Книга - Grass and Grassland

Grass and Grassland
Ian Moore


The use of natural and seeded grass pastures for the feeding of livestock and other unfamiliar uses for the ubiquitous grass family are described in this succinct and beautifully illustrated work.The New Naturalist series has already covered many facets of the interrelationship between man and nature, but the grass family is probably the most important man in the whole plant kingdom - just how important is shown in this book. Dr. Moore, the Principal of Seale Hayne Agricultural College in Devon, is our leading authority on grasses and their utilization. His special interest is the use of natural and seeded grass pastures for the feeding of livestock. Striking advances have been made in recent years in the improvement of such pastures and Dr. Moore deals very fully with this vital link in the feeding of the human race; but he also covers that other equally important role of the grass family in our economy, the cultivation of cereal crops for the production of grain. Grass lawns and playing fields form a centre-piece in most British gardens and public parks and there is a chapter on these, but the horticultural value of grasses as ornamental plants in herbaceous borders and woodland gardens is less well known.These and many other unfamiliar uses for the ubiquitous grass family are described in this succinct work.








Collins New Naturalist Library48




Grass And Grasslands


by




Ian Moore














Editors (#ulink_ccc7ef2b-6d54-5f51-86d7-ae2c3a42578c)







James Fisher, M.A.

John Gilmour, M.A., V.M.H.

Sir Julian Huxley, M.A., D.SC., F.R.S.

Sir L. Dudley Stamp, C.B.E., D.LITT., D.SC.



PHOTOGRAPHIC EDITOR

Eric Hosking, F.R.P.S.



The aim of this series is to interest the general reader in the wild life of Britain by recapturing the inquiring spirit of the old naturalists. The Editors believe that the natural pride of the British public in the native fauna and flora, to which must be added concern for their conservation, is best fostered by maintaining a high standard of accuracy combined with clarity of exposition in presenting the results of modern scientific research




Table of Contents


Cover Page (#u270715e3-caab-577a-bad6-958272ee002b)

Title Page (#u5b1fa604-8e86-533b-a964-8df2dedaae92)

Editors (#ud94dce44-8171-588b-87f9-d2403fea48d1)

Editors’ Preface (#u2065440c-a949-52f4-8581-1d6f532404e4)

Author’s Preface (#ubc1090d6-ff3b-5126-acb4-59c8cea1c5c3)

CHAPTER 1 (#ud7867e34-32e1-59d6-8029-36b792bf96a6) THE ROLE OF GRASS IN NATIONAL LIFE

CHAPTER 2 (#u3c3d524a-5a34-58eb-a7aa-56ebd504aff6) THE ORIGIN AND DEVELOPMENT OF GRASSLAND

CHAPTER 3 (#u81af7ccb-2640-5272-ac03-f7af507a0b43) THE GRASS PLANT AND ITS VALUE TO MAN

CHAPTER 4 (#uffb2ce00-90a3-50e8-9dba-210413c9dcfd) TYPES OF BRITISH GRASSLAND

CHAPTER 5 (#litres_trial_promo) THE BREEDING OF GRASSES

CHAPTER 6 (#litres_trial_promo) THE CONSTITUENTS OF GRASSLAND

CHAPTER 7 (#litres_trial_promo) SEED PRODUCTION AND TESTING

CHAPTER 8 (#litres_trial_promo) WEEDS IN GRASSLANDS

CHAPTER 9 (#litres_trial_promo) PESTS AND DISEASES OF GRASSLAND

CHAPTER 10 (#litres_trial_promo) THE INFLUENCE OF THE ANIMAL

CHAPTER 11 (#litres_trial_promo) THE INFLUENCE OF MAN

CHAPTER 12 (#litres_trial_promo) TOOLS AND THE GRASSLAND FARMER

CHAPTER 13 (#litres_trial_promo) THE CONSERVATION OF GRASS

CHAPTER 14 (#litres_trial_promo) ANIMAL HEALTH ON GRASSLAND

CHAPTER 15 (#litres_trial_promo) THE MEASUREMENT OF GRASSLAND OUTPUT

CHAPTER 16 (#litres_trial_promo) THE ECONOMICS OF GRASSLAND FARMING

CHAPTER 17 (#litres_trial_promo) OTHER IMPORTANT ECONOMIC GRASSES

CHAPTER 18 (#litres_trial_promo) LAWNS AND PLAYING FIELDS

CHAPTER 19 (#litres_trial_promo) SUMMING UP

Bibliography (#litres_trial_promo)

Index (#litres_trial_promo)

Plates (#litres_trial_promo)

Copyright (#litres_trial_promo)

About the Publisher (#litres_trial_promo)




EDITORS’ PREFACE (#ulink_5b7832de-4234-5dfc-ba19-012eafffff57)







The New Naturalist series has already covered many facets of the interrelationship between man and nature, and the Editors are glad to be able to add a further volume of this kind to the series. The grass family has a strong claim to be regarded as the most important to man in the whole plant kingdom, and we are fortunate to have persuaded Professor Ian Moore, the Principal of Seale Hayne Agricultural College in Devonshire, to draw on his unrivalled knowledge of grasses and their utilisation for the writing of the present volume. His special interest is the use of natural and seeded grass pastures for the feeding of livestock. Striking advances have been made in recent years in the improvement of such pastures and Professor Moore has naturally dealt very fully with this vital link in the feeding of the human race; but he also covers that other equally important role of the grass family in our economy, the cultivation of cereal crops for the production of grain. Grass lawns and playing fields form a centre-piece in most British gardens and public parks, and Professor Moore has a chapter on these, but the horticultural value of grasses as ornamental plants in herbaceous borders and woodland gardens is less well known. Professor Moore touches on these and many other unfamiliar uses for the ubiquitous grass family, but grass as fodder is his central theme and his chapters on the historical development of our pastures, their economic significance, and their improvement through the selection and breeding of new strains of wild species make a fascinating story.

Professor Moore does not give detailed descriptions of our 160 or so wild British grasses, as these are easily available in Dr. C. E. Hubbard’s excellent Penguin volume, but his keys to the commoner species will enable anyone with a minimum of botanical knowledge to identify these both in flower and from vegetative characters.

Grasses do not lend themselves to coloured illustrations, so we have confined ourselves to a frontispiece of Dürer’s superb study, and we hope readers will feel that the fine series of black-and-white photographs adequately represents the family and its contribution to the British landscape.

THE EDITORS




AUTHOR’S PREFACE (#ulink_0104e15f-4f9a-50a5-9294-a4d293305bad)







Our life is so inextricably interwoven with that of the grasses which grace our fields that the study of grassland is both fascinating and intriguing to all who possess an inquiring mind, be they born and bred in towns or sons of the soil. What is more, the management of the grass sward for farming, sport or pleasure offers a real challenge to skill, in the feeding of plants and the tending of them throughout their life, as well as to one’s understanding of technical developments in the realm of botany, chemistry, engineering and economics.

Where should we be without grass? Our life is so dependent on this humble, oft-neglected plant that we must appreciate its real significance in the nation’s economy. Without grass our country would lose its scenic beauty, so many sports their colourful background and in scores of ways our lives would be changed. The ordinary grass field one sees every day on any farm, the sports ground with which one is so familiar at school or college or in the wider arena of national games, the small patch of green which graces the front or back of so many English homes, is a complex community of plants each displaying likes and dislikes, and different reactions to varying treatment, yet supplying an essential need whether on the world or simply the individual scale.

For over thirty years my special interest has been grassland and when I was asked by the Editors of the New Naturalist Series to present the story of grassland for their readers, I accepted with alacrity.

