30,2 ON SOILS AND SUBSOILS SUITED FOIl PLANTING. 



that if the soil be not deep the amount of moisture collected is 

 apt to become too great. 



Underneath the sand of the North German plain there occurs 

 in many districts (especially around Burgdorf, Uelzen, and Celle), 

 an impervious layer of sand firmly cemented by heather humus, 

 and containing approximately 2°/^ of sesqui-oxide of iron, and 

 known as moorpan. This, lying at the depth of from 6 inches 

 to 2 1 feet from the surface, has first to be broken up by the 

 steam-plough, or the subsoil plough drawn by oxen, or, if too 

 deep for that, by manual labour. Tlie thickness of this imper- 

 vious layer is usually 9 inches to 1 foot, and on exposure to the 

 atmosphere for about one year it crumbles to a yellow sand, after 

 which the soil is fit for growing the Scotch fir — which is here 

 planted in preference to being sown. As it would be a needless 

 expense to upturn the whole of the subsoil, the moorpan is 

 brought to the surface in bands, 6 to 8 feet in breadtli, and with 

 a space of 6 feet between eacb, so that about y of the whole area 

 is upturned. If performed by manual labour, this costs from 

 L.3 to L.o, 10s. per acre. Again, on part of the same plain, in 

 Mark Brandenburg, fine oaks grow over sand, which has 17% of 

 kalkfeldspatli, and a subsoil of peat and loam underneath. 



The soil yielded by the red conglomerate of the Eothtodlie- 

 gendes being shallow (and generally poor in earthy matter), 

 usually rests on a subsoil of the same rock, and this, being- 

 capable of retaining moisture, tends to improve the surface soil, 

 otherwise almost unfit for sylviculture. Peats, marshes, and 

 moist clays are most favourable to the rearing of timber when 

 over sand, or any other subsoil which absorbs and retains within 

 itself the water w^hich collects above. 



Limes and loams form, as a rule, like marls, good subsoils, 

 absorbing the moisture, and then giving it back again gradually 

 when there is a necessity for it. 



The effect which the soil and the subsoil have on the quality 

 of timber may be expressed shortly but scientifically as follows: — 

 The combustiUc tissues of timber, i.e., those liable to decay 

 either by exposure to atmospheric or other agencies are — carbon, 

 oxygen, hydrogen, and nitrogen. The absolutely necessary con- 

 stituents of the ashes, or portions of the timber not liable to decay, 

 are — iron, ccdcium, 2^otassium, and sodium ; along with these 

 are often to be found magnesium, mcmganese, silicon, sulphur, 

 and 2jhosj)horus. It follows, then, that according as the percen- 

 tage of combustible tissue exceeds that of the incombustible, the 

 timber will be less durable, and hence for technical purjDoses of 

 less value. Therefore, soils and subsoils in which there is a fair 

 amount of lime, potassium, silica, &c. ; in short, those rich in 

 alkalies, produce timber of the best quality, while such as con- 

 tain an over abundance of moisture yield timber neither of such 

 durabilitv, nor of so high a value. 



