204 MANUAL OF TROPICAL AND SUBTROPICAL FRUITS 



successfully in ground the surface of which is white with alkaline 

 efflorescence, provided the lower soil reached by the roots is 

 less salty ; but it is probable that the limit of tolerance is some- 

 where about 3 per cent of alkalinity, and the grower who looks 

 for the best results should not plant on soil whose total alkaline- 

 / content exceeds one-half of 1 per cent. Naturally, old date 

 palms will stand more alkali than young ones. It should be 

 noted that the so-called black alkali, consisting of carbonates 

 of sodium and potassium, is more harmful than the more or less 

 neutral chlorids, sulfates, and nitrates of sodium, potassium, 

 and magnesium which go by the name of white alkali. 



If the irrigating water is free from alkalinity, it will, of 

 course, help to counteract any alkali present in the soil ; whereas 

 the grower who needs to irrigate with brackish water must 

 plant his palms in fairly alkali-free soil. Desert landowners 

 sometimes calculate that soil which is too salty for anything else 

 is good enough for a date plantation. This is short-sighted 

 reasoning. Date-growing is, when rightly conducted, so 

 profitable that it is worth giving the best conditions available, 

 and the wise grower will plant his palms in his best soil. The 

 ground should be tested to a depth of six or eight feet to deter- 

 mine its alkali-content, particularly if there is salt evident on 

 the surface. Unless at least one stratum of alkali-free soil is 

 found not far from the surface, the ground should not be used 

 for date palms. 



It is the custom in the United States to plant date palms 50 

 to the acre. The grower with plenty of land may find that 40 to 

 the acre (33 feet apart each way) is more convenient, Arabs 

 plant them much closer but do not cultivate their plantations 

 frequently. The question of spacing is affected both by the 

 nature of the soil and by the variety planted; according to 

 Bruce Drummond, such kinds as Saidi and Thuri give the best 

 results if spaced 35 or 38 feet apart. 



Drummond gives the following advice about planting : 



