558 NATURE AND PROPERTIES OF SOILS 



320. The balance sheet. — For convenience of compari- 

 son, the data previously presented are drawn together in a 

 single table and presented below as pounds to the acre an- 

 nually. These figures are considered as relating to the Dun- 

 kirk silty clay loam carrying a five-year rotation of maize, 

 oats, wheat, and two years hay. It must always be remem- 

 bered that such data are specifically applicable to only one 

 soil. Nevertheless the practical deductions that may be drawn 

 are of wider scope. 



Table CXXXI 



SUMMARY TABLE OP LOSSES AND ADDITIONS THAT MIGHT OCCUR 

 TO DUNKIRK SILTY CLAY LOAM UNDER A FIVE-YEAR ROTA- 

 TION. EXPRESSED IN POUNDS TO AN ACRE A YEAR. 



It is immediately apparent that when farm manure and 

 green-crops are not utilized, a notable decrease occurs in every 

 constituent cited. Such a system of soil management must 

 reduce the productivity of the soil very quickly and 

 certainly is not a rational scheme of soil and crop adjustment. 

 Nevertheless, it is the condition under which much of the 

 arable land is producing crops today. 



When farm manure is utilized, even allowing for a large 



1 Obtained by subtracting the natural additions from the normal 



