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TION, AND SURVEY Ch. II <br />ted_root_zone, (e)_low~ r- <br />•ate_alkali or s_alini[y, and (h) <br />:onser~ation_pr.actices. Those ' <br />freaueady m combination with `=' <br />drainage systems may also be <br />cultivation. but there are very - <br />\Iso, very careful mannaeement _; <br />.se soils are more limited than ~; <br />sed extensively, and row coops = J <br />hoice of crops may be limited-=~ <br />ds. = --_ <br />v be one or more of the follow-~_ ~- <br />~tibility, (c) severe past erosion, °~ - <br />~acity, (fl_poor drainage. and° <br />uon practices must be applied' F <br />so, they are usually combined .` <br />:rally not suited to cultivation. "_ <br />by f_ac[ots other than erosion <br />low: (a).subject to frequent <br />tt for crop plants, (c), stony or <br />laee is no[ feasible. Oftentimes, %, <br />d. <br />: limitations that restrict their , <br />or wildlife. The limitations are ;,, <br />,Ire more rigid. <br />vere limitations which restrict ; <br />he physical limuations are the _= <br />.re improvement is impractical. <br />tt should not be usedl~o~Y ~' <br />use is restricted to "recreation, •„<,: <br />.." Examples of kinds of soils '- <br />vbeaches, river wash, and rock ~ - <br />y classe_s_are subclasses which <br />ins for aericultural use- s. the <br />$eC. 1?:12 LAND CAPABILITY CLASSIFICATION 351 <br />Four kinds oC limitatioas.recoenized in these subclasses are risks o erosion <br />(e); wetness, drain_aee, or overflow (w); _oot-zone limitations ); and <br />CI1m3UC hIIISCa[10R5 (C). Th'as. a soil may be n m c ass e., m tcatmg <br />that it is in class III because. of risks of erosion. <br />Pretlpminantly unsuitable far cultivation (classes V~VII I) <br />®More than 67 percent unsuitable <br />050-66 percent unsuitable <br />N 3so <br />300 287 297 278 287 <br />U <br />a 2so <br />0 200 lao <br />z Iso <br />°- loo <br />~ 50 r7 32 29 <br />~ 1 1 1 1 1 1 I l l n I i i I n <br />Class Class Class Class Class Class Class Gass <br />I II III IV V VI VII VIII <br />FIGURE 12:18. Geographic distribution (upper) and quantitative distribution flower) <br />of land capability classes In the United Stales. [from U. S. Department of Agrtcu/tune <br />(IO),) <br /> <br />it <br />Predominanny suitable for cultivation (classes I-IVI <br />More than 67 Oercent suitable <br />®5066 percent suitable <br />