Weather and Agriculture

224 Pages·1967·9.072 MB·English

by  James A. Taylor (Eds.)

WEATHER AND
AGRICULTURE
Edited by
JAMES A. TAYLOR
Senior Lecturer in Geography,
University College of Wales, Aberystwyth
SYMPOSIUM PUBLICATIONS DIVISION
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Copyright © 1967
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First edition 1967
Library of Congress Catalog Card No. 67-13993
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DEDICATION
THIS volume is dedicated, as a token of deep and affectionate respect, to
the memory of the late Sir L. Dudley Stamp, a truly great man who did
so much for geography and in particular land use studies not only in Britain
but also in many countries abroad. His encouragement, inspiration and
example helped to create and guide the series of symposia on which this
volume is based.
PREFACE
THE book that follows will be seen by its readers, as I did, very much as a
tribute. It is dedicated to Sir Dudley Stamp, whose all-pervading interest in
the land and its use deserves all the tributes it can have. But it is a tribute also
to Aberystwyth—to its university and its experimental stations, to its unique
role in Welsh affairs, to its long-established primacy in the study of Highland
Britain. It is often said (by Welshmen) that Wales lacks a natural focus.
Physically this is true, and with the withdrawal of centripetal rail services it is
becoming truer all the time. Intellectually it is not true, thanks to the various
university colleges. And of these none has been more central than Aberyst­
wyth. We have come to accept, across all Britain, periodic summonses to the
University or the Plant Breeding Station. This volume is a direct outgrowth
of these activities, and of invitations accepted.
But the volume is not Welsh, nor are these symposia seen as serving only
the parochial interests of Welsh farmers. Far from it. The scope is at least
British, and at best universal. I expect the book to be valuable—and to be
bought—in New Zealand, in the United States, in the Argentine Republic.
Its editor and presiding genius, James A. Taylor, has brought great enthusiasm
to his task; combining as he does great energy with shrewd understanding, he
is able to see the details of the various specialist contributions in a thoroughly
ecumenical light—thereby removing from the text one of the curses of
microclimatology and its related fields—what, for the lack of a word, I'll
call W hoccishness\ Everyone who reads the book will want to join me in
congratulating him, and in urging him on. The individual contributors
deserve high praise too.
Agriculture is a curious economic art. It is one of the few major industries
in which the economists dream of a competitive system, based on very large
numbers of producers, can be said to come true. Of course its price structure
is everywhere clouded by official action, by subsidies, guaranteed prices and
tariffs. No one will look to British agriculture for illustrations of economic
theory. But one element of the dream world remains—the persistence of
innumerable small farms, isolated men with limited capital and technical
resources. It is the key to Mr. Taylor's approach that the number of decision-
makers is very large indeed. The "matrix of management decisions" to which
he refers is a very big matrix indeed. But more bluntly, the weather bears on a
lot of people at once in farming—with no guarantee that they will take
identical or even similar decisions at the sight of the black cloud. The myth
ix
X PREFACE
of the weather-wise farmer needs exploding. I have known many, and was
born on a large arable farm in southern England. I have watched Wiltshire
farmers pulling their men off the fields because of grey stratus which to them
threatened a downpour, and which to the sun represented an hour's work to
disperse! The farmer thus needs his broadcast forecasts.
But of course he needs much more—he needs expert advice on the en­
vironmental impact of the weather. He needs to know much more, for
example, about soil moisture and its conservation; about the ecology and
control of insects, rodents and spore-borne pathogens. Particularly he needs
more than his own experience can teach him about the effect of his own
management practices on the impact of weather. It isn't long since the
agronomist persuaded farmers in the dry interior plains of North America
that the creation of a shallow dust mulch, and its constant recultivation, lost
water rather than conserved it. It isn't likely that the guilty farmers will read
this book—those farmers who read it will already be among the industry's
sophisticates. But it will be read by his technical advisers, and will hence have
its effects.
