Grass mix diversity a century past

Innovative seed mixtures from the early 1900s based on functional properties of species. Legumes around 20% of seed mix by weight. Increasing complexity to suit purpose and longevity of the sward. De-diversification in the last 100 years. One of a series of articles on crop-grass diversification.

Diverse grass fields were once a common feature of the agricultural landscape. Mixtures of grass, legumes and other species were widely trialled and adopted in the Improvements era after 1700 [1]. Mixtures were promoted throughout the late 1800s and early 1900s, the topic of this article.

The aim of mixtures was to provide a balanced diet for livestock and to regenerate soil condition and fertility. Nitrogen-fixing legumes in mixtures had the specific roles of enriching soil with nitrogen, before mineral fertiliser came to be widely used from the mid-1900s, and offering livestock a high-protein bite compared to the grasses.

Most traditional meadows have now been converted to fertilised grass or crop. Much of the grass now grown for hay or pasture consists of one or two grass species, with occasionally white clover and often some noxious weeds. Legume forages are now uncommon. Managed grass is usually supported by mineral fertiliser and by imports of high-protein legume-based feed supplement.

Grassland. Shapinsay, 27 May 2019

Change may be afoot! Recent EU funding rounds have brought together researchers and specialists to design and trial new food and feed systems which aim to reverse some damaging trends both in the field and the wider food supply chain [2]. Part of the solution is a re-diversification of agriculture.

To explore some of the main current themes, the Living Field [3] and this web site are running a series of articles on diversification in land use and food production. Many of the forgotten practices of the past are still relevant. Here we look at the structure of diverse ‘grass’ mixtures recommended in the late 1800s and early 1900s.

Groups and species

Traditionally in Scotland, managed ‘grass’ (as distinct from rough grazing) was rarely just left as permanent, untended grazing land. It was either sown for hay or pasture over one, two or three years or left longer as ‘permanent’ grass, but even the latter was usually re-sown after a time to re-introduce species forced out by the more competitive grasses. Published in 1925, W M Findlay went into some detail on how grass mixtures were managed, but the specific interest is that he described mixtures in terms of the mass of seed of each component species [3].

 

Fig. 1 A seed mix made up of grass (blue-green) and legume (red): the inner circle showing all grass and all legumes; the outer circle showing two grass and two legume species.

The lists in Findlay are here presented as circular diagrams of the type illustrated in Fig. 1. The inner circle shows the percentage of seed from the grass family (blue – green) and the legume family (red). The outer circle shows the percentage seed of each species of grass or legume, individual species distinguished by different colours or shades.

In the example shown, the grass makes up about 80% and the legume 20%. There are two species of grass and two species of legume. This is a simple mixture but is still more diverse than many grass fields today.

Cattle on rolled hay field, Inverness-shire, 22 June 2019
Mixtures of increasing complexity

Four mixtures are shown in Fig. 2, the one top left is that from Fig. 1 but with species indicated. It is a mixture recommended for one year’s hay, after which it will be cultivated and turned to arable or transformed into another mix. The next three, moving clockwise, are mixtures of increasing complexity – top right is for two years’ grazing,  lower right for hay followed by grazing and the lower left for permanent grass.

The number of species increases in both grass and legume categories from top left clockwise. The permanent grass mix contains a third category – broadleaf or ‘dicot’ species that are not legumes (orange brown). Of the latter category, chicory and yarrow are included but not plantain which was commonly sown in ‘grass’ mixtures in the Improvements era.

Fig. 2 Four ‘grass’ seed mixes of increasing complexity from top left clockwise, intended for different purposes shown above each circle. Plant species and their proportions, based on sown seed mass, are indicated by different blue-green colours for grasses, red for legumes and orange-brown for broadleaf-but-not-legume plants. Original data in Findlay (1925)

In all categories, grass occupied about 80% (four fifths) of the mixture and legumes 20%, or a little less in permanent grass. The legumes include red clover (two forms), white clover (including a ‘wild’ version), alsike and kidney vetch. The permanent grass mix also has chicory and yarrow.

Findlay also gives an example (Fig. 3 here) of one of R H Elliot’s mixtures from his book Agricultural Changes (1898) which was later published as The Clifton Park System of Farming [5]. Notable in Elliot’s mix is the presence of legumes but also the much greater proportion of other broadleaf plants, most of which were included for specific functional properties [6]. Findlay does not agree wholeheartedly with Elliot’s recommendations, relating for example from his own trials that some of the broadleaf plants did not penetrate a hard soil pan, as Elliot suggested they would.

Fig. 3 Proportions of main groups and species in one of Elliot’s seed mixes [5] given in Findlay [4]: grasses, blue-green; legumes, red; other, orange yellow.

The proportion of seed in mixes was based on trials to assess how much seed of each was needed to cover an acre. Then seed mass was adjusted to suit the balance in the mixture, seed size and germinability and whether hay (flowering heads, less dense) or pasture (leaf, more dense) was the aim.

Were native plants used? Many of the grasses and legumes are native to Britain, but there was an international trade in seed then as now. Many varieties were imported for testing and usage. Over time, lays and pastures would have become a mix of native and imported populations.

The mixtures recommended by Findlay and those by Elliot are based on serious investigative studies that imply a sound knowledge of plants. They were devised at a time before mineral nitrogen fertiliser became cheaply available and among the primary aims of the mixtures was to increase the ‘health’ and fertility of soil as well as feed livestock.

