244 THE ESSEX NATURALIST.
limestone areas. The porous nature of chalk results in a fairly
high moisture content and percentages above 20 per cent of
water are far from uncommon in winter. It will be realised that
this high figure when compared with the 3 per cent or 4 per cent
common in the non-cretaceous limestones must make the
burning of the former rock much more costly.
One other factor inclined Essex and the eastern counties
generally to favour the use of chalk in its natural state rather than
burnt chalk. Any form of liming is carried out to neutralise
acidity in the soil, to supply calcium, and to lighten heavy land.
The second reason may be dismissed as far as Essex—and
particularly the Chalky Boulder Clay—is concerned. Heavy
soils may be lightened by a variety of materials such as cinders,
straw and sand as well as chalk, but chalk is generally favoured
because it is cheaper and easier to handle. Further the heavy
clays of Essex tend to be acid—ths London Clay particularly
so—and thus chalking achieves the dual purpose of neutralising
acidity and of lightening the soil, which renders it easier to work
and allows drainage to act more freely.
It is, therefore, not surprising to find that Essex farmers
retained their preference for chalk when liming the heavy clay
lands of Essex. Chalking, too, was favoured by the farmers
of the light sandy loams since its use counteracted acidity without
burning the organic content—a characteristic of quicklime,
which is so undesirable on the generally humus-deficient sandy
soils.
Nevertheless the 20th century chalking activities in the county
did not see a repetition of the very heavy rates of spread common
in the 19th century. At that time dressings of forty and fifty
loads—or approximately thirty or forty tons per acre—were
frequent, if not the general rule. It must be realised, however,
that in previous years chalking was a long term policy and a
dressing of this intensity was intended to last for a generation.
In a few instances the ploughing-up of permanent pastures has
revealed pieces of chalk remaining over from early 19th century
operations, whilst it has been asserted that similar evidence of
chalking in Roman days has been found in old derelict pastures
ploughed-up in the last few decades. At the present time speedy
increased crop production is essential and a short term policy
is the main consideration.
Lump chalk, as dug, naturally takes some years to break
down completely and become assimilated by the soil. During
the first years there is no doubt that its lightening effects are
immediately felt and by promoting free drainage some neutralising
action must make itself apparent. Most corn crops—particularly
wheat and barley—cannot, however, grow in an acid soil