SOILS. 25 



plant can become vigorous, whatever may be tbe richness of 

 the soil in which it may be placed. The more the soil is pul- 

 verized, the more numerous are the absorbing fibres of the 

 roots, the more extract is consequently absorbed, and the more 

 vigorous does the plant become. Pulverization therefore is 

 not only advantageous previously to planting or sowing, but 

 also during the process of vegetation, when applied in the 

 intervals between the plants. 



We thus learn from experience the good effects of tilling 

 lands well. Soils once tilled are rendered for the most part 

 more productive by the process. Peaty turf, if suffered to 

 remain in its original state, may continue to produce nothing 

 but the most useless plants; but if merely ploughed and ex- 

 posed to the influence of the atmosphere, it will at once tend to 

 produce grass of a better kind and of greater variety. 



Another purpose sometimes promoted by tillage, and sub- 

 servient to the amendment of the soil, is the deepening of the 

 upper stratum. The sub-soil, as has been already shown, is 

 distinguished from the soil, properly so called, by the former 

 containing less vegetable and animal matter, and so being less 

 suited to the nourishment of plants; and in certain cases it is 

 even found to be injurious to vegetation. But as a good depth 

 of soil is necessary, (unless under rare and peculiar circum- 

 stances,) it is often expedient, in order to effect a permanent 

 improvement of the surface, to plough up and mix with it a 

 portion of the sub-soil, even though that sub-soil should be in 

 itself infertile. 



Another means possessed by us of adding to the productive- 

 ness of soils, by changing their composition, is by incineration, 

 commonly called paring and burning. These are the prin- 

 cipal mechanical means by which we can improve the soil. 



The third mode referred to of increasing the productive 

 powers of soils, is changing their relation with respect to mois- 

 ture. The water of the soil where superabundant may be 

 withdrawn, and when deficient supplied. The first method is 

 termed draining, and the latter irrigation, both of which 

 form a peculiar branch of agricultural improvement, and will 

 be treated of in this work. 



The last of the means referred to of increasing the produc- 

 tive powers of soils, is by changing their relation with respect 

 to temperature. This mode is less within our control than 

 any of the others. It is only by slow degrees that we can im- 

 prove the climate of a country. It is chiefly by draining and 

 by the rearing of hedges and wood; and all of these accord- 

 ingly form important objects of rural economy.* 



* Low's Practice of Agriculture. 



