10 
Colorado Experiment Station 
Fi^-. 4 shows three tile lines. The first two are 20 feet apart, the 
second and third, 16 feet apart. It shows the progress of the perco¬ 
lating water from 24 hours to 14 days. The horizontal and vertical 
divisions represent i foot. From this drawing the lateral downward 
and upward percolation of the water may be easily ascertained. We 
find that, in this soil, moisture has a tendency to percolate downward 
much faster than to the side, and the depth of the moist soil between 
lines is such as to be beyond the reach of roots of many plants. This 
condition is further developed in studying the crops grown upon the 
ground and will be spoken of again. 
AMOUNT OF WATER REQUIRED TO SUPPLY TILE LINES 
The amount of water necessary to keep the tile lines full, varied 
with the amount of moisture in the soil and the length of time irriga¬ 
tion had been in progress. When irrigation was first started, .2 of i 
second-foot of water was sufficient to keep all tile lines full. As the * 
irrigation proceeded it was necessary to cut down the amount of water 
supplied, or the water would rise in the cement boxes and overflow. 
During the latter part of an irrigation approximately .1 of i second- 
foot was sufficient to supply all pipe lines. 
CROPS GROWN 
During the four years that the experiment was in progress, the 
apple orchard mentioned above and shown in Fig. i, thrived. All the 
irrigation water that it received was from the subirrigation system. The 
tile lines in this orchard were run about 4 feet to one side of a row of 
trees and within easy^reach of the roots. The foliage of the trees would 
always respond to the application of water and a few days after the 
water was turned into the pipe lines, this foliage changed color slightly 
and looked fresher than it did preceding the irrigation period. No 
records were kept of the crop produced from this orchard as it was an 
old orchard and had been neglected for a number of years. 
ALFALFA 
The installation of the subirrigation system injured the alfalfa 
somewhat for the first year after installation of the system. The 
trenching cut out many plants, and the dirt at the side of the trench 
injured the first cutting of alfalfa materially for 1913. In 1914, ’15 
and T6, however, this alfalfa did well. The stand was even at the 
start and continued so. The roots of the alfalfa seemed to be able 
to reach plenty of moist soil, even at the midway points between tile 
lines. Fig. 5 shows a typical view of this alfalfa field. The alfalfa 
always responded immediately to the irrigation from the underground 
pipes, and within two days after the water was turned on at any time 
the foliage of the plants would show the effect of the water. 
