Effect of Climate and Soil upon Agriculture 13 
in the size of farm south of T 8 N is caused by level upland and 
the Platte Valley. North of T 8 N critical moisture and sand 
hills cause an abrupt increase in the size of farm. 
ACRES PER FARM 
a 
cee 
N 
Fic. 14. Graphs illustrating the rate at which size of farm changes along 
north and south lines in Nebraska. (See Fig. 12, lines 3, 4 and 5.) 
Graph No. 5 is a composite of several drawn for western Ne- 
braska. Moisture gives it its position relative to graphs No. 3 and 
No. 4 while topography and soil texture are the principal elements 
determining its trend. 
Though the above study is based largely on Nebraska data it 
has more than a local bearing. Moisture problems from southern 
Texas to the head of the Mississippi river are closely related. 
To the south they are influenced by high temperature, while to 
the north they are modified by low temperature. From the head 
of the Mississippi northwest into Saskatchewan and Alberta a 
103 