Speaking as a climatologist, I welcome this book on other grounds. Much
of the land surface over which the wind blows is a cultivated surface. Farming
practice, the crop calendar and so on, have a marked influence on the prop­
erties of the air itself. The meteorological profession knows much too little
about these questions—because meteorologists and agricultural scientists
are trained apart, in widely different intellectual environments. I hope my
colleagues on this side of the fence will read and profit.
Master of Birkbeck College, F. KENNETH HARE
London, 6 January 1967
EDITOR'S ACKNOWLEDGEMENTS
THE Editor is deeply indebted to countless assistants without whose spon­
taneous and continuing co-operation the series of Symposia on which this
volume is based could never have been initiated and successfully maintained.
It is impracticable to nominate all persons and institutions that have helped,
but special thanks are due to all those colleagues who have given papers and
stimulated discussions at the Symposia. For domestic facilities I acknowledge
with gratitude the University College of Wales, Aberystwyth, in particular
the services of the Department of Geography (kindly provided by the Head of
Department, Professor E. G. Bowen, M.A., F.S.A.) and in latter years of
the Welsh Plant Breeding Station. For production of the Memoranda my
warmest thanks are due to the secretarial, photographic and cartographic
staff of the Department of Geography. For prompt and efficient assistance
with typing I thank Mr. Brinley C. Jones. Innumerable students over the
years have given willing help when needed. Last but by no means least I
acknowledge the assistance of my wife who cheerfully abstracted many spools
of tape often at short notice, and assisted with the typing of several of the
Memoranda. Without her support and encouragement, or that of all the
others who have helped, nominated or unnominated (including those
confessedly under mild duress!), little could have been achieved.
The printing of a sequence of papers taken to some extent out of context
from the flow of the individual Memoranda and their re-grouping into a new
three-fold sequence may have involved one or two local editorial dis-con-
tinuities if the papers are read consecutively.
Finally I should like to thank most warmly all contributors to this parti­
cular volume for their commendable editorial cooperation, again without
which progress would have been impossible. Also to Pergamon Press Ltd.
my thanks are due for their efficient management and unfailing courtesy.
Aberystwyth JAMES A. TAYLOR
New Year's Day, 1967
XI
INTRODUCTION
IT IS ironic that weather and agriculture should be so intimately related in
practice and that, in Britain at any rate, integrated academic studies involving
both subjects have been relatively few and ineffectual until comparatively
recently. This is in part due to certain educational traditions whereby both
agriculture and meteorology at the higher education and professional levels
have been relatively self-contained, the former being especially concerned with
the theory and practice of agricultural systems per se, and the latter with the
physics of the atmosphere, often at Stevenson screen level or in the higher
atmosphere rather than the air layer near the ground where agricultural
activities take place. Agriculturalists have been prone to accept generalized
impressions of regional differences in climate—and soils—which in mid-
twentieth century have less effect on regional differentiation of farming
systems than formerly, but which register continuously on a daily, weekly,
monthly and seasonal basis in the individual turnover, efficiency and pro­
ductivity of any given farm, be they measured in physical or monetary terms.
Meteorologists have been so extensively preoccupied with the measurement
of the atmosphere and the mathematical expression of its processes that the
application of meteorological data to agricultural problems has developed
only very recently. The unavoidable standardization of meteorological data
derived from instruments of standard exposure has meant that much of it
is not properly applicable to the first metre of the atmosphere within which
the major cultivated crops and grasses grow. The late academic and profes­
sional development of applied meteorology, and indeed of pedology, in
Britain tended to perpetuate the view that the British climate and the weather
patterns that formulate it are mostly of the moderate or 'equable' variety
without an adequate frequency of extremes or hazards such as to rank the
meteorological factor as a serious priority affecting agricultural development
and planning. The same view tended to be attached to soils which could be
chemically manipulated as required. The individualism which has charac­
terized the evolution of farms and types of farm management in Britain and
the general laissez-faire system which obtained until the 1930's both spelt
resistance to the operative significance of weather factors expressed in losses
or gains in pounds, shillings and pence.