In writing such a book one must draw from many sources of knowledge and from many writers of the past and I hope I have made due acknowledgements to the many who have contributed to our understanding of grassland. I am deeply indebted to my own colleagues in College for their ready help and guidance and particularly to Mr. K. C. Vear, Professor H. T. Williams and Mr. R.J. Halley. Not being a botanist, I have had much assistance from Mr. Vear, Head of the Biology Department and as I am not an economist, Professor Williams, formerly Head of Agricultural Economics and now of the University of Aberystwyth, has been of material assistance with Chapter 16; Mr. Halley has given me invaluable assistance with the more practical aspects of grassland husbandry, and Mr. R. W. Younger with Chapter 18. To Mr. D. J. Barnard I am very indebted for help with the proofs.

To the Editors I am grateful for their help in the preliminary stages of writing the book, while to Mr. John Gilmour I am especially indebted for his most valuable criticism and guidance at all stages of preparation. While I hope the book will have a wide appeal generally, I am particularly hopeful that the many schools throughout the country now using a school plot or a school farm or maybe a neighbour’s farm as a living medium for teaching, will find it of value. To the many students now attending the recently instituted day-release classes organised by County Education Authorities in agriculture, to those at Farm Institutes and to all students gaining practical experience prior to College or University courses I hope this book will serve as encouragement to a deeper appreciation of the value of the grass crop and an added incentive to further investigation and wider reading.




CHAPTER 1 (#ulink_0b3690a6-7d8a-5b71-8053-515c1981d2a9) THE ROLE OF GRASS IN NATIONAL LIFE







The significance of grass in the life of man was recognised in earliest times but the distractions of modern life in great cities and the speed with which man now passes through the countryside have caused him to underestimate its importance.

Wherever one travels throughout the British Isles grass is to be seen. Our temperate climate and high rainfall, especially in the western areas, favour the growth of grass which in some parts has a growing season of nine months a year, from March to November. Grassland farming, therefore, is our predominant type of farming, and the efficient production and utilisation of grass are obviously of the greatest economic significance to British agriculture. Agriculture is still Britain’s largest single industry and the annual turnover accounts for about 5 per cent of the gross national product thereby exceeding coal (3.2 per cent) and iron and steel (2.8 per cent) which are the next largest industries in gross output. In turn grass, which is our most important crop, makes the greatest single contribution to the farming income. This apart, grass is of prime importance for leisure hours, and our playing fields, which are so much a part of our national life, depend upon grass.

There is obviously a wide range in the types of grassland found in this country, according to the purpose for which they are used. These include bowling greens and cricket pitches with their velvet, close-knit turf, pastures which fatten cattle or carry large herds of milch cows, and moorland sheep walks. Nor must one forget the importance even of the small garden lawn. This may well be the pride of the owner, who mows it with great care each week-end in the summer months. Each type of turf requires specialised treatment and the potential productivity of the different types of farm grassland—permanent meadows, pastures and cultivable leys as well as the rolling hills and moorland which are classified as rough grazings—varies greatly.

Grass provides some two-thirds of the total requirements in terms of starch, and even more in terms of protein, of all the cattle, sheep, and horses in the country. This is shown vividly by the following figures for the area under crops and grass in the United Kingdom in 1961.

TABLE I. AREA UNDER CROPS AND GRASS IN THE UNITED KINGDOM




The astonishing fact is revealed that on 4th June, 1961, when these agricultural returns were made, some nine-tenths of our farmland was under grass of one sort or another, i.e. members of the family Gramineae.

Grass is not, in the great majority of cases, a natural clothing for the earth’s surface, provided by a beneficent nature. It is a community of widely differing species and varieties of plants living together in a constant struggle one with another and overshadowed always by the threat of being overwhelmed by weeds, rushes, bracken, heather, gorse, thorns, alder and other trees until, if man allows this process to go unchecked, scrub or even forest reigns supreme once more. Even the patch of lawn is subjected to the same forces and only by constant attention is a weed-free, close-knit, verdant green turf maintained.

During the lean times of farming in the 1920’s and 30’s, thousands of acres of farm land reverted to derelict grass and scrub, the farmers being forced to save labour, cut out expensive arable crops, and be satisfied with mere subsistence standards of life, since following the first world war the prices obtained for many farm products were less than the cost of production. Then too, in those days cheap imported cattle cakes and food were readily available, which could serve as a substitute for the grass normally fed to stock, not only during the winter months but even in summer. It was by no means uncommon for dairy herds in industrial areas, such as those in Lancashire and the West Riding of Yorkshire, for instance, to be fed wholly on imported feeding stuffs. In extreme cases the cows probably never left the byre, except perhaps to take exercise in a nearby field during the summer months. Under these conditions the productivity of the grassland was negligible and mineral deficiencies in the soil determined that the land was little more than exercise ground.

Grass is a crop requiring the same care and attention as wheat, potatoes, or sugar beet. It needs cultivating, fertilising, and utilising to best advantage and when it receives this treatment the returns per acre can be as high as from any other crop. Moreover, it has a valuable function in restoring fertility to the soil. In two world wars, by ploughing up a large proportion of our grassland and cropping with cereals, good crops were produced with the minimum of fertiliser, valuable shipping space was saved and a decisive contribution to victory was made.

Mention has been made of the fertility-restoring power of grass and one may rightly ask how this is brought about. The very serious problems of erosion which concern authorities in various parts of the world serve to highlight this vital question of soil conservation. Soil fertility is dependent upon good tilth, maximal water and air, and maximal plant nutrients. Tilth represents the physical condition of the soil in relation to plant growth and each crop has its own requirements for a seed bed. Ploughing, rotovating, cultivating, disc harrowing, and the use of rollers and spiked harrows disturb the soil so that it becomes granular in structure and suitable for the reception of small seeds, yet capable of resisting the shattering and erosive effects of heavy rain until such time as the crop itself provides a close canopy which protects the soil and prevents the fine particles from being washed away by flood waters.

The soil needs to have what is termed “structure.” The extremes are sand, which is devoid of structure, on the one hand, and clay, in which the particles are so small that pore space for air and water is virtually non-existent, on the other. Between these extremes lies a “crumb structure” with aggregated particles usually greater than 0.5 mm. in diameter and preferably from 1 to 55 mm. in diameter. When this crumb structure is attained the soil has the capacity to hold enough moisture for the needs of the crop and can resist both “drying-out” during periods of drought and the mechanical stresses of farm equip ment. Flora and fauna play their part in achieving this ideal through the medium of microbiological activity in the decomposition of organic matter and in fixing atmospheric nitrogen through the medium of leguminous plants. Grassland swards have a vital role to play in the maintenance of fertility since they contain legumes in most cases and when ploughed provide necessary organic matter.

Sandy soils have the advantage of free drainage, good aeration and ease of cultivation, as any gardener on a sandy soil will admit. But these are often too loose and too open in texture and lack the capacity to absorb and hold water and plant nutrients. They are termed “hungry” soils and the limitations of such soils are best overcome by grasses, the fine roots of which physically bind together the mineral particles. Farmyard manure, and green crops which are ploughed in—“green manuring”—perform the same function but a good deal less effectively and at considerably higher cost to the farmer or gardener. Moreover, a long ley or permanent grass sward gives complete coverage from storm water and thus prevents erosion.

