GROWTH AND COMPOSITION OF ORANGE TREES IN 
SAND AND SOIL CULTURES* 
By H. S. Reisd, Professor of Plant Physiology, and A. R. C. Haas, Assistant Professor 
of Plant Physiology, College of Agriculture, University of California 
The limited control over the factors of nutrition operating in the field 
{loY {4) has, perhaps, contributed in a large measure to the hetero¬ 
geneous array of causes assigned to specific effects. Before any explana¬ 
tion of so-called nutritional disturbances of citrus trees can be accepted, 
they must be produced experimentally under conditions admitting of 
scientific analysis. The method subsequently described for growing 
citrus trees under controlled conditions should make such an analysis 
possible. The present paper deals with a comparison of the growth and 
composition of trees when grown in sand and in soil cultures. 
It is important to determine, first, whether citrus trees can be gro\TO 
successfully for several years in sand cultures receiving only inorganic 
salt solutions; second, whether the growth obtained in sand receiving a 
nutrient solution (which has been shown to be well suited to the growth 
of barley) compares favorably with that obtained in soil receiving oc¬ 
casional additions of the same nutrients; and, third, how the composition 
of the trees grown in sand compares with that of the trees grown in soil. 
The importance of the method and the successful results thus far ob¬ 
tained seem to justify a brief description of the way in which these 
cultures were installed and cared for. The procedure to be described 
was adopted only after considerable study and experimentation. 
As experiments upon trees are usually of long duration, adequate 
protection and cultural attention are quite essential. A screened en¬ 
closure with suitable windbreaks provided the necessary protection 
against animals and destructive winds. The experiments were conducted 
in sheet-iron tanks and in large galvanized iron cans. The former were 
sunk in the ground; the latter were placed in trenches for protection from 
the direct rays of the sun. 
The trenches were 28 inches to 30 inches wide, about 3 feet deep, and 
were lined on both sides with boards. In the bottom of each trench were 
two 2-inch by 4-inch pieces of redwood extending the entire length of the 
trench, which served as supports for the cans and prevented rusting. 
Thus far it has not been found necessary to provide wooden covers for 
the trenches. The necessary protection against rain has been obtained 
by placing frames of roofing paper on wooden trapezes swung by wires 
from the roof of the enclosure. 
Each of the galvanized iron cans (PI. i. A) is about 20 inches in diam¬ 
eter and about 26 inches in depth. In order to have a means of weighing 
the cans, three wrought-iron lugs inch by i inch, each bearing a three- 
eighths inch hole at the top, were fastened by bolts to the inside of the 
heavy upper rim. The lugs were equally spaced around the rim and pro¬ 
truded through holes cut in the lid (PI. i, B). 
1 Accepted for publication Nov. 6, 1922. Paper No. 77, University of California, Graduate School of 
Tropical Agriculture and Citrus Experiment Station, Riverside, Calif. 
* Reference is made by number (italic) to “literature cited,” p. 813-814. 
Journal of Agricultural Research. Vol. XXIV, No. 9 
Washington, D. C. June 2, 1923. 
aer Key No. Calif.-3S 
( 801 ) 
