HARROWS FOR DRY-FARMING 313 
is, everything considered, the most useful. The 
cutaway harrow is often used in cultivating old alfalfa 
land; the spade disk harrow has a very limited appli- 
cation in dry-farming; and the orchard disk harrow is 
simply a modification of the full disk harrow whereby 
the farmer is able to travel between the rows of trees 
and so to cultivate the soil under the branches of 
the trees without injuring the leaves or fruit. 
One of the great difficulties in dry-farming con- 
cerns itself with the prevention of the growth of 
weeds or volunteer crops. As has been explained in 
previous chapters, weeds require as much water for 
their growth as wheat or other useful crops. During 
the fallow season, the farmer is likely to be overtaken 
by the weeds and lose much of the value of the fallow 
by losing soil-moisture through the growth of weeds. 
Under the most favorable conditions weeds are dif- 
ficult to handle. The disk harrow itself is not effec- 
tive. The smoothing harrow is of less value. There 
is at the present time great need for some implement 
that will effectively destroy young weeds and prevent 
their further growth. Attempts are being made to 
invent such implements, but up to the present with- 
out great success. Hogenson reports the finding of an 
implement on a western dry-farm constructed by the 
farmer himself which for a number of years has shown 
itself of high efficiency in keeping the dry-farm free 
from weeds. It is shown in Figure 87. Several 
improved modifications of this implement have been 
