14 
Colorado Experiment Station 
Fig. 9.—Surface-irrigated Corn 
CONCLUSION 
The conclusions drawn from this experiment are as follows: 
1. Snbirrigation by means of underground pipe is not to be 
recommended for any of the ordinary farm crops on account of the 
'excessive cost for installation. It can be recommended only for the 
most intensive farming where water is very scarce and valuable, and 
only a small stream is available. 
2. The lateral percolation of the water from the tile lines in dee]:) 
silt-loam soil is not sufficient to warrant these lines being placed from 
16 to 25 feet apart. More water percolates downward than upward or 
to the side, and it would be necessary to place these tile lines not more 
than 8 feet apart in order to bring the moisture to the roots of the 
growing crop. This applies to soil similar to tliat on the snbirrigated 
field at the College farm only. It may be, and probably is, a fact that 
with a hard-pan or an impervions stratum of some kind slightly below 
the tile, and especially in early or porous soils, the lateral percolation of 
the water would be increased very much and tbe success of a system, 
with tile lines as far apart as 16 or 25 feet, could be guaranteed, but in 
deep silt-loam soil the lateral percolation of the water is disappointing. 
