but many arsas of heavy soils are susceptible, such as the lake 
plain soils of northern Ohio. Damage is frequently less severe 
in regions where heavy frosts are common. Damage due to the 
formation of surface crusts is most pronounced in sandy loams 
and silt loams. 
Alkali Accumilation 
Soil deterioration from the accumulation of deleterious salts 
may follow the application of salty irrigation water, inadequate 
development of drainage, or both. It is limited largely to the 
irrigsted areas of the 19 Western States. Particularly affected 
are the San Luis Valley of Colorado, the Lower Gila in Arizona, 
the Imperial Valley of California, and the Riverton and Kendrick 
projects of Wyoming. For the base period this irrigated region 
averaged about 22 million acres, of which 25 percent, or 5,500,900 
acres, was materially affected and 10 percent, or 2,200,000 acres, 
was seriously affected. In addition to the chemical effects of 
toxic concentrations of salts, alkali accumulation frequently leads 
to deterioration in the physical structure of the soils, making 
them impermeable and untillable. It is usually accompanied by 
waterlogging of the soil. Unlike losses due to severe soil erosion, 
losses arising from alkali accumulation and waterlogging are 
generally reversible. Most of the affected areas could be re- 
claimed by improved drainage, application of water of lower salt 
content, if available, and the use of soil amendments, such as 
gyosum, or sulfur and lime. 
Losses on Grazing and Forest Land 
This report covers the 631 million acres of range and pasture, 
320 million acres of forest range, and 257 million acres of une 
grazed forest and woodland in the United States. 
The most important causes of agricultural losses on grazing lands 
are wind and water erosion, overuse, the invasion of trees and 
shrubs, and drought, 
Wind and water erosion have removed the topsoil over vast areas 
and caused a decline in both the quality and quantity of vegeta= 
tion. Furthermore, the runoff and erosion debris from grazing 
lands has increased the destructiveness of floods and added to 
the silting problem of reservoirs and irrigation works. 
Overuse has accompanied such soil erosion and, in fact, has 
frequently been the cause of it. This factor has seriously ree 
duced the productivity of grazing lands over wide areas. 
The invasion of trees and shrubs into new areas and the thicken- 
ing up of existing stands have also reduced the production of 
usable forage on rangelands, and to a lesser extent on pasture= 
lands. Estimates of the area seriously affected by such in- 
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