WITH A VIEW TO HORTICULTURE. 11 



be desirable to burn the surface soil, on account of the quantity of 

 organic matter which it contains ; but it may still be very desirable 

 to burn such a portion of the clayey subsoil as may be sufficient, 

 when reduced to a sandy powder, to render the surface soil of a proper 

 texture. In this case the surface soil should be removed to the depth 

 to which it has been cultivated, and a portion of that below taken up 

 in lumps, and dried and burned. The burning is performed on the 

 spot by the aid of faggot-wood, or any description of cheap fuel. The 

 burned lumps being reduced to a powder, and scattered equally over 

 the soil when also in a dry and powdery state, the whole should then 

 be intimately mixed together by repeated diggings and trenchings. As 

 an example of the strong clayey soil of a garden having been improved 

 by burning, we may refer to that of Willersley Castle, near Matlock, 

 which the gardener there, Mr. Stafford, has rendered equal in friability 

 and fertility to any garden soil in the country. " When I first came 

 to this place," says Mr. Stafford, " the garden was for the most part a 

 strong clay, and within nine inches of the surface ; even the most 

 common article would not live upon it ; no weather appeared to suit 

 it at one time being covered by water, at another time rendered 

 impenetrable by being too dry. Having previously witnessed the 

 good effects of burning clods, I commenced the process, and produced 

 in a few days a composition three feet deep, and equal, if not superior, 

 to any soil in the country." (' Hort. Reg.,' vol. i. p. 210.) The success 

 was here greater than can be expected in every case, because the clay 

 contained a large proportion of calcareous matter. 



Pulverizing soils comes next in the order of improvement, and is 

 effected by trenching, digging, and other modes of reversing the 

 surface and mixing and transposing all the different parts. By 

 changing the surface,, fresh soil is exposed to the action of the 

 weather ; by changing the position of all the parts, new facilities for 

 chemical changes are produced ; and by loosening the whole mass of 

 the soil, air and rain are more readily admitted, and greater freedom 

 is given to the growth of the roots. By loosening soil the air is 

 admitted among its particles and confined there, and hence it becomes 

 a non-conductor of heat, and is consequently warmer in winter and 

 cooler in summer than if it were in one firm mass. By the confine- 

 ment of air in the soil, the heat imparted to it by the sun during the 

 day is retained, and accumulates in all free open soils to such a degree 

 as sensibly to raise their temperature over that of the air, especially 

 during night. From thermometrical observations made at different 

 places, it appears that the mean temperature of the soil, at about one 

 foot below the surface, is somewhat higher naturally than the mean 

 temperature of the atmosphere on the same spot ; and hence we may 

 reasonably suppose that, by draining and pulverization, the temperature 

 of the soil may be permanently increased as well as that of the 

 atmosphere. From experiments made by Mr. Thompson, in the 

 garden of the Horticultural Society of London, it appears, that " in 

 the valley of the Thames, the maximum mean of terrestrial tempera- 

 ture, at one foot below the surface, has been found to be 64'81 in 



