EXPERIMENT STATION BULLETINS. 



351 



new importance. A large number of samples have been taken from the 

 predominating soils types in Michigan and subjected to analyses. The 

 samples were placed in two groups : cropped and uncropped. The former 

 were taken from fields which have been under cultivation for a long 

 period of years and the other group from line fences, woodlots and 

 virgin timber, which have never been under cultivation. A summary 

 of the results of many analyses is given in table 1. 



Table 1. — Pounds of nitrogen, phosphoric acid and humus in cultivated and uncultivated soils. 



The decreased fertility shown in this table is supported by observations 

 of the older settlers, who in many communities tell us of the large wheat 

 yields and luxuriant stands of clover of earlier years. 



FiGUBB 7. — During one generation the fertility of some fields has been materially reduced. 

 On the right wheat growing on 70 year old field, on the left line fence. 



FEETIj:.ITir REMOVED P¥ CROPPING. 



Since unquestionably there hag been a decrease in the fertility of 

 most of oy/ soils it U well to study some of the farming systems followed 



