In a great many, perhaps the majority of instances, marl owes its fertilising influences to the lime which it contains, and then its effects are precisely those which lime would produce—sweetening herbage, increasing the quantity and improving the quality of crops. This it cannot do so energetically as is done by caustic lime, what limo it contains being in a state of carbonate : its dilution however, by other earthy matters gives it almost as great facility of mixture with the soil as is possessed by caustic lime on its reduction to powder by slaking.
In so far, however, as marliug acts by its calcareous ingredient, its use has been supplanted by that of burnt limestone ; and the marl pits of the country in Devonshire, 'Worcestershire, Staffordshire, Cheshire, Surrey, Sussex, Kent, and other counties, now have, many of them, largo trees growing in them, proving how long a time has elapsed since they were used. Accordingly, where the use of marls still prevails, and it certainly does prevail to a very large extent in some district in England, their effect is chiefly due to the other ingredients which they contain. We will specify a number of instances in which the ferti lising effects of this application have been apparent. Holkham Park, in Norfolk, was let in 1770, to Mr. Brett, et 3s. per acre, and on the expiry of his lease, it was offered to him at an advance of 2s.; he refused to take it, and Mr. Coke, the landlord, took it into his own hands. The surface soil of the whole district is very light sand, but nearly throughout it there is a stratum of rich marl, at various depths underneath. Pits accordingly were opened, and the marl dug out and laid upon the surface. This not only increased its fertility, but gave to the soil the solidity which is osseutial to the growth of wheat. Here then the effect was due, not merely, nor perhaps chiefly, to the lime which this marl contained, but to its clayey, part, which corrected the excessive looseness of the top soil. Take another instance of the effect of clays upon light sandy soil. In some of the lighter districts of Lincolnshire, it has been long a common practice to apply the white clay on the chalky soils in its neighbourhood, and the blue marl which lies in their valleys to alter end improve the nature of their red sandy soil The white buttery marl used in these localities gives both strength and solidity to the lighter soil on the green-trand formation, and in a particular instance in our knowledge a farmer having applied it only to two lands in one of his fields, found that the yield of corn from those lands was fully 2 or 3 sacks per acre greater than from the remainder of the field. The marl is also found to prevent the
clubbing of turnips, or the disease called }lagers and toes, to which that Land was subject. The blue marl is beneficial, but in a less degree. it is common to put on 40 loads per acre, and one dressing of the white clay is found to be amply sufficient for a great many years, It being questionable whether a second application on the red land is calculated to be useful.
In Suffolk the marl, which iu cLay containing small particles of chalk, is geuerally applied to the light soils, where it improves the mechanical texture of the soil, stiffens the straw of wheat, prevents the finger and too in turnips, and seems to add the food which clover requires.
Take now the instance of marl applied upon peaty soils throughout the fens of Cambridgeshire and Lincolnshire. The best method is to dig trenches in the soil some two feet wide at intervals of 20 to 30 feet, taking one or two feet of clay out of them and spreading it over the surface ; 100 cubic yards may thus bo spread for 30s. to 36s. per acre.
The light fen soil will after this grow first-rate crops of wheat, flax, and even beans. And even where the stone crops are retained in culti vation, their greater produce amply repays the cost of the operation putting that at 50s. per acre or 6d. per cubic yard of the clay applied.
in illustration of the quantity of clayey marl which is put upon light and fon land in some district of the country, we may name the case of Mr. Edward Witt, of Foreham, Suffolk, who has during six years applied on 183 acres of arable land nearly 52,000 loads, of 24 bushels each, at a cost of 4631. in manual labour ; this is an average of 283 loads per acre of a cost of 50s. The West Suffolk Agricultural Society offers a prize of 4/. to the tenant who shall have carried and spread the greatest number of load.s of clay during the previous twelve months, and a list for many years, given in the 8th voL of the English Agricultural Society's Journal, shows the universality of the practice on light and fen land farm.