15 



under glass. Something may certainly be gained by rotating 

 leguminous crops, but with land costing $2,000 an acre and 

 upward, and crops worth as much or more than that amount 

 annually, the growth of a crop merely as a nitrogen gatherer 

 is not to be thought of. 



The same general principles apply here, however, as to field 

 culture, namely, that the soil supply of nitrogen, phosphorus, 

 potassium and lime must be maintained, and that in proportion 

 as we understand and apply the principles governing the 

 economical maintenance of this supply, in that proportion will 

 be our success in crop production. 



