3S AGRICULTURAL BSSaYS* 



vegetable manure, of itself, cannot be rendered productive with- 

 out the agency of some of the primitive earths, c^'rom what 

 has been disclosed on this subject, the intelligent farmer may 

 be convinced that amixture of the primitijt-e earths, as well as 

 the application of vegetable manure, is indispensable to the fer- 

 tility of the soil. It is very evident too, that the proportion of 

 these several ingredients of a fertile soil must be somewhat va- 

 ried, according to the climate. In a very warm climate, on a 

 soil composed principally of sand, the expediency of applying 

 clay, when it can be had, as well as a due proportion of vege- 

 table manure, is obvious. As it is of great importance in a ju- 

 dicious system of farming, to learn the condition of the natural 

 soil, or the apportionment of the simple earths which constitute 

 it, the following remarks of a distinguished agriculturalist, 

 more fully explain the principles which relate to it, and are of 

 too much interest to the farmer to be omitted : "The obsta- 

 cles which baJSie the hopes of improvement are just as likely to 

 lie in the subsoil which is placed beyond the reach of the plough- 

 share, as in the upper surface, w^hich is more immediately sub- 

 jected to culture ; and for this reason neither of them ought to 

 be disregarded. A coat of stiff clay has been rendered pro- 

 ductive by the mere circumstance of resting on a bed of sand, 

 or a rock of limestone; and therefore, every cultivator, if he 

 would pursue a successful course, should (if he finds invisible 

 defects in his soil Vvhich defeat liis efforts) dig pits in various 

 places of it, at least eighteen inches down, that he may discov- 

 er the materials on which he is to operate. The subsoil may 

 furnish him with the means by which to meliorate the surface. 

 Clay, called in agricultural publications, alumine, or argillace- 

 ous earth, is a substance so familiarly known that it needs no 

 particular description. When pure, it is white ; but in general 

 it is found discolored by the mineral waters, which are perpet- 

 ually escaping from their beds and running on the surface. It 

 is tinged with blue, brown, grey and red shades, for it has a 

 strong affinity to all coloring matter. As an ingredient of soil, 

 it has the four following properties, by which it exerts a power- 

 ful effect on vegetation : it absorbs water like a sponge, and 

 is so close in the texture, as to prevent it from filtrating through 

 its pores. When thoroughly soaked and afterwards dried, it 

 hardens and cakes into a solid mass. It shrinks considerably 

 in bulk when exposed to heat, and the contraction of its parts is 

 in proportion to the intensity of that heat. It powerfully re- 

 tards putrefaction, by enclosing animal and vegetable remains, 

 and thus shutting out the dissolvent action of the external air.* 



''Mr. Davy, ia his elements of agricultural chemistry, remark?, 



