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LEAF Comment

A new page to stimulate comment and discussion on topical issues, trends and new findings in sustainable agriculture and food.

A series of commentaries and opinions on current topics in food security, sustainable agriculture and environment. A fuller version of some articles will be available as a downloadable file.


Mapping pesticide loading in Scotland's maritime arable-grass

An update on progress with agroecological mapping to aid environmental risk assessment: a method for estimating pesticide loading in Scotland’s arable-grass production systems By Geoff Squire, Nora Quesada and Graham Begg.   

The combination of grassland for grazing animals and arable land for growing crops has sustained human life here since the first farmers occupied the land in the late stone age. This balance of managed grass and arable, unploughed and ploughed, gives the countryside a diversity that changes with the seasons and over the years as arable moves to grass and back. The climate is ‘oceanic’, in that the large body of sea water dampens fluctuations in temperature, the land rarely suffers drought and the solar income during long summer days supports a high potential yield. The climate is ideal for grass and for temperate grain crops, such as barley and wheat, which typically yield more here than in any other part of the UK.

This proximity of farmland to sea, while beneficial to yield, also brings a potential risk to estuarine and marine ecosystems through loss and transfer of some of the agrochemicals that are applied to most farmland to support high production.

A question addressed by the Agroecology group at the James Hutton Institute was how to define and quantify the potential agrochemical loading on different parts of the region.

Significant progress has been made in the last year by combining three sources of data: the EU’s Integrated Administration and Control System or IACS and government surveys of pesticide and fertiliser. 

An example of a pesticide map derived by combining these data sets is shown to the left, this one for the east of the country between the Moray Firth and the Borders. It is based on an average of a five-year sequence of crops.The areas coloured yellow had 0 to 2 pesticide treatments a year on average, but most of them, consisting of mainly grass, would have had none. The areas coloured the darkest brown had 9 or more treatments due to the combination in successive years of winter cereals, potato and vegetables. The white areas outside the colouring tend to be upland rough grazing, of which less than 0.5% in the country as a whole is treated with pesticide.

The research update (three pages) can be read in full in this PDF file: Mapping pesticide loading in Scotland's maritime arable-grass.


Impressions of the James Hutton Institute as a LEAF Innovation Centre

Tom Bodman, a masters student, was funded by a Macaulay Travel Grant to visit the Institute late 2017 and form impressions of the role of the Institute as a part of the LEAF network.

He introduces his report as follows: "This report was produced during a two week stay at the James Hutton Institute (JHI) in Dundee. This visit was enabled by the Macaulay Travel Fund, and a partnership between the James Hutton Institute, Scotland, and McGill University, Canada."

Tom spent his time here researching LEAF, talking to people involved in LEAF activities and writing a concise report of his impressions. Here are his conclusions:

"The work related to LEAF appears to be a significant feather in the Hutton Institute’s cap. It allows scientists and farm staff to demonstrate the high quality and broad scope of work that is being done at the JHI. This is through the LEAF Open Farm Sunday and Technical Days, but also through submissions to various technical notes or leaflets for LEAF and general involvement with the LEAF Network.  On the farm side, compliance with the various stringent LEAF certifications demonstrates the expertise and dedication of the farming staff. Whether more support should be provided by the Institute for LEAF activities is up for debate. While there are definite and substantial benefits in terms of publicity and knowledge exchange, the financial returns are less certain. It appears without doubt, however, that continued involvement with LEAF is nothing but a positive when it comes to raising the profile for the James Hutton Institute as a leading researching centre.

As this report was created in a very short time frame the number of people engaged was limited. Those spoken to and interviewed were all based at the Dundee branch of the JHI and are, for the most part, highly engaged with LEAF. This undoubtedly influences the impressions given throughout this report. It would be interesting to engage staff members who are less directly involved with LEAF and those at the Aberdeen branch to the Institute to gain a more well-rounded insight into LEAF at the JHI. This very preliminary look into how LEAF at the JHI functions, is my own opinion, based on conversations and then secondary semi-structured interviews with various members of the JHI at Dundee. While the situation is undoubtedly more complex than presented here, I hope this report is of some use in highlighting some potential topics for future consideration."

