CLXXIV. ECONOMIC ASPECT OF ARTESIAN BORING IN N.S.W. 
as to wash accumulated salts out of the land. The total amount 
of salts contained in the successive masses of irrigation water are 
thus accumulated and retained in the soil, and this accumulation 
soon becomes formidable if the water is at all strongly charged or 
if the soil should contain an amount of alkali closely approaching 
the limits of tolerance. 
“When the amount and kinds of salts in the water have been 
determined by a chemist it is a simple question of arithmetic to 
estimate how much alkali is added to the soil each year, and 
accordingly to calculate the number of years within which the soil 
will become incapable of bearing ordinary crops. To illustrate 
this by example :—Suppose a water used for irrigation to contain 
100 grains of alkali salts per gallon, as in the case of Lakes 
Elsinore and Tulare, in California, and that irrigation is used to 
the extent of supplying an annual deficiency of 15 inches of rain- 
fall (or 15 acre inches), to wit, 408,375 gallons, this amount of 
water would contain something over 5:300 ibs. of salt, and were 
these fully retained in the land, this addition would be made 
‘annually. Comparing this with some of the actual amounts found 
in land approaching the limits of tolerance, we find that in the 
experimental plot at the Southern California substation, which 
contains within the first three feet from 7,000 to 12,000 ibs. of 
comparatively mild alkali (chiefly glauber salts) most of the com- 
monly cultivated grasses clover and vegetation refuse to grow or 
fail to produce satisfactory crops, while, nevertheless, excellent 
high-grade sugar beets are grown upon the same ground. At the 
Tulare substation it was found that sugar beets failed to produce 
satisfactorily when 18,000 to 20,000 tbs. were contained in the 
land. Nearly the same limit of toleration applies there to wheat, 
while barley will under favourable conditions, resist as much as 
32,000 tbs. to the acre in 3 feet depth, which may be considered 
as its extreme limit of tolerance. But, on the same land, ordinary 
fruit trees already planted either die or maintain but a feeble 
existence. Citrus trees of a considerable age have died out under 
these conditions, so soon as the soil in which they grew was by 
ee 
