558 NATURE AND PROPERTIES OF SOILS 



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

 son, tlie 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 O-K-K-Ki 



SUMMARY TABLE OF LOSSES AND ADDITIONS THAT MIGHT OCOUE 

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

 TION. EXPRESSED IN POUNDS TO AN ACRE A YEAR. 



Conditions 



N 



40.3 

 21.1 



4ia 



20.0 



43.5 

 21.7 



21.7 



K^O 



CaO 



SO3 



Organic 



Matter 



Reductions when farm 

 manure and green ma- 

 nure are not used ^. . . . 



Additions from farm ma- 

 nure 



174.1 

 31.6 

 31.6 



370.2 



7^3 

 7.3 



84.5 

 12.4 

 12.4 



1200 

 1000 



Additions from farm ma- 

 nure and green-manure 



Additions using green- 

 manure 



1600 

 600 



It is immediately apparent tliat 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 



^Obtained by subtracting the natural additions from the normal 

 losses. 



