482 



SOILS. 



There is, however, a strong intrinsic reason pointing in the 

 same direction, namely, the almost invariably high and lasting 

 productiveness of these lands when once rendered available to 

 agriculture. This is foreshadowed by the usually heavy and 

 luxuriant growth of native plants around the margins and be- 

 tween alkali spots (see fig. 60) ; i. e., wherever the amount 



ist year, id year, 3d Fourth year-42 bushels. 



FIG. 75. Wheat grown on black alkali land at Tulare Substation, California, showing improve 

 ment in successive years < >f reclamation treatment. 



df injurious -alt- present is S( small a- not t<i interfere with 

 the utilizatii m ' >t tin- abundant store < if plant-f< i< id which, under 

 the peculiar conditions of soil- formation in arid climates, re- 

 mains in the land instead of being \\a-hed into the ocean. 

 Extended comparative investigations < f -oil composition, as 

 well as the experience of thousands of years in the oldest 

 settled countries of the world, demonstrate this fact and show 



