Table 31. Relation of Corn Yield to Depth of Surface 
Soil, Towa 1/ 
: Yield (bushels) 
Depth (inches) ‘Mars s oam tama silt loam Shelby silt loam 
lle-12 119.9 63.9 == 
9-10 109.0 58.1 oe 
7=8 9267 45.8 49.8 
506 79 6 42.8 45.2 
Zeeks 65oh 38.h 38.9 
0 == == 2.7 
1/ Uhland, R. E. 19h9. Crop yields lowered by erosion, 
Soil Conservation Service, TP=75, p. 17. 
The yield figures represent various outputs from comparable inputs. 
Yield effects of soil erosion are commonly masked, or even reversed, 
where increasing inputs are applied to eroding soils. Surprisingly 
high yields have been obtained from some badly eroded soils, 3/ but 
only where other inputs have been increased far above what would 
have been required for equivalent production from the uneroded soil. 
Thus, the true effects of erosion might be reflected more in cost 
of production, or in input-output ratios, than in physical yield 
values. 
In total soil lost, the Southeastern States have suffered the 
most from soil erosion. The wide adoption of needed land-use 
adjustments, however, has reduced the rate of loss in that region. 
For the base period the greatest annual soil loss was in the 
Corn Belt, particularly in problem areas such as western Iowa 
where, in many fields, corn was grown almost continuously on 
long, unbroken slopes. For the country at large, about 80 percent 
of soil-erosion losses have occurred in the area east of the 100th 
meridian. 
Soil Blowing 
While few reliable figures are available on the areas affected 
by soil blowing (wind erosion), it may be assumed that over 100 
million acres are subject to this type of loss, of which perhaps 
10 million acres are seriously affected. 
3/ Bawer, Le D. 1950. How serious is soil erosion? Soil 
Science Soc. Amer. Proc. 15(1): 165. 
+ 166 - 
