HOW THE SOIL BECOMES POOR 83 



absorb the soluble plant-food, leaving very little that can 

 be dissolved by the rain water as it drains through the soil. 

 Even weeds that keep green during the winter do this 

 much good. 



Loss of vegetable matter. Another cause responsible 

 for much of the poor soil in the South is the loss of vege- 

 table matter. This occurs whenever the farmer grows 

 corn, cotton, or any other crop that is kept thoroughly 

 cultivated, and does not leave on the land a large amount 

 of roots, leaves, or stems. Fire is one of the farmer's 

 worst enemies, because it destroys vegetable matter needed 

 to improve the soil. 



When vegetable matter in the soil disappears, the soil 

 becomes lighter in color, drier in dry weather, more cloddy, 

 and harder to work. Clay soils then become too compact 

 for roots to thrive in them. In dry weather the crop on 

 such land is parched and stunted or ruined, while on simi- 

 lar land, well supplied with rotted vegetable matter, the 

 crop is much better able to withstand drought. This is 

 partly because rotted vegetable matter is somewhat like 

 a sponge in having the power to hold moisture. When 

 the roots come in contact with this decayed vegetable 

 matter, they absorb its moisture and also use a part of it 

 tor food. 



The farmer can replace the vegetable matter that dis- 

 appears where clean cultivated crops are continually 

 grown by producing an occasional crop that leaves 

 large amounts of roots or foliage and stems on the 

 ground. Some of the crops that thus increase the sup- 

 ply of vegetable matter are the clovers, cowpeas, and kin 



