Normal Soil and Its Requirements 7 



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

 bacteria are generally more abundant in the upper 

 eight inches. Table 1, 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 Bul.8 : 283-321, 1912. 

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

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



