through this ideal condition 

 we are able to keep up the supply of plant elements in a 

 soluble condition, thus giving to the plant that dark green, 

 healthy, prolific growth without a set-back, which is, by 

 the way, the secret of large yields. 



Now let us take a last look at the field of grain trying 

 to exist on a piece of land the root-bed of which is coarse 

 and loose. The excessive heat has caused such a rapid 

 evaporation from the leaf and the upward movement of 

 moisture by capilliary attraction has been so slow that 

 the moisture aboua the roots has become so depleted that 

 nitrification ceases; all fertility has become unavailable, 