Hay field recently cut & baled, Carse of Gowrie, 20 July 2019
The contribution of nitrogen fixing legumes

By the early 1800s, forage legumes had become standard in sown grass mixtures.  Writing well before Findlay and Elliot, H Stephens in The Book of the Farm [6], first published 1841,  gave weights of the grasses and legumes in mixtures designed for a range of purposes. (The author farmed in Angus for part of his life.) Stephens gives the seed weights for mixtures suited to various durations and conditions: he even includes all-legume mixes and his short-term lay contains about one-third legumes by seed weight.

In all these accounts, the main forage legumes were red clover Trifolium pratense in various forms and white clover T. repens. Others referred to by these authors, included in mixes for specified durations and soils, were alsike T. hybridum,  suckling clover T. minus and crimson clover T. incarnatum (the latter generally considered unsuitable for northern latitudes of Britain but will grow here) Other species were the medic or hop-trefoil Medicago lupulina, bird’s-foot trefoil Lotus corniculatus,  lucerne Medicago sativa and kidney vetch Anthyllis vulneraria.

These are by no means the only ones trialled in Scotland. There was clearly a thirst in the 1700s and 1800s to explore a wide range of species before settling on the clovers. In The Book of the Farm (1908 edition revised by MacDonald), they write about clovers:

” …. the most valuable herbage plants adapted to European agriculture – the white and red clovers. Notwithstanding what has been said of the superiority of lucerne, and of the excellence of sainfoin in forage and hay, the red clover for mowing and the white for pasturage, excel, and probably ever will, all other plants.”

Despite the uncertainty in how seed mass translated to plant mass, Findlay provides one of very few quantitative descriptions of the proportion of nitrogen-fixing legumes in a mix from the period shortly after WW1 when the scientific study and practice of agriculture was becoming established.

Clovers used in grass mixtures: (top left c’wise) red, white, crimson with white, crimson flower and alsike.
Mixtures were planned based on functional characteristics

The mixtures suggest there was a practical understanding of how species would interact when growing in a field. The author points to eight different properties that should be considered in choosing a mix.

  • Adapted to the local soil:  particularly to sandy or peaty soils.
  • Longevity: early or fast growth coupled to short life, e.g. red clover not expected to survive in permanent grass.
  • Habit of growth: a correct mix of ‘top’ plants that provide much of the fodder and ‘bottom’ plants that cover soil and ensure no gaps.
  • Time of year: a correct mix of developmental phases to ensure growing foliage is present for as long as possible.
  • Readily eaten by stock: (fairly obvious but) need to avoid plants that are less palatable or which become unpalatable with age.
  • Feeding quality: (again fairly obvious but) need by experience to assess quality depending on local conditions and manage so as not to diminish quality (and Findlay admits that quality was at that time difficult to measure).
  • Must die when ploughed: so as not to occur as weeds in subsequent crops (less important if permanent pasture is the aim).
What happened next?

One of the great uncertainties in defining agricultural trends is how the composition of grass mixtures changed since the annual census began over 100 years ago. Whereas, the areas sown with grains such as peas and beans were recorded [8], legumes in grass mixtures were not recorded. The census restricts managed grassland to the two main categories, short-term and ‘permanent’. For a time, the census also recorded the proportion of each used for hay or grazing.

There has been no consistent recording of the composition of grass, so the trajectory from the recommendations of the 1920s to the present is unknown. Yet travelling around the country, observing grass and crops, usually from the other side of the fence, leads to the conclusion that most current grass is far from diverse. In some fields there is one or two species, typically perennial ryegrass and timothy. Legumes except for the occasional white clover are absent. In the main, managed grass in Scotland has been de-diversified.

But not all of it …… [Further articles in this series will look at remaining sources of grassland diversity in low-input and organic farming and in commercial seed mixtures.]

 

 Sources, references, links

[1] Andrew Wight’s travels in the late 1700s describe first hand the improvements in field practice that commonly included sowing mixtures of grasses, legumes and other plants. Available online: Wight, A. 1778-1784. Present State of Husbandry in Scotland. Exracted from Reports made to the Commissioners of the Annexed Estates, and published by their authority. Edinburgh: William Creesh. Vols I-VI (e.g. search for title in Google Books).

[2] Recent EU research funding in agricultural and food systems is distinguished by the inclusion of a wide range of small enterprises that will be effective in rediversification. Agroecology at the James Hutton Institute (Dundee, UK) is leading several EU initiatives of this type including TRUE true-project.eu and Diversify plant-teams.eu.

[3] The Living Field project www.livingfield.co.uk at the James Hutton Institute promotes outreach and education. Its garden near Dundee displays many of the plants grown for food and feed, including most of those noted above.

[4] Findlay, W M. 1925. Grassland in Scotland. In ‘Farm Crops’ edited by W G R Paterson. The Gresham Publishing Company, London.

[5] Elliot RH. 1898. Agricultural Changes, later published as The Clifton Park System of Farming. Available online at journeytoforever.org.

[6] Stephens H. 1841. The Book of the Farm. Blackwood, Edinburgh. Printed in many subsequent editions in the later versions of which, revised and re-written, it was named Stephens’ Book of the Farm. Available online from various sources.

[7] Most plants in Fig. 2 and Fig. 3 are recognisable from the common names given by Findlay.  Burnet probably refers to fodder burnet, now given the botanical name Sanguisorba minor and recognised as subspecies muricata to distinguish it from salad burnet (subspecies minor).