His short report can be read in full in this PDF: Impressions of the James Hutton Institute as a LEAF Innovation Centre by Tom Bodman

Engineered potato with durable resistance to late blight

Following from his exhibit at the LEAF technical day, Ewen Mullins from Teagasc, Ireland, writes about his work on potato late blight and the EU AMIGA project.

The European potato sector is estimated to be worth ~€6bn per annum but potato late blight disease, caused by Phytophthora infestans, induces control costs and losses valued at ~€1bn per annum. For Ireland, in the period from 1983 to 2007 late blight disease reached epidemic proportions in all but 4 years. Since 2008, more aggressive strains of late blight have migrated across mainland Europe through the UK and into Ireland. So while Irish farmers have to apply fungicides up to 15 times a season to control late blight, during what are becoming more regular wet and humid summers, they have still struggled to control the disease as opportunities to spray become irregular. Combined with the imposition of increased EU legislation governing the use of pesticides, it is clear that the future sustainability of an economically viable potato sector is in doubt.

From the perspective of the late blight fungus, its success is due to its ever increasing ability to cause disease and its remarkable capacity to adapt. Significant research has focussed on identifying the genetic mechanisms the fungus uses to infect and destroy potato plants. Over the last 10-15 years, advances in biotechnology-based techniques have allowed researchers to investigate the control mechanisms of the fungus; for example how it perceives a potential host, how it evades the plants’ resistance proteins and how the late blight organism adapts as the plant tries to defend itself.

The article continues on the PDF file accessible below. Here are some excerpts - " The most important word here is ‘durable’; for if resistance is not resilient enough, the late blight fungus will quickly evolve to overcome the resistance .......  it is important to highlight the fact that unlike humans and animals who have legs to run away, plants have to fight standing still .... comparable to our body’s ability to develop antibodies to fight infection, plants have a series of defence proteins, the blueprint of which is coded by the resistance genes ....... this point is the most critical; for unlike in Ireland where potato and late blight have only known each other since the 1800s, the potato genes taken from wild, weedy potato species that inhabit Central and South America have experienced late blight for hundreds of millions of years and as a result are not averse to dealing with this pest."

Continue to read about the need for durable resistance, mechanisms of gene transfer, the EU AMIGA project, GM environmental risk assessment and public debate on this PDF file Leaf_Hutton_lateblight_MullinsE_01.03.2017


Conservation at the crop edge

Edward Baxter writes 'The I.F.M. (Integrated Farm Management) wheel encourages cross-disciplinary thinking amongst farmers and the idea that actions primarily intended to have one consequence will have incidental effects elsewhere.

An example is the impact on conservation and biodiversity of plant protection products used to control weeds. Removing almost all weeds in cereal crops through effective herbicides has had unintended consequences on the wider food web. The seedbank of many arable soils has declined substantially over the last 40 years with many once common weeds of arable crops becoming increasingly rare and this may be having impacts on ecosystem function. The IFM wheel challenges farmers to think through the consequences on their own farms and to address the problem for themselves. Solutions are site-specific in line with the LEAF doctrine “to do the right thing in the right place for the right reason”.

At Gilston Mains, a LEAF demonstration farm in Fife and habitual study site for the Institute, a program was put in place 25 years ago to address the scarcity of partridge chick-food invertebrates in cereal crops. A detailed appraisal of the impacts after such a long period is now underway comparing fields at Gilston Mains which have had treatment over the past 25 years with fields on adjacent farms which have not.

More on Edward's preliminary finings can be found in this PDF file: Conservation at the crop edge


Whole system approach to design

An agricultural production system consists of many interconnecting processes operating across different temporal and spatial scales. It has a range of outputs - an economic return, the need to keep soil healthy and in place, a habitat for living things many of which are beneficial to farming and a landscape valued by those who work in it and visit it. The system can be manipulated through a wide range of interventions including type of crop, crop sequence, tillage, nutrition and pest control. In between these interventions and the end-products are a mass of uncertainties – not just the weather but the complex interactions between all the living things that make up an agricultural ecosystem.

