quality of irrigation water in relation to 
LAND RECLAMATION 
By Carl S. Scofield, Agriculturist in Charge, and Frank B. Headley, Agriculturist , 
Office of Western Irrigation Agriculture, Bureau of Plant Industry, United States 
Department of Agriculture 
The so-called alkali problem on irrigated lands has two distinct phases. 
In one case the difficulty is due to the fact that, because of inadequate 
drainage or because of excessive quantities of salt in the irrigation water, 
the salt content of the soil solution comes to exceed the limit of tolerance 
of crop plants. In the other case the soil becomes relatively impermeable 
to water, difficult to work into good tilth after wetting, and in some cases 
nearly or quite unproductive. The present paper deals with this second 
phase of the alkali problem. 
These impermeable soils or hard lands are of wide occurrence in the 
irrigated regions. The condition may be found in desert soils that have 
not been irrigated, or it may develop after a period of irrigation. It is 
of very common though not universal occurrence in lands that have 
been swamped through the rise of the ground water and later reclaimed 
by drainage. The condition of impermeability or hardness is one of 
degree, some lands though hard being much more permeable than others. 
It is rather uncommon to find land that is completely impermeable to 
irrigation water. 
These hard lands sometimes contain soluble salts in excess of the 
generally recognized limits for crop production, but more often this is 
not the case. Very salty land may take water well and be soft or even 
“puffy” on the surface when dry, but when reclaimed by drainage and 
irrigation it may become so hard as to be very difficult to irrigate and 
difficult to work into good tilth when dry. 
The subject of the slow permeability of soils has been extensively 
investigated, both in this country and in Europe. The condition is not 
confined to desert or irrigated land but is found also in many regions 
where the rainfall is abundant. In the latter case it is manifested 
either by apparent infertility or by surface erosion of the soil or by 
both conditions. It is a matter of common observation that the erosion 
of soil by rainfall is more directly associated with conditions of slow 
permeability to water than with conditions of topography. In other 
words, with a given slope a soil that is readily permeable to water is 
much less subject to erosion by rainfall than a soil that takes water 
slowly. 
Journal of Agricultural Research, Vol. XXI, No. 4 
Washington, D. C. May 16,1921 
ye Key No. G-234 
(265) 