[8] Trends in grain legumes and the benefits of increasing their presence in modern agriculture and food supply chains are examined by: Squire, Quesada, Begg & Iannetta. 2019. Transitions to a greater legumes inclusion in cropland ….. Food and Energy Security https://doi.org/10.1002/fes3.175 doi (available free online).

Author/contact: geoff.squire@outlook.com or geoff.squire@hutton.ac.uk.

Funding  The author currently has honorary (unfunded) status at the James Hutton Institute. A background knowledge of crop-grass mixtures was gained in past years through funding from the Scottish Government Strategic Research Programme and EU projects, mainly TRUE [2].

Resilience in a three-grain production system

Summary 

Cereal farming in the north Atlantic region improved to a point in the mid 1900s where starvation and famine were a distant memory. Half a century on from then, impending pressures through soil, climate and economics are threatening stable and reliable grain production. Yet the dire predictions of some commentators are unlikely to happen. Cereal farming has repeatedly adapted and survived since the first settlers brought grain to these islands.

This article summarises the changes that have occurred over the past century and suggests the system has in-built resilience through its combination of three grains – oat, barley and wheat. 

Cereal country, Scottish Borders, August during harvest (@curvedflatlands)Cropland in the northern part of the British Isles has grown barley, wheat and oat as its main cereal grains for thousands of years. Barley and wheat have been recorded since the neolithic, oats perhaps later. Cultivation of all three has sustained people and had been demonstrably sustainable, in that it continues.  There is no reason in principle why it should not continue well into the future.

Until the mid-1900s, these three home-grown grains were the main food of people and livestock. Other crops such as rye have occupied little area. However, at no time were the areas or proportions or uses of these crops fixed. Rather, they have changed as part of long term societal trends and over shorter time scales in response to international markets and bad-weather years.

In 1900, oats dominated. Then the next 100 years saw major changes in the proportional area of the three cereals (Fig. 1).

 

Fig. 1. The proportions of oats, barley and wheat in selected years of the annual agricultural census for Scotland [1, 2]. In 1990 and 2018 w and s refer to winter and spring barley.

It is sometimes assumed that the period of agricultural intensification following WWII, and operating mainly between 1960 and 1990, caused the greatest upheavals in the history of agriculture, but major change in crops and output occurred during the Improvements after 1700 and then in the later 1800s.

Winter wheat, ripening in late August (@curvedflatlands)
Change at the turn of the century – 1900

Figures taken from the official agricultural statistics from 1883 [1] show a steady decrease in the area grown with arable crops compensated by an increase in the area of ‘permanent’ pasture. The total land area grown with all crops and grass was more stable.

In just less than two decades before 1900, around 10% of the cereal area was lost to grass. Turnips and swedes – the winter lifeline for people and stock since the 1700s Improvements – had begun a steady descent that was to continue well into the next century, and the grain legumes – peas and beans – had even then become minor crops.

Fig. 2. Proportions of the three cereals in 1900 at a time when the area of grass was rising and arable (tilled) crops was falling. The area grown with cereals is shown under the pie diagram [1].

Symon labelled the period 1875-1914 ‘Forty bleak years’ [3],the bleakness caused as least as much by international trade pressures and inequalities in local society than anything biophysical. Yet he pointed to Scottish farming being ‘elastic’, enable to withstand the shocks of depression due to the three grains and the varied stockraising.

In and around 1900, oat occupied about three-quarters of the cereal area, barley around 10% and wheat the rest. The proportions of the three cereals changed little until after WWII. Economically, oats was less profitable than the other two but was hardier and easier to grow on the little nutrient resource available.

Spring barley, sown early, photographed 24 April, Angus coast (@curvedflatlands)
Intensification 1960 to 1990

The hard lessons of agricultural insufficiency in 1914, repeated in the 1940s, led to government-backed programmes for agricultural improvement, which also took advantage of new opportunities for international trade and technological advances [4]. Deeper cultivation allowed roots to explore an increasing volume of soil. Mineral nitrogen fertiliser became widely available and relatively inexpensive; and from the late 1970s chemical pesticides proliferated to control the many weeds and diseases that sought their share of the nitrogen! New cultivars were introduced with higher yield potential, mostly through a larger the grain ‘sink’, allowing a rising harvest index (grain/total mass).

Fig. 3. Proportions of area (pie diagrams) and total area (figures beneath) sown with oats, barley and wheat in 1945 and 1990. Barley in 1990 is separated into winter and spring varieties [1, 2].

The results of intensification were stunning. Cereal yields increased sharply from the 1960s. Most of the wheat was autumn sown, as was a proportion of the barley. Together these ‘winter’ crops came to occupy about 20% of the total cereal area. Compared to spring barley and oats, they were in full leaf at the time of peak solar income in late May, June and July. This shift in timing enabled them to accrue more photosynthetic mass to feed their higher grain ‘sink’.

Barley and wheat became more profitable as sources of alcohol and stockfeed. Oats – the only one of the three now used to feed people – declined to an area equivalent to that of wheat a century earlier. Most other cereal carbohydrate eaten by people is imported as bread, pasta, rice and maize.

Winter barley ready for harvest, late July, Borders (@curvedflatlands)

A quarter century of level output

During intensification, the area grown with cereals recommenced its pre-war decline (Fig. 3). By 1990, the cereal area was 90% of that in 1945.

But another and more significant change occurred. By the early 1990s, the rapid rise in yield due to intensification came to an end in the main cereal areas (for reasons that are not entirely clear). Yield increased a little over the next decade but then levelled. Despite many technological advances, total cereal output stabilised after 1990 except for fluctuations due to the advent of set aside and variable weather [3].

