BULLETIN 318 THE EFFEC TS OP ALKALI ox CITRUS TREES 315 



have the power of reacting with heavy types of soils to a greater degree 

 than with sandy soils. The reactions result in removing limited 

 amounts of sodium from solution and bringing into solution corre- 

 sponding amounts of other bases, composed mainly of calcium. The 

 physical arrangement of the soil particles also undergoes alteration. 

 In view of the fact that soils are extremely variable,, it is not surpris- 

 ing, that the effects of irrigation have not been uniform over a given 

 grove. 



Analyses of two irrigation waters from Tulare County are also 

 reported in table 1 (Nos. 103 and 105). They contain unusually 

 large amounts of salts. Information at hand does not made it possible 

 to state the exact length of time these waters have been applied. The 

 wells from which the samples were drawn were deepened about four 

 years previously and there is some evidence that water of a radically 

 different character was obtained as compared with that originally 

 supplied. It is probable that one of these wells (No. 103) supplied 

 fairly pure water previous to being deepened. The orange trees to 

 which these waters have been applied are approximately twelve years 

 old and have shown severe injury during the past two years. 



Soil samples were drawn from these groves and also from adjacent 

 unirrigated fields apparently similar in every way to the soils in the 

 groves. One of these has been used for grain for a number of years, 

 the other still remains in its native state. The soil of one of these 

 groves (T) is of a sandy loam character most of which is underlaid 

 with a dense hardpaii at a depth of from two to three feet. The other 

 is located on the heavy type of soil, belonging to the Porterville clay 

 loam adobe series, locally known as "dry bog." The analyses are 

 reported in tables 8 and 9. 



The data confirm the results obtained in the study of the groves 

 located near Kiverside. By comparing the irrigated with the unirri- 

 gated soils, it is seen at once that the irrigation has greatly increased 

 the amounts of soluble salts in the soil. While the concentration of 

 practically every constituent has been increased, the chlorine and 

 sodium have been increased to the greatest extent. Comparison of the 

 soil analyses with those of the irrigation waters shows that those con- 

 stituents present in the water in greatest amounts have accumulated 

 in the soil to the greatest extent. The rates of increase, however, are 

 not proportional to the composition of the irrigation water, owiiiir in 

 part, at least, to the fact that citrus trees absorb large amounts of 

 certain constituents, and only small amounts of others. As will be 

 shown elsewhere, eitrus trees do not absorb sodium salts to any <rreat 

 extent, but absorb relatively large amounts of calcium. 



DIVISION OF SUBIKOPKAL HPRHCULllM 

 COLLEGE OF AGRICULTURE 



