172 SUCCESSFUL FARMING 



production and the relation to the labor problem of the farm as a whole. 

 The relative cost per unit of digestible nutrients is the safest basis for 

 comparison. 



Usually the farms should provide sufficient pasture or the number of 

 animals should be regulated in accordance with the available pasture. 

 Generally the cropping system should provide all of the necessary pasture 

 and roughage for livestock. To secure these from the outside usually 

 entails much additional expense. In most cases the farm may also produce 

 the major portion of the concentrates, and in many cases will produce all 

 of the concentrates. This will generally be true in case of the production 

 of swine, beef cattle and sheep. It is less frequently true in case of the 



HOGGING DOWN CORN.* 



production of dairy products. There are many factors that determine 

 the proportion that should be produced and that should be purchased. 



Cropping System Related to Future. The plan of the cropping system 

 should take into consideration the future productivity of the soil. Humus 

 and nitrogen are most important in this connection. No cropping system 

 will prove satisfactory for a long term of years that does not include at 

 intervals of four to five years a leguminous crop such as clover, alfalfa or 

 some of the annual legumes. Nitrogen in commercial form is much more 

 expensive than that secured through the production of legumes. There is 

 about $11,000,000 worth of nitrogen in the air resting on each acre of land. 

 It is of prime importance to secure the soil nitrogen for crop production 

 from this abundant supply. The humus will be maintained largely 



Courtesy of South Dakota Experiment Station, Brookins, S. D. 



