138 scientists, farmers and policy makers joined us at St. Catherines for the event. Read on for a summary by Independent Ecological and Environmental Consultant Geoff Radley.
Rethinking Agricultural Systems – report of the BES/AAB conference held in Oxford 18th – 19th December 2013
Why do we need to re-think agricultural systems?
Barbara Smith introduced the conference by stressing that the fundamental challenge facing agriculture was that of how increase agricultural production whilst reducing its adverse environmental impacts. This was also the principal conclusion of the 2011 Foresight Report on the Future of Food and Farming (Foresight 2011).
Jonathan Foley, Director of the Institute on the Environment at the University of Minnesota provided a concise summary of the global context. He explained that, for the first time in human history, we are starting to hit the physical limits of the planet. Agriculture is making major demands on the earth’s resources. It occupies 40% of the land area, uses between 20 and 90% of available freshwater and makes a very significant contribution to emissions of greenhouse gases. Whilst he stressed that meeting current demand for food was primarily an economic and political problem, rather than an ecological one, agricultural production would need to double in coming decades to meet the extra demand for food resulting from population growth and dietary change.
Achieving a doubling of food production without causing irreparable environmental damage is going to be difficult. The area of agricultural land could only be increased significantly by destroying ecosystems such as tropical rain forest that are vital for the provision of other ecosystem services. Yield growth, which has been the main factor behind the increases in production in recent decades, also seems to have reached plateau for some crops, though yields of maize and soya bean are still increasing.
Jonathan suggested a number of global issues that, if tackled together, could help food production keep up with demand whilst also improving the sustainability of agriculture. These are:
- Halt deforestation – clearing forest does enormous environmental damage, and most of the cleared land produces very little food.
- Drive up yields, particularly of maize, in areas where there is a big gap between the yields that are possible and those currently being achieved. This will require effort to optimise nutrients, water and soils but can be done using current technology.
- Improve the efficiency of resource use – of water by finding more efficient irrigation techniques than spray irrigation and of fertiliser by optimising N applications.
- Change diets – The US corn belt could feed 16 vegans per hectare but only 5 people on a normal western diet. Dietary change doesn’t have to involve everyone becoming vegan though. Beef conversion rates are only 3 to 5%, but poultry conversion rates are between 16 and 40%.
- Reserve agricultural production for food – Currently 40% is used for non-food crops, particularly biofuels.
- Reduce food wastage, particularly losses due to poor storage.
Jonathan concluded that the bulk of the supply side issues could be tackled through the application of current technologies in 6 critical areas of the world, which don’t include N W Europe, where agriculture is already highly productive and where much of the reduction in farmland biodiversity associated with intensive agriculture has already occurred.
However, Professor Tim Benton’s analysis included consideration of the likely impact of a 4o C increase in mean global temperatures. He said this would increase the significance of NW Europe, as this is just about the only major food producing area of the world where climate change may actually benefit food production over the next 50 years. This was likely to lead to very strong market and political drivers to maintain and further increase production in this area. Ensuring that high levels of production can be sustained alongside the other ecosystem services that we need from our limited land area will be the major challenge facing UK agriculture.
Tim also agreed with Jonathan that global sustainability could only be achieved if issues of diet and waste were also tackled.
What are the ways in which agricultural systems could be re-thought?
Accepting that there are significant challenges relating to changing the pattern of demand for food and reducing food wastage that need to be tackled to ensure future food supplies, there remains a need to address how food is produced. The conference heard about a very wide range of possible ways in which current agricultural systems could be changed to help improve productivity and reduce environmental impact. These can be grouped into four categories:
- Incremental improvements in resource use efficiency using the best currently available technology
- Improvements in resource availability and utilisation through better use of soil processes and symbiotic organisms.
- Improvements in overall yield through more diverse agricultural systems
- Landscape-scale approaches, where sustainability is achieved partly through the optimal use of agricultural land and partly through management of the landscape elements such as boundary features, wetlands and farm woodlands that are not directly supporting production.
