SOIL BACTERIOLOGY AS A FACTOR IN CROP PRODUCTION.' 



By Karl F. Kellerman, Physiologist in Charge of Soil-Bacteriology and Plant Nutri- 

 tion Investigations. 



IMPORTANCE OF SOIL BACTERIOLOGY. 



This day and generation are in the grasp of the invisible, the tilings 

 infinitesimal, the things minute. The physician and the engineer 

 have learned that they can battle with the complex conditions of 

 to-day only by understanding a wealth of microscopic detail that 

 formerly would have been considered ridiculous. These two pro- 

 fessions have now joined with biology in recognizing the microscope 

 as a necessity. It is not surprising, therefore, that the most impor- 

 tant profession in the world, that of farming, should awaken to the 

 desire of comprehending and controlling the tremendous although 

 imperceptible forces which may enrich or ruin fields and crops. 



It no longer thrills an audience to say that soil is a living thing; it 

 is either a trite remark, a commonplace relegated to the shelves as 

 uninteresting, or it is a statement quoted impressively to explain 

 everythmg in soil fertility. Both attitudes are unfair to this new 

 science. Real progress is slow, and there are good reasons for asking 

 the farmer to maintain a deep interest in the unseen population of 

 the fields and to beware of dogmatic explanations unsupported by 

 properly marshaled facts. The average mind is more than willing to 

 believe a fairy tale, but unquestioning belief in hasty conclusions is 

 more injurious to future progress than temporary lack of interest or 

 appreciation. 



Most readers of modern agricultural literature are familiar with the 

 generalization that but for the various agents of decay the world 

 would in a very short time become uninhabitable. It is through the 

 constant disintegration and decay of dead plants and animals that 

 fertile soils are regenerated and that the processes of growth of plants 

 and animals can continue. Only during the last half century has the 

 science of bacteriology shown how remarkable is this transmutation 

 of the dead plants and animals back to soil. Bacteria themselves are 

 plants. They form the simplest group of the fungi, or plants that are 

 lacking in chlorophyll. They are exceedingly minute; the majority 



1 Issued Feb. 15, 1913. 



This paper was presented Jan. 7, 1913, as one of a series of lectures given before the scientific staff of the 

 Bm-eau of Plant Industry. 



[Cir. 113] 3 