Given this complexity, aiming for a single output is not the way to manage the system. The rise of grain output, post-war and up to the 1960s ensured food security, but the further rise in grain output until the early 1990s led to over-use of nitrogen, pollution, soil erosion and massive loss of life forms. There are good grounds therefore that system has to be managed as a whole, through attempts to satisfy its multiple outputs as far as possible at the same time. If they can’t be satisfied then the trade-offs need to be understood and choices made as who in society should pay for what.

In recent years, science has explored multi-attribute decision models (or MADMs) to get a handle on these complex systems. The most widely used MADMs take the form of a decision tree. Agronomic interventions may combine to give an effect such as ‘control of grass weeds’, which in turn combines with ‘current grass seedbank’ and ‘relative competitive ability of weed and crop’ to influence crop growth and yield. Of course, yield is influenced by many other variables which form other branches of the tree and in their turn combine to determine the overall outcome. The difficulty, and interest, comes in deciding on the merits of two or more branches that are expressed in different currencies – monetary or aesthetic for example. Yet the decision tree can be worked there and then by a group of people and the outcomes manipulated to find the optimum solution.

A decision tree built in DEXi open source software is being developed at the Hutton. It has over 100 input variables, mainly agronomic, which affect life forms (microbes, crops, other plants, invertebrates) that in turn mediate ecological processes (primary production, nitrogen fixation, pest control, carbon turnover) and give rise to the desired outputs. The ‘wiring diagram’ to the above right shows part of the structure. Working the tree aims for the best balance among these processes.

The current DEXi decision tree will be demonstrated at LEAF Technical Day on 9 June 2016. The basic software is available through the DEXi web site.

People: Marion Demade, Mark Young, Geoff Squire (Hutton), Antoine Messean, Frederique Angevin, INRA France. Contact:

IPM in practice: what does IPM look like on modern conventional farms?

Alice Midmer from LEAF attended this year's Crop Protection in Northern Britain, held in Dundee, and presented a poster and abstract. The poster (right, and downloadable below) sets out LEAF's overall view of Integrated Pest Management and gives working examples of how principles can be turned to practice.  Morrison Farms in Ayrshire grows largely forage crops for neighbouring stock farms and finds that species-rich field margins help with pest control by offering habitat for predators. The margins also encourage beetles which attract birds which in turn keep down the slug populations.  A neat bit of ecological engineering! A second case study is given for Eric Wall Ltd who routinely use biological control to regulate pests in their glasshouse-based tomato production systems.

More generally, LEAF encourage IPM through their Sustainable Farming Review, a decision based framework intended to help farmers move into more sustainable practices. However, LEAF state that the main avenue for successful communication is via demonstration farms, of which there are 36 in England and Scotland. 

Abstract: Midmer AE, Drummond CJ, Mitchell KF. Proceedings Crop proptection in Northern Britain 2016. Contact:

Downloadable PDF file of poster: IPM in Practice

Threatened arable plants

Of Britain’s flora, the group most under threat are the plants living in and to a large degree dependent on the arable habitat. They are mainly annuals, germinating and flowering within 12 months or biennials, germinating one year and flowering the next.  They rely on disturbance of soil for their existence and do not persist where perennial plants dominate. Many of them have been here since the first agriculturalists created fields; others have arrived within the last few hundred years.

The five noxious ‘Weeds Act’ weeds are now largely controlled and might even be rare in arable fields. Poisonous plants such as corncockle had to be controlled in cereal harvests. Several of the species are still classed as serious weeds in arable land – grasses such as wild oat, and broadleaf species such as chickweed and cleavers. However, most of this section of the flora bring little detriment to yield but rather contribute to the farmland food webs that mediate functions such as pest biocontrol and pollination. Some are also ikons of the countryside – cornflower and poppy among them. The diminishment and passing of these plants brings no benefit to agriculture and harms its perception.