The key findings presented at the conference under each of these categories were as follows:
Incremental improvements in resource use efficiency
These were not a major focus of this conference, but Susanne Padel (Padel et al. 2013) showed that calculating NPK balances could improve nutrient management and resource use efficiency in low input and organic dairy farms, despite the difficulty of making accurate estimates of nutrient applications in such systems. Application of the method to a sample of 69 farms across the EU showed that there was very considerable room for improvement.
Tony Waterhouse (Waterhouse and Ricci 2013) provided insight into the question of whether extensive or intensive beef production was better for minimising greenhouse gas emissions, and also considered the impact of different systems on the conservation of biodiversity. His modelling suggests that for Scotland the optimal solution for minimising greenhouse gas emissions is to rear beef animals extensively but finish them intensively. It is however not easy to devise a system that simultaneously maximises production, minimises pollution and optimises biodiversity management.
Improvements in resource availability and utilisation through better use of soil processes and symbiotic organisms
Ron Stobart (Stobart and Morris 2013) explored the impact of cover cropping on soils and on yields. It describes the impact of two different cover crops and a clover bi-crop on soils and yields under a range of nitrogen application rates and cropping regimes. The clover bi-crop improved soil infiltration rates, which is likely to reduce soil erosion, nutrient loss and diffuse pollution, but had a variable impact on yields. Use of a legume mix cover crop was shown to produce a consistent yield benefit regardless of nitrogen application regime. None of the treatments showed a clear net short term financial benefit, but several have the potential to deliver longer term economic benefits.
The paper presented by I Brito (Brito et al. 2013) explored the potential for using mycorrhizal fungi to improve crop yields and increase resource use efficiency. The potential benefits of mycorrhizal fungi for crop plants have been known for some time, but the cost of inoculation and the short cropping cycle have meant that such benefits were considered too difficult and expensive to realise. The paper describes a new approach in which the extra-radical mycelium of indigenous arbuscular mycorrhizal fungi was developed using mycotrophic plants and kept intact by lack of soil disturbance. In a greenhouse-scale experiment, this approach reduced the application rates of phosphate needed to maintain yields in intensive systems and protected crops against manganese toxicity. Brito’s work suggests that at field scale, naturally occurring weed species could be used in combination with zero or minimum tillage to encourage mycorhizzal colonisation of wheat and other crops, and that this would allow yields to be maintained with lower fertiliser inputs and allow cropping to be more resilient.
Pete Iannetta (Iannetta et al. 2013) identified the inefficient use of nitrogen as a major cause of the adverse environmental impacts of modern conventional farming practices. The use of nitrogen-fixing legumes in legume-supported cropping systems, combined with precision farming technologies and conventional pest and disease control measures, have the potential to allow yields to be maintained whilst reducing adverse environmental impact. To maximise the benefits of legume-supported cropping systems it is important to develop new markets for grain-legume derived food products. These have additional potential benefits for human health.
Improvements in overall yield through more diverse agricultural systems
The links between diversity, productivity and resilience in ecological systems were discussed by Martin Wolfe (Wolfe and Smith 2013). He suggested that increased diversity of cropping could hold the key to sustainable intensification and he set out the potential advantages of agroforestry as a means of increasing the diversity of cropping. He cited studies showing that agro forestry systems can increase carbon sequestration, reduce nutrient leaching, improve soil conditions, benefit biodiversity and increase overall productivity as measured by the Land Equivalent Ratio. He did not dwell on the factors inhibiting commercial uptake of agroforestry systems, but a major factor does seem to be that they are much more labour intensive than conventional monoculture systems.
The potential for increased diversity in agricultural systems to improve the resilience and sustainability of food production systems was explored by Hannah Jones (Jones et al. 2013). She presented results from two detailed studies. One of these showed how the vulnerability of pollen development, flowering and grain set to abiotic stress could be ameliorated by genotypic diversity and through the buffering effect of pollinating insects. The other showed that leys containing multiple legume species as well as grass supported a greater abundance of bumblebees early and late in the season, when pollen is particularly scarce. Such leys also produced better quality forage with a greater percentage of crude protein.
