CHARACTERISTICS OF SOILS 21 



occur. The roots are more likely to advance along the 

 fissure, and most of their usefulness to the plant is thus 

 lost. 



30. Injury to roots by fissuring. When fissuring or 

 cracking occurs in soils or subsoils already filled with active 

 roots, all those roots lying across the plane of the fissure 

 are almost sure to be broken, and their service beyond 

 the breaks, and that of all their branches is lost to 

 the plants to which they belong. Crops, therefore, may 

 suffer greatly from soil fissuring. 



WATER 



Water is the great servant of nature. It is also the 

 great servant of agriculture, and its usefulness is propor- 

 tional to the degree of its successful control. Its functions 

 are many. 



31. Moisture and food preparation. In the prepara- 

 tion of food, water plays a most important part. Few, 

 if any, chemical reactions can take place in the absence 

 of moisture. Moisture, in contact with the surface of 

 the soil particles, assists in the actions resulting in the 

 liberation of the plant-food which the soil particles may 

 hold. 



Those germs, usually designated as nitrifiers, whose 

 important function it is to transform the unusable nitrogen 

 of the organic matter of the soil into usable nitrogen, can- 

 not perform their work without moisture ; nor can they 

 grow and multiply without moisture. The forms engaged 

 in nitrogen fixation cannot work in the absence of mois- 

 ture. These are the forms which we know best, as they 

 are found established on the roots of the clovers, beans, 

 alfalfa, and other legumes. 