Clay soils are very finely-textured and retain moisture to such an extent that a field may be unworkable for several months in the year. Clay is a colloid and therefore very cohesive and highly plastic. Thus when clay soils are cultivated in too wet a condition they become even stickier and are said in farming terms to “poach.” Poached land dries out into hard, intractable clods which defy all the efforts of man and machine to break them down to produce a seed bed. In this case granulation of the clay particles to form aggregates—“flocculation” to the chemist—must be brought about, and here again grasses and deep-rooting clovers have a vital role to perform. Farmyard manure, though more effective with clay than with sandy soils, does not increase soil permeability to the same extent as do the fibrous roots of grasses.

I hope I have stressed adequately this unseen function of our grassland. Most people understand the milk or meat-producing relationship between our grassland and the needs of man. Very few appreciate how essential the grass plant is to the whole cropping system of the country.

Grass provides the cheapest way of feeding herbivorous animals during its growing season, while grass conserved as silage or hay, or dried by artificial means, can be used for feeding during the winter months. The following table compares the cost of each food unit (“starch equivalent”) from various forms of grass with other succulent foods and clearly underlines the vital necessity of having an adequate supply of fresh grass for feeding.

TABLE 2. COST OF STARCH EQUIVALENTS




Recent research work both in the United States and on farms in this country points to the fact that it may be cheaper and more efficient to mow the grass during the summer months and cart it to the cows, which remain in covered yards—a practice known as “zero grazing,” “green soiling” or “mechanical grazing”—rather than to allow the cattle to graze. We shall deal with this question later on.

What are the products of grass? It contributes some 67 per cent of the total feed requirements of all our livestock and since pigs only account for about 3 per cent and poultry 6 per cent, it means that grass provides on the average at least 70 per cent of the diet of cattle and sheep and the few goats. Home-produced veal, beef, mutton, and lamb, our leather and wool, our milk, butter, and cheese, are largely the final product of grass. Few realise the magnitude of these products and their importance to the economy of the country. The table below gives some idea:

TABLE 3. THE GROSS OUTPUT FROM ANIMALS MAINLY DEPENDENT UPON GRASS—UNITED KINGDOM 1961–2




If grass contributes 70 per cent of the total feed requirements of the above stock groups, £492,300,000 of production can be attributed to grassland. This figure represents 31 per cent of the £1,592,000,000 output from national agriculture in 1961–2.

We are all eaters and users of grass. Numbered within the great grass family Gramineae are the cereals—wheat, barley, oats, rye, maize, rice, millet, and sorghum—which provide many of our staple foods. Most of the world’s really fertile grassland areas grow cereals so well when ploughed that they are known as “bread baskets.” In this category fall the wide prairies of the United States and Canada, the vast grain belts of the Ukraine and Australia, and the pampas of Argentina. Cane sugar is derived from a grass (Saccharum officinale). Those giants amongst the grasses, the bamboos, include majestic trees towering to a height of a hundred and twenty feet and some three feet in circumference, forming impenetrable forests as well as providing a variety of useful articles from musical pipes to furniture and domestic utensils. Some grasses are necessary to bind sand and combat the encroaching sea which at certain points along our coastline is ever striving to engulf more and more land. Other grasses provide fragrant oils and perfumes. Lemon grass or Indian grass (Cymbopogon citratus), which grows wild in India, is also cultivated both there and in Ceylon and is used for infusing a tea which is reputed to have medicinal properties. Andropogon nardus is cultivated in Ceylon and Singapore for the production of citronella oil which is used extensively in the manufacture of soaps and perfumes as well as for the treatment of rheumatism in India. Finally, still other grasses provide the turf we use for sport and recreation.




CHAPTER 2 (#ulink_9923fa75-7046-5e17-a8a7-71b1ce4a0a64) THE ORIGIN AND DEVELOPMENT OF GRASSLAND







For many generations the term “grasses” as used by farmers had an all-embracing significance and included companion plants like clovers, yarrow, dandelion, ribgrass, and so on, the blending of which made up the turf or sward of a pasture or a meadow which was eaten by horses, sheep and cattle. The term “pasture” usually refers to grassland grazed by animals, while “meadows” are mown for hay. These terms are often used loosely and frequently synonymously, for grassland may be grazed and mown in the same year. Moreover, grazing land is commonly referred to as “meadow” when it borders a stream or river, and in all probability in days gone by it was our poets who contributed to this confusion of terminology. Only in recent years have farmers consciously distinguished between the various plant species composing a particular type of grassland and realised the significance of the grazing animal or the mowing machine in determining the botanical composition of a particular sward or piece of turf. The groundsman, unlike the farmer, abhors all plants other than the special grasses required to produce a hard-wearing turf. Thus the clovers and other miscellaneous plants commonly seen in farm swards and indeed encouraged to flourish there, are eliminated as speedily as possible by both mechanical and chemical agencies when found in the domestic lawn, the cricket field or the golf green.

The history of our grasses from the Ice Age can be traced through the pollen grains which have remained preserved for thousands of years in peat bogs. The pollen of many plants, including the bulk of our forest trees, is liberated in vast showers of golden dust, and is wind-borne for considerable distances. Even the centres of large cities receive their quota as the sufferers from hay fever know to their cost. Each pollen grain is protected by a thin skin which is highly resistant to decay; consequently when down the ages millions upon millions of these grains have settled on the land and been covered by further deposits they have not disintegrated. It is possible in the laboratory to separate the pollen grains from soil particles obtained by the simple process of boring into ancient lake beds and peat bogs. These can be identified and in this way precise records of the local vegetation can be secured from the glacial period onwards. Such information can then be cross-checked with any geological and archaeological data available enabling a complete picture to be built up.

With the improvement in climate after the final retreat of the ice, the country was covered with vast woods of pine and birch, the only grassland being in parts of the forest cleared by early man. Then elm, oak, and hazel scrub gradually became established as conditions improved.

What of the livestock whose development is intimately interwoven with that of the grasses? Animals clearly related to our present-day grazing animals appear in the fossil records early in the Eocene period, some seventy million years ago. Judging by the structure and arrangement of their teeth, these early ungulates were, however, mainly browsing animals, feeding by cropping the leaves of forest trees. This seems to have been true throughout the Eocene and the succeeding Oligocene period, but at the opening of the Miocene, some forty million years later, there appears to have been a decrease in rainfall and a consequent diminution of forest cover, leaving grasses and other low-growing plants in possession of the plains, both in the Old and the New World. True grazing animals, closely related to modern types, then developed. Antelopes and sheep are recognisable from the Upper Miocene, and oxen, goats, and horses from the following Pliocene period.

The pastures which supplied the needs of the stock of primitive man were as can be imagined but a pale shadow of the excellent swards of to-day. It is unlikely that they did more than keep mature cattle alive, although for a short period during the summer months the best milk cows might have produced a few pints of milk per day, compared to the four, five or six gallons expected now. Nor was the farmer of those times conversant with the needs of the soil, and the constant leaching of nutrients by rain water and the removal of minerals by the stock themselves in the herbage consumed meant that phosphate, lime and potash deficiencies were common. As the fertility of the cultivated ground fell to the point where the yield of grain no longer rewarded the efforts of cultivation, this ground was abandoned. The former arable was then allowed to revert to some form of grass again. Such conditions favour the growth of mat grass (Nardus stricta), purple moor grass (Molinia caerulea) sheep’s fescue (Festuca ovina), bent (Agrostis spp.), bromes (Bromus spp.) and the oat grasses (Arrhena-therum, Trisetum and Helictotrichon), grasses of poor feeding value. These are in marked contrast to the broad-leaved succulent grasses of high feeding value which comprise a good pasture. Farm stock in those early times was small and stunted as shown by the skeletons which have been found and this was only to be expected under such conditions.

