44 



VERTICAL FARMING 



ready present in a properly combined form. Even in soils rich in 

 nitrogen the growth of these crops is materially benefited by the 

 presence of the bacteria. 



Other forms of bacteria and kindred plants of microscopic 

 size have the power of gathering bacteria from the soil air and 

 their development should also be encouraged. These forms are 

 not so well known as those that produce the nodules on the 

 roots, but their benefits are marked. They demand a well 

 drained and well aerated soil. 



Helping a Friend Along. Aside from the nodule forming 

 bacteria, most of the other beneficial forms are found in all 

 normal soils. It is not necessary to add them in artificial cult- 

 ures, but their activities can be materially increased by keeping 

 them in suitable surroundings and supplying their constant but 

 simple desires. These forms get their oxygen from the air, 

 and must therefore not be closed up in a tightly sealed soil. 

 They do not thrive in the deep subsoil unless it is well aerated. 

 Large excesses of water that clog up the pores of the soil also 



SWAMP CONDITIONS OR EXCESSIVE AMOUNTS OF WATER SEAL 

 THE SURFACE AND STOP BENEFICIAL BACTERIAL ACTION 



