Journal of Agricultural Research 
Vol. XXI, No. 3 
156 
solubility of ferric phosphate. The other soils on which chlorosis occurred, 
however, did not give any such high phosphorus analysis. The fact that 
the solubility of ferric phosphate is sufficient to make it a good source of 
iron in water-culture experiments prevents any probability of a relation 
between the amount of phosphorous found by analysis and the availability 
of iron. 
All the analyses indicated normal quantities of iron. The results are 
in agreement with the general experience that acid-digestion soil analyses 
yield little information of value from the plant physiological or patho¬ 
logical standpoint. Petrographic examination by the United States 
Bureau of Soils of the Pocatello soil and of the nursery soil which con¬ 
tained carbonates without chlorosis gave no clue to the difference be¬ 
tween the plants on them. Acidity determinations by Dr. L. J. Gillespie, 
of the Bureau of Plant Industry, showed a P H of 7.8 for the Pocatello soil 
and 8.4 for the nursery at which there were carbonates but no serious 
chlorosis. The main facts to be drawn from the examination of the soils 
of the different stations was that all the soils on which chlorosis occurred 
contained carbonates and that two of them were underlaid with lime¬ 
stone. 
Analysis by the United States Bureau of Chemistry of the water supply 
showed 320 mgm. of bicarbonic acid (HC0 3 ) per liter of water at the 
Pocatello Nursery, and practically no other anions, while at the nursery 
at which there were soil carbonates but no chlorosis there were reported 
180 mgm. of bicarbonic acid per liter, as against 450 mgm. of sulphate (S0 4 ) 
per liter. This is of some interest in connection with the difference in 
the amount of chlorosis at the two places, as the arid conditions made 
necessary the application of considerable amounts of water to the nursery 
beds during warm weather. The soil solutions during the periods of 
greatest growth must, therefore, have been influenced to a considerable 
extent by the character of this water. It was noted at the Pocatello 
Nursery that the chlorosis was more prevalent in beds which had been 
under nursery management for several years than in beds which had just 
been included in the nursery area and had therefore received less of the 
water. 
KIND AND EXTENT OE INJURY 
At the Pocatello Nursery there was so much chlorosis and the growth 
of affected stock was so unstisfactory that a detailed study of it was 
undertaken. The nursery is at an elevation of 5,200 feet, well below the 
lower limit of natural coniferous forest growth in this region. Precipita¬ 
tion for the period during which the nursery is usually free from snow 
(April to October, inclusive) averaged but 11.2 inches for the years 1909 
to 1917, inclusive. The days are warm and the nights cool during the 
growing season, only 2% months being entirely free from killing frost. 
The soil is a rather heavy black silt loam; composite samples from 8 to 10 
