IDEAL FERTILIZERS 63 



Chapter XI 



Fertility 



Perhaps the most important lesson for the prospective 

 grower to learn is that fertile soil is not an inert mass 

 but, instead, is teeming with living organisms too small 

 to be seen with the unaided eye but of inestimable value. 

 Then he must also learn that there are other organisms 

 just as ready and powerful to work against him if soil 

 conditions are allowed which are favorable to their de- 

 velopment. These micro-organisms (called "micro" be- 

 cause they are seen only through microscopes) are in- 

 numerable forms of both vegetable and animal life, 

 bacteria, fungi, etc. the bacteria having by far the great- 

 est influence on agricultural conditions. 



Bacteria 



Lipman says : "In agriculture, the development of bac- 

 teriology has given us a new insight into the nature of 

 soil fertility. We have learned to regard the soil as a 

 culture medium with its almost endless number of species 

 and varieties of bacteria, specialized to do important 

 work in the transformation of soil nitrogen, carbon, hy- 

 drogen, and sulphur ; in the transformation, also, of com- 

 pounds containing lime, magnesia, phosphoric acid and 

 potash. We have learned to reckon with these organisms 

 in our methods of soil improvement, and have made some 

 progress toward successful systems of soil inoculation." 



Bacteria are the simplest and smallest forms of vegeta- 