The Second World War and its immediate aftermath proved to be the
turning point. Domestic agricultural production attained new intensities and
in the postwar years the maintenance of marketing arrangements, subsidies
1
2 JAMES A. TAYLOR
and price reviews prevented a repetition of the depression which followed the
First World War. As increasingly sophisticated farming methods became
available involving specialized machinery, competition became keene
especially per acre and per man and inevitably on the smaller farms in parti­
cular. Thus farmers became more sensitive to new methods of intensifying
production. It was in the immediate postwar period that the Meteorological
Office established a special section concerned specifically with agricultural
meteorology, and by now the meteorological services for farmers are well
established and becoming increasingly used.
The 1950's in fact saw an increasing liaison between agro-meteorological
research and agricultural practice in Britain. At university level the trend was
stimulated directly or indirectly by the introduction of courses in biogeo-
graphy in geography departments and by the development of applied ecological
work in departments of agriculture and botany, the latter, however, still
retaining a dominant emphasis on plant physiology. Aberystwyth by tradition
and location was well placed to contribute to this acceleration in agro-
meteorological studies.
The University College of Wales, Aberystwyth, had already established
strong interests in both agriculture and geography. The nearby Welsh Plant
Breeding Station had already achieved international renown under the leader­
ship of the late Sir George Stapledon. Only a few miles inland at Trawscoed
was the headquarters of the National Agricultural Advisory Service for Wales.
Aberystwyth itself also housed the local offices of the Ministry of Agriculture,
the Agricultural Land Service and also the Forestry Commission. Thus in
close proximity were university departments, research units and advisory
and consultative units, all with a common interest in countryside environ­
ment, in particular its local agricultural systems and their problems.
The appointment of the writer to the Geography Department at Aberyst­
wyth in 1950, initially to teach agricultural geography, was appropriate in
view of the potentialities available for both academic and technical liaison
with cognate departments and institutions. The writer had previously
become familiar, under the stimulating guidance of the late Professor
Wilfred Smith at the University of Liverpool, with cash-cropping systems in
south-west Lancashire where a remarkable relationship was revealed between
individual crop distributions and soil types (Taylor, 1949, 1952). This
relationship was subsequently confirmed on the basis of farm unit analysis by
Aitchison (1964). A major outstanding problem emerged from the south-west
Lancashire research—that of the peculiar liability of peatland to late frosts. In
1952 a meteorological investigation was conducted by the writer to measure the
differences in soil and air temperatures at selected sites on peat, sand and clay
on the south-west Lancashire plain. A series of subsequent investigations took
place culminating in the marling experiments reported and discussed herein.*
* See pp. 213 et seq.
INTRODUCTION 3
In the meanwhile the pastoral landscapes and the moorlands and mountains
of West Wales were providing contrast and stimulus. Interest in the effect
of land aspect on growing season created the Pen Dinas investigation (1954—
5) described and summarized herein.* It showed that on comparable slopes
of the order of 22° to the horizontal as much as 48 per cent more growth
potential, in terms of temperature, is available, ceteris paribus on a south
slope as compared with a north slope in West Wales. Advice on the lay-out
and conduct of this investigation was made available by the then Agricultural
Branch of the Meteorological Office, of M.O. 19 as it then was. Its staff,
viz. Messrs. L. P. Smith, R. W. Gloyne and W. H. Hogg, visited Aberystwyth
from time to time in the mid-1950's to lecture and initiate discussions which
attracted a wide range of staff and students, together with members of the
technical and advisory staffs of the local government services. The need for
regular organized symposia was thus created and in 1958 the first one was
convened, on the subject of "The Growing Season". The three papers in­
volved plus a summary of the discussion were published on foolscap cyclo-
styled format and circulated locally.
