19G 
Causes of Fertility or Barrenness of Soils. 
rotation, generally after the first ploughing of the stubbles for 
the fallow crop, is strongly recommended. Where the subsoil 
consists of a stiff yellow clay, care must be taken not to bring up 
too much at once ; for else, being of a poisonous nature, it would 
injure the land for some time, until in fact the oxygen of the air 
had effected the necessary chemical changes, and sweetened the 
mass. Deep soils are much less injured by sudden changes of 
weather than shallow ones, for being open and friable, the rain- 
fall passes slowly through them, and after nouiishing vegetation 
disappears in the subsoil ; and during a dry time they maintain 
their moisture, owing to their powers of absorption and capillary 
attraction. Many of the most fertile loams, resting upon a gravelly 
and very porous subsoil, owe their fertility to their depth. The 
same rule holds good with soils resting on chalk or limestone ; 
they are rich or poor according to depth. Therefore it is evident 
that in farming, besides the mere routine of preparing the ground 
for the crop, we have the important business of deepening 
the soil to attend to. Draining, in all cases where the land re- 
quires it, will be found a most important assistant, lowering 
the water level to the bottom of the drains, some 3 or 4 feet 
from the surface, enabling the atmosphere, that great fertilizer, 
to penetrate into the crevices formerly filled with moisture, and 
by diminishing the tenacity, lessening the difficulties of deep 
cultivation. 
In cases where porous soils rest upon stiff subsoils, occasional 
subsoiling, by bringing to the surface much valuable matter, which 
had passed through, will be found equal to a dressing of manure. 
In the case of clay soils, we are often enabled by deep cultiva- 
tion to insure a supply of those mineral substances so essential 
to vegetation, but which are naturally in an insoluble state; 
requiring the action of the air and rain water to reduce them to 
an available condition for the wants of plants. The only caution 
required, as was before mentioned, is to avoid bringing up more 
of the sour subsoil at a time than the winter's frost and rains can 
fertilize, and always to plough deepest in autumn for the fallow 
crop ; for the frequent stirrings and mixings, which the soil re- 
ceives for the fallow, whether bare or green, will tend to fertilize, 
and prevent any injurious effects which might otherwise follow. 
The way in which the stubbles are managed on a clay farm is a 
good criterion of the ignorance and poverty, or the intelligence 
and capital, of the occupier ; if horses are short, they are left 
untouched till spring, and all the benefits of winter frost, &c., 
lost ; indeed I have met with men who professed to agree with 
such a system, and argued against the autumn ploughing as being 
injurious to the land. It is possible that, in a peculiarly wet 
season, we should do more harm than good by attempting to 
