UTILIZATION AND RECLAMATION OF ALKALI LANDS. 477 



salt is in small proportion. Generally speaking, the citrus 

 tribe are rather sensitive to alkali salts, and more especially to 

 common salt. In fact, as to the high tolerance-figure given in 

 the table, observed in sandy land, the alkali there contained 

 only a trace of common salt. Young seedling trees are par- 

 ticularly sensitive; so that it is often difficult to obtain a stand 

 even when, later on, the feeding roots descend beyond the 

 reach of injury. In the close-textured lands of Chino, young 

 trees hardly maintained life with more than 5,000 pounds of 

 total salts. Near Riverside, full-grown trees perished under 

 the influence of bottom water containing 0.25%, or 146 grains 

 of salt per gallon, which impregnated the ground; correspond- 

 ing to about 9,000 pounds per acre in four feet. 



In the sandy loam lands near Corona, trees eight years old 

 suffered severely when by irrigation with alkali-water the 

 alkali-content of the land reached 11,000 pounds per acre; as 

 illustrated in Figs. Nos. 44, and 45. At another point in 

 the same region, two representative trees were selected for 

 comparison, five rows apart on land absolutely identical; one 

 of these retained its leaves, though suffering, the other was 

 completely leafless. The leaching of the alkali to the depth of 

 four feet gave the following results, calculated to pounds per 

 acre : 



Sulfates. Carbonates. Chlorids. Total. 



Poor tree 4,7~o 1680 2,520 8,920 



Better tree. .. 4,120 2,360 720 7,200 



Here it is apparently the excess of common salt to which the 

 difference is due, and this despite the higher content of carbon- 

 ate of soda in the soil bearing the better tree. 



On the other hand, at the Tulare substation orange trees 

 (sour stock) maintain vigorous growth and good bearing in a 

 very sandy tract which to the depth of seven feet showed an 

 aggregate content of 26,840 pounds of salts (or 22,780 to 

 four feet depth) ; but which is never irrigated. (See diagram 

 No. 66). The salts in this case consists wholly of sulfate and 

 carbonate of soda in the ratio of fifty-four to forty-two, im- 

 plying the presence of nearly 12,000 pounds of salsoda within 

 reach of the tree roots ; yet in the absence of common salt, no 

 perceptible injury or even stress upon the trees has been noted. 



According to observations made in San Diego county, Calif., 



