1836.] 



FARMERS' REGISTER. 



207 



become more profitable, instead of being made ac- 

 cording fo a political as.?ociation, by Departments 

 for example, ought to be made by the basins of 

 rivers; it would give rise to many lewer mistakes, 

 and consequently, to much more success. The 

 rules and successful practices of a basin, should be 

 studied anew, if we wish to make an application 

 of them to another basin in which the composition 

 of the soil is owing to difi'erent circumstances. 



XIII. This caution, this fear of mistakes, ought 

 to have its full efli^ct when agriculture is practiceJ 

 on the great argilo-silicious ileposite which covers 

 such vast extents, and presents every where tlie 

 greatest analogy. The practice c^f agriculture on 

 this deposite, might then have general rules which 

 it would be very important to collect; but it must 

 first be well characterized, in order that it may be 

 every where known. We shall therefore resume 

 the course of our observations. 



The soil and the subsoil of this stratum, calthough 

 of different shades, appear to be ol" identical cosn- 

 position, as experience daily proves in a slrikinir 

 manner. When by any circumstance the whitish 

 stratum of the surface is removed, so as to leave 

 only the reddish stratum of the sub-soil, some 

 years of cultivation and manuring, or even of 

 spontaneous vegetation without culture, are sufli- 

 cient to give to This reddish sub-soil the gray color 

 of the rest; and, in the same manner, when this 

 reddish earth is carried out on a cultivated soil, 

 the shade which it gives quickly disappears by 

 mixture with the rest, and by the effect ofcultivation. 



The proof of this identity is still .more complete, 

 if we remark that in digging into the lower parts 

 filled up by the tailing of more elevated portions of 

 the soil, we find the red soil shaded with gray, or 

 the gray shaded with red veins in the middle of the 

 rubbish; which proves the new increment, with 

 all the characteristics which it has elsewhere, its 

 stiffness and its impcrmeahility. 



The sub-soil and the stratum of the surface, are 

 then nearly identical, its formation throughout its 

 whole thickness is therefore the production of the 

 same aqueous revolution; only the oxide of iron 

 which colors the sub-soil, loses its color by culti- 

 vation. 



XIV. The effect of frost upon this soil charac- 

 terizes it in a peculiar manner; the water at the 

 surface when it is in no great quantity, often fi'eezes 

 in vertical threads which sometimes rise six inches, 

 and resemble a vegetable growth. But what is 

 still more remarkable, is, that the soil rises up by 

 freezing much more than the greater part of cal- 

 careous or alluvial soils. New vegetables, plant- 

 ed, or even sown, are torn out of it in a manner 

 truly astonishing; plantations of wood of that year, 

 or even of the year preceding, were torn out at two 

 different times by tlae freezing without snow, in 

 February, 1831; and sowings of sea-pines, (mari- 

 times,) made the year before, were thrown out of 

 the soil. It is therefore prudent to wait till the 

 end of winter to make plantations in such soils, 

 and not to dig the holes beforehand, that water 

 may not get into them and remain; and as the ef- 

 fect of frost is less sensible on the parts covered 

 with turf; the little holes, after planting, should be 

 re-covered with turf, to prevent as much as possi- 

 ble new losses. 



The rising of this soil from freezing, occasions 

 besides the great inconvenience of much deeper 

 roads than on calcareous soil. 



These effects are explained in a plausible man- 

 ner from the nature of the soil itself. This soil con- 

 tains much silex in a state of very minute division, 

 either free or combined with the clay; this silex as 

 we have seen, takes a greater quantity of water 

 than other descriptions of soil; the water which 

 penetrated this soil expands, as we know, by 

 freezing; it expands then at the same time the soil 

 which it penetrates; the expanded soil rises up, 

 and raises with itself the plants and their roots 

 when they do not reach to great depths. 



The surface of the soil in thawing first, and 

 losing a part of its water by evaporation, is con- 

 tracted and sinks upon the rest of the soil, and 

 leaves expo.-ed a part of the roots which cannot 

 descend again with it because their extremities 

 are fixed in a soil still frozen: the next day this 

 effect is renewed, and the plant is soon pardy or 

 entirely out of the ground, according to the length 

 of its roots. 



The rising of the soil is greater in proportion as 

 it is more clayey, because then it contains more 

 silex in the state of impalpable powder, or it ab- 

 sorbs more water; it is greater than in the ordinary 

 calcareous soil, because carbonate of lime receives 

 only 85 per cent of water to 100 of impalpable 

 powder, while silex takes 280 per cent. There 

 are, however, some calcareous soils which also 

 greatly expose the roots of vegetables; these are 

 the marly {vxarnevx) calcareous soils; thus, in the 

 freezings without snow in February last, our calca- 

 reous soils of the plateaux, whether terres-mares, 

 or our marled lands, had more plants thrown out 

 than our common while lands, (terres blanches. J 

 We attribute this to the fact that our ierres mares 

 are nothinij more than a mixture of the argilo- 

 silicious soil of the plateaux with the inferior marly 

 stratum; but our marl which contains commonly 

 40 per cent, of carbonate of lime, has 60 per cent, 

 of clay or very fine silex, while our white lands 

 contain a great deal of silex in the state of sand. 

 Our terres mares and our marled lands, contain 

 then, relatively, more fine silex than our ordinary 

 ridge or table lands, and for this reason may ex- 

 pose the roots of plants still more. 



XV. But with the same sub-soil, almost al- 

 ways clayey, the surface varies much in stiffness 

 and tenacity: it passes from a state the most tena- 

 cious, and the most difficult to work, to the light- 

 est sand, which is carried off by the wind; and yet 

 under all these diversities of soil, there is found 

 almost every where the impermeable red sub-soil. 



When the upper soil is clayey, it is then acci- 

 dente, formed of a collection of small basins or 

 ponds, which serve to drain it; the waters have not 

 levelled the surface, or rather after having levelled 

 it, thej^ attacked it in places, and formed in it ba- 

 sins or hollows which receive the water of the sur- 

 face, and without which it would be impossible to 

 cultivate it. 



In this case, it may be conceived that the soil 

 and the sub-soil are in their nature clayey, of an 

 impermeability almost absolute; this soil is also 

 very wet, since it contains a great deal of fine silex, 

 which absorbs 280 per cent, of water, and to de- 

 rive advantage from it, the cultivator is obliged to 

 add to its natural declivity by artificial beds or 

 ridges by the plough. Wheat, rye, and most ag- 

 ricultural productions, succeed more or less upon it 

 when the drawing off ol' the superabundant water 

 has been effected. 