A similar pattern of levelling outputs has occurred in many parts of Europe and much farther afield. Is all now stagnation and decline?

Not quite. Recent records of yield and sown area suggest that while yield may be sensitive to bad weather years, such as the wet 2012 and dry 2018, farming has a capacity to shift land between the three cereals to offset the worst the weather can throw at it. Moreover, the yield per unit area of oats has increased to become close to that of spring barley [5].

Despite cereals giving poor economic returns at this time, the ‘system’ is not mired and should be still able to respond to the inevitable impending change.

Whole-crop oats, being cut 30 July, Orkney (@curvedflatlands)
External and internal pressures / capacity for adaptation

The cereal- and grass-based croplands of lowland Scotland face a set of internal and external pressures to which they must adapt. They include –

  • internal degradation of soil, element cycles and food webs due to intense cultivation, a factor likely to increase pressure on surrounding ecosystems but also to decrease the capacity of land to yield;
  • climatic change and extreme events of the type that dented output in 2012/3 and 2018;
  • continued reliance on external sources of nitrogen and phosphate fertiliser;
  •  further pressure on the economic  position for mass-market grain, for example, owing to competition from other countries and products.

One threat that should be no longer feared, however, is that of repeated crop failure, starvation and famine that hit parts of the country as recently as the mid-1800s. And there are increasing positives –

  • greater demand for home-grown cereal products, for example through an increased desire for local, sustainable food and drink;
  • technical innovations in cereal varieties and agronomy that open new higher-value markets.

 

Winter wheat ripening before harvest, late August, Borders (@curvedflatlands)

The line of census records since the early 1880s has shown massive shifts in the total and relative areas cultivated with the species and in the agronomic inputs to those areas. If farming has adapted in a certain way, then it should be able to repeat or reverse the change. Among options are –

  1. Broad scale shifts in the proportions of crops and grass, possibly reversing in part the shift towards grass (Fig. 3).
  2. Continued decrease in the area grown with cereals but concentrating on higher-value products or higher yield (i.e. by taking cereals off the less productive land, a trend already apparent).
  3. Altering the proportions of winter and spring varieties to manipulate the trade offs between yield, inputs and selling price.
  4. Replacement of high-input winter cereals with less demanding spring oats in response to challenging conditions (as happened in the 2012-2013 wet years).
  5. Growing more ‘mixed grain’ (two or more cereals in the one field) or cereal-legume mixtures such as mashlum, that need fewer agronomic inputs [6].
  6. Introducing grain legumes or grass-legume leys into crop systems to reduce reliance on mineral nitrogen and hence cut GHG emissions.
  7. And there are many others   ….

Now these might not seem like anything markedly out of the ordinary (when surveying the past 150 years) and indeed they are not. Yet cereal farming in many parts of the world would envy these possibilities: there are vast areas in some continents grown with only one main cereal that offers little scope to engineer change.

Moreover, the climate here, on the Atlantic seaboard, will probably not extend to real extremes due to its oceanicity. Complete crop failure caused by weather is still very unlikely here compared to places (for example) like New South Wales and Victoria in Australia where much of the cereal farming is already at risk without irrigation in a ‘normal’ year.

Ps. This article offers background to subsequent notes on this site that will examine the subtle and temporary shifts in the area of the three cereals that occurred in the ‘extreme’ weather years of 2012 and 2018, with consequences that lessened the overall yield ‘hit’ at harvest.

Cereal fields in stubble, Strathspey, January (@curvedflatlands)
Sources, references

[1] Agricultural Statistics 1912. Volume 1, Part 1. Acreage and livestock returns of Scotland, with a summary for the United Kingdom. Board of Agriculture for Scotland. Some data included for the census years back to 1883. And subsequent yearbooks in this series up to 1978.

[2] Economic Report on Scottish Agriculture: 1980 onwards. Scottish Government – links to all data at Agriculture and Fisheries -Publications.

[3] Symon JA. 1959. Scottish farming: past and present. Edinburgh, London: Oliver and Boyd.

[4] Squire GR. 2017. Defining sustainable limits before and after intensification in a maritime agricultural ecosystem. Ecosystem Health and Sustainability 3/8 (open access, available at https://doi.org/10.1080/20964129.2017.1368873

[5] Cereal and oilseed rape harvest: 2018 final estimates. Scottish Government. Published 12 December 2018. Downloads available from link.

[6] For references to cereal-legme mixtures: Living Field posts Mashlum  – a traditional mix of oats and beans and Mashlum no more! Not yet.

Author/contact: geoff.squire@hutton.ac.uk, geoff.squire@outlook.com

Funding  The author currently has honorary (unfunded) status at the James Hutton Institute. A background knowledge of crops, weather and climate was gained in past years through funding from the UK Overseas Development Administration and UK Department of the Environment while based at Nottingham University (1970s, 1980s) and more recently through the Scottish Government Strategic Research Programme.

Transitions to a legume-based food and agriculture

A summary with diagrams and photographs of an invited talk at the recent Conference on Advances in Legume Science and Practice organised by the Association of Applied Biologists in Glasgow 21-22 March 2018. Topics at the meeting covered a wide range of experience and disciplines from crop physiology, nutrition, molecular and traditional breeding, symbioses, landscape processes and food security.

Background – summary

Our invited presentation on Transitions to a legume based food and agriculture [1] introduced the aims and approach of the EU TRUE project, notably its central matrix consisting, first, of the quality chain from production through to markets and consumption, and second, sustainability, assessed through  economic, societal and environmental indicators.

