96 
The Agriculture of Pembrokeshire. 
Rotations. — The next point that strikes me relates to the 
present systems of rotation, and their management. It was 
previously remarked that land was not now left in ley for as 
many years as was formerly the custom ; and, as is well known, 
the shorter time a field is in grass before being again ploughed, 
so much more nitrogen does it require in the manures applied for 
the arable crops. This necessitates a few words on what really 
is meant by " resting " land in the manner practised. 
The principal effect of pasture plants on the soil is to 
increase its organic constituents ; this results from the decay 
of the roots of these plants. It has been calculated that the 
roots are equal in weight to about one-third of the crop, and 
as roots mature and decay — as the part of the plant above 
ground does, — it is easily understood that this decay of roots 
means a great deal. Again, the constituents of the roots vary, 
like those of the plant, in different species, consequently the 
decay of the roots of some species produces more effect than 
others. Every farmer knows what a fertilizing effect the decay 
of clover-roots has. Another effect of pasture is, that as the 
roots of the plant penetrate deeply they assist in the permeation 
of the soil by rain and air ; these not only act beneficially on 
the soil, but also carry down fertilizing elements, which are 
absorbed and stored. Again, as the soil is not disturbed the 
earth-worms increase, and the most superficial observer knows 
how continuously they deposit the best of mould on the 
surface. Thus it is desirable, in order to obtain the greatest 
benefit from two or three years' ley, that the valuable grasses 
shall be sown. I consider that the result usually obtained in 
this county is one heavy crop of rye-grass and some rank- 
growing clover ; the second year an inferior crop ; and the 
third year little rye-grass, or the rank clover, but plenty of 
bare patches, and the soil exhausted to an unprofitable 
extent. 
Why rye-grass should be in such favour is, I suppose, because 
it makes a good show, and throws a heavy crop; but if its feeding 
qualities, and the effect of its growth on the soil be compared 
with some other grasses, probably opinion will alter respecting 
it. I would suggest growing a lighter crop of better quality, 
and to obtain this I would exclude rye-grass — except the sort 
known as perennial, — substituting cocksfoot and timothy grasses 
in increased quantities. 
Deeper ploughing, where possible, would probably help the 
grass seeds ; though most of the land in the county, if 
laid down in good condition, produces excellent natural 
pasture. 
There is little to be said of the other crops of the rotation, 