Her paper went on to review the potential benefits of increased within crop and within farm diversity. She detailed the potential advantages and disadvantages of increased intraspecific diversity within a crop and pointed out that more work is needed to find the right balance between maximum productivity and increased resilience under different conditions.
Sally Westaway (Westaway et al. 2013) included a specific example of the potential benefits from agro-forestry; alley cropping of willow and hazel between organic arable can produce land Equivalent Ratios of 1.4 to 1.5. She suggested that the benefits could be further increased by using nitrogen-fixing trees or shrubs, something also advocated in Pete Iannetta’s paper (Iannetta et al. 2013).
Tim Benton warned against using narrow definitions of sustainability, such as GHG emission reductions, to assess agricultural systems as these can have perverse environmental effects. As sustainability is a complex and multi-faceted concept, it could only be achieved through smart, multi-functional landscapes. Achieving such landscapes would require action at a range of levels, and Governments would have a critical role. If there was a commercial argument for this approach it was that greater diversity might improve the resilience of agricultural systems.
An example of this approach was provided by Chris Stoate (Stoate & Szczur 2013) for a mixed farming catchment in Leicestershire. Approximately 7% of the arable land is outside the normal cropping cycle at any one time and is managed to produce multiple ecosystem services. There is a trade-off between food production and other ecosystem services, but the loss of production is minimised by taking the least productive areas out of production and by the intensive, multi-functional environmental management of these areas. Some of the ecosystem services that these areas produce, such the supply of pollinating insects and crop pest predators, may also benefit crop yields, or at least make production more resilient. Reduced cultivation of the cropped land also reduces soil loss and improves soil structure and function.
Sally Westaway (Westaway et al. 2013) provided a specific example of multi-functional management of non-cropped areas, showing how existing hedges could be managed to produce modest amounts of biomass without detriment to the other ecosystem services that hedgerows provide.
According to Gavin Siriwardina (Siriwardina 2013) a landscape-scale approach can be tailored to benefit specific species and species groups. Enough must be known of the target species’ ecology to identify the resources that are limiting their spread and design management to provide these resources. If management is not tailored to species needs in this way, there is a risk that it will only benefit generalist species.
Felix Herzog (Herzog & Schuepp 2013) considered whether biodiversity conservation and agricultural production were best reconciled in Europe through land sharing or land sparing; in the more productive agricultural areas it is important to have an element of land sparing to allow for the survival of semi-natural habitats. These can provide ecosystem services relevant to agriculture, conserve endangered farmland species and allow non-farmland species to migrate through the agricultural matrix. In more marginal areas it is important to maintain low intensity production methods that can support large areas of valuable wildlife habitats whilst producing limited quantities of high quality agricultural products. Species which cannot easily be accommodated on agricultural land will still need to be conserved on dedicated nature reserves.
Most farmers prefer to separate environmental management from their cropped area, said Nigel Boatman, suggesting that small-scale land sparing is their preferred approach (Boatman 2013). Most farmers are very unwilling to modify their production practices solely in order to produce environmental benefits.
Nigel agreed with Felix Herzog that it is important to retain within intensively farmed areas those ecosystem services that are of importance to agricultural production. He also emphasised that in the UK, with its dense population leaving close to areas of highly productive farmland, it is important to ensure that even highly productive areas of farmland can support wildlife and provide attractive landscapes.
Christine Watson’s paper (Watson, Edwards and Topp 2013) concluded that re-integrating arable and livestock production could improve resource use efficiency, improve soil condition and reduce pollution. Re-integration at a landscape scale might deliver these benefits whilst also retaining the economic benefits of farm-scale specialisation.
How might change be achieved?
The conference heard a number of papers that focused on two questions; how change in agricultural systems might be achieved and what types of change should be prioritised.