The argument runs as follows. (A) Crops and their management alter the flows of energy and matter to various functions in the managed ecosystem. (B) Legume crops and forages have unique roles in channelling energy and matter to crucial functions related to soil quality, the nitrogen economy, pollinators and the production of plant protein. (C) To achieve a balanced and sustainable system, different types of crop, including legumes, need to be grown in planned configurations, whether within fields as mixtures, in  sequences or rotations and in spatial mosaics in the landscape. Practical designs need to consider those configurations that achieve the desired combination of functions.


Fig. 1 Faba beans Vicia faba: young crop, plant in flower, pods and fresh beans, and (small squares l to r) dried beans, flour, shelled split beans and bran.

Increasing legume production and output can be designed and managed in three stages. First, the area grown with existing legume crops such as field bean (Fig. 1)  can be increased with no change to the existing system. Second, the existing system can be modified – but not fundamentally changed – through (for example) mixed cropping of legumes and cereals, rhizobial inoculation of legume seed and  new legume products. Third, the system can be changed completely, with new crops, biotechnology and methods and untried configurations.

The presentation concentrated on  stage 1, but related work in Agroecology at the Hutton is already advancing in stage 2 though experimentation with crop mixtures, rhizobia and new products such as bread, beer and tofu made from beans [2].

Diversifying agriculture using grain and forage legumes

The flows of energy in production systems are investigated through a chain of effect linking interventions, such as agronomic management and choice of crop, through biota, including crops, to ecological processes which in combination satisfy (or not) desired higher level outputs [3].

The main crops in temperate Europe today are managed so that most of the energy is channelled to grain, oilseed or tuber yield (Fig. 2). In consequence,  other channels have been closed, or at least severely restricted, leading to long term declines in farmland wildlife and soil quality. Ultimately, such losses will feed back to limit economic output itself.

Fig. 2 The flow of energy in a winter cereal is concentrated into resource capture by the crop, then formation of yield and product, at the expense of trophic functions and soil.

The solution is to diversify the production systems of the region, in effect opening and regulating channels to other functions.  The diagram in Fig. 3 offers a highly simplified depiction of the wider balance of flows that should be realised in a forage legume.

Fig. 3 The flow of energy in a legume forage is distributed across a range of functions, notably N-fixation and trophic activity, e.g. through invertebrates.

The scope for diversification is being examined in this way for the case study of lowland Scotland. Grain legumes, mainly peas Pisum sativum and beans Vicia faba have been present from the neolithic and bronze periods and a wide range of forage species have been tried and grown over the millennia. Grains and forages are therefore being quantified as to their effect on flows such as represented in Fig. 2 and Fig. 3. Species are then modelling alone and in various spatial and temporal combinations to find optimum states.

Much can be learned from the way legumes and other crops have been grow in in the past, including in-field mixtures, often broadcast from a single ‘bag’ of mixed seed, such as mashlum, and temporal sequences, in some of which the legume and non-legume overlap (Fig. 4). Fields and sequences then combine to give additional properties at the scale of the landscape.

Fig. 4 Examples of crop diversification used traditionally in the region: B is a legume and A another crop (e.g. a cereal, root, oilseed, grass); C is an in-field mixture, such as mashlum, D a blocked, in-field mixture where the crops are separated, Ea a sequence or rotation, Eb a sequence in which some crops overlap in time (e.g. nurse crops and undersowings) and F a spatial configuration in a landscape.

The main problem facing the study was uncertainty in the locations within the region in which legumes appeared historically. However, crop census data, beginning in the mid-1800s is being examined to get the missing information.

First census of the mid-1800s

Legumes became integral to both crop sequences and forage mixtures in the Improvements era after 1700, but while some records suggest legumes occurred  1 in 4 years [4], there is little hard data on the areas grown with them compared with cereals such as oat and barley.

The 1700s and 1800s witnessed a phase of innovation and trialling of both grain and forage legumes, but for reasons that will be explored elsewhere on these pages, most forage legumes dropped out of mainstream usage with the exceptions of clovers and vetches, while grain legumes were reduced to various forms of pea Pisum sativum and bean Vicia faba.

The census of crops and grass in 1854 carried out by the Highland Society, covered most of Scotland and initiated a period of regular crop censuses which have proved invaluable in charting the phasing in and out of different crops. Data on the main crops [5], summarised for each of the old counties of Scotland (current up to to 1890), were transcribed from the 1854 records. Data were available for peas, beans and vetches: as an example, that for vetches is shown in Fig. 5, where the area of the circles, each representing an old county, indicate the relative area occupied by each crop. The circle out to the north-east represents Orkney and Shetland.

Fig. 5 Distribution of the vetches crop in 1854, sown areas represented by circles centred on the old counties of Scotland, superimposed on current administrative areas.

Beans occupied the largest area, followed by vetches and peas which covered similar areas. Most of the crops would have been grown for animal feed. Their combined areas were small, about 5% of that grown with cereals. Other sources specify that mixed forages, such as red clover, ryegrass and plantain, were also grown extensively, but no records are available of their composition and coverage. One of the recurring deficiencies of agricultural census is the classification of mixed forages as ‘grass’.

The distributions of vetches (Fig. 5) and peas were similar, both concentrated in the east and today’s central belt, but extending both south-west and north to Orkney and Shetland. That of beans was more concentrated in the east and centre.

Various crop census after the 1880s continued to show a similar distribution. When peas and beans were distinguished as to whether they were intended for human and animal consumption, those for human occupied a more restricted area in the east of centre.

