THE PROBLEM OF EROSION IN BUFFALO COUNTY 
67 
the fertility and yield of fields by removing fine soil and organic 
matter from the surface. The causes of removal of soil from the 
surface without formation of gullies generally lie in improper 
methods of cultivation or poor arrangement of fields. Fields 
where this kind of erosion occurs are often only gently rolling or 
undulating and the rain water does not collect in larger swift¬ 
flowing rills or streams which have power to cut ditches, but fol¬ 
lows the cultivated rows such as corn or potatoes or the drill 
rows of grain fields and the soil is removed only from the knolls 
and deposited in the hollows. 
Contour cultivation and arrangement of the crop rows across 
the slope instead of with or down the slopes retards the move¬ 
ment of soil in such fields. Keeping the most exposed places in 
sod as much as possible and the cultivation of the field in alter¬ 
nate strips of crop and sod across the slopes are inconvenient 
but often necessary methods. 
Rotation of crops in such a way that two cultivated crops do 
not follow in succession gives the field opportunity to recover 
from its losses under cultivation and avoiding a hard bare condi¬ 
tion of the eroded ground after harvest as much as possible pre¬ 
vents surface wash in the fall. A cover or catch crop of rye or 
peas in the corn rows helps protect the soil after harvest and fur¬ 
nishes pasture until winter. 
Deep plowing and plowing under of straw, manure, or a sec¬ 
ond crop of clover to increase the organic matter in the soil also 
give the surface of the field greater absorbing capacity and 
resistance to erosion. 
Gullying occurs where greater volumes of water collect form¬ 
ing cutting-streams where steeper slopes cause the water to flow 
faster or in places where the soil has an unstaple foundation of 
sandy material which easily undermines when the water once 
cuts through the surface soil and establishes a fall which cuts 
back in the sandy subsoil. In favorable situations large gullies 
y 2 mile or more in length are sometimes cut during a single sea¬ 
son. 
In their beginnings most small gullies are easily handled. 
Small drainage-ways or shallow ditches can be filled with straw 
or manure and plowed shut. Such shallow drainage-ways should 
be left in permanent sod. The plow can be easily thrown out in 
passing across them. On the level terraces or where heavy soil 
lies on light sand or sandy gravelly subsoil, small ditches must 
