RANGE PRESERVATION AND EROSION CONTROL. 
21 
counted for by the more luxuriant growth of the individual plants 
on the noneroded soil regardless of the smaller amount of water re- 
quired for the production of a unit of dry matter. 
In the case of native bromegrass and wheat the same behavior 
holds as to vegetative growth and other facts as in the case of the 
peas. Hence 2.4 and 2.1 times as many leaves of bromegrass and 
wheat, respectively, were produced on the noneroded as on the 
eroded soil; the leaf length, dry matter, and water used per plant 
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Peas Brome Wheat Wheat Reacts 
Wafer requirements per unit cfry weight 
mamm Eroded 6 oil 
zzzzzzz Non-eroded soil 
— • Per cent difference 
Fig. 4. — Relative water requirements per unit dry weight for peas, native bromegrass, 
and wheat grown in eroded and in noneroded soils of the same type. 
were greater on the noneroded soil by 0.8 and 1.3, 1.1 and 1.2, 0.7 
and 0.5 for native bromegrass and wheat, respectively. And here, 
again, the water requirement per pound of dry weight was greater 
on the eroded soil by 20.6 per cent and 37.6 per cent for the native 
bromegrass and wheat, respectively. 
Erosion is detrimental to plant growth chiefly because it brings 
about the two following conditions of soil impoverishment: (1) 
Lack of adequate soil moisture for the full development and seed 
