Dr Davy's Agricultural Discourse. 366 



ture ; liable to become indurated from drought, and boggy from ex- 

 cess of rain, physically great defects. Their composition, I believe, 

 is somewhat variable, always abounding in alumine, never deficient 

 in silica ; they have most commonly a small proportion of lime and 

 magnesia, especially of the former. Those clayey soils which have 

 a greasy feel when dry, usually contain a good deal of magnesia. 

 In their natural state, I apprehend that the bad preponderate over 

 the good qualities of these soil, but the reverse in their improved 

 state. 



3c?/y, Of Sandy Soils. — The peculiarities of these soils are the re- 

 verse of the last, being most readily pervious to air and moisture, and 

 nowise retentive of moisture. Such is invariably their physical con- 

 dition, whatever may be their chemical composition ; a condition 

 most unfavourable to fertility, and fatal to it, excepting under pecu- 

 liar circumstances of situation, or seasons, such as low situations 

 where water is abundant, or where there is a substratum or subsoil 

 retentive of moisture, or rainy seasons. Next to these circumstance* 

 their composition is of most importance ; those which are almost 

 purely siliceous are almost barren ; such exist in the parishes of St 

 Joseph and St Andrew ; whilst those which consist of comminuted 

 shell and coral, are, in favourable circumstances, fertile. 



4:thly, Of Alluvial Soils. — I have already spoken of the soil which 

 occurs in the valley of the hilly district as an example of this kind, 

 that is, in the parishes last mentioned. The red soils of the higher 

 grounds may also be considered as such ; and even the greater part 

 of the soils in the valley of the Sweet Bottom and of St George, and, 

 in brief, of a large portion of the island ; in some instances the tend- 

 ency being to an excess of the aluminous ingredient, with undue 

 stiffness and tenacity, in some others, and I believe more rarely, to 

 a deficiency of it, and undue porousness. The black soils, too, may 

 be considered as belonging to them, exclusive of the peculiarity of 

 colour, depending, as I have already mentioned, on a peculiar state 

 of vegetable matter. Some of these soils appear to be excellent, in 

 which the several ingredients are in a very fine state of division, and 

 it may be inferred, duly proportioned, as in the instance of the 

 Bloomsbury estate soil, and some others similarly situated, and also 

 in the instance of some of those in the lower grounds, especially in 

 the valleys of St Andrew's and St Joseph's. Generally, I apprehend, 

 putting aside those of the highest quality, they may be considered as 

 average soils, and from this circumstance, that fhoy contain com- 

 mingled the essential elements of good soils ; and average also, as 

 regards their capabilities and produce. 



Having thus taken a rapid glance at the qualities of some of the 

 principal varieties of soils, I shall enter on the third part of my task, 

 \ brief consideration of the means of correcting those qualities which 

 are most faulty. It would be tedious and out of place on this oc 

 'asion, were I prepared with the requisite information, to enter into 



