404 THE HOME, FARM AND BUSINESS CYCLOPAEDIA. 



a subsoil of rock or clay. It is preferred at present to limit the term soil 

 to the cultivated section. Subsoil is then made to express the section or 

 zone which immediately underlies the plough-sole. By this use of 

 the word, the term subsoil harmonises with the operation of subsoilino-, 

 which always refers to the breaking up of the section immediately under 

 that usually cultivated. 



CALCAREOUS PAN. Cases are on record in which, after a long period of 

 shallow cultivation, a lime, or calcareous pan is formed. It is well known 

 that lime tends to sink through the land, and this tendency is most likely 

 to be favoured by shallow cultivation. When a lime pan has formed, it 

 must be broken up and mixed with the surface soil, which will in all 

 cases be greatly benefited, while the drainage of the field will be rend- 

 ered more perfect. 



INDURATED PAN. The constant treading of horses and the passage of 

 the plough-sole at one depth gradually indurates the .bottom of the furrow 

 to a mischievous extent, and forms a hard, beaten track, or pan, best 

 removed by the adoption of deep cultivation, either by means of steam or 

 horses. 



Good cultivation is found to react upon the subsoil, and improve its 

 texture and physical character. Thus liberal manuring, thorough drain- 

 age, and deep ploughing allow the access of air, and effect the pulverisation 

 and aeration of the subsoil. It changes in colour from a blue or black 

 to a red, from the same cause as converts the dark venous blood into the 

 bright arterial stream the action of oxygen upon iron. This is followed 

 by a true sweetening of the subsoil, caused by the complete decay of effete 

 vegetable matter, and when this has taken place, the roots of plants strike 

 deeper into the subsoil, and the consequence is a deepening of the staple 

 and an improvement of the subsoil to a depth of several feet. 



SUBSOILS WHICH EXERT A BENEFICIAL EFFECT ON THE SURFACE SOIL. 

 In alluvial soils, and where from any cause the subsoil is of similar 

 character with the cultivated surface soil, deep tillage produces excellent 

 results. To break up or disturb the subsoil is not by any means an oper- 

 ation to be promiscuously recommended, but in this case it may be fol- 

 lowed without hesitation. 



A light- topped soil, resting upon a retentive substratum, is on the whole 

 to be considered a happy combination, although artificial drainage may 

 be required to facilitate the percolation of water. In some cases the clay 

 or marly subsoil may be dug up and spread upon the surface with good 

 effect . A clay resting upon sand or gravel, if not of too open a character, 



