10 BULLETIN 180, U. S. DEPARTMENT OF AGRICULTURE. 
ing action is taking place. Soils composed almost entirely of either 
sand or clay particles are not so good as those with a fair amount of 
each. 
The quality of the soil is greatly impaired by the continual process 
of erosion. Rapid leaching takes place, removing a large part of the 
soluble salts; the surface soil is often washed down to the lowlands 
and sometimes out to the sea; gullying so defaces the land that it 
becomes difficult to cultivate. The organic matter is one of the first 
losses of eroded soils. Abandonment of the field follows, because 
the land is considered too poor for agricultural use, having lost its 
productiveness through the process of erosion. 
The gullies in a field act as drainage ditches. The land between 
such gullies drains too rapidly, the water-table is lowered, and it is 
difficult for the crops to obtain sufficient water for proper growth 
or to withstand even a moderate period of drought. As these gullies 
occur on hillsides, the natural drainage is ample, if not excessive, so 
that the additional drainage furnished by the gullies is a positive 
disadvantage. 
This removal of the best soil material and the impairment of that 
remaining results in the occurrence of much waste land. In the 
South the abandonment of land is traceable more often to erosion 
than to any other cause. In some of the States vast areas amounting 
occasionally to 50 per cent of the arable land of those sections have 
been abandoned to the ravages of water wash. 
THE PREVENTION OF EROSION. 
The necessity for the prevention of erosion is obvious. There is 
every indication that the public conscience is being quickened in this 
respect, and several States are beginning to appreciate the necessity of 
conserving their soil. The State of Tennessee is making a serious 
effort in this direction. The State geologist, with the aid of soil and 
forestry experts, is waging a campaign of education to teach the 
farmers how to prevent erosion and reclaim eroded lands. Some of 
these lands with proper care can be reclaimed for agricultural use, 
while others can be utilized for forestry. It is the function of the 
experts to determine the best use of eroded lands in various sections 
of the State. 
A number of papers on the subject of erosion and its prevention 1 
point out the damage from erosion and the general means of con- 
trolling it. 
METHODS OF PREVENTION. 
Methods employed for the prevention of erosion must embody 
either one or two principles: They must increase the capacity of the 
soil for absorbing water or must decrease the velocity of the running 
1 Farmers' Bui. No. 20, U. S. Dept. Agr.; 111. Expt. Sta. Cir. No. 199; Soil Rept. No. 3, 111. Expt. Sta. 