Grain legume coverage today

Going forward 160 years, IACS data – from the EU’s Integrated Administration and Control System [6] – allows more precise definition of the current area grown with grain legumes.  There is still no data for grass-legume forages which must all classified under one or other of the forms of ‘grass’. Four types of grain legume are reported,  in decreasing order of area – beans for animal consumption, peas for human and for animal consumption, and least, beans for human consumption.

The total areas grown today are even smaller than the combined area of legumes in the 1850s. Maps of legume distribution after 2000 are in preparation. Examples  can be seen at the Living Field post Can we grow more vegetables? and further analysis of changes over time will be given later in these pages. However, the combined areas of the four legume types recorded tend to remain <2% and in some years near 1% of the total cereal acreage.

Low inclusion of legumes in a dynamic production ecosystem

The main conclusion so far is that grain legumes (pulses) were minor components of agriculture in the mid-1800s and have remained minor. Yet many aspects of the the crop and grass production systems in the region have been far from stable. For example, ‘root’ crops, mainly swede and turnip, covered large expanses in the late 1800s, but are relatively minor now, while of the cereals, oat was dominant in the 1800s and early 1900s but  supplanted by barley and now occupies less than 10% of the cereal area.

Recently, other crops have risen to much greater coverage than the legumes, notably winter wheat and oilseed rape in the later part of the 1900s. During all these changes, grain legume areas remained small or decreased.

One of the questions being examined is why legumes have occupied such low acreage in the region and whether and where they could be increased. Investigations of the phenomenon are continuing but one reported contribution is a greater reliance historically on clover and other legume forages for soil fertility.

There seems no particular reason, however, due to limitations of soil or climate, for the restricted area grown with legumes today within the eastern and central ranges shown in Fig. 5. Nor should it be assumed that increases will come only from existing crops. In response to CAP Greening measures, small fields of assorted legumes have appeared in the region.

That in Fig. 6 comprised three species of clover, the well know red Trifolium pratense and white Trifolium repens species, but also an unusual one, crimson clover Trifolium incarnatum which was once tried as a forage at these latitudes. A few plants of sainfoin were seen near the edge of the field, but it was not certain they were sown as part of the mixture.

Fig. 6 Legume forage, mainly of white, red and crimson clover: (top l c’wise) the field, young and older flowering head of crimson clover, sainfoin (image from plant in the Living Field garden) and  plants in an approx 0.5 m width of field (images by curvedflatlands).

Assessment by multi-attribute decision modelling

Opportunities for expanding the area of existing grain legumes are now being examined. It should also be possible to quantify potential savings of mineral nitrogen fertiliser and pesticide as the legume area is increased. The IACS data again provides the wherewithal, allowing us to assess not only which fields contained grain legumes in any year, but also which other crops were grown in the same fields in years before and after the legume. With knowledge of the crops grown in each field, nominal attributes can be assigned based on the pesticide and fertiliser applied to each crop as quantified from national surveys.

Each field can then be given a nominal agronomic ‘intensity’.  The reduction of intensity due to the substitution of an existing crop with a grain legume can then be calculated, as can the trade offs in the areas and output of other crops and products such cereal grain. The four current grain legumes offer plenty of scope for substitution, since some are grown with high-input crops, mainly winter wheat and potato, while others are grown with short-term grass and spring cereals.

Placing a value on each system, and then comparing systems, is facilitated by multi-attribute decision models (MADM) built in DEXi software [7]. A  part of the ‘tree’ structure of the current MADM is shown in Fig. 7. The interventions are shown to the right. They affect in turn the biota and ecosystem processes that determine a higher-level attribute, in this case the N loss in water leaving a field. The full MADM will include the wide range of attributes determining the economic, environmental and societal contributions of production systems.

Fig. 7 Part of a decision tree or multi-attrbute decision model built in DEXi software showing the way interventions combine in effect to influence field-scale attributes, in this case loss of nitrogen (N) in water.

Sites for expansion of legumes are therefore being selected on the basis that (a) they lie within an area, soil and climate in which grain legumes are or have been grown, and (b) they have a balance of crops very close to those fields that already include legumes in the crop sequence.

The aim is to quantify the benefits of legume expansion for the purpose of informing government policy and encouraging food and agriculture to use and grow more legumes. While concentrating on the grains at this stage, there is no reason why the approach cannot be extended to forages such as those in Fig. 8. More widely, the results will form a comprehensive study in the EU TRUE project of an approach to define long term trajectories of legume-based production systems and to extend those trajectories across Europe and farther afield.

Fig. 8 Legume species historically trialled in the region as forages: (top l, c’wise) sainfoin, milk vetch, kidney vetch, tufted vetch and white melilot,all grown in the Living Field garden (images by www.livingfield.co.uk)

Acknowledgement of funding

The main work summarised here and presented at Glasgow was funded as part of the EU TRUE project.  Background knowledge of the maritime production system of lowland Scotland was acquired with funding from Scottish Government (Rural and Environment Science and Analytical Services Division). The authors are based at The James Hutton Institute, Dundee UK.

Sources, references

[1] Squire GR, Iannetta PPM. 2018. Transition paths to sustainable legume production. Aspects of Applied Biology 138, 121-130.  Squire GR, Quesada N, Begg G, Iannetta P. 2018. Transition paths to sustainable legume production. Invited presentation at Advances in Legume Science and Practice, Association of Applied Biologists Glasgow UK, 21-22 March 2018.

