Advantages of Abundant Moisture 11 



a high degree, the magnitude of the specific crop which 

 is to be harvested. The germs which react upon the 

 dead organic matter in the soil, converting it into 

 ammonia, the germs which change the ammonia into 

 nitrous acid, and the germs which transform the nitrous 

 acid into nitric acid, which is the real nitrogen supply 

 of most of the higher plants, each and all are depend- 

 ent for their proper activity upon the right amount of 

 moisture in the soil. Then, there are those symbiotic 

 forms of lowly organisms whose great mission it is 

 to take the free nitrogen from the air and compound 

 it into such forms as shall leave it available for the 

 higher plants, and which, like all other forms of life, 

 must have water and to spare if they are to perform 

 their work. Let the water content of any soil be 

 reduced below a certain amount, and all of these vital 

 processes are inevitably slowed down ; let it be reduced 

 to a still lower degree, and the whole line is at a com- 

 plete standstill. 



Now, in humid regions, where the subsoils are much 

 of the time water -logged, and where, as a consequence 

 of this, there is but little soil ventilation, the * plant- 

 food "builders to which reference has just been made 

 are all of them forced into a thin zone close to the 

 surface of the ground, where their work must all be 

 done ; but if this surface zone is allowed to become 

 dry, then the nitrogen - supplying processes must come 

 to a standstill, and the crop which is growing above 

 the ground must have its growth checked, even though 

 it has put its roots down into the subsoil where mois- 

 ture for its own purposes may be had. Indeed, we may 