Three other events in the late 1950's stimulated interest in local rural and
agricultural ecology, including agricultural meteorology. The first was the
introduction of courses in Biogeography at Aberystwyth. Specifically agri­
cultural studies survived within a newly constructed third-year option in
Biogeography, and a new course in Biogeography was inserted at the
second year level. The second was the establishment of Shelter Research Unit
within the Department of Animal Husbandry, most of whose staff were
trained in the Biogeographical section of the Geography Department. It was
appropriate that the second symposium in 1959 should concentrate on
"Shelter problems as related to crop and animal husbandry". The third was
the parallel development of teaching and research in soils. Liaison with the
University College of North Wales at Bangor, where the late Professor
G. W. Robinson, up to his untimely death in 1949, had stimulated a permanent
interest in soil studies, culminated in the formation of the Welsh Soils Dis­
cussion Group in 1959 with the writer as secretary and convener. Subsequent
to the third symposium on "Hill Climates" in 1960, it was logical that the
fourth in 1961 should adopt "Soil Climate" as a theme. By this time the
memoranda based on the Symposia had an international circulation and it
became necessary to re-print earlier memoranda.
It was the growing awareness of the role of meteorological factors on the
incidence and spread of certain diseases in plants and animals which
provided that theme for the fifth meeting in 1962. The inclusion of no less
than four of the papers in this volume is indicative of the value and success
of this particular session. Supreme interest focused on the progress made in
the forecasting of potato blight and liver fluke {vide subsequently, Ollerenshaw,
* See pp. 15 et seq.
4 JAMES A. TAYLOR
1966). Here was the first evidence of success of integrated research into related
meteorological and biological data to provide a practical mechanism for
forecasting a hazard in such a way as to provide economic benefits for the
individual farmer or grower. Liaison had gone full circle. It was an increasing
consciousness of the effects of weather factors on agricultural productivity
which led to the adoption of that subject for the sixth session in 1963. This
was followed up in 1964 by a discussion of the major weather hazards
affecting British agriculture. The inclusion of papers herein by Taylor, Hurst
Warboys, Duckham and Chambers is an illustration of the special significance
of the economics of agro-meteorological advice and services. Quite recently
the Director of the Meteorological Office has summarized the role of meteor­
ology in the national economy (Mason, 1966). A rough estimate is made to
the effect that for the United Kingdom, probably not less than £20,000,000
per annum, or 1 per cent of the annual gross agricultural production (in­
cluding horticulture and forestry) which is estimated at £2,000,000,000 per
annum, is spent on meteorological services to agriculture.
In 1965 the escalating general interest in the subject of climatic change
favoured a broad approach to the topic with special reference to Wales and
its agriculture in pre-historic, as well as historic and recent, times. Three of
the nine papers given, those by Seddon, Oliver and Thomas, are included in
this volume. The writer concluded at the end of Memorandum 8: "Changes
or trends in the British climate are too gradual, too variable and too un­
predictable to affect directly or in any way universally contemporary agri­
cultural systems and policies except in terms of the productivity or efficiency of
particular weather-sensitive methods of production or weather sensitive areas."
The ninth symposium held in March 1966 was on the subject of "Early
crop production in the British Isles", and attracted fourteen papers. In
March 1967 the tenth session will adopt "Frost" as its subject for discussion.
Having outlined the origin and development of the symposia series in
agrometeorology at Aberystwyth, it would seem appropriate, also by way of
introduction, to indicate some of the major principles involved in the inte­
grated study of weather and agriculture to which the selection of papers herein
is a contribution.
In broad terms, agro-meteorological studies may involve two major
approaches which have too often been alternative rather than complementary.
They are, firstly, the physical or meteorological approach, which calibrates
the environmental factors related to agriculture, and secondly the biological
or agricultural approach which examines the pattern and trend of biological
and agricultural systems and assesses them in terms of the physical environ­
ment. The first estimates physical potentialities; the second determines
biological usage or agricultural adaptation. A comparison of the two affords
a comparative measure of the intensity or efficiency with which inherent
resources of a given site are being appropriated, and whether in fact the