THE SOILS OF TENNESSEE. 171 



the Kentucky line about fourteen miles. Eight geologic formations are 

 represented within this area, but the major portion of it is covered by 

 only four, which run in narrow parallel belts across the State. 



Although there is considerable variation, the soils of this section are in 

 general not equal for agricultural purposes to those of the loess and La- 

 grange areas. For the most part, they are silt loams of fair natural fer- 

 tility and suited to the usual crops of the climate ; but much of the area 

 has suffered very severely from erosion and the continued production of 

 cultivated crops. Much of the county is hilly and the eastern edge is a 

 continuation of the Highland Rim of Middle Tennessee. The specific 

 plant food requirements of the various soils have not been worked out, 

 but both liming and phosphating are apt to be beneficial, and the need of 

 increased supplies of nitrogen and humus is evident. Considerable areas 

 are better suited to pasture and timber than to cultivated crops. 



Bottom and bench lands. Overflow lands in West Tennessee are com- 

 paratively little used for farming purposes, the major part being in tim- 

 ber. The reason for this condition, which is so different from that found 

 elsewhere in the State, is that special drainage systems are necessary in 

 order to warrant cultivated crops. The overflow lands form fairly wide 

 margins along the streams, the channels of which are not large enough in 

 this gently sloping country to carry off the surplus waters from the large 

 areas drained. In addition, while the bottom lands are richer than the 

 neighboring uplands, they do not as a rule have the high fertility of the 

 bottom lands of the other sections of the State. Rather large areas of 

 gray-colored silty soils occur, and where the leaves and other loose mate- 

 rial have been swept away from year to year by the floods the soil may be 

 very deficient in humus matter. 



These bottom lands are valuable chiefly for their timber, but in addition 

 furnish some grazing for cattle. State laws are favorable to comprehen- 

 sive drainage projects which have been carried out successfully in some 

 counties, and are in progress in others. The increased value of the re- 

 claimed lands for pasture purposes alone is probably worth all the expense 

 incurred by drainage. Also a considerable portion makes highly produc- 

 tive land for the usual farm crops. 



Along the Mississippi River there are some alluvial lands of very great 

 fertility, comparable with the best found anywhere in the world. All the 

 common crops are grown, including alfalfa, which thrives without atten- 

 tion to either liming or manuring. 



In the northwestern part of West Tennessee, especially in Obion County, 

 occur rich valley lands which are very durable under cultivation. The soils 

 are dark-colored silt loams and have a moderately high content of humus. 

 For the most part they require tile drainage. These soils are excellent for 



