Feb. 26,1917 
Effect of Water and Manure on Nitrates in Soils 
337 
VEGETATION-HOUSE RESULTS 
From an experiment begun in 1913 to study the effect of various 
moisture treatments on the growth of wheat under controlled condi¬ 
tions, samples were taken for the second part of this report. Galvan - 
ized-iron tanks, 2% feet high and 2 feet in diameter, filled with a fertile 
loam soil containing a high percentage of magnesium and calcium car¬ 
bonate, were used in this experiment. This is not the same soil as that 
used in the laboratory study. Enough New Zealand wheat was planted 
in each tank to make 
<?00 
sure of an even distribu¬ 
tion of 30 plants in each 
cropped pot. A half¬ 
inch layer of clean sand, 
covered with paraffined 
paper, was put over the 
top of each pot after the 
plants were up, to re¬ 
duce water loss by evap¬ 
oration. 
These tanks were 
placed in groups of six 
on low cars in an in¬ 
closure, 26 by 54 feet, 
protected on the north 
and east by board fences 
10 feet high. When 
weighings were to be 
made, the cars were 
wheeled beneath a large 
steelyard and each tank 
raised from the car by 
means of hooks at¬ 
tached to the steelyard. 
The weighings were ac¬ 
curate to 1 pound. 
Twenty tanks were 
«oo 
700 
Cropped — 
Fa now — 
500 \ 
3 00 
\j 
ts %o 2S 30 
Percent Water 
Fig. 2. —Graph showing the total soluble salts and nitrates in cropped 
and fallow soil maintained at various moisture contents in large 
tanks. 
kept at a uniform moisture content throughout the season, one of each 
treatment being fallow and one cropped each year. Nine other tanks were 
used, in which the moisture given the plants varied with the stage of growth. 
The first stage included the period until the plants had five leaves, or 
until about the last of June; the second from this time until the plants 
were in the boot just ready to head; and the third from the boot stage 
to maturity, which usually occurred about the middle of August. 
In 1914 and 1915, samples of the soil were taken from each of the 
tanks after the crop was harvested, and determinations made of total 
