Effect of Climate and Soil upon Agriculture 9 
along this line the growing season falls below 140 days, the ele- 
ment moisture proves to be the important limiting factor. 
In the scale chosen, the size of farm varies from an average 
of 158 acres in Richardson to an average of 640 acres in Dundy. 
The technical use of the word farm refers to the land directly 
operated by one man. He may own all the land, rent all the land, 
or own part and rent part. At first thought it might appear that 
farms at the western end of the scale are larger simply because 
the country is relatively new. This cannot be correct, however, 
for when the government first disposed of the land the average 
size of farm was nearer 160 than 640 acres. 
After long and trying experiences people in the western coun- 
ties are more and more coming to understand that conditions 
there are very different from those even a short distance east. 
But regardless of this fact there is even to-day no clear idea of the 
rapid change from favorable to adverse conditions after passing 
the 24-inch line of rainfall. The number of acres required to 
pasture a horse or cow may be used as a rough measure of this 
change. To provide five months’ pasture for a mature animal in 
western Nebraska requires about four times the number of acres 
necessary in eastern Nebraska. From this fact alone it is not 
-out of reason to infer that a decrease in the effective value of 
moisture reduces the available pasture growth from I to about %. 
Man is as dependent upon plant growth as are other animals. 
All of the food which he consumes is derived either directly or 
indirectly from plants. Since in Dundy county the effective value 
of moisture is such that the total usable pasture growth is only 
about %4 that in Richardson, it is not surprising to find that the 
size of farm must be at least four times that in Richardson. 
Many people though recognizing a decrease in native vegetation 
in western Nebraska hold strongly to the idea that correct culti- 
vation is the only thing necessary to produce high average yields. 
All open-minded field studies in this state indicate that in general 
cultivated plant growth per acre varies quite in harmony with the 
growth of native vegetation. If it were true that 160 acres of 
land in Dundy county naturally produced plant food equivalent 
in value to that produced on 160 acres in Richardson—capital, 
99 
