ON THE IMPROVEMENT OF SOIL. 



this description on the plains of Grace, near Aries. 

 They exhibit the singular spectacle of flocks of sheep 

 feeding on dry stones, as the grass which grows beneath 

 them is not visible ; but the sheep find a tender, if not 

 abundant pasture, by turning up these stones, or nibbling 

 beneath them ; while the pebbles, thus overturned, afford 

 shelter to the adjacent blades which are just sprouting, 

 and would be burnt up without such protection. 



In some instances the ground in which fruit trees are 

 planted, have been paved with stones, in order to retain 

 the moisture beneath by preventing evaporation. 



In cold countries stones are sometimes considered ad- 

 vantageous as communicators of heat, those of a dark 

 color especially. They act on the surface of the earth 

 both as reflectors and radiators of heat ; and are frequent- 

 ly placed round the stems of plants in a vineyard, in or- 

 der to give them additional heat. It must be allowed, 

 however, that those occasional uses to which stones are 

 applied in husbandry, are to be considered rather as ex- 

 ceptions to the general rule, and that stones may be 

 looked upon in most cases as either useless or pernicious. 



The improvement of soil by the admixture of foreign 

 ingredients, amendement, is one of the most important 

 operations of agriculture. 



If the soil be too stiff from excess of clay, it will be 

 improved by sand ; and if too loose from excess of sand, 

 it will be improved by clay : but when sand is mixed with 

 argillaceous soil, the latter must be broken and pulveris- 

 ed, which may be effected by exposing it to the frost, 

 and afterwards drying it. Marl is a natural compound 

 earth, used with great success in the amelioration of 

 soils: it consists of a mixture of clay and calcareous 

 earth or lime in various proportions. 



Argillaceous marl, which contains more clay than lime, 

 is advantageous for a dry sandy soil ; while calcareous 

 marl, in which the lime predominates, is suited to an ar- 

 gillaceous soil. The great advantage of marl is, that it 

 dilates, cracks, and is reduced to powder by exposure to 



889. What is said of them in relation to fruit trees'? 890. And 

 what is said of their influence upon the soil in cold countries'? 891. 

 Are stones generally useful in agriculture'? 892. What is one of the 

 most important operations of agriculture'? 893. How are the differ- 

 ent kinds of soil to be changed'? 894. What is Marl! 89.5. What 

 is said of argillaceous and calcareous marls? 