[2] Links to bean beer on the Hutton website – Feed the world, help the environment and make great beer. Link to ‘tofu’ make from beans on the Living Field web site – Scofu: the quest for an indigenous Scottish tofu. See also Feel the Pulse.

[3] Squire GR 2017. Defining sustainable limits before and after intensification in a maritime agricultural ecosystem. Ecosystem Health and Sustainability, 3:8, DOI: 10.1080/20964129.2017.1368873

[4] Wight, A. 1778-1784. Present State of Husbandry in Scotland. Extracted from Reports made to the Commissioners of the Annexed Estates, and published by their authority. Edinburgh: William Creesh. Vol I, Vol II, Vol III Part I, Vol III Part II, Vol IV part I, Volume IV Part II. All available online via Google Books. Note from GS: Wight’s journals of his travels through the agricultural regions of Scotland present an unrivalled account by a farmer of the state of agriculture in the Improvements era.

[5] The agricultural census of the Highland Society, 1854, summarised by:  Thorburn T 1855. Diagrams, Agricultural Statistics of Scotland for 1854. London: Effingham Wilson. The Living Field web site has more on Thorburn  at Thorburn’s Diagrams.

[6] Integrated Administration and Control System, IACS on the EU web site.

[7] Decision trees, multi-attribute modelling and DEXi software at Marko Bohanec’s web site DEXI: a programme for Multi-Attribute Decision Making.

Contact: geoff.squire@hutton.ac.uk

 

 

New EU TRUE project holds first meeting

Fantastic news that one of our new EU-funded H2020 project is getting underway. The inaugural meeting was held in Edinburgh, 19-21 April 2017. Around 50 people attended from all EU partners.

The project is coordinated by Pete Iannetta from Agroecology at the Hutton. The aims and methods of the various Workpackages were aired and discussed during two full days. A great feeling among partners of delight that the project would be funded and of looking forward to several years of intense collaborative effort ahead.

Here is the first group photograph.

Project description to follow …..

mixed cropping in Burma

Growing crops as mixtures of different species in the same field was commonplace in Britain during the Improvements era but gradually fell out of favour in the 19oos as single crops became easier to manage and could command a high value on the grain market. ‘Grass seeds’ in the 1700s often meant not just one or more grass species, but a mix of a grass, a clover or several legumes and another species such as ribwort plantain. A cereal (corn) and a nitrogen fixing legume (pea) were also broadcast over the same field, as were mixtures of different cereals.

Mixed cropping is now being reconsidered in northern Europe as a possible means to producing the same with less input of fertiliser and pesticide. In our most recent outing, at the December 2016 meeting of the British Ecological Society, Pete Iannetta talked about the benefits of a barley-pea intercrop grown at the Institute (links at Latest). But for inspiration we can look to other places.

Mixed cropping is still widespread in the tropics, but the reasons for planting different species close together, sometimes in strict spatial patterns, are not always obvious. The scientific tendency is usually to look for a biophysical mechanism behind the pattern. Perhaps the two or more species take resource from different parts of the environment or use the resource more efficiently. Mixed cropping works – the two species together tend to produce 1.1 to 1.3 (110 to 130%) times the equivalent yield of the crops grown alone.

This is a useful but not a great advantage, and it may well be that the plants are grown in mixtures for other reasons also. Sometimes the arrangement might arise simply out of convenience or as a means of lowering the risk of not putting all your eggs (i.e. the few seed of one crop) into one basket (i.e. a small area of soil).

This mixed cropping, named intercropping when the plants are in rows, was frequently observed on a self-funded trip to Burma (Myanmar) during the dry season of 2014. Our interpreter, knowledgeable about local farming, was still not always able to explain what was behind the crop configurations.

Planned intercrops

The biophysical basis of the intercrop was best appreciated for perennial plants such as the pigeon pea Cajanus cajan grown at Bagan with cotton, probably one of the shrubby species, and another plant that had shrivelled to unrecognition in the dryness. The pigeon pea would have fixed and released nitrogen to the soil for the cotton to take up. In some fields, the pea had recently been cut back to stop it using water, whereas the cotton, most likely deep rooting, was in full flower and fruit and using the water and nutrients stored in the ample soil-space between cotton rows.

On the banks of the Irrawaddy, highly regimented rows of groundnut Arachis hypogaea had maize Zea mays sown within every 5th row (image below). The land would have been awash as the river rose in the wet season, when presumably the silty soil, and any nitrogen fixed previously by a legume, would have been picked up in the current and deposited somewhere else.

The crops were therefore growing on nutrient-rich alluvium and soil-stored water. The maize was starting to flower but the groundnut was still in leaf only. It was unlikely that this year’s N fixation by the groundnut would have ‘leaked out’ so early in its growth. Rather, the maize was taking advantage of additional resources, sunlight above ground and residual soil nitrogen from the bordering rows.

Elsewhere, a field of the nitrogen-fixing chickpea Cicer arietinum had been planted with widely spaced rows of sunflower Helianthus annuus.  The sunflower would have benefitted as the maize in the previous example, but it was difficult to see the advantage to the chickpea. Possibly, the farmers wanted some sunflower seed or oil and grew a few plants in what was otherwise a chickpea field.

But why plant in rows …? Rows are generally easier to establish with animal-drawn implements than are small blocks of crop. Intercrop rows also make it more difficult for a farmer to lose a large proportion of one or other species. Repeatedly, patches of a few square metres occurred in the intercropped fields where the crops were stunted or dead, probably due to poor soil or disease. Planting in rows allows both crops to experience the whole field, its good and bad parts.

