Normal Soil and Its Requirements 7 



ent depths of the same soil. Brown 1 has shown that 

 bacteria are generally more abundant in the upper 

 eight inches. Table I , adapted from Brown throws 

 much light on this phase of the problem. 



TABLE i 



Bacteria as Found in Various Depths of Soil and Under 

 Different Cropping Systems - 



1 Brown,P. E., Iowa Agr. Expt.Sta. Research Bui. 8 : 283-321, 1912. 

 3 Plot No. 601. Continuous corn. 602. 2-year rotation, corn 

 and oats. 604. 3-year rotation, corn, oats, and clover. 



