102 
Journal of Agricultural Research 
Vol. II, No. 2 
Means and Holmes, 1902, p. 601) a wide variation in the percentage of 
carbonates, chlorids, nitrates, and sulphates, chiefly of sodium, potassium, 
calcium, and magnesium, which are the salts usually present in apprecia¬ 
ble quantities. From a casual examination of these data there appears 
to be no relation between soils of high salt content and malnutrition of 
trees. In figures 1,2, and 3, however, it is evident that when adjacent 
areas are compared, the soils from the vicinity of deteriorating trees are 
richer in nitrate nitrogen. The quantities of other salts show no constant 
relationship to good or poor areas. Except for a slight increase in the 
quantity of bicarbonates during the spring, there is no evidence of seasonal 
Fig. 1 .—Diagram showing relative nitrogen-fixing power, nitrifying power, and salt content of soil 
samples from good and poor areas in an orange grove which was unproductive and markedly chlorotic 
throughout. The good areas were themselves very unproductive. 1 Black columns show good areas; 
hatched columns indicate poor areas. 
variation for the various salts. Though decided variations in salt 
content of the soil were observed occasionally, they were evidently due 
to the infrequent rains. 
The nitrate content of the soil of so-called “poor” areas is not exces¬ 
sive unless the crust analyses shown in figure 4 are taken into account. 
During irrigation it is obvious that in the poor areas the numerous 
shallow lateral roots (Mills, 1902) will be bathed in a solution which 
temporarily is relatively stronger than during the intermediate periods. 
The reports that in some cases applications of fertilizers high in nitrogen 
to orange groves showing symptoms of malnutrition have accelerated 
instead of retarded the deterioration offer corroborative evidence of the 
danger of an excessive supply of readily available nitrogen. It is, of 
1 The samples were collected near Riverside, Cal., in June, July, August, and October, 1912, and February, 
March, and June, 1913. The averages of the analyses are given. 
