114 THE DATE PALM. 



FERTILITY OF THE SOILS OF THE SALTON BASIN. 



On the other hand, the Salton Basin alkali contains a considerable 

 proportion of useful plant foods, especially sodium nitrate and -potas- 

 sium chlorid, which render the soils very fertile to any plant which, 

 like the date palm, can withstand a considerable percentage of alkali 

 in the soil. The Sahara soils are often mediocre or poor, and date 

 culture suffers in southern Algeria for the want of nitrogenous ferti- 

 lizers, wh'ich are very hard to supply at reasonable prices in such a 

 remote arid sparsely settled country. In the Salton Basin it may pay 

 to wash the surface crust down into the soil in order to carry the nitrate 

 of soda down within reach of the roots, in places where it is known that 

 there is little alkali in the subsoil. For instance, if a crust such as 

 No. 6308 of Table 44 (p. 113), containing 2.5 per cent of its weight of 

 nitrate of soda, occurred over such a soil as No. 6285, collected near 

 by, containing only 0.44 per cent of alkali to a depth of 3 feet, it is 

 probable that the crust might be washed down to the level of the roots 

 of the date palm without danger of their suffering from any excess of 

 alkali. Such an operation must, however, always be carried out with 

 caution, and is permissible only when it is known that the soil is rela- 

 tively free from alkali, and that the amount contained in the crust 

 would not suffice to raise it to the danger point for the date palm in 

 any soil stratum in which the roots ramify. 



Considerable amounts of potassium chlorid exist in most of the 

 Salton Basin soils probably enough to suffice for the needs of vege- 

 tation for a long time to come. Besides being naturally so rich, these 

 lands will be improved by the deposition of silt a from the Colorado 

 River water used in irrigating and from the addition of the small 

 amounts of nitrates and potash contained in solution. (See p. 106.) In 

 particular the small amount of phosphates the water contains is likely 

 to prove very beneficial to the soils of the basin, naturally poor in this 

 element. Analyses of the Colorado River water made daily for a 

 period of seventeen months show that on the average it carries 13.8 

 pounds of phosphoric acid in an acre-foot of water or 55.2 pounds in 

 the 4 acre-feet probably needed annually by a date plantation when the 

 trees are full grown. What with the considerable supplies of nitrogen 

 and potash contained in the alkali of these soils and the phosphoric 

 acid brought by the river water, it is probable that the date palm will 

 show a most luxuriant growth and bear heavy crops in the Salton 

 Basin without any fertilizers being needed for many years, at least. 



It must be kept in mind that much of the silt is deposited in the canal before it 

 reaches the land, and in consequence the fertilizing value of the water is not so great 

 as when it leaves the river. (See Means and Holmes, Field Operations of the Bureau 

 of Soils, U. S. Department of Agriculture, Third Report, 1901, p. 598. ) 