Unplanned(?) intercrops

In a further set of configurations, the growers appeared not to have planned the mixture. Rather, they took advantage of a situation in which other species emerged with the sown crop.

One such was a small plot of groundnut in which plants of the Chenopodium genus (probably C. album) were growing in a random configuration. Someone nearby, who knew the practice, said that Chenopodium appeared whenever groundnut was grown. It probably emerged from the soil seedbank, stimulated by conditions peculiar to groundnut cultivation. It was encouraged – the ‘weed’ is widely used as a salad vegetable, as it was once in Britain.

Another example was a field of groundnut again, but one that appeared invaded by two or three other species. Chenopodium was there again but also maize and sunflower, and each was located irregularly, not in rows. The groundnut had been sown but the others, including the two crops, had emerged from the soil seedbank. They were ‘volunteer’ weeds, and had been left, not weeded out.

Multiple crops

In Shan agriculture, a mixed crop new to my experience was one of taro Colocasia esculenta, ginger (Zingiberaceae, species uncertain) and chillie, species of Capsicum. It was easy to walk past the field, because the chillies had been harvested and the taro tubers and ginger were mostly invisible underground.  This was an intentional mixed crop. There would have been biological interactions between the three, but perhaps the main advantage was one of getting three crops from the same bit of land in one year – the chillies first, finally the taro.

Repeatedly, crops were seen growing in intended and apparently random configurations. Fruit trees were grown in small orchards, where they usually had an understorey of legumes or mustards. Fruit trees were also dotted around the landscape, enjoying the benefit of nearby fixers and fumigants.

Palms were common, often grown in lines or groves within the general mix of annual cropping. On the high land, fruit and beverage trees were commonly grown in planned (tea and oranges) or semi-random configurations.

Comment

This brief experience, over only a few weeks, introduced the sheer diversity of crops and farming methods here, the ubiquity of legumes, the widespread use of ‘wild’ plants, and the frequent desegregation of the sown and the wild.

Perhaps the lasting impression is one of nitrogen-fixing legumes being among the commonest crops, essential to the mix, whereas in north-west Europe, they have been reduced to minor status.

In some areas, the people had a very advanced understanding of how plants complement each other and together provide human dietary needs, an understanding that has almost lapsed in mainstream farming in north west Europe.

Subsequent pages will deal in more detail with (2) perennial pigeon pea-cotton at Bagan, (3) groundnut-maize by the Irrawaddy and chickpea-sunflower near Mandalay and (4) assorted mixtures which may or may not have any biological advantage.

Sisal plants in the foreground, grown for the fibres in their leaves. The small trees just behind them have been pruned, with one ‘lung’ (a leafy branch) remaining.
Author’s note and further reading

We visited Burma, not in any official capacity, but as ‘tourists’. I had intentionally not read any of the reports from international development agencies before going there, wanting instead to get a first-hand (even if fleeting and random) feel for the soil, people, plants and agriculture. Many of the reports read since have seemed to me to be a bit impersonal, not fully accepting and promoting the great ingenuity and knowledge of the people who live and farm there.

We were more than fortunate to be guided during a crucial part of the visit by Ei Ei Lin (or Lin Latt). Her farming background and natural curiosity introduced us to many hidden wonders of (plant) life in the dry season.

For factual and largely non-judgemental information, the following report offers much on the conditions in Burma’s dry zone:

Improving water management in Myanmar’s Dry zone – for food security, livelihoods and health. 2015. International Water Management Institute (IWMI) 52 pages. doi:10.5337/2015.213. Based on 3 reports published in 2013. http://www.iwmi.cgiar.org/Publications/Other/Reports/PDF/improving-water-management-in-myanmars-dry-zone-for-food-security-livelihoods-and-health.pdf?

Books read during the visit included (and both freely available in bookshops there):

Aung San Suu Kyi. 2010. Letters from Burma. Penguin.

Emma Larkin. 2006. Finding George Orwell in Burma. Penguin Random House.

why so few estimates of nitrogen fixation?

A recent open-access paper Iannetta et al. 2016 gives a comprehensive account of the contribution of legume crops and forages to the nitrogen cycle in temperate agriculture.

Iannetta et al. 2016. A comparative  nitrogen balance and productivity analysis of legume and non-legume supported cropping systems: the potential role of biological nitrogen fixation. Frontiers in Plant Science, 21 November 2016 http://dx.doi.org/10.3389/fpls.2016.01700

Using data from existing field experiments across Europe, nitrogen fixation by legumes was estimated as a residual when other main fluxes of N were accounted for. Annual fixation ranged from 30 to 115 kg/ha of nitrogen. For comparison, the upper figure is a little higher than the fertiliser N given each year to spring cereals.

Why are these figures important? There’s a dearth of estimates or measures of biological N fixation in north temperate agriculture. But while such information is essential for designing sustainable systems, it is not in itself considered to be high-profile (and therefore fundable) science.

Hence the need to add value to existing datasets to get these first estimates. Work is in progress to measure actual fixation rate in arable fields.

Hutton Agroecology group contributions to this paper are as follows. Pete Iannetta developed the overall concept and fronted the paper. Graham Begg designed and led the statistical analysis and modelling. PI, GB and Mark Young carried out the N balance calculations. Geoff Squire and Euan James offered specialist insights.

Page 2 gives some background to the article.

Images: the red clover looked to be part of a natural patch (i.e. not sown) growing locally; the vetch root and nodules were unearthed on a field trip in Attica, Greece during the EU Legume Futures project.