Nitrogen Fixation 13 
ANALYSIS IX. 
RESIDUE FROM GROUND WATER. Orchard No. 1. 
Per Cent. 
Calcic Sulfate . 15.164 
Magnesic Sulfate . 9.890 
Magnesic Cholrid . 11.358 
Sodic Chlorid . 7.225 
Sodic Carbonate . 1.825 
Sodic Nitrate . 53.299 
Potassic Oxid . Trace 
Iron and Aluminic Oxid . 0.372 
Silicic Acid . 0.061 
Loss (water, organic matter, etc.) . 0.906 
100.000 
This residue containing 53.3 per cent of sodic nitrate gives 
us 941.0 grains of this salt to each imperial gallon. As iodine com¬ 
pounds sometimes occur associated with the nitrates, I tested this 
residue, using 30 grams, but obtained negative results. 
This gives us an idea of the conditions obtaining in this or¬ 
chard which may be summarized as follows: The surface soil has 
a brownish color, efflorescent salts are scarcely present. There is 
some incrusting of the surface soil, beneath which there is 
sometimes as much as an inch of mealy material, soil particles and 
fine crystals. At a depth of two to two and a half feet the ground 
becomes muddy, but there is no free water to a depth of 5J/2 to 
6 feet. There is no vegetation on parts of this ground and the 
young trees have failed to live. The country is quite flat but is 
not particularly low; it probably is not less than 50 feet above the 
river which flows within four miles of it. We find an abundance 
of nitrates in the uppermost portion of the soil, the maximum being 
6.541 per cent of the soil; this soil was incrusted with some efflores¬ 
cent salts, commonly called alkalis. The next, a sample of very 
wet soil taken to a depth of five inches, gave 2.571 per cent of 
nitrates. These percentages are followed by 1.706, 1.107 and 1.016, 
for what we may consider the first foot of soil, with 0.226 for the 
upper portion of the second foot and 0.198 for the rest of the soil 
to the depth of 29 inches. 
In the next orchard which I shall designate as Orchard No. 2. 
we have the same conditions only greatly intensified. This is an 
older orchard, what is left of it, and we can see the effects more 
plainly than in Orchard No. 1. What was once an orchard is now 
absolutely barren, not so much as a weed growing on several acres 
of this land. See Plate II. There are a few trees remaining in 
one corner and a few isolated trees on one edge. These will have 
a great interest for us. The first samples from this orchard were 
taken in 1907. The soil was glistening, brown and apparently 
wet on the surface but was really dry. Mr. Whipple who was 
with me dug a hole close to a small apple tree which was alreadv 
