28 COOPERATIVE MARKETING 



by the use of force pumps, or from mountain streams, or 

 from storage reservoirs built to impound storm waters from 

 the winter rains. The first method is very expensive, the 

 second costs almost nothing, the third may be advanta- 

 geous or prohibitively expensive according to local con- 

 ditions. The problems of water supply and irrigation are 

 among the most stubborn which the grower is called upon 

 to face, and without question drastic measures must be 

 taken for the conservation of water if the citrus industry 

 is to retain its prosperity. 



Next to irrigation, cultivation occupies the most im- 

 portant position in the care of a grove. The purpose of 

 cultivation is primarily conservation of moisture, hence 

 tillage is intensive from about March to November. By 

 means of specially designed chisel cultivators or by disc 

 harrows the soil is frequently turned or loosened so that a 

 crust is never allowed to form. In common with all dry 

 farming practice, a dust mulch is formed to a depth of 

 several inches which effectually prevents evaporation. This 

 loose soil also facilitates irrigation by making it possible 

 for the water to be more readily absorbed. 



During the fall a cover crop is usually drilled between 

 the citrus rows. Vetch, melilotus, field peas, bur clover and 

 barley are the most popular cover crops, vetch and melilotus 

 being much the most widely preferred. This cover crop, 

 which is plowed under toward the end of the rainy season, 

 serves several purposes: it supplies the soil with nitrogen 

 (if a legume) and also furnishes humus, in which the semi- 

 arid and arid soils of the West are especially deficient; it 

 helps to hold the rainfall on the land, and prevents gullying 

 by the winter rains; it tends to check certain fungous dis- 

 eases, like the brown rot of the lemon. 



Just as is the case with other fruit growing industries, 

 the fertilization of citrus groves has not been reduced to an 



