8 IMPROVEMENT OF SOILS, CONSIDERED 



texture of the soil and the inclination of the surface. Flat surfaces 

 and retentive clays require the greatest number of drains, and inclined 

 surfaces and porous soils the smallest number. There are very few 

 soils that may not be improved by draining ; and it is almost unneces- 

 sary to observe, that, where draining is requisite and not performed, 

 the application of other modes of improvement will be made in vain. 



Altering the texture and composition of soil by the addition of other 

 soils is the improvement next in importance to that of draining, and 

 requires only to be mentioned to be understood. Too sandy soils will 

 be improved by the addition of clay, and the contrary ; and both clay 

 and sand by the addition of lime ; because without alkaline matter no 

 soil can be permanently fertile. Though on a large scale the expense 

 of this kind of improvement is too great to be generally adopted, yet 

 in the case of the grounds of small country residences it is practicable 

 at a moderate expense. The proportion of any particular soil that 

 must be added to any other soil so as to perfect its texture, can 

 only be determined by experiment. The first thing to fix on is the 

 depth to which the soil is to be cultivated. In kitchen gardens this 

 may be between two and three feet ; but in pleasure-grounds, where 

 the surface is to be chiefly in grass, nine inches or one foot in depth 

 will suffice. " It is astonishing," Mr. Kham observes, " how small a 

 portion of pure alumina will consolidate a loose sand, and convert it 

 into a good loam, the parts of which, when moistened, will adhere and 

 form a clod in drying." (' Jour. Agr. Soc.,' vol. ii. p. 51.) If we take 

 an extreme case, and suppose that any given soil is so sandy as to 

 require the addition of one-sixth its bulk of clay, or so clayey as to 

 require one-sixth its bulk of sand, then, in the case of kitchen gardens 

 where the soil is three feet deep, every square foot of the clayey surface 

 will require the addition of half a cubic foot of sand ; and in the case 

 of a lawn where the soil is a foot in depth, every square foot of sand 

 will require the sixth of a cubic foot of clay. To cover a statute acre 

 with soil to the depth of one inch requires 121 cubic yards. Hence, 

 to add two inches to the soil of a garden of one acre, exclusive of the 

 space occupied by the walks, would require 242 cubic yards or cart- 

 loads, which, at 2s. each, amount to 24/. 4s. The cost, however, will 

 depend chiefly on the distance from which the soil is to be brought. 

 A case is mentioned in the ' Journal of the Agricultural Society of Eng- 

 land,' vol. ii. p. 67, in which a white sand varying in depth from one 

 to four feet, and so barren that it never had been cultivated to profit, 

 had the surface improved to the usual depth penetrated by the plough 

 (nine to twelve inches), by laying on clay at the rate of 150 cubic 

 yards to the acre. The clay being dug from the subsoil, the expense 

 was not more than 5/. 10s. per acre. It frequently happens that a 

 sandy or gravelly soil is incumbent on a bed of clay, and the contrary ; 

 in either of which cases the supply of the required soil may be obtained 

 by digging pits, or sometimes even by deep trenching. The earth 

 thus obtained will generally be without organic matter, but that can 

 be supplied afterwards by manuring. Where the soil required for the 

 improvement of another soil can be obtained in the state of surface 



