Sorls 61 
SOIL STRUCTURE 
Structure refers to the arrangement of the soil particles, 
which may be wedged tightly together or so arranged that 
there is considerable air space between. The numerous 
sizes of particles present in any soil make possible a great 
difference in structure, particularly in fine soils. Soil 
tilth, which has such great practical importance, is 
determined largely by its structure. or the grouping of 
particles. Soil grains packed tightly together form a soil 
of poor tilth. When plowed, such a soil breaks up into 
clods instead of falling apart in granules or floccules. A 
loose structure gives lines of weakness extending in every 
direction through the soil. When this condition exists. 
the soil crumbles readily, but when the opposite condition 
is found, much work is necessary to put the soil in good 
condition. The facts that sugarbeets in growing expand 
greatly and that they require considerable air make very 
desirable a soil with a good structure. 
IMPROVING SOIL TILTH 
The tilth of a coarse-grained soil cannot be greatly af- 
fected, since it is always fairly good. but a clay requires 
constant care to prevent its becoming puddled. Many 
farmers have learned through experience that by culti- 
vating a clay soil when too wet, they can so injure the tilth 
that several years are required to get it back into good 
condition, Almust anything causing a movement in soil 
may affect its tilth, Among the common factors are: 
(1) tillage, (2) the growth of roots, (8) alternate freezing 