The conversion from forest to pasture can be seen in minature on the broad verge of many a farm road crossing or common. Nearest the road, the constant trampling back and forth of cattle, sheep, and horses promotes the growth of the best pasture grasses, such as the ryegrasses (Lolium spp.) and the meadow grasses (Poa spp.) with wild white clover (Trifolium repens) and probably bird’s foot trefoil (Lotus corniculatus). As the trampling and grazing become less intensive further from the road-side so the bents (Agrostis spp.) the fescues (Festuca spp.) and Yorkshire fog (Holcus lanatus) become more dominant and these in turn are replaced by coarser grasses, the tall fescues, tussock grass (Deschampsia caespitosa) and oat grasses until bramble, hazel, blackthorn, wild rose, and hawthorn dominate the scene. It is then only a short step to true forest. This gradual progression from good grass to forest follows any change which results in less intensive grazing or neglect. Should a field be ranched, allowing only a few head of stock on a large acreage of grassland, as opposed to close grazing where many stock are concentrated in a field, or more especially if grassland is allowed to become derelict, young saplings of forest trees spring up and the once valuable turf soon becomes colonised by coarse grasses and scrubby growths reverting back in time to the original forest from which the pasture had been won by the efforts of man.

Not until about 50 B.C. was the liming and marling of fields practised by the Belgae as a means of replenishing the fertility of the soil, and it was very much later that the droppings of animals were collected to be spread as farmyard manure. We owe much to the Belgae; with the eight-ox plough which they introduced, cultivation on a much bigger scale became possible and, moreover, they affected considerable forest clearance with their implements. So successful were their efforts, indeed, that corn and cattle were exported to the Continent, and when Caesar invaded Britain he was able to supply the food needs of his troops from the soil of Kent.

The Romans did little for the grassland of Britain, but after they had withdrawn, the Anglo-Saxon invaders, with great vigour, began clearing more forest land and converting lowland soils into meadows and cornfields. Many more were enclosed for better cropping and compact villages were created. These were usually surrounded by large open fields in which each settler had a number of scattered strips, some for cultivation and others to be mown for hay, the underlying principle being to divide up as evenly as possible the different types of soil with their varying levels of fertility. After harvest the arable and the meadow land were opened for common grazing, the stock feeding on the straw which was left on the arable ground, together with any growth of grass which had been made since the hay was carted. The Anglo-Saxons were really the first farmers to appreciate the need for adequate pasture during the grazing season and the necessity of safeguarding their stock in winter time with a good supply of hay. By so doing, the former practice of slaughtering in the autumn all the stock which could not fend for itself during the winter was avoided. Each occupier of thirty acres was given at the beginning of his tenancy a cow, two oxen, and six sheep by the lord of the manor and there were no farmers who merely rented the land as they do now. It was possible to increase the acreage of pasture by paying money rent to the lord or by rendering services in the form of additional ploughing. The Anglo-Saxon period was fruitful for Britain, and central and eastern England was dotted with villages which were later recorded in Domesday Book. It was a period of winning from the forest, of settlement, and of organised farming.

Domesday Book includes a remarkably comprehensive survey of the land initiated by King William to ensure accurate assessment and punctual payment of tax. The prosperity of each manor depended upon the amount of land which could be ploughed; in essence, upon the strength of its oxen. Plough-teams were in their turn dependent upon an adequate supply of meadow hay for the winter and so large fertile meadows were the key to the farming economy of those days. This is seen in the relative value per acre of meadow land compared with arable, the former often being worth four times as much as the latter. The value of enclosed pasture was usually less than that of meadow land, while the common pasture land in many instances surrounded the village and gradually merged into scrub and woodland which served as a line of demarcation between neighbouring villages. The scarcity of good pasture is a constant theme of all manorial documents of the period.

Reclamation was continued until around A.D. 1500. The twelfth and thirteenth centuries were the period of greatest colonising activity in England, but this colonisation drive was largely over by about A.D. 1300. Pressure of population seems to have kept peasant demand for land at a high level up to the Black Death in A.D. 1349 although there was considerable contraction of the arable, and hence an increase in grassland, on many estates before A.D. 1300 or very soon afterwards. The Black Death resulted in the death of large numbers of labourers and hence wages rose and the landlords were unable to get their fields cultivated and in spite of legislative measures to resolve the problem a good deal of land simply reverted to grass. This contraction of the arable acreage continued through the late fourteenth century and the first half of the fifteenth. With the break-up of the manorial system a gradual consolidation of holdings took place mainly by exchange. Then too, the trend from a two field system of farming—one field under crop while one lay fallow—towards a three-course system of two fields under crop and one fallow became evident. Ultimately this system gave way to the four course system whereby grass appeared in the open fields which had hitherto been exclusively arable.

The Tudor period was marked by a spate of writings from farmers and historians, and such names as Fitzherbert, Tusser, Leland, Camden and Morden are an essential part of agricultural history. From them a clear picture of the husbandry of the time is obtained and it is quite evident that farmers were becoming very concerned about grass. The meadows of Leicestershire, Northamptonshire, Devon and Somerset brought forth ecstatic praise and it is significant that by A.D. 1600 graziers were obviously men of substance, and wealthy classes of butchers and tanners were arising. The records of the period abound in such cases as the Earl of Derby, whose household in 1590 consumed 56 oxen and 535 sheep, while that of Sir William Fairfax in Yorkshire consumed 49 oxen and 150 sheep, and the household of the Bishop of Aberdeen consumed 48 oxen, 160 sheep, and 17 pigs. Fresh meat in winter was for the wealthy only, for the problem of feeding cattle and sheep on a large scale during the winter months still remained to be solved; the poor, when they had meat in winter, had to make do with salted. England lagged behind the times on this problem, for the value of turnips for cattle during the winter months was already appreciated in the Low Countries.

Wheat as an economic crop offers many attractions to farmers with suitable land and many of the enclosed pastures which had carried cattle and sheep for many years and had as a result increased appreciably in fertility were ploughed, and good yields were obtained which were markedly better than the medieval yield from the open fields, which was recorded as being a meagre 10 bushels per acre. A statute of 1597 had given official recognition to the fact that worn-out arable land regained its fertility when it was laid down to pasture and devoted to grazing stock for a number of years.

We do not know exactly when grass and clover became regarded as a crop and part of a recognised rotation. Richard Weston, a refugee from the Civil War, brought back from Holland a bag of red clover seed when he returned to England. The Spaniards had initiated the Dutch into the growing of red clover (Trifolium pratense) a century before and it was usually sown as a pure crop in the arable rotation. In 1653, Andrew Tarranton wrote The Great Improvement of Lands by Clover and, following much of the advice of Weston and Blyth, gave practical demonstrations of its value for stock feed, either when grazed or made into hay. He also managed to convey something of the fertility-restoring powers of clover and the immense increase in the stock-carrying capacity of clover pastures compared with ordinary grass. He instanced the need for careful control of the grazing to avoid the distressing trouble of “bloat” or “hoven” in which affected animals became “blown up” due to an accumulation of gas in the stomach resulting from failure of the mechanism which normally enables relief to be secured by belching. The trouble usually occurs when animals are suddenly introduced to young rich herbage and unfortunately it may prove fatal within an hour or so. (It is interesting to record that some three hundred years later we have not yet found a wholly reliable remedy.) Finally, he encouraged other farmers to visit him and see his ideas put into practice, and to-day we are broadly speaking still following the technique which he practised.

