June 2,1923 
Orange Trees in Sand and Soil Cultures 
803 
between the oilcloth and the tree. A cyHnder of heavy brown wrapping 
paper was placed about the base of eadi trunk to give added protection 
from sunburn. 
Where soil was employed the cans were prepared as stated before, 
which made possible the removal of salts while the tree was in the soil. 
Wilting-point determinations were made on the soils and they were then 
brought to a suitable water content prior to being gently compacted in 
the cans. 
In the case of sand, additions of carbon-treated distilled water were 
continued until the first indications of drainage water appeared in the 
drainage pipe. Air suction was then applied. Nutrient solutions (6 to 
9 liters or more) made up with carbon-treated distilled water were then 
added and the drainage continued until complete. If drainage water 
appeared later in the bottom of the cans, the air-suction was again ap¬ 
plied until all the free solution had been removed. The problem of drain¬ 
age was subsequently simplified by providing a means for gravity drain¬ 
age. The cans were placed on supports over the trenches and a short 
iron pipe was inserted into the bottom of each can. As drainage water 
percolated to the bottom of the can, it dripped through the short pipe 
into a bottle standing in the trench. This arrangement is decidedly 
advantageous because it precludes the accumulation of water in the 
bottom of the can and also materially lessens the amount of labor 
required in caring for the cultures. The cans were shielded from the 
direct rays of the sun by housing them in a wooden box. The treat¬ 
ments were applied every one to three weeks as conditions required. 
During hot weather a small tree growing in sand (about 225 pounds of 
moist sand) may require from 24 to 30 liters of distilled water each 20 
days. A Bamstead still capable of giving 5 gallons of distilled water 
per hour, with a block-tin-coated tank capable of storing 2,000-^2,500 
liters of distilled water, and 24 large carboys for treating the distilled 
water with carbon black together with filtering facilities, have made it 
possible to maintain in operation 136 trees in cans as well as several 
trees in tanks of sand. 
In the case of cans of soil when drainage water may not be desired, 
the weighing device patterned after that of Briggs and Shantz (2) is 
used (PI. I, C). A windlass with wire rope and pulleys is mounted on a 
frame work of 2-inch galvanized-iron piping to which wide swivel castors 
are attached. Two spring scales with circular disks, 500 and 600 pounds 
capacity, respectively, are used for bringing the cans to constant weight. 
As the trees develop in cans of soil, it is necessary to make allowance for 
the increased weight of the tree in order to maintain suitable moisture 
content of the soil. The criteria used for this purpose are, appearance 
of the tree, presence or absence of drainage water, and appearance of 
the surface of the soil upon slightly raising the lid, or preferably by 
examining a sample of the soil. It is a good practice occasionally to raise 
the lids of the cans of soil to ascertain whether channels have been 
formed in the surface layers. It is best to weigh the cans frequently, 
since if large additions of solution are required, channels may appear 
throughout the soil and drainage water may appear without much of the 
soil being appreciably above the wilting point. 
In order to carry on experiments with trees for a longer period of 
years, containers of a larger capacity than that of the cans are necessary. 
Tanks of two sizes are being used. The smaller are 3 feet 8 inches in 
diameter by 4 feet deep (PI. 2, A), the larger are 7 feet 8 inches in diam- 
