228 THE FUTURE OF ARID LANDS 
Erosion Damage 
Studies in the southern Great Plains indicate that lands being 
used beyond their capability deteriorate more rapidly than any 
others. 
Lands used beyond their capabilities are likely to be sandy or 
shallow phase soils, have steeper slopes, and, in the western part 
of the plains, have lower annual precipitation. Under such condi- 
tions the production of vegetative cover for the land is frequently 
not adequate to keep the soil in place and both wind and water 
erosion take a high toll. Such damage is destructive to any soil, 
but on shallow phase soil the damage is more likely to be irrepa- 
rable than on the deeper better grades of land. And yet because in 
wet cycles these lands often produce high yields, there is a strong 
tendency to gamble on them each year. This results in their being 
used beyond their capability. 
In the southern Great Plains experience has proved that shal- 
low, moderately sandy, and deep loose sand-hill soils of steep or 
even gentle slopes cannot be kept permanently productive under 
cultivation in the 14- to 20-inch rainfall belt. Shallow, fine- 
textured soils under cultivation on both flat and sloping fields 
have failed in all areas of less than 18 inches of rainfall. 
On the other hand, level to nearly level medium depth, moder- 
ately sandy soils have stood up well under cultivation with suitable 
practices under rainfall as low as 16 inches. 
Deep, nearly level, heavy soils have stood up well and can be 
farmed with suitable precautions wherever found in the southern 
Great Plains. This kind of soil does not occur, however, in large 
amounts in areas of less than 16 inches of rainfall. 
Research findings, which are verified by the experiences of many 
farmers in this area, emphasize one of the most serious conse- 
quences of using the land beyond its capability—permanent dam- 
age to the land. Productive soil is the most important part of the 
capital structure of farm businesses, and it cannot be replaced. 
This capital loss showed up in a very pronounced way in lower 
crop yields after the damaging soil blowing of the 1930’s. 
Low plant vigor was generally evident in the variation of green 
coloring of the plants from different fields. This variation empha- 
sized the sharp variation in the amount of nitrogen available. 