While the Hutton, and SCRI before it, have been studying coexistence between crops and these wild plants for some time, we began last year to map where they reside in Scotland with collaboration from the Botanical Society of Britain and Ireland, who are responsible for surveying and mapping all plants of these islands. We compiled a list of the uncommon and rare arable plants and BSBI provided survey data on their known locations. The map to the right shows the initial result. Red squares contain 31-50 species, blue squares 0-5 species. Our next step is to compare the species maps with intensity of management, which depends mainly on the crops grown, and then to determine which areas might be most under further threat.

People:  Geoff Squire, Nora Quesada, Graham Begg. We thank the BSBI for their considerable help in providing data on plant distributions. Contact:

LEAF - its history, aims and achievements

The Scottish Ecological Design Association SEDA asked Geoff Squire for a brief summary of LEAF and what it stands for. Here is a revised and updated version of the article.

LEAF is an organisation that promotes Integrated Farm Management. It encourages farmers to consider their business and the environment as an entity, to farm in balance with nature. It recognises that farming has to be a profitable enterprise, yet not exploitative of the natural resources at its disposal. LEAF has grown beyond expectations in the 21 years since its beginning in 1991. Its core objectives were and remain “Building public awareness of food and farming and developing more environmentally friendly farming systems”. The basis of LEAF was aired by David Richardson, its first Chairman, in the first newsletter published April 1992 ....

The basis of LEAF since 1991 has been the development of practical guidance on integrated management. Central to that guidance was the LEAF audit, which began in 1993 as a self-assessment form to monitor and evaluate farming practices, and the accompanying Practical Guide to Integrated Farm Management. The audit has been repeatedly revised over the years to incorporate experience, technical developments and scientific advances in farming. Further to the audit, LEAF has produced a series of advisory tools for the assessment and management of biodiversity, water, soil and drainage systems. 

More on the Green Box, the LEAF Water Management Tool, Simply Sustainable Soils, the LEAF Marque, Demonstration farmers and innovation centres, Open Farm Sunday, etc. ....

... is available through the following PDF file: LEAF: history, aims and achievements.

Diverting a disaster: food for thought

Jaleh Bahri-Esfahani, a doctoral student at the James Hutton Institute and the University of Dundee, gave a talk at Cafe Science Extra, Dundee Science Centre, 12 June 2013, on the topic Diverting a disaster: food for thought. She placed her project - on the ability of natural soil organisms to break down minerals in the soil and make them available to plants - in the contexts of global food production, pollution caused by agriculture and the depletion of global stocks of fertilisers such as phosphorus. She writes "To summarise our predicament, we have a restricted area of land with a high demand for its use, a requirement for doubling food production, downstream pollution of freshwater food stocks, and are depending on plant breeds that rely on a dwindling source of fertiliser." 

She likened modern crop breeds to modern humans, who would be unable to cope if relocated to a jungle, where food even if plentiful would be unseen. Modern crop breeds are 'lazy plants', selected to thrive on excess, 'no longer able to hunt, gather or form valuable relationships with soil'. 

Her article, based on the talk, is available as a downloadable pdf file 303kb: Diverting a disaster: food for thought

Why has yield stopped rising? 1. Background and questions


Between 1940 and 1990, the average yield of the main cereal crops in the UK rose about four-fold as a result of continuous scientific and technological innovation. Since then, yield has levelled. Given the many calls that agricultural production (per unit area) has to increase, the cause of this levelling must be understood before any realistic predictions can be given of the scope for further increase and how it might be obtained.

[PDF of previous article removed 19 June 2016, replacement in preparation].

Contact for this page: Geoff Squire

Learning & Resources

Printed from /learning/leaf/comment on 12/04/24 03:30:09 PM

The James Hutton Research Institute is the result of the merger in April 2011 of MLURI and SCRI. This merger formed a new powerhouse for research into food, land use, and climate change.