MAKING THE SOIL PRODUCE CROPS 



the roots of the desired plants and not by the 

 intruders we call weeds. Cultivation does more 

 than destroy weeds, however. It opens up the soil 

 so that air containing atmospheric nitrogen can 

 penetrate it and so that the bacteria requiring 

 air for their best growth may have it available. 

 Furthermore, cultivation conserves moisture 

 and is more essential during dry periods in the 

 growing season than at any other time. 



We know that in entering the soil the rain 

 water follows certain channels in and around 

 the soil particles on its way to the subsoil. 

 When the rain has ceased and the top layer of 

 soil becomes dry, the tendency is for the water 

 to work up through these same channels to the 

 surface, where it evaporates. Cultivation, by 

 breaking up these channels, or capillary tubes, 

 checks the escape of moisture into the air. 

 It creates a blanket of dry surface soil which 

 insulates the soil moisture from the air above. 

 The tendency of soil moisture to reestablish 

 capillary methods of escape makes recultivation 

 necessary from time to time in dry weather. Care 

 must, of course, be taken that the cultivation 

 is not harmful to roots of growing plants. If 

 these roots are disturbed or destroyed through 

 cultivation, more harm than good may result 

 because of the damage to the root systems. 



