APPLIED rilYSlOGRAPIIY IX SOlTIf (AllOLISW ir,3 



been plowed and planted in cotton. The successful fjrowing of 

 this crop requires such clean culture that, in the almost total 

 neglect of croj) rotation, the soil is soon deprive<l of nearly all 

 its vegetable matter, while the cotton plant furnishes far too few 

 root fibers to hold the Soil together and prevent it from washing 

 down into the valleys. \Mien to this is added the fact that ter- 

 race plowing is almost unknown, it is readily seen that the rain 

 falling on these slopes rapidly gathers into hillside gullies and 

 quickly finds its way down to the effluent stream, carrying 

 with it an immense amount of detritus. The stream is now 

 overloaded, and does the onh' thing possilde under the circum- 

 stances — it drops the portion of its load that it is unable to carry. 

 Thus the channel that of old was often five to ten feet deej) is 

 soon filled until it is scarcely more than twice so many inches 

 in depth. \\"\{\\ every heavy rain the stream now overllows its 

 banks, covers the rich flood-plain soil with l)arren sand, and 

 spreads desolation over almost its entire area. In the case of 

 small streams the waste has been showered down from the val- 

 ley sides during heavy rains i'n such quantities as, in many 

 instances, to comi)letely fill the stream's channel and leave it to 

 wander as an outcast hither and thither over the surface which 

 it formerly drained and rendered fertile, Init on which it now 

 aids in producing marshes and malaria — in just retrilnition, 

 as it Avere. for its owner's neglect of physiogra[>hic laws. 



It might be well to note more fully the regular cycle of change 

 through which tbe flood-plain passes before assuming the com- 

 jdetely Avasted state. As the stream bed begins aggrading, over- 

 flows become easier and hence more frequent; the mouths of 

 the artificial drainage ditches leading from the flood-|ilain into 

 tbe stream channel soon silt up; the drainage becomes poor, 

 and as a consequence the land is longer after overilows in be- 

 coming sufficientlv drv for cultivation. As the aggradation 



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gradually raises the stream surface nean-r the surfat-r of tlu- 

 flood-i)lain (/;, c', t"), the water level in the land on either si.h- of 

 the stream rises, iiari passu, nearer the land surface ' /», !>', I>") antl 

 thus con.'stantly decreases the distance through which capillary 

 attraction must act in raising water to the plant roots, and hence 

 makes the land wetter and wetter until finally the culture of 

 corn must be abandoned. Though now too wet for cultivation. 



