Mixture Of Soils is one of the most ready and cheapest modes of improving their staple, and thus rendering them more fertile; and upon the subject I have nothing to add to the following excellent remarks of my brother, Mr. Cuthbert Johnson: -

"I have witnessed even in soils to all appearance similar in composition, some very extraordinary results from their mere mixture. Thus in the gravelly soils of Spring Park, near Croydon, the ground is often excavated to a depth of many feet, through strata of barren gravel and red sand, for the purpose of obtaining the white or silver sand, which exists beneath them. When this fine sand is removed, the gravel and red sand is thrown back into the pit, the ground merely levelled, and then either let to cottagers for gardens, or planted with forest trees; in either case the effect is remarkable; all kinds of either fir or deciduous trees will now vegetate with remarkable luxuriance; and in the cottage garden thus formed, several species of vegetables, such as beans and potatoes, will produce very excellent crops, in the very soils in which they would have perished previous to their mixture. The permanent advantage of mixing soils, too, is not confined to merely those entirely of an earthy composition; - earths which contain inert organic matter, such as peat or moss earth, are highly valuable additions to some soils.

Thus, peat earth was successfully added to the sandy soils of Merionethshire, by Sir Robert Vaughan. The Cheshire farmers add a mixture of moss and calcareous earth to their tight-bound earths, the effect of which they describe as having ' a loosening operation;' that is, it renders the soil of their strong clays less tenacious, and, consequently, promotes the ready access of the moisture and gases of the atmosphere to the roots. The cultivator sometimes deludes himself with the conclusion that applying sand, or marl, or clay, to a poor soil, merely serves to freshen it for a time, and that the effects of such applications are apparent for only a limited period. Some comparative experiments, however, which were made sixteen years since, on some poor, hungry, inert heath land in Norfolk, have up to this time served to demonstrate the error of such a conclusion. In these experiments, the ground was marled with twenty cubic yards only per acre, and the same compost; it was then planted with a proper mixture of forest trees, and by the side of it, a portion of the heath, in a state of nature, was also planted with the same mixture of deciduous and fir trees.

" Sixteen years have annually served to demonstrate, by the luxuriance of the marled wood, the permanent effects produced by this mixture of soils. The growth of the trees has been there rapid and permanent; but on the adjoining soil, the trees have been stunted in their growth, miserable in appearance, and profitless to their owner.

" Another, but the least commonly practiced mode of improving the staple of a soil by earthy addition, is claying ; a system of fertilizing, the good effects of which are much less immediately apparent than chalking, and hence one of the chief causes of its disuse. It requires some little time to elapse, and some stirring of the soil, before the clay is so well mixed with a sandy soil, as to produce that general increased attraction and retentive power for the atmospheric moisture, which ever constitutes the chief good result of claying poor soils. Clay must be moreover applied in rather larger proportions to the soil than chalk ; for not only is its application rarely required as a direct food for plants for the mere alumina which it contains ; since this earth enters into the composition of plants in very small proportion, but there is also another reason for a more liberal addition of clay being required, which is the impure state in which the alumina exists in what are commonly called clay soils."-Farm. Encyc.