108 CALCAREOUS MANURES-FRAC TICE. 



would not last much longer, no matter how mildly treated. This opinion, 

 which would seem at first so absurd, and in opposition to all the received 

 rules for good husbandry, is considerably supported by the properties 

 which are here ascribed to such soils. When these lands are first cut 

 down, an immense quantity of vegetable matter is accumulated on the 

 surface, which, notwithstanding its accompanying acid quality, is capable 

 of making two or three crops nearly as good as the land was ever be- 

 fore able to bring. But as the soil has no power to retain this vegetable 

 matter, it will begin rapidly to decompose and waste, as soon as exposed 

 to the sun; and will be lost, except so much as is caught, while escaping, 

 by the roots of growing crops. The previous application of marl, however, 

 would make it profitable in these, as well as other cases, to adopt a mild 

 and meliorating course of tillage. 



Less improvement will be obtained by marling worn soils of the kind 

 called " free light land," than other acid soils which originally produced 

 much more sparingly. The early productiveness of this kind of soil, and 

 its rapid exhaustion by cultivation, at first view seem to contradict the opi- 

 nion that durability and the ease of improving by putrescent manures are 

 proportioned to the natural fertility of the soil. But a full consideration of 

 the circumstances will show that no such contradiction exists. 



In defining the term natural fertilily, it was stated that it should not be 

 measured by the earliest products of a new soil, which might be either 

 much reduced, or increased, by temporary causes. The early fertilily of 

 free light land is so rapidly destroyed, as to take away all ground for con- 

 sidering it as fixed in, and belonging to the soil. It is like the effect of 

 dung on the same land afterwards, which throws out all its benefit in the 

 course of one or at most two years, and leaves the land as poor as before. 

 But still it needs explanation why so much productiveness can at first be 

 exerted by any acid soil, as in those described in the 14th experiment. The 

 causes may be found in the following statement. These soils, and also their 

 sub-soils, are principally composed of coarse sand, which makes them of 

 more open texture than best suits pine, and (when rich enough) more 

 favorable to other trees, the leaves of which have no natural acid, and 

 therefore decompose more readily. As fast as the fallen leaves rot, they 

 are of course exposed to waste ; but the rains convey much of their finer 

 parts dov.'n into the open soil, where the less degree of heat retards their 

 final decomposition. Still this enriching matter is liable to be further de- 

 composed, and to final waste ; but though continually wasting, it is also 

 continually added to by the rotting leaves above. The shelter of the upper 

 coat of unrotted leaves, and the shade of the trees, cause the first as well 

 as the last stages of decomposition to proceed slowly, and to favor the 

 mechanical process of the products being mixed with the soil. But there 

 is no chemical union of the vegetable matter with the soil. When the 

 land is cleared, and opened by the plough, the decomposition of all the 

 accumulated vegetable matter is hastened by the increased action of sun 

 and air, and in a short time every thing is converted to food for plants. This 

 abundant supply suffices to produce two or three fine crops. But now, 

 the most fruitful source of vegetable matter has been cut off — and the soil 

 is kept so heated (by its open texture) as to be unable to hold enriching 

 matters, even if they were furnished. The land soon becomes poor, and 

 must remain so, as long as these causes operate, even though cultivated 

 under the mildest rotation. When the transient fertility of such a soil is 

 gone, its acid qualities (which were before concealed in some measure by 

 so much enriching matter,) become evident. Sorrel and broom grass cover 

 the land, and if allowed to stand, pines will then take complete possession, 

 because the poverty of the soil leaves them no rival to contend with. 



