304 
SCOURING LANDS OF CENTRAL SOMERSET. 
Some people evidently think that drainage is a talisman 
which converts every unproductive soil into a fertile one. 
But a little consideration will show that the radical changes 
which draining usually produces in the agricultural capabi¬ 
lities of land cannot take place in every instance, and that 
the general character of scouring land is, in many cases, not 
affected by drainage. 
Let us look for a moment at two pastures of a similar 
character in their natural, undrained condition. Both are 
wet, equally unproductive, and to all appearance there is no 
difference in the two fields ; probably both scour. But we 
will suppose that in one field we have only two or three 
inches of surface-soil, and, under it, say three or four feet 
or more of tenacious lias clay, whilst in the other the same 
clay subsoil lies at a depth of eighteen inches, or still more 
remote from the surface. Though perfectly equal in their 
undrained condition, the greatest difference must be produced 
in the character of two such fields after draining ; for with 
the removal of the surface-water in the one field only two or 
three inches of soil are improved, and in the other eighteen 
inches or more. We can without difficulty take away the 
surface-water equally well from both fields, but we cannot 
in an equal degree change their general character. If scour¬ 
ing were caused by an excessive quantity of water in pasture 
land, drainage would remove the evil in every instance ; but 
as the scouring effects of herbage are most perceptible during 
dry weather, it follows that the mere presence of surface- 
water in a field does not account for its scouring properties. 
As drainage produces radical changes in the condition of 
some soils, and as such changes cannot take place in soils 
in which a thick, impervious, clay bed comes close to the 
surface, we can understand why drainage cures scouring land 
in one place and not in another. 
I am unacquainted with a solitary instance in which 
scouring land rests on a porous subsoil, but I know many 
fields in scouring districts where a deep, tenacious, blue clay 
subsoil comes very near to the surface. Wherever this is 
the case, drainage, I am of opinion, will not remedy the evil; 
and in particular cases I can understand that it may even 
aggravate it. But should newly reclaimed peat land or clay 
soils, in which the blue-lias subsoil lies at least eighteen 
inches from the surface, be found to have scouring properties, 
I am inclined to think under-drainage will cure the evil on 
such land. 
