BULLETIN 318 T HE EFFECTS OF ALKALI ON CITRUS TREES 317 



produced by the irrigation waters discussed above are quite similar 

 to the effects produced at Corona by water from Lake Elsinore more 

 than twenty years ago. The analyses reported by Loughridge also 

 show that the salt content of Lake Elsinore was actually less than 

 that of some of the present supplies. It would seem that the unfor- 

 tunate experience at Corona has either been forgotten or largely over- 

 looked by citrus growers. 



In addition to the above and a considerable number of other saline 

 irrigation supplies, that are at present being applied to certain citrus 

 groves in California, there is a much larger quantity of the irrigation 

 water that contains somewhat smaller amounts of alkali salts. In view 

 of the economic aspects of this phase of the subject, it is a matter of 

 interest to study the effects of this latter class of waters. For this 

 purpose, a lemon grove has been chosen. While the irrigation supply 

 in this case has been drawn from more than one source, the proportions 

 of which have varied from time to time, the analysis given in table 1 

 (no. 150) probably represents the average composition of the water. 

 It contains considerably less alkali than the irrigation waters discussed 

 above. As judged by current standards, this water would certainly 

 not be considered to be excessively saline. 



The lemon trees, now twenty years old, grew thriftily and produced 

 heavy crops of fruit for many years. During the past two or three 

 years, however, some of them have begun to decline. The older leaves 

 have turned yellow or brown and have fallen excessively in the winter 

 and spring. Many of the trees have lost their former thrift and the 

 yields and quality of the fruit have been considerably reduced, in 

 spite of the fact that reasonably good care and liberal amounts of 

 manure and other fertilizers have been applied. 



Soil samples have been analyzed from this grove, and also from 

 an area near by that has been under irrigation with water from 

 the same source for only two years. The results are submitted in 

 table 11. The data show that the total soluble matter has been very 

 materially increased as a result of the longer period of irrigation. 

 Considerable amounts of sodium salts, composed principally of the 

 chloride, have accumlated in the soil. Sulfate has also increased 

 considerably. It is again found that the greatest increases have 

 taken place among those constituents that are absorbed by lemon trees 

 in least amounts and have, at the same time, been added in greatest 

 amounts in the irrigation water. 



As might have been predicted from the analysis of the water, it 

 has required a longer period of time to effect a given increase in the 

 concentration of salts in this grove than has been required where some 



DIVISION OF SUbfhOFlCAL 



COLLEGE OF AGRICULTURE 



PV .' im&MIA 



