S6'^ ' IMrnOVIMi P005>. SOILS. 



Observations good system of Imsbandry. Whenever plants hare drawn 

 aiid enquiries ^ ^j^ ^^^j, -^^ ^1^^ neighbourhood in which they are 

 respecting the . 



improvement placed, all the materials that happen to be duly mixed, 

 of poor soils, ^jjgy j^j.g jjQ longer capable of thriving, until, by a new 

 operation, more particles are brought into contact with 

 them. This has been sufficiently proved by persons who 

 are in the practice of horsc-hoeing, and is in effect the 

 very object of those repeated ploughings which are per- 

 fornied with the view of preparing the ground for the 

 reception of fresh seed. By this theory we see why marl 

 becomes so admirable an addition to some soils, as to he 

 even called a manure. Marl is formed by the deposition 

 of clay*, arid chalk from water, which, during floods 

 and rains, has held these earths suspended^ and which 

 component jjarts are so intimately combined, as to be capa- 

 ble of being acted upon by plants. Marl I apprehend will 

 < be found in this neighbourhood at some future time, when 

 repeated borings shall have given us the exact state of the 

 different strata of this district +. 



If I shall have the good fortune to establish this theory, 

 vre shall not have occasion to seek for the reason why 

 ehalk renders clay productive, by supposing that the latter 

 contains an acid +, which the chalk absorbs, for that 

 ■would be begging the question, as no such acid has been 

 proved to exist, nor shall we have any difficulty in ac- 

 counting for the different opinions of authors upon the 

 value of lime, chalk, &c. as improvers of the soil; for, 

 when the lime has exerted all its powers as a manure, (that 

 is, such of it as has suffered decomposition through the 

 medium of Avater, in which, till it recovers its air, it is 

 soluble) the remainder being mere (^halk, mixes with the 

 soil, and, as it may happen. Mill be useful or not accord- 

 ing to the nature of the ground it is laid upon. Lime may 

 answer to the farmer as a stimulus, but it can only improve 

 the soil to the land-owner, when it is laid upon clay or 



* All clay contains a portion of sand. 

 t Vide Kirwans Mineralogy. 

 t See idome, Mills^^ ancj others, 



sandy 



