Depth to the water table is also 

 important. If the water table remains 

 at a constant level close to the surface, 

 most plant roots will not live below 

 that level even though the material 

 is open and otherwise easily pene- 

 trated by roots. If the water table 

 fluctuates during the season, a plant 

 with roots extending only to the 

 highest water level may suffer from 

 drought during dry weather. If the 

 roots grow downward during the dry 

 period, they will be drowned when 

 the water table rises again; so, 

 strange as it may seem, wet soils may 

 also at times be droughty soils. 



Depth to a layer of very loose, 

 open gravel or coarse sand is an im- 

 portant factor in some soils. If the 

 surface soil is very coarse, or if there 

 is only a foot or two of liner soil 

 over coarse material, the soil has a 

 low capacity for holding available 

 water. Such soils are droughty. Very 

 few plants grow well on droughty 

 soils and these are mostly of the 

 deep-rooted type. Alfalfa roots, for 

 example, may extend to great depths on such soils. Even if irrigation is 

 practiced, it must be done frequently on these droughty soils. 



Allan B. Prince 



Deep-rooted plants are better adapted 

 to the coarse-textured gravelly soils. 



Structure 



The arrangement of the particles, which is known as soil structure, 

 affects the use and treatment of the soil. The particles may not stick to- 

 gether at all or they may join together to form crumbs or granules. The 

 soil particles may form one solid mass with no particular pattern of break- 

 age when twisted in the hands, or they may give a massive appearance bu' 

 still break easily into definite sized blocks. The blocks may be arranged 

 in upright columns, separated by cracks large enough to carry off an\ 

 excess water. Soil particles may also be arranged in plates, lying parallel 

 to the ground and overlapping like shingles, so that the downward move- 

 ment of water is greatly impeded. Even in the sands, which are usuallv 

 open, compaction can force the particles together with fine grains between 

 the bigger ones, so that the pores are smaller and the ease of water move- 

 ment and root penetration is reduced. 



