Farm Types in Nebraska 
Fig. 2. — The principal boundaries of the agricultural region of Europe. The 
small circles mark temperature limits and the dashes rainfall limits. 
characteristic of semidesert regions. Within the favorable 
region one finds most of the broad-leaved forests and good 
growths of temperate grasses. 
Figures 4, 5, and 6 illustrate the relative importance of 
soil, rainfall, and heat in various parts of any great agri- 
cultural region. The curved surface of a figure represents 
the great divisions of substance and the plane surface a few 
of the greater forces that are important to plants. Man, 
of course, is actively concerned with only such factors as 
happen to fall low enough to hinder him in maintaining his 
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