CHARACTERS OF ALKALI SOILS 35 



small quantities of this salt are sufficient to make clay soils unworkable 

 because of the puddling effect it has on clay, and similarly very small 

 quantities of it have the power of stopping the important process of 

 nitrification. Since poorly aerated soils in the arid regions are favor- t 

 able to the reactions which produce "black" alkali, especially where 

 carbonates are plentiful or where excessive amounts of nitrate of soda 

 are used for fertilizing, no pains should be spared to insure to soils, as 

 nearly as possible, perfect aeration through drainage and tillage ; great 

 care should be exercised in the use of irrigation water, and nitrate of 

 soda should be employed sparingly. 



The term "white alkali" is usually applied to either common salt 

 or Glauber salt or both in soils. Where present in sufficient quantity 

 white alkali salts may, through evaporation of water, be deposited on 

 the surface of the soil as a white efferescence, such as that seen in 

 exaggerated form on the Nevada desert, on some soils of the San 

 Joaquin Valley and on some of the Coachella Valley soils. Of the 

 "white" alkali salts common salt is by far the more harmful and most 

 fruit trees are not very resistant to it. They can, however, be success- 

 fully grown in very considerable quantities of Glauber salt. 



The actual tolerance of fruit trees for the various salts men- 

 tioned, varies greatly with the different trees for the different salts, 

 and it is always best, when planting on alkali land is contemplated, 

 to consult the revised reprint of Bulletins 128 and 133 of the California 

 Experiment Station, and after having determinations for alkali made 

 on the soil, to be guided by the information therein contained. The 

 same publication also contains much valuable information with refer- 

 ence to the reclamation of alkali land and describes conditions under 

 which it may and may not be feasible to reclaim such lands so as to 

 preclude the possibility of useless expenditures. 



Prospecting for Soil Defects. For subterranean prospecting, 

 Professor Hilgard commends a steel rod not less than a quarter of 

 an inch in diameter (round or square, preferably the latter), well 

 pointed at one end, and provided at the other with a stout iron ring 

 for the reception of a stout cross-handle, such as is used for post-hole 

 augers. With such a prod, or sounding rod, not less than five feet in 

 length, the exploration of the subsoil for hard-pan or dense clay 

 layers becomes a matter of a few minutes. It is easy also to detect 

 thus the presence of underlying layers of quicksand, gravel, or other 

 loose materials through which irrigation water would waste, or which 

 would prevent the rise of bottom water within the reach of plant roots, 

 by the large interspaces between their grains. Any remaining doubts 

 as to the nature of such underlying materials ati particular points can 

 then quickly be solved by the use of a post-hole auger or by digging, 

 for thorough inspection of each foot of depth which may be found 

 desirable. Subsoil prospecting or sampling can also be very easily 

 done by boring with an ordinary carpenter's auger, \ l / 2 inches in 

 diameter the shank being lengthened by welding-in a piece of steel, 

 three or four feet in length, according to the depth it is thought de- 

 sirable to penetrate. Separate samples for each foot of depth are thus 

 easily taken. 



