ECONOMICS 131 



follow. There are few types of agriculture 

 which utilize land, labor, or products more com- 

 pletely than the dairy industry and none which 

 maintains fertility more perfectly, yet the net 

 returns when measured by cash receipts are 

 small. 



On the other hand, a highly developed mar- 

 ket garden may utilize the land and labor just 

 as thoroughly but within itself produce no 

 means of keeping up soil fertility, and yet re- 

 turn a handsome net profit. The defect in 

 such a system is that it is dependent upon out- 

 side sources for one of its important fac- 

 tors, viz., manure to maintain the fertility of 

 the soil. Fortunately, however, the city which 

 uses the products of the garden has an ample 

 supply of fertilizer to return to it. 



Special crops usually require the purchase of 

 commercial fertilizers or manures in order to 

 maintain fertility. In some cases highly prof- 

 itable special crops, such as oranges, lemons, or 

 other tree fruits which occupy the land for a 

 period of years may be so handled as to provide 

 the nitrogen requirements of the crop by means 

 of the growth of legumes, which when turned 

 under also add to the humus content of the soil. 

 Such a system of management will reduce the 

 cost of maintenance and increase the production 



