48 



CHEMISTRY OF FARM PRACTICE 



TABLE II. THE SOLUBILITY OF CERTAIN MINERALS IN 

 DISTILLED WATER AND IN CARBONATED WATER 



ammoniacal compounds. These compounds are oxidized 

 by the activities of another group of bacteria into nitrous 

 compounds, which are further oxidized by other bacteria 

 into nitric compounds. The nitric acid thus produced 

 forms, with the basic elements of the soil, soluble nitrate. 

 Examples of these have already been mentioned. It should 

 be remembered that all nitrates are soluble in water. The 

 formation of nitric acid and its subsequent conversion of 

 bases, formerly in insoluble compounds, into nitrates, which 

 are soluble in water, and the increased solvent power of 

 the soil water through carbonation, are examples of the 

 natural solvents and their action. There are a number of 

 organic acids both in the soil and in animal manures that 

 have solvent powers; but the study of them requires a 

 large mass of data which is as yet incomplete. It is suf- 

 ficient to say that they exert marked activities in making 

 available food for plants. 



42. Factors Influencing Availability of Plant Food. 

 Nature provides that the more the soil is worked, the 

 more responsive it becomes and the more plant food be- 

 comes available. There are many factors influencing the 

 availability of the plant food of the soil. We may mention 



