THE HOUSTON CLAY. 5 



crops to good advantage, and its continued fertility under constant 

 one-crop farming is a notable feature of the type. 



A considerable proportion of the total acreage of the Houston clay 

 can not be occupied for general farming operations. The level, 

 rolling, and gently sloping areas of the type, where the surface soil 

 extends to a depth of 6 inches or more, are well suited to general 

 farming, but within many fields and universally along the margins 

 of the type, erosion has proceeded so rapidly that the surface soil 

 can not be maintained under the ordinary conditions of clean culti- 

 vation for cotton and corn, and many "galled" areas, numerous 

 gullies, and other evidences of excessive erosion indicate less valuable 

 soil areas than the normal for the type. Upon such eroded areas 

 little moisture is absorbed during the periods of rain, and the surface 

 soil is bodily removed with every heavy shower. In consequence, 

 crop yields on such areas are small, even when any stand can be 

 secured at all. Land of this character should be seeded down to the 

 grasses, using alfalfa where it is possible to obtain a stand, and per- 

 mitting Johnson or Bermuda grass, or even Melilotus to cover the 

 ground where erosion has proceeded to such an extent that it is not 

 practicable to seed down to alfalfa. 



The Houston clay occurs under a considerable range of rainfall 

 conditions. In Alabama, Mississippi, northern Louisiana, and north- 

 eastern Texas the precipitation is abundant for the production of 

 the ordinary staple crops, but in west central Texas there are areas 

 of the type which occur under semiarid conditions and in these 

 localities periods of drought late in the summer frequently interfere 

 with the production of either cotton or corn. In such localities large 

 areas of the type are permitted to grow up to wild prairie grasses, 

 which are either grazed off or cut for hay. 



There is thus considerable variation in the character of the agri- 

 culture which is conducted upon the Houston clay. 



IMPROVEMENT IN SOIL EFFICIENCY. 



There are two almost equally important improvements in soil 

 efficiency which may be effected in connection with the tillage of the 

 Houston clay. The first of these is the prevention of excessive 

 erosion, already indicated. Wherever the surface slopes within this 

 type exceed 10 degrees of declivity it is practically impossible to 

 maintain the land under cultivation. With the adoption of contour 

 farming and of terracing, together with deep plowing, even the 

 steeper slopes may be tilled to advantage, but in general it would be 

 better to secure a stand of alfalfa, or, if this proves to be impossible, 

 to allow Johnson grass, Bermuda grass, or Melilotus to grow upon 

 such slopes, to be cut either as hay or to be grazed off by the work 



