54 HARNESSING THE EARTHWORM 



nutrition. The aerating tunnels have the important function of 

 greatly increasing the air capacity of the soil. In some cases 

 the air capacity is increased as much as 60 to 75 per cent. 



Water penetration is improved where there is adequate earth- 

 worm population. Plow sole is eliminated. The rainfall is 

 quickly absorbed, instead of running off or standing on the sur- 

 face. 



Wormcasts in acid soil are much less acid than the soil from 

 which they are derived, the reduction in acidity in some instances 

 amounting to as much as 75 per cent. In large numbers, the 

 earthworms produce a topsoil that is practically a neutral humus. 

 Also, earthworms reduce the alkalinity of the soil, so that alkaline 

 soils are rendered less alkaline, while acid soils are rendered less 

 acid. 



Wormcasts commonly contain a high percentage of car- 

 bonates as well as a high percentage of nitrogen. 



Earthworms increase the organic content of the surface soils 

 by concentrating the organic content of the soil in the top layers. 

 Colloid humus is increased in the topsoil. 



Bacterial multiplication and functioning are favored by the 

 action of earthworms. Where there are numerous earthworms, 

 the soil also has a greatly increased number of soil bacteria, espe- 

 cially those concerned in the decomposition of cellulose. Decom- 

 position of vegetable matter is much more rapid under the 

 influence of earthworms. 



Earthworms continually restore the plant food elements to 

 the surface soils from the subsoils, thus overcoming the effects 

 of leaching. Through the action of the earthworms, the poten- 

 tial fertility of the soil is rendered available by the fact that in 

 the digestive processes of the earthworm the elements of plant 

 nutrition are made water-soluble. 



Earthworm castings have much greater productive value for 

 plant growth than other soil, due to the fact that the nutritional 

 elements have been concentrated in the castings in water-soluble 

 form and in a more balanced condition. It is very much like 



