EFFECT OF IRRIGATION WATER AND MANURE ON THE 
NITRATES AND TOTAL SOLUBLE SALTS OF THE SOIL 
F. S. Harris, Director and Agronomist, and N. I. Butt, Assistant Agronomist , 
Utah Agricultural Experiment Station 
INTRODUCTION 
Plants obtain their food from the soluble salts of the soil; therefore the 
study of these salts is of great importance to agriculture. There is no 
method available for measuring exactly what portion of the plant food 
in the soil can be taken up by crops at any given time; the nearest ap¬ 
proach is to extract the soil with some solvent and to determine the 
quantity of plant food in the solute. 
Imperfect as this method is in approximating the available plant food, 
it yields many valuable data which help to an understanding of some of 
the complex soil changes. 
In the present paper an attempt has been made to determine the 
effect of varying quantities of soil moisture and manure on the total 
soluble salts and nitrates that can be extracted by water from the soil. 
Some of the soils under investigation were kept in the laboratory, others 
were allowed to stand for long periods in large tanks, while still others 
were studied under normal field conditions. Comparisons were also made 
of cropped with uncropped soils in tanks and in the field. 
REVIEW OF LITERATURE 
Most of the former work on the soluble salts of the soil has been done 
in humid climates, where conditions are different from those under which 
the experiments herein reported were conducted. For this reason there 
is not a complete agreement in the results. 
King (8, p. 92-107) 1 found that the ratio of total soluble salts to ni¬ 
trates varied between 2.14 to 1 and 9.97 to 1 under different conditions. 
The total soluble salts, and especially the nitrates, were higher in fallow 
than in cropped soils; and crops used the nitrates faster than they did 
the other soluble salts. 
Investigations by Stewart and Greaves (13, 14) show the application 
of irrigation water to have a distinct beneficial effect on nitrate forma¬ 
tion, being greatest where 15 inches of water were applied. In cropped 
land there was less nitrogen in the soil during the fall and spring than 
during the summer. More nitrogen was found in fallow ground in the 
fall than in the spring, but most of the surplus disappeared during the 
1 Reference is made by number to "Literature cited," p. 359. 
Journal of Agricultural Research. 
(Dept, of Agriculture, Washington, D. C. 
hi 
( 333 ) 
Vol. VIII, No. 9 
Feb. 26,1917 
Utah—5 
