50 THE DATE PALM. 



when the canals are full of the water from melting 1 snows on the sur- 

 rounding mountains, the temperature would be much lower. 



The Salton Basin is supplied with water diverted from the Colorado 

 River near Yuma and conducted some 40 to 60 miles in open ditches 

 before it is put on the land. The annual overflow of the Colorado 

 River occurs in early summer, usually in June or July, and is caused 

 by the melting of the snows on the Rocky Mountains in Colorado, 

 Utah, and Wyoming. This cold water fortunately reaches the Colo- 

 rado Desert at a time when the heat is great, so that in flowing in the 

 large open canals and in the shallow laterals and in soaking through 

 the hot surface layers of the' soil it will undoubtedly be warmed con- 

 siderably before it reaches the roots of the date palms. On the whole 

 the conditions are exceptionally good in the Salton Basin, for the most 

 abundant supply of water occurs in early summer or midsummer, just 

 when the plants have greatest need for it. 



The annual overflow of cold waters from the melting snows is doubt- 

 less the principal cause of the failure of the date palms to mature their 

 fruit properly on Mr. Hall Hanlon's place in the Colorado River flood 

 plain in California, near Yuma, Ariz, (see PI. XX, fig. 2). The tempera- 

 ture of the soil and of the air in this overflowed area and in adjoining 

 areas at nearly the same level is doubtless much lower than at the 

 town of Yuma, for instance." Even at Yuma the summer heat is less 

 than at Phoenix and very much ICGG than in the Salton Basin. It is 

 clear then that no conclusion unfavorable to the culture of dates in the 

 Salton Basin can be drawn from the failure of these palms in the flood 

 plain to mature their fruit. Early varieties, such as the Rhars and 

 Teddala, will probably ripen even on these overflowed lands (see p. 132). 



DRAINAGE FOB THE DATE PALM. 



Although the date palm can withstand very much more alkali than 

 any other crop plant, it does not endure having the soil about the roots 

 water-soaked. Good drainage is as essential for it as for any other 

 fruit tree if good crops are to be expected, and, unless the soil drains 

 naturally, the superfluous water must be removed, usually -by means of 

 open ditches or with tile drains. Proper aeration of the soil about 

 the roots is essential to enable the date palm to grow well and yield 

 abundantly (see p. 80). Good drainage also permits the alkali to be 

 washed out of the soil by means of heavy irrigation, and, doubtless, 

 this also favors the growth of tho palms. It is, however, worthy of 

 being noted that the excessively alkaline water which flows off in the 

 drainage ditches is used in some parts of the Sahara to irrigate date 

 palms which occupy land lying at a lower level. Such palms, though 



According to Mr. Bernard G. Johnson, of Mecca, CaL, there is a drainage of cold 

 air from the hills toward Mr. Hanlon's date plantation which renders it one of the 

 coldest sites in the vicinity of Yuma. 