Progress was slow and more than a hundred years elapsed before the first stages in ley farming were generally adopted. The Society for the Encouragement of the Arts, Manufactures and Commerce did much to encourage land improvement and indeed in 1763 imported the seed of cocksfoot (Dactylis glomerata) from Virginia and also offered awards for the best herbage seed crops grown in this country. Benjamin Stillingfleet, in his Calendar of Flora 1762, invented English (as opposed to Latin) names for such species as had not already acquired them. Unfortunately, he included sweet vernal (Anthoxanthum odoratum) and other useless grasses amongst those recommended as valuable for agricultural purposes. This error was still unnoted 150 years later when excellent samples of this weed were offered for sale as a useful “bottom grass” by the agricultural merchants of the day.

The saving of good seed each year has been stressed by agricultural writers from earliest times. In the eighteenth century Coke of Norfolk and the Duke of Bedford employed children to go into the fields and hedgerows and collect the seed heads of different grasses when they were ripe, in order to have available a store of seed for sowing the following year.

During the latter half of the eighteenth century, agricultural progress was rapid. Tillage methods underwent revolutionary changes, substantial sums of money were invested in farm implements and machinery, in drainage and buildings, and every effort was made to improve both crops and livestock. Agricultural Societies were established all over the country and many of these are still in existence.

After the Napoleonic wars agriculture went into decline. The Board of Agriculture was dissolved in 1822.

When the virgin and fertile lands of the New World came into full production, causing a fall in world grain prices, the British farmer had to face a very real challenge. United Kingdom agriculture turned to dairy farming and animal husbandry generally. A good deal of land was allowed to revert to grass, buildings were not maintained, drainage was neglected, and sheep and cattle as alternative sources of income took the place of corn. By 1874, a vast acreage of arable land had been sown down to grass, no less than 1,688,487 acres between 1877 and 1884. Agriculturists were greatly concerned with the sowing down of land to permanent pasture and so we have J. Caird in his English Agriculture (1850) and M. H. Sutton (Laying Down Land to Permanent Pasture, 1861), J. Howard (Laying Down Land to Grass, 1880), C. de L. Faunce-De Laune (On Laying Land to Permanent Grass, 1882) and William Carruthers (On Laying Land to Permanent Grass, 1883) all in the Journal of the Royal Agricultural Society, devoting much attention to the problem but indicating at the same time that the tide would turn, that permanent grassland would again be ploughed for cropping and that the crops would be the better if good grassland had been established. The whole matter was summarised very effectively in Robert H. Elliott’s book The Clifton Park System of Farming (1898).

In 1889 the Board of Agriculture was re-established, and in 1896, the classical experiments at Cockle Park, Northumberland, were initiated to demonstrate the value of basic slag as a source of phosphoric acid for the grass sward. Basic slag, superphosphate, and combinations of lime, slag, potash and nitrate of soda were under trial, the merit of the fertiliser being assessed by the liveweight increase of sheep which grazed the plots, or by the weight of hay. The outstanding treatment was an application of 10 cwt. per acre of basic slag as a first dressing, followed by 5 cwt. per acre every third year afterwards and this treatment was adopted by large numbers of farmers throughout the country. The effect of the slag was to so encourage the growth of wild white clover that the stock-carrying capacity of the grassland was increased threefold. Even to-day, it is quite common to find farmers using slag in these amounts.

By now attention was being given to the value of native strains of grasses in addition to wild white clover, and work at the North of Scotland College of Agriculture, and by Professor A. N. McAlpine at Glasgow, had indicated something of the potential of grass output when the right types of grasses were linked to wise fertilising. In 1919, Lord Milford, by a generous gift to the University College of Wales at Aberystwyth, brought into being the Welsh Plant Breeding Station which, under its director Professor R. G. Stapledon, was to make a far-reaching contribution to the realm of grassland husbandry in the production of leafy, indigenous strains of the principal grasses. Their names to-day carry the prefix “S” and are known throughout the world.

Other land-marks in the history of grassland in this country are the establishment of Jealott’s Hill Research Station in Berkshire by Imperial Chemical Industries in 1936, the formation of the British Grassland Society in 1945, and the opening of the Grassland Research Institute at Hurley in Berkshire in 1949, the first station to be devoted solely to fundamental research problems in the sphere of grassland husbandry.

Spectacular progress has been made in British agriculture during the past quarter-century. It has become much more productive, has reached a high level of technical efficiency and is probably the most highly mechanised in the world. The acute dangers of two world wars and their aftermath have indicated the vital national need to reduce the dependence of a very large industrial population upon imported food supplies.

The need for maximum self-sufficiency in terms of home-grown feeding-stuffs has placed greater and greater emphasis on the production of more and better grass and upon its more efficient utilisation by grazing and conservation. A greater cattle population has thus been maintained at a higher level of output of both milk and beef, and there has been a marked revival in the sheep industry.




CHAPTER 3 (#ulink_13de4614-1cf9-50d2-b0c5-5dcae21d4a93) THE GRASS PLANT AND ITS VALUE TO MAN







In this chapter I shall begin with a brief description of the various parts of a grass plant, emphasising the features that are of importance to agriculture. A fuller and more detailed account may be found in Dr. Hubbard’s excellent Penguin volume Grasses (1954).

To the non-botanist all grasses look very much like one another at first sight. On closer inspection, however, differences in habit and form of growth and particularly of inflorescence are very apparent. There are grasses which are Lilliputian in size, contrasting violently with the largest members of the family, the bamboos, bearing great masses of blooms on spikes or panicles a foot or more long. Grasses, too, display an immense capacity for adapting themselves to their environment, some making their home in water or along the banks of streams and rivers, while others survive the scorching heat of the desert and or the intense cold of the polar regions. Some grasses are annual and complete their life cycle in one year, such as the very common annual meadow grass (Poa annua). Others like the soft brome grass (Bromus mollis) are biennial, the seed germinating in late summer or autumn and the plant flowering and seeding the following year. Finally, there are vast numbers of perennials, like perennial ryegrass (Lolium perenne) and couch grass (Agropyron repens), which are potentially immortal, producing new shoots or new lengths of rhizomes for ever if conditions allow. A bamboo may survive for thirty or forty years or even longer. Unlike the annuals and biennials, which bear flower-heads on all or most of the shoots, in the perennials the flowering shoots are accompanied by vegetative shoots, the number of which depends upon the duration of the grass.

These vegetative and flowering shoots are not different in origin. Both shoots start off as a vegetative structure—a very short-jointed stem bearing two ranks of leaves, one leaf at each of its closely-spaced joints or nodes and arranged alternately along the stem, which is constantly producing new leaves at its tip; thus there is a continuous sequence of growth. As each leaf reaches full size the older ones die away, to be replaced by fresh leaves. Meanwhile the stem remains extremely short, but branching often takes place. Buds in the axils of the leaves grow out to form a new short-stemmed leafy shoot, and these in turn produce further shoots in the axils of their leaves, so that a dense tuft is quickly built up. This process of increase in the number of shoots, without any marked lengthening of the stem, is particularly noticeable in young cereal plants during the first few months of growth, and has been given the special name of “tillering,” each shoot being referred to as a “tiller.” Obviously tillering capacity in the cereals means that less seed per acre needs to be sown than would be the case were only a single shoot formed from each seed. If each tiller produced an ear to be harvested flowering would be spread over a long period, hence ripening would be very uneven and farming operations complicated; but the normal wheat-field is sown thickly so that only one or two of the earliest-formed tillers on each plant are able to flower, which ensures that all the ears of grain are ready for cutting at the same time. Pastures, on the other hand, produce more stock food since the grasses cover the ground more rapidly to form a sward or turf, and recover from mechanical damage comparatively quickly because of this characteristic.