Joern Fischer (Fischer et al. 2013) used the debate on land sharing versus land sparing to address the first of these questions, how to achieve change. He highlighted that much current debate is bogged down because the different groups involved do not accept the assumptions and values that the others use as their starting points. Environmentalists do not accept the assumption in the agricultural industry that ‘we must grow more’ and agriculturalists do not always appreciate the importance of the other ecosystem services provided by farmed land. A more constructive starting point for the debate might be the concept of land scarcity. Joern suggested that there should be less emphasis on trade-offs between ecosystem services and more on integration to optimise the sum total of the benefits that land management can provide. Returning to land-sparing versus land sharing he suggested that this was a false dichotomy which largely reflected the different spatial scales at which the problem of integration was being tackled.
Pablo Tittonnell addressed the need to respond to the challenge of sustainably increasing food production. Systems that are currently very unproductive need to be intensified and systems that are currently very intensive need the process of ‘ecologicalisation’. Increasing agrodiversity was key to this process and he gave a number of examples of ecologicalisation in practice. Pablo warned that there were no simplistic solutions and tried to describe a pathway to sustainability. Resource use efficiency would be a valuable first step but would not be enough on its own to achieve the goal. The main bottleneck in moving to more productive and sustainable systems was input substitution, the use of ecological processes to substitute for manufactured inputs.
Bill Sutherland advocated the maximum use of systematic reviews of the literature and warned of the danger of relying on experts. He advocated use of Delphic techniques for generating an expert consensus when called on to give advice.
Lisa Norton (Norton 2013) reminded the conference of the environmental cost of the first green revolution and stated that agro-ecology could play a vital role in helping to ensure that we learn from our mistakes. She emphasised the need to adopt sustainable production systems and outlined what some of the elements of these systems might be. These include:
- Optimising the use of agricultural land to provide the full range of ecosystem services in an integrated way, using both land sparing and land sharing at a range of scales, and recognising the dependence of agricultural production on biodiversity.
- Developing new approaches to intensive agricultural management including bio-fertilisation using mycorrhizae, improved targeting of nutrients and the selective use of GM technology, for example to transfer nitrogen fixation into major crop species.
Agro-ecologists may have some of the answers, but they do not have all of the knowledge necessary to develop new commercially viable, sustainable production systems. Lisa stressed the need for close collaboration with agricultural scientists and with practitioners.
Her paper also stressed that achieving change in agriculture is just as much about changing attitudes and perceptions as it is about new ecological insights or new technologies.
Some overall conclusions
- Achieving long term food security at a local and a global level is a complex challenge which is as much about economics, governance and future dietary preferences as it is about food production methods. There is nevertheless likely to be a need to increase food production and to do so in ways that do not further exacerbate environmental degradation, as recommended by the Foresight report.
- Although the UK is not in one of the six critical areas identified by Jonathan Foley as holding the key to sustainably increasing future food production, climate change may mean that the significance of NW Europe as a food producing area will increase in the coming decades, leading to intense commercial and political pressure to maintain and further increase food production.
- Through a combination of agri-environment schemes and voluntary measures, some progress has been made in persuading farmers to adopt small-scale land sparing approaches. These efforts need to be continued, as the semi-natural habitats and landscape features that they allow for help to broaden the range of ecosystem services that farmed land can provide.
- The next big challenge is to make the core farming operations of crop and livestock production more sustainable and environmentally benign, whilst also maintaining or increasing yields.
- There are no simple solutions to developing agricultural systems that are both more productive and more sustainable. The conference has however identified a number of interesting developments that could become elements of such systems:
At the field scale
- The integration of leguminous species into cropping and forage production in ways that improve soil structure and reduce the need for manufactured nitrogen whilst minimising the periodic nutrient releases that have been a feature of conventional organic systems
- The use of reduced tillage and developer plants to encourage mycorrhizal connections to the roots of crop plants to improve nutrient and water uptake
- The development of more diverse production systems such as agroforestry that can more efficiently exploit the resources of an area of land and so increase total yields per hectare, whilst at the same time reducing adverse environmental impