SOILS AND MANURES. 



25 



Clay is a constituent of all good soils ; in fertile 

 ones there may be 15 per cent. ; but in those 

 which are barren 40 per cent. Its absence makes 

 a soil too dry, while too much of it constitutes a 

 soil retentive of moisture, and apt to harden and 

 crack with heat. The rays of the sun cannot 

 penetrate stiff clays. The red clay soils are the 

 hardest, and the black clay the most plastic. The 

 purest clay contains at least 60 per cent, of sand, 

 and is always mixed with mineral and other sub- 

 stances. Clay soils, properly treated, are among 

 the very best for stone fruit. The first considera- 

 tion is to drain them thoroughly of superabundant 

 water, which would otherwise result in soft, spongy 

 wood, and moss on the trees. The next thing is 

 to incorporate with them all such materials as 

 will render them permeable by the air. This 

 should be done to the depth of at least 2 feet, 

 by means of steel forks, using for this purpose 

 such materials as sand, coal ashes, gravel, lime 

 from very old buildings (of this a large pro- 

 portion), broken pottery, pounded oyster-shells, 

 &c. ; in fact, any thing to keep the soil open. 

 The general border- drainage of such soils should 

 be itself 12 or more inches in depth, according to 

 the quality of the clay. Drainage withdraws the 

 water from the roots, and allows the air and sun's 

 heat to reach them, and supply that warmth 



