IMPROVEMENT OF SOIL 



21 



rine, all win jh, except alumina, exist in plants, and some- 

 times form ten per cent, of their "weight. 



If any of these constituents are "^^anting, the soil is 

 defective, but it will not he fertile if all of them are pre- 

 sent, unless there is organic matter in the soil to afford an 

 abundant supply of ammonia and carbonic acid to the 

 growing crop. 



Improvement of the Soil. — A soil may be improved 

 in texture by the addition of any necessary constituents 

 for the growth of plants which may be wanting. 



The texture of a clayey soil can be rendered more per- 

 vious by thorough draining, deep trenching, and by the 

 application of sand, ashes, lime, and unfermented manure. 

 So much sand is rec|uh'ed to produce any perceptible ef- 

 fect in improving a heavy clay, that it is the most expen- 

 sive mode of improvement. Ashes and lime both 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 cal- 

 careous soils. In cold climates, ploughing clay lands 

 deeply in the fall, and exposing them to the action of the 

 Winter's frost, is very beneficial, but in sections where 

 there is little frost and abundant and heavy rains, it is 

 worse than useless. Turning under coarse vegetable or 

 carbonaceous matter, as straw, leaves, pine brush, corn- 

 stalks, a crop of cow peas, or any other green crop, bog or 

 leaf mould, decomposed peat, and even tanbark itself, so 

 deeply beneath the surface as not to interfere with culti- 

 vation, will by the slow decomposition of these materials 

 much increase the fertility of a clay soil by im]jroving its 

 texture. 



The frequent worldng of the soil with the hoe and 

 spade, admitting the ammonia and fertilizing gases of the 



