THE RE-AFFORESTATION OF HAINHAULT. 17
afterwards to Fiorin which, in its turn, is giving way to Sheep's
Fescue and Yarrow, and the field has now a very fair turf not
dissimilar to that in the adjoining forest. The lower half
received precisely the same treatment, but instead of Rye-grass
and White Clover nothing appeared but a dense mass of Fiorin
which has persisted ever since, and is only now, six years after
it first appeared, just beginning to give way to Sheep's Fescue
and Yarrow, while self-sown Bramble and Dog-Rose, springing
up in various parts of the field, give hopes of its reverting to a
natural wilderness of thorn and scrub.
De-calcified Boulder-clay.—There can be no doubt that this
striking difference between the two parts of the field is due to a
geological difference in the soil. The lower half is situated on
the slope below the deposit marked on the drift map as Boulder-
clay, although there are no plants in the forest characteristic of
a calcareous formation. Boulder-clay, when exhausted of chalk,
assumes a plastic form, far more unworkable than London-clay.
There are examples of such Boulder-clay soils in many parts of
Central Essex, notably in the Hedingham and Colne district.
What constitutes the chemical or physical difference between
the London-clay and the decalcified Boulder-clay is a subject
that would well repay investigation and might lead to methods
for the amelioration of the latter. There can be little doubt that
in this lies the secret of the barrenness of this particular field.
So defective is this plastic soil in drainage and aeration that
hardly any plant can thrive except this stoloniferous Fiorin,
at any rate until the decay of this grass leaves on the surface
some humus in which fescues can obtain a rooting. It is note-
worthy that this plastic soil extends into the 16 acres adjoining
the Romford Road, and on the part of this field adjoining the
35 acres the expensive mixture sown in 1903 completely
failed, and it is only now, five years later, that Cocksfoot and
Sheep's Fescue are beginning to make their appearance.
Manurial Experiments.—Having dealt with the seeds used in
laying the farm down to grass, the manurial treatment must next
be referred to. The particular plant food that is deficient in
almost all Essex soils is phosphate, and it seemed almost certain
that a phosphatic manure, especially the basic phosphates of
lime or "Basic-slag," would assist the growth of the young
B