Feb. 26, i 9 i7 Effect of Water and Manure on Nitrates in Soils 
335 
later moved upward as the water was evaporated from the surface of the 
soil. 
For a humid soil Hall (3, p. 230) showed that no more nitrates were 
leached from a 60-inch lysimeter at Rothamsted than from one 40 inches 
deep, from which it was concluded that nitrification does not take place 
below 40 inches from the surface. 
Buckman (1) has shown that under dry-farm conditions the formation 
of nitrates is greater where there is a good supply of soil moisture than 
where the soil is dry. Intertilled crops after fallow did not seriously 
deplete the soil for the succeeding grain crop, either in moisture or in 
nitrates. 
Eyon and Bizzell (10), as well as other experimenters, found the forma¬ 
tion of nitrates to be influenced by the crop growing in the soil. 
At the Rothamsted Experiment Farm (9) nitrates were found to in¬ 
crease, evidently from better moisture conditions, in the fall after a 
heavy rainfall. 
A report of the Washington Agricultural Experiment Station (2, p. 
17-18) shows a tendency for the larger quantities of nitrates to be 
formed in the upper foot of the soil and the smaller quantities deeper, 
down to 36 inches (the lowest depth analyzed); but there were a greater 
number of high-nitrate samples below 20 inches than above. The high¬ 
est nitrate content was found in the spring before the plants began to 
grow. 
EXPERIMENTAL WORK 
methods of analysis 
In determining the total soluble salts and nitrates 100 gm. of freshly 
sampled soil were used. To this, 500 c. c. of distilled water were added 
and stirred thoroughly, then allowed to settle for 20 minutes, after 
which it was filtered through a Chamberland-Pasteur filter, the first 100 
c. c. of the filtrate being discarded. 
To get the total salts, 100 c. c. of the filtrate were evaporated to dry¬ 
ness on a steam bath and the residue weighed. The nitrates were de¬ 
termined by the colorimetric method described by Schreiner and Failyer. 1 
Both the nitrates and the total salts are expressed in parts per million of 
dry soil. 
SOIL CHANGES IN GLASS JARS 
The first experiment was conducted in the laboratory, the object 
being to study the influence of different quantities of moisture on soil 
changes under controlled conditions. Glass jars holding 800 gm. of dry 
soil were made up to percentages of water from 2.95 to 54.47, with dif¬ 
ferences of about 5 per cent. These were loosely covered with lids to 
1 Schreiner, Oswald, and Failyer, G. H. Colorimetric, turbidity, and titration methods used in soil 
investigations. U. S. Dept. Agr., Bur. Soils Bui. 31, p. 39-41. 1906. 
