366 Dr Davy's Agricultural Discourse. 



miuute details on this important practical subject. It may suffice, 

 if I venture to offer some general remarks and suggestions. As in 

 considering the qualities of soils, so in attending to their defects, it 

 may be well to observe the distinction between those which are 

 physical, in contradistinction to those which are chemical. As re- 

 gards the first, the main defects of faulty soils are considered in the 

 greatest degree of generality of two different and opposite kinds, 

 excess of tenacity or stiffness, and want of adhesion (and this in 

 excess) or looseness ; the one defect most conspicuous in the most 

 perfect clay soils, the other in the most perfect sandy soils ; the one 

 depending on the argillaceous element being too predominant, the 

 oth«r, on the absence of this element in its plastic state, and on the 

 predominence of sand, or of particles, compact and firm, without 

 tendency to cohere, which constitute what we commonly call sand. 

 In one or other of these two kinds of defects, I believe are compre- 

 hended all the imperfections of your soils physically viewed, and that 

 they are to be corrected, by attending to them as principles. 



If a soil is too adhesive, too stiff, presenting, during a period of 

 drought, a hard fissured surface, during wet weather a state of bog, 

 How is it to be treated for the removal of these great and fatal de- 

 fects in the way of successful agriculture ? Is it not best done by 

 the addition of matter of a different kind, such as sand, chalk com- 

 minuted, marl, or burnt clay 1 Either of these will tend to dimi- 

 nish the stiffness, render the soil less adhesive, more pervious to air 

 and water, especially if followed by thorough draining and subsoil 

 ploughing, which will aid most materially in preventing the stagna- 

 tion of water, and I may add, of air, in the upper stratum of soil, 

 and conduce in a remarkable manner to preserve the soil of a just 

 degree of humidity and of aeration, even in times of severest trial — 

 those of flood and drought. Such measures of improvement are 

 necessarily expensive, and demand, for their correct performance, a 

 large outlay of capital. In England and Scotland these measures 

 have had a most extensive trial, and, as you are no doubt aware, with 

 most successful results, proving that capital so invested is most 

 profitably placed, often doubling and tripling the value of the land 

 in relation to produce and rent, and that not for a short term of 

 years, but for an indefinite period ; in brief, land so treated and im- 

 proved, may be considered as reclaimed land, a great acquisition to 

 the proprietor, a great acquisition to the country ; an element I may 

 say of wealth, and even of health ; for it is clearly proved that by 

 thorough draining, even the climate of a district may be improved, 

 the air rendered drier, less liable to fog, even warmer in a cold 

 country, and also free from malaria. In this island how many situ- 

 ations there are, and not inconsiderable tracts, which might be bene- 

 fited more or less by such treatment. Wherever water rests long, 

 after heavy rain, there we may be sure the defect in question is pre- 

 sent, existing either in the soil or subsoil, and admits of correction. 



