Distributive Relationships of the Agricultural Pattern 112 
ridges or relatively high flats. The loams have intermediate positions 
with reference to sands and clays or occupy higher land instead of sands. 
The only significant area with clay soil is in the northern part of 
the American Bottoms (F ig. 19). It is relatively low and has poor 
drainage. In the northeastern part of the bottoms, a sand ridge is the 
backbone of an agricultural section (Figs. 17 and 19), and scattered 
patches of sand help to account for a diversity of crops in an agricultural 
section adjoining the urban centers of Wood River and Roxana. Loams 
cover a much larger acreage than clays and sands combined. 
The loams, in general, are held in higher esteem than either the 
clays or sands. The loamy type of soil can be handled mechanically 
more readily than either clay or sand and is highly productive. Loams 
have considerable capacity to hold water and yet the particles of soil 
are sufficiently compact to retard its escape. 
When clay is wet, it becomes sticky and large masses of soil particles 
cling together; when clay is dry, large cracks develop and the soil be- 
comes so hard that an ordinary tractor cannot pull a plow through it. 
If the soil is neither too wet nor too dry, the preparation of a seed bed 
and cultivation are easy. If heavy rains occur every week or two during 
the growing season, gumbo soils tend to yield abundantly. The clay 
types are not in ill-repute because of a deficiency in plant food, but 
because of mechanical difficulties in tillage and unsatisfactory conditions 
of soil moisture that are sometimes encountered. 
Because of the rapid disappearance of water and the loose cohesion 
of particles, sandy soils can be worked almost any time, although better 
When somewhat moist. However, plows are dulled quickly by the 
Coarse heavy grains of sand. Since the sandy types are deficient in 
plant food, only such crops can be grown profitably on them as will 
Stand a heavy outlay for fertilizers. In the Poag Section, where sandy 
soil has molded the crop pattern, a ridge with sandy soil is more highly 
valued than adjoining land with heavy loams (Figs. 17 and 19). 
The differentiated agricultural economy of the American Bottoms is 
due in part to soil variations. Although wheat and corn are grown on 
both loams and clays, wheat acreage tends to become relatively more 
important on the clays. Potato and horseradish fields are almost 
wholly confined to loams. Trucking has reached its best development 
on loams. Perhaps the most distinctive adjustment of agriculture to 
# particular soil type is in the Poag Section, where cantaloupes and 
tye are grown almost exclusively on sands. Although the correlation is 
Not perfect, since many other factors help to determine particular crops 
