26 GARDENING FOR THE SOUTH. 



drains, and the warmer water can percolate through and 

 raise the temperature of the soil. As the warmer water 

 settles, the porous space it occupies will admit warm air. 

 (Thompson.) Drainage, also, by admitting the atmos- 

 phere, renders the soil much more friable. Soils well 

 drained have likewise been found to suffer far less from 

 summer droughts than before. Underdrains should be 

 not less than three feet below the surface, and four feet 

 is much to be preferred. 



Trenching renders the upper stratum of soil more light 

 and friable, acting as drainage, but imperfectly. Its great 

 utility is in increasing the quantity of soil to which the 

 roots of plants find access. 



Ashes and lime each have the property of rendering 

 heavy soils lighter, and light soils more tenacious, and 

 both more productive, especially for potatoes, turnips, 

 beets, and peas, which delight in calcareous soils. In cold 

 climates, plowing clay lands deeply in the fall, and expos- 

 ing them to the action of the winter's frost, is very bene- 

 ficial, but in sections where there is little frost and abun- 

 dant and heavy washing rains, it is worse than useless. 

 Turning under coarse vegetable or carbonaceous matter, 

 as straw, leaves, pine straw, corn-stalks, a crop of cow- 

 peas, clover, or any other green crop, bog or leaf-mould, 

 decomposed peat, and even tan-bark itself, so deeply be- 

 neath the surface as not to interfere with cultivation, will 

 by the slow decomposition of these materials much increase 

 the fertility of a clay soil by improving its texture. It is 

 most improved by drainage if needed. 



The frequent working of the soil with the hoe and 

 spade, thereby admitting the ammonia and fertilizing 

 gases of the atmosphere, is itself very beneficial to clay 

 soils, if done when the earth is dry. A clay soil is ex- 

 ceedingly injured if worked while wet. It is so difficult 

 to work, and so liable to bake into a hard crust after ev- 

 ery rain, that it will well repay, where materials for the 



