34 



VERTICAL FARMING 



pumped all of the available water out of the soil. This season 

 is followed by the fall and the winter rains which can then 

 find their way deep into the cracks and fissures where they are 

 absorbed and held indefinitely if proper care is given to the sur- 

 face. The heavy rains following such a shattering of the sub- 

 soil have the additional advantage of resettling any parts of 

 the soil where the explosion may have opened it up too much. 

 In the spring and summer following such a soil treatment, the 

 young roots find an easy path into the deeper soil, where they 

 can continue to draw their full ration of water from the stored 

 supply and thus nourish the crop during long seasons of drouth. 



SUBSOIL SHATTERED BY A BLAST THE CHEAP WAY OF STORING 



WATER FOR PLANTS. 



Excesses of Water Must be Drained Away. Field plants 

 will not grow in a soil saturated with water. An ample supply 

 is necessary and must be maintained, but a great deal depends 

 on how the supply is kept up, or in other words, on the moisture 

 condition. Land animals require water to drink, but perish if 

 immersed in it, for the air necessary for their existence is then 

 shut off. Plant roots die if the soil is saturated with water 

 because their air is cut off. Fortunately, soil will hold only a 

 certain amount of moisture if the water is free to move, the 

 excess gravitating downward and draining away. This is 

 called gravity of free water. The gravity water sinks until met 

 and checked by impervious material or reaches standing water ; 

 that is the water table. Unless such free water sinks too deep, 

 it is not entirely lost to the plant, as it not only sinks through 

 gravity, but is also brought back to higher levels, when the top 

 soil begins to dry, by capillary attraction, just as water climbs 



