Book V. ELEVATION OF FARM LANDS. 775 



subsoil, information may be obtained in regard to the soil itself; for the materials of the 

 latter are often similar to those which enter largely into the composition of the former, 

 though the substances in the soil are necessarily altered, by various mixtures, in the 

 course of cultivation. The subsoil may be of use to the soil, by supplying its defi- 

 ciencies and correcting its defects. The hazard and expense of cultivating the surface 

 are often considerably augmented by defects in the under-stratum, but which, in some 

 cases, may be remedied. Disorders in the roots of plants are generally owing to a wet 

 or noxious subsoil. Subsoils are retentive or porous. 



4761. Retentive subsoils consist of clay, or marl, or of stone beds of variou* kinds. A retentive clayey 

 subsoil is in general found to be highly injurious. The surface soil is soaked with water, is ploughed with 

 difficulty, and is usually in a bad condition for the exertion of its vegetative powers, until the cold slug- 

 gish moisture of the winter be exhaled. By the water being retained in the upper soil, the putrefactive 

 process is interrupted, and manures are restrained from operating, consequently the plants make but 

 little progress. Hence, its grain is of inferior quality, and when in grass its herbage is coarse. 



4762. A stony subsoil, when in a position approaching to the horizontal, is in general prejudicial, and, 

 if the surface-soil be thin, usually occasions barrenness, unless the rock should be limestone; and then 

 the soil, though thin, can easily be converted into healthy pastures, and, in favourable seasons, will feed a 

 heavy stock. They will also produce good crops of corn, though subject to the wire- worm. 



also produce good crops of corn, though subject to the wire-worm, 



4763. A porous subsoil is uniformly attended with this advantage, that by its means all superfluous 

 moisture may be absorbed. Below clay, and all the variety of loams, an open subsoil is particularly 

 desirable. It is favourable to all the operations of husbandry; it tends to correct the imperfections of 

 too great a degree of absorbent power in the soil above ; it promotes the beneficial effects of manures ; it 

 contributes to the preservation and growth of the seeds ; and ensures the future prosperity of the plants. 

 Hence it is, that a thinner soil, with a favourable subsoil, will produce better crops than a more fertile 

 one incumbent on wet clay, or on cold and non-absorbent rock. Lands whose substratum consists of 

 clean gravel or sand can bear little sun, owing to their not having the capacity of retaining moisture, and 

 their generally possessing only a shallow surface of vegetable mould. In England this soil was formerly 

 called rye-land, being more generally cropped with that species of grain than any other. When such 

 soils are cultivated for barley, they should be sown early and thick, with seed soaked forty-eight hours in 

 water or in the exudation from a dung-heap. Thus its simultaneous germination and its simultaneous 

 ripening may be secured. 



Sect. IV. Elevation of Lands relatively to Farming. 



4764. The elevation of lands above the level of the sea has a material influence on the 

 kind and quality of their produce. Land in the same parallel of latitude, other circum- 

 stance being nearly similai', is always more valuable in proportion to the comparative 

 lowness of its situation. 



4765. In the higher districts the herbage is less succulent and nourishing, and the 

 reproduction slower when the land is in grass ; while the grain is less plump, runs more 

 to straw, is less perfectly ripened, and the harvest is also later when the produce is 

 corn. It has been calculated that in Great Britain sixty yards of elevation in the land 

 are equal to a degree of latitude ; or, in other vvords, that sixty yards perpendicularly 

 higher, are, in respect of climate, equal to a degree more to the north, [n considering 

 the crops to be raised in any particular farm, attention ought therefore to be paid to its 

 height above the level of the sea, as well as to its latitude. In latitude 54 and 55'^, an 

 elevation of 500 feet above that level is the greatest height at which wheat can be cul- 

 tivated with any probable chance of profit ; and even there the grain will prove very 

 light, and will often be a month later in ripening than if sown at the foot of the hills. 



4766. The usual maximum of elevation may be reckoned between 600 and 800 feet for the more common 

 sorts of grain ; and in backward seasons the produce will be of small value, and sometimes will yield 

 nothing but straw. It is proper, at the same time, to remark, that in the second class of mountains in 

 the county of Wicklow, in Ireland, where no other grain is considered to be a safe crop, rye is cultivated 

 with success. "Where the soil is calcareous, however, as on the Gloucestershire and Yorkshire wolds, 

 from the superior warmth of that species of soil, compared to cold clays or peat, barley grows in great 

 perfection at an elevation of 800 feet above the level of the sea. Some experiments have been made to 

 raise corn crops, at even a higher elevation, on the celebrated mountain Skiddaw, in Cumberland, but 

 unsuccessfully. 



4767. The greatest height at which cmn will grotv, in the more remote parts of Scotland, so as to yield 

 any profit to the husbandman, is stated to be at 500 feet above the level of the sea. At the same time 

 corn has been produced, in other districts of that country, at still higher elevations, in particular at the 

 following places : 



FM above the Level Feet above the Levti 



of the Sea. qfthe Sea. 



Parish of Hume, in Roxburghshire - 600 Doubruch, in Braemar, Aberdeenshire 1294 



Upper Ward of Lanarkshire - - 760 Lead-hills, in Lanarkshire - - - 1564 



4768. These and other instances of land being cultivated on high elevations, however, are merely small 

 spots, richly manured, and, after all, producing nothing but crops of inferior barley and oats, and seldom 

 fully ripe or successfully harvested. It is chiefly where the soil is sandy or gravelly, that corn will answer 

 in Scotland on such elevated situations ; and even then, only when the seasons are propitious, and when 

 there are local advantages, favourable to warmth and shelter, in the situation of the lands. 



Sect. V. Character of Surf ace in regard to farming Lands, 



4769. A hilly irregular surface, whether at a high or low elevation above the sea, is 

 unfavourable to farming. The labour of ploughing, carrying home produce, and carrying 

 out manure, is greatly increased ; while the soil on the summit of steep hills, mounts, or 

 declivities, is unavoidably deteriorated. On the sides of slopes the finer parts of the clay 

 and mould are washed away, while the sand and gravel remain. Hence the soil in such 



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