A turf of vegetative shoots may be a foot or more in height, but it consists almost entirely of leaf. The stems are still extremely short and completely hidden, so that in a typically tufted grass at this stage of growth all the stems and buds are within about half an inch of the ground. It is only in exceptionally tall-growing grasses, such as the bamboos, that long, upright vegetative stems are produced at an early stage. In the case of creeping grasses there may be some elongated stems but these are horizontally directed and spread along or through the ground as stolons or rhizomes. By way of contrast, the lower internodes of some grasses may become swollen with plant food, and these grasses are known as “bulbous.”

This characteristic of the grasses—the growth-buds remaining close to the ground—determines their value as food for grazing animals. If an upright-growing plant, like kale or a young tree seedling, is grazed off to within an inch or two of the ground it will have lost the greater part of its stem, together with its apical bud and most of its axillary buds. It may recover by the development of new shoots from the base of the stem, but it is unlikely to survive many such grazings. In marked contrast to this a vegetative grass plant grazed

in this way suffers very much less damage. It is clear that unless the grazing is exceptionally close as a result of many animal mouths to the acre or continuous stocking, only the leaves will be removed and all the stems and buds will be left intact and able to continue their growth with comparatively little check. Grasses can therefore withstand repeated grazing and treading by stock. In the face of such grazing, grasses obviously have a great advantage over other taller-growing plants; indeed, except where drought or extreme exposure prevents the growth of taller plants, grassland exists mainly because of grazing. If there were no grazing animals there would be, in a climate like that of Britain, very little grassland, only scrub and forest.






Grass shoots do not, however, remain indefinitely in this vegetative stage; eventually they change to the flowering condition. When this occurs the stem apex ceases to produce new leaves and instead forms a rudimentary inflorescence. Once this change has taken place in a shoot, it produces no more new leaves and no more axillary shoots or tillers; the inflorescence develops, the stem elongates to bring it up above the level of the leaves, the flowers are pollinated, the fruit ripens and is shed, and the whole shoot dies. Growth of the plant is then continued by other tillers which are still in the vegetative state. The change from the vegetative stage to the flowering stage is usually a response to length of day; most British grasses are “long day plants” and so these changes take place in them as the days lengthen from spring to early summer.

The tiller must, however, have reached a certain size before it can respond to the increasing hours of daylight and this size varies in different grasses. If a small tiller can respond, then all the tillers will reach the necessary size during the year, before the days become too short again. In this case therefore all tillers will flower and die. Thus there will be no vegetative tillers left to continue growth and the plant behaves as an annual. If, however, the tiller cannot respond until it has reached a larger size, it will not flower until the late summer (aftermath flowering) or it may not flower that year. If, as is true of some grasses, a period of low temperature is necessary before response can take place, flowering will be delayed until the following spring. Meantime, the tiller, while still in the vegetative condition, will have produced further tillers so that the plant behaves as a long-lived perennial. Such plants produce some flowering shoots each year but always remain sufficiently vegetative to ensure continued growth.

With few exceptions grasses have fibrous roots—in some species they are tough and cord-like—which arise adventitiously from the lowermost node or nodes of the stem. This capacity of grasses to produce numerous fibrous roots is of prime importance for it means that grasses, unlike plants with a main tap root, have great powers of recovery after injury. When the main tap root of such a plant is injured the plant probably dies; root injuries to grasses on the other hand may even stimulate new growth. Thus severe harrowing of an old pasture with heavy spiked harrows, which cut into the turf, tears out much of the matted growth, increases aeration, and brings about rejuvenation, with the result that the pasture “freshens up” with new growth. Similarly the groundsman, using “pruning” machines on the sports turf or lawn, encourages new, strong root and leaf development.

The roots of different species vary in length and are equipped with a very great number of root hairs. In some cases, like couch grass, underground, scaly, whitish or brownish creeping stems or rhizomes are formed and both roots and scale leaves are produced from the nodes of these rhizomes. In other cases, like creeping bent (Agrostis stolonifera) and rough-stalked meadow-grass (Poa trivialis), thin, greenish or purplish, surface-creeping stems or stolons, like strawberry runners, are formed from the nodes, from which fibrous roots and green leaves are produced. Thus rhizomes and stolons are really modified stems, and grasses with such rooting, mat-forming systems cover the ground very rapidly in consequence. Such a characteristic is not always desirable and in some cases it presents serious problems. Any bud-bearing portion of a rhizome which is broken off from the root system can start a new and independent plant. Thus couch grass which can be a very serious weed on some types of arable land, becomes a menace by the very speed with which it reproduces itself. The small pieces of rhizome broken and dispersed in the course of cultivation give rise to new colonies of plants and it is not unknown for the growth of couch to be so great that the intended crop is smothered. Moreover, the diversion of food materials to the formation of such non-photosynthetic and inedible structures as stolons and rhizomes has the effect of reducing the maximum yield, and such grasses as bent and couch are, therefore, most unproductive. The highest yielding agricultural grasses, such as the ryegrasses, cocksfoot and timothy, are tufted, non-creeping species.

The flowering stems (“culms”) of the grasses are usually cylindrical and hollow except at the nodes or joints, where the stem is firm and solid and from where the leaves emanate. Culms vary not only in size, rigidity and number of nodes but may grow erect, prostrate or arise from a curved or prostrate base. The stems are usually smooth and highly polished. The leaves are parallel-veined and arranged in two rows alternating one with another on the stem. Each leaf is composed of a lower portion known as the “sheath” which may form a cylindrical tube enclosing the stem, or may be split, with the margins overlapping one another. Near the ground, the sheath may be coloured red, purple or brown which is constant for each species and constitutes an aid to identification. In some species, only the veins are coloured. The upper portion of each leaf is called the “blade”; this may be flat, rolled up and bristle-like, or folded about the mid-rib with the upper surface inwards, while the blades may be erect, drooping, or at right angles to the sheath. The blade, usually long and narrow with parallel sides or tapering to a pointed or blunt tip, often widens out at its base to form either a ledge or ear-like projections or teeth called “auricles,” which clasp the stem. Where the blade joins the sheath there is usually a membranous outgrowth, called the “ligule,” which may be pointed, blunt or ragged, long or short, or may be represented by a line of hairs. These characteristics afford still further means of identification. The leaves of some grasses are hairy, others free from hairs (glabrous); if present, the hairs may be most abundant on the sheath, on the upper or lower surfaces of the leaf blade or, in some instances, confined to the ribs or margins.

This key to the identification of the commoner pasture grasses by means of their vegetative characters has been compiled to enable the enthusiast when walking over a farm to distinguish the chief species making up the swards. It has been made as simple as possible and deals with only a few of the better known grasses. Readers who wish to identify a much wider range of species should consult Hubbard’s Grasses (1954).

KEY FOR IDENTIFICATION OF COMMON GRASSES WHEN NOT IN FLOWER




The inflorescence varies widely in the different genera and, if present, is the easiest means of identification. It is made up of a varying number of “partial” inflorescences called spikelets, each of which is composed of one or more flowers, each with two enveloping protective structures, the lemma and the palea. In most cases the grass flowers bear both stamens and pistil but in maize (Zea mays), for instance, the male flower is produced in the “tassel” and the female on the “cob” with its greatly thickened axis. Very rarely male and female flowers may be borne on different plants, as in buffalo grass (Buchloe dactyloides). The form of inflorescence is determined according to the way spikelets are arranged on the stem. The spikelets may be borne directly on the main axis to form a spike as in the ryegrass or couch grass; they may be borne on simple branches to give a raceme, as in false brome (Brachypodium spp.), or, as in the majority of grasses, borne on secondary, tertiary or even more sub-divided branches to give a panicle. The length and stoutness of the branches provide a wide variety of panicles between the extremes of an erect, close inflorescence, superficially resembling a spike, as in foxtail (Alopecurus spp.) or timothy, and one which is long and drooping, loose and spreading, like the bromes.

Flowering usually takes place from May to July, although in mild winters a number of species develop flower-heads in December or even January. Annual meadow grass, on the other hand, can generally be seen in bloom throughout the year. The first grass to flower in the spring is holy grass (Hierochloë odorata), which is in bloom about the end of March, but this species is very rare in the British Isles, and is confined to three Scottish counties and one Irish. Meadow foxtail (Alopecurus pratensis) and sweet vernal grass may flower in April, the ryegrasses in May, cocksfoot and the fescues in June, and timothy in July. Woodland and mountain species are somewhat later in flowering than species of the same genera growing in more open habitats or at lower altitudes. The early-flowering grasses are usually those in which only a comparatively short day is required for flower initiation; the later are those needing a longer day.

Since the actual flowers of grasses are very simple and show comparatively little variation, classification and identification have to depend largely on the structure and arrangement of the spikelets. Each true flower consists only of a single pistil with (usually) two styles, and (usually) three stamens, plus, in most grasses, a pair of minute scales which are known as “lodicules” and which have been regarded as representing very reduced sepals. Each flower is protected by two much larger structures, the inner, usually two-keeled, palea and the round, single-keeled, lemma. The lemma and palea fit closely together over the flower and are only separated for a short time when the lodicules swell up temporarily, pressing them apart, and allowing the styles and stamens to protrude and wind-pollination to take place.

Each true flower plus its lemma and palea is known as a “floret” and the spikelet consists of from one to about twenty florets. At its base there are two (occasionally one or none) protective structures, the glumes. Both the lemmas and the glumes may be furnished with bristles (awns), which are useful features for identification.

The following key will enable the more important species to be identified in the flowering stage.

KEY FOR IDENTIFICATION OF COMMON GRASSES WHEN IN FLOWER




Grasses show an amazing tolerance to external conditions. For instance sheep’s fescue, which grows down to sea level in this country, has also been recorded on the highest mountains in Britain and at nearly 18,000 ft. in the Himalayas. Then again, many grasses from low-lying habitats in temperate regions adapt themselves to high altitudes in tropical countries. Others survive wide differences of climate, the classic example of adaptability being perhaps sweet vernal grass, which flourishes from sea level to above the snow line, is equally at home on sand, loam or clay, and is found in many countries of the world with vastly different climates, ranging from North Africa to Siberia.

A number of other grasses are on the other hand very specialised in their habitats. Moor mat grass is usually associated with the margins of peat moors, not because it will not grow elsewhere, but because it grows better under such conditions than any other. A number of grasses can endure strong salt water, such as marram grass (Ammophila arenaria), the salt marsh grasses (Puccinellia spp.), and sea lyme grass (Elymus arenarius), and these are confined to our coasts. Marram and sea lyme are used for stabilising wind-blown sand, while the salt marsh grasses and rice grass (Spartina townsendii) are mudbinding plants of salt marshes.

Other grasses adapt themselves well to a high water content in the soil, and “water meadows,” where periodic and controlled flooding was carried out, were in use until quite recent times. To a limited extent this is still practised in Wiltshire and Dorset. The operative phrase is “controlled flooding” for good drainage of the soil is imperative for the growth of the best types of grasses useful to the farmer. Under waterlogged conditions the deficiency of an adequate air supply to the plant roots spells failure for the ryegrasses, cocksfoot, timothy, rough stalked meadow grass, and similar productive species. Under such conditions tussock grass (Deschampsia caespitosa), rushes (Juncus spp.) and sedges (Carex spp.), which are inedible for livestock, become dominant.

The true seed of grasses is not normally seen, since the fruit-coat is very thin and firmly attached to the single seed. This type of fruit is known as a caryopsis: a wheat grain is a good example. Most grass “seeds” consist of a single grain tightly enclosed within the lemma and palea; attached to the base is generally a small portion of the axis of the spikelet. In the case of Yorkshire fog, meadow foxtail, and a number of other grasses the “seed” is, however, an entire spikelet and consists of the two glumes, and the lemma, palea and grain of one or more flowers, while in the case of the brown “seed” of timothy and most wheats the grain is shed free from its lemma and palea. The bulk of timothy seed, however, is the silver grey “seed” composed of the caryopsis complete with lemma and palea. These examples illustrate how the grass “seed”—that part of the plant which is actually sown either naturally or in agricultural practice—differs from the true seed.

Grasses are distributed in the main by the wind, for the caryopses with their enclosing glumes are light and capable of being carried long distances. Some seeds are plumed, others possess tufts of hairs which doubtless increase their buoyancy. Gales and whirlwinds are likely to exert a great influence in conveying seeds from one place to another. In Lincolnshire, for instance, a whirlwind has been known to tear up a tuft of couch grass by the roots and carry it for over twenty miles, and it has been suggested that since gale force winds are common during the period July to September, when many grasses are seeding, they must be a very important means of dispersal and probably of greater influence than normal wind-drift.

One must not overlook the influence of water in carrying grass seeds long distances. Their buoyancy in the air is equalled in many cases by their facility in floating on water, while the upper peduncles act as sails to assist them in their passage across estuaries and round coasts. In addition too, it is not unknown for whole plants to be transported by the sea and it is recorded that the sugar cane on Cocos Keeling Island was derived from a clump from Java, seven hundred miles away. Bamboos have also been known to be moved from place to place. Drifting rhizomes in rivers and in the sea also bring about dispersal and in Europe, Puccinellia maritima, Elymus arenarius and Ammophila arenaria are known to be dispersed by these means. Tufts of annual meadow grass are often carried long distances by rivers and indeed, of all grasses this is perhaps the most determined to establish itself by some means or another. At Seale Hayne it is regularly removed from the roof gutters and spoutings thirty feet above ground level. It springs up between cobblestones and flags in the heart of our largest industrial cities and I have found it growing in birds’ nests in late autumn after the nests have been abandoned and are well soaked with rain. This is particularly the case in thrushes’ nests which are mud-lined. It has also been found 12,000 feet up in the Himalayas where it was concluded that man or his yak must have been the means of conveyance. The glumes of some grasses bear stiff reflexed spines which help the seeds to cling to clothing, to the wool or fur of animals, or to the feathers of birds. In the Belgian Congo termites store large quantities of a species of Cynodon in their nests and when these are abandoned the grass is established. I heard of a most interesting case when in New Zealand, where man quite unwittingly was the means of introducing red-top. Emigrants before leaving Nova Scotia filled their mattresses with hay which included red-top. They travelled to the Cape of Good Hope, thence to Australia, and finally settled in New Zealand where the mattresses were abandoned; the grass seeds germinated and thus an American grass became established in a strange country!

The farmer classifies a grass as useful or useless according to its particular value to him. There are over a hundred and fifty different species of British grasses but of these no more than twenty are of real agricultural value and indeed, on the majority of farms, considerably fewer are regarded as of consequence.

The value of grass to the farmer depends upon (a) productivity, or yield, (b) feeding value or chemical composition, (c) palatability, (d) persistency, (e) winter greenness and (f) earliness. To the groundsman, however, it is obvious that such factors as (a) slowness of growth, and (b) wearing capacity and ability to recover from harsh treatment, are of much more importance, while the landscape gardener must also look for very different qualities in grasses to form ornamental lawns or for foliage work in border and greenhouse. Quite naturally, in the case of both groundsman and gardener, the species used are often different from those used in agriculture, and in these pages I have concentrated on the latter.

The yield of herbage produced by any grass, which is the farmer’s first consideration in making a selection, depends upon its tillering capacity, the facility with which it recovers from cutting or grazing, and the duration of growth each season. An excellent illustration is obtained by comparing perennial ryegrass and bent grass. The former tillers freely and grows steadily from early spring until late in the autumn and indeed, in the mild wet south-west of England it grows all the year round. In contrast to this, bent grass grows for a short period only and yields comparatively little bulk, and in consequence is discarded by the farmer as being of no value. To him it is in fact a weed.

Then the ability of a grass to recover from cutting or grazing is also of great importance, defoliation being more favourable to the development of young tillers in some species than in others. Recent work has tended to stress the importance of the influence of intensity of defoliation on the yielding capacity of grasses. It appears that by leaving some growth—say one to two inches—when cutting or grazing a sward, more rapid recovery of growth follows, and hence more bulk or weight of grass over the whole season is obtained, than when animals are allowed to graze tightly to the ground or the mowing machine blades are set as closely as possible to the bare earth. The full answer is not yet known, for species vary in this respect and are also subject to seasonal variations.

While most grasses are palatable if eaten in the early stages of growth, quite a number develop harsh or hairy leaves, or even spines on the leaf margins, as they grow older, and hence are rejected by stock. A grass which may be highly valuable in all other respects can be rendered useless by this factor; Yorkshire fog and the coarser forms of tall fescue are typical examples. In practice it is not always possible to utilise a field at the ideal stage of growth, when the grass is most palatable to stock, and thus grasses which retain their palatability over a long period are particularly valuable. Yield and feeding value are complementary factors, the one without the other being useless to the farmer. In this connection the structure of the grass is important, for species with a high proportion of leaf to stem are much more valuable than stemmy ones, since the leaves are more palatable and contain more protein than the stalks. Grasses become coarse and stemmy with a corresponding reduction in feeding value as they reach the seeding stage. Plant breeders of recent years have endeavoured, therefore, to produce strains of grasses with a high proportion of leaf to stem and with a natural reluctance to produce flowering heads.

From the farming angle as well as the ornamental, a capacity to remain green during the winter months is important. This extends the grazing season and reduces the need for expensive artificial feeding of livestock. Certain varieties of meadow foxtail and red fescue, for instance, have been bred to produce leafage during February and March.

In the last thirty years a great deal of attention has been paid to variations of type within each grass species. Perennial ryegrass, for example, may be tufted, stemmy and short-lived or it may be leafy and persistent. Some types are very prostrate in growth whilst others are erect. Some are very palatable, others less so. The same comments are applicable to all the important species of commercial value such as cocksfoot, timothy, and meadow fescue, and these are classified into what are technically known as “cultivars” (but more familiarly as varieties or strains), and multiplication by division and seed of these strains is carried out on a large scale.

It is very evident there can be no simple answer to the question, “Which is the best grass?” Quite apart from the great variations which we have seen exist within the grasses themselves, the complexity of the problem is magnified by varying systems of management whether for grazing or conservation, by the use of different seeds mixtures, by fertiliser and herbicidal treatment, by disease and insect pest, and by the varying requirements of sheep and cattle. The whole fascinating study is unfolded in the following chapters.




CHAPTER 4 (#ulink_f1f89a5d-3a1e-50cd-b0b3-6e832840a61c) TYPES OF BRITISH GRASSLAND







Centuries of biotic influence have brought about the formation of our so-called natural types of grassland, for even the wild stretches of hill and moorland, which to most people epitomise natural grassland, owe their existence to the influence of countless generations of grazing animals, particularly sheep. Without man’s influence heather, bracken, and scrubby growth soon colonise the land to act as the forerunners of bush, pine and rowan until a dense forest growth occupies the countryside. Let us, therefore, be precise and speak of uncultivated and cultivated grassland. The former group includes moors, downs, wolds, heaths and fens, broadly termed rough grazings, while the latter includes the rich permanent pastures and meadows which are “cultivated” by regular mechanical treatment with harrows and rollers and receive periodic applications of the essential plant nutrients though the turf is left undisturbed. Included in this group is the ley or short duration grassland which is ploughed periodically. The subdivisions are clearly seen in table 4:

TABLE 4. SUBDIVISIONS OF GRASSLAND




The transition from ley to permanent pasture or meadows, thence to rough grazing and scrub, and finally to forest, is an orderly, gradual process, the different phases being clearly recognisable yet merging one with another. The great areas of rough grazings are known to all countrymen and townsmen alike and a brief outline of the different types of grassland in this group will give added interest to the countryside.

The soil of our moorland areas, including those of Scotland and the Lake District, the Pennines, the Yorkshire moors of the north-east, the Welsh mountains, and the moors of Cornwall, Devon and Somerset, is acid or “sour” and a marked lime shortage is invariably associated with a deficiency in phosphate and potash. Under such conditions our useful grasses and clovers cannot survive and the flora is very restricted and specialised, the degree of acidity, the rainfall and the drainage determining the specific type of herbage found in any particular stretch of moor. Free-draining land is often in close proximity to bog, but in the majority of cases the sterile condition of the soil has resulted in an accumulation of undecomposed vegetation, “mat,” near the surface and the grassland is said to be “matted.”

On the wetter soils the dominant species is often flying bent (Molinia), the long straws of which were once used by country people for making stiff carpet brushes. Should the peat be waterlogged then cotton grass, deer grass, heath or square-stemmed rush will be found in varying amounts. If the peat is well drained, as on hill sides and knolls, the soil still being very acid, then the dominant grass is matgrass, so named because it grows in dense matted tufts, the hard bristle-like wiry leaves being much too tough for cattle or sheep to eat. Often associated with matgrass will be sheep’s fescue, bilberry and heather. On really deep soil, which is fundamentally good land, bracken is frequently dominant, and when this land is cultivated it yields excellent crops of potatoes and oats. So runs the old adage, “Copper under Heather, Silver under Gorse, Gold under Bracken,” which proved so true in the wartime ploughing-up campaign of 1939–45. Heather land yielded poor crops, even with generous fertiliser treatment, for the soil was too hungry and lacked body, whereas surprisingly good crops followed the ploughing in of bracken. Gorse land gave results somewhere between the heather and the bracken.

Heather moor is primarily sheep country and normally carries about one ewe to four or five acres. Hardy cattle, such as the Galloway, may sometimes be seen in association with sheep on the best moors. The periodic burning of the heather prevents the development of scrub and encourages new growth and, in late winter especially, young heather shoots are valuable in providing adequate sustenance for the sheep. When the burning is too slow, i.e. the fire does not sweep rapidly over the heather and the roots are damaged in consequence, bilberry frequently replaces the heather which represents the next phase in the succession.

The most valuable of the moorland or hill pastures contain sheep’s fescue, red fescue and bent as the dominant species and although these grasses are at the bottom of the nutritional scale as we shall see, they have the advantage of demanding the minimum of attention from the farmer in order to keep a stable sward. Bracken is generally the most serious intruder but this can be kept in check with regular attention. On the moors of Cornwall and Devon rough uncultivated pastures contain Agrostis setacea





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