40 GARDENING FOE THE SOUTH. 



In short, they are very cold when they are wet, and very 

 hard when they are dry. The crops are full ten days later 

 in coming to maturity than in a good, sandy loam. Ordi- 

 nary clays contain about twenty-five per cent, of sand. 

 If less than fifteen per cent, they are only fit for brick- 

 making and pottery. 



('lays are rich in alkalies, and have the property of 

 retaining potash, phosphoric and silicic acids, and ;ill 

 salts necessary to the growth of plants; also of con- 

 densing ammonia and other gaseous matters. Hence 

 they retain the virtues of manure better than most other 

 soils. Where there is present lime and organic matters 

 in sufficient quantity, clays, not too stiff, are excellent 

 for wheat. 



A sandy ■soil is in texture the opposite of the preceding 

 and the lightest of all soils. It contains not over ten 

 per cent, of clay. Such soils are harsh to the feel, lack 

 cohesion, permit the water that falls upon them to pass 

 instantly through them, and, as they heat up quickly, the 

 crops raised in them soon suffer from drought. In them 

 vegetation is early, but less vigorous and sustained. They 

 do not readily combine with manures, the soluble parts of 

 which are leached into the subsoil, or are washed out by 

 the rains; so that, if manure be not constantly applied, 

 they will yield but a moderate crop. Gravels are, in this 

 respect, from the coarseness of their particles, still worse 

 than sands, and are very properly called "hungry soils." 

 Indeed, the fertility of a soil depends in a very great 

 degree upon the fineness of its particles. Sand is spar- 

 ingly soluble in water containing alkaline matter in solu- 

 tion, and in this state forms a portion, and sometimes an 

 important portion, of the food of plants. It is soluble 

 silica; in other words, dissolved sand, which the plant of 

 Wheat or maize has extracted from the soil and deposited 

 upon the exterior of its stem, that gives the stalk or straw 



