56 Colorado Experiment Station 
DRAINAGE NOT THE MAIN PROBLEM 
That our ordinary crops, oats, wheat, alfalfa or potatoes, cannot 
be successfully grown with the water-plane an inch above the sur¬ 
face, no one doubts, and lands that become filled with water to such 
an extent as this should be provided with an outlet for the excess 
water. This can be effected by surface drains. The practice of sub¬ 
irrigation, under which crops are grown with a water-plane main¬ 
tained within 18, or even 12 inches of the surface, gave my ideas on 
aeration, etc., a decided shock at first. While some drainage is nec¬ 
essary, this is not the main problem to be solved in this section. In a 
great big sense, the problem has been, for a period extending back to 
the draining of the old lake and the building of the bed of the Rio 
Grande, a drainage question. 
HEIGHT OF BED OF RIO GRANDE CAUSE OF EXCESS SODIC 
CARBONATE 
I believe that the sodic carbonate owes its origin to the fact that 
the drainage south has been no better since the valley itself was formed 
than it is now and for the same reason as now. The bed of the Rio 
Grande has never been cut down so as to let the water north of it 
drain southward out of the valley. The efficiency of this simple cause 
to account for the concentration of sodic carbonate in this area to the 
extent that we find it, is impressive on a little consideration. Under 
this condition, the water-plane has always been high in this section of 
the valley. Evaporation has gone on rapidly from the surface of the 
land at all times. Assuming that this evaporation has been 3 feet per 
annum over an area of 500,000 acres, we have 1,500,000 acre-feet of 
water. Taking 720 acre-feet as equivalent to a flow of 1 second-foot 
for a year, we account for a discharge of 2,000 second-feet of water 
into the territory. The evaporation of 1,500,000 acre-feet of mountain 
water, carrying only 2^2 grains of sodic carbonate in each imperial 
gallon, will deposit 145,500,000 pounds of sodic carbonate, or 291 
pounds on each acre which must remain within the area if there be no 
drainage to remove it, so there would be an accumulation of this salt 
just in proportion as this drainage was inadequate. In this sense the 
whole situation resolves itself into a drainage problem, but no one has 
heretofore suggested this question. 
There are intelligent men in the valley who appreciate that the 
water, per se, is not the most important question that they have to deal 
with. Many of them have become convinced that the liberal applica¬ 
tion of water to the surface, so long as there is space enough between 
the water-plane and the surface of the land to let the water applied 
pass a few inches below the surface, ameliorates conditions materially 
though the water-plane has not been lowered. They know that this is 
only a palliative, but it enables them in some cases to establish a crop, 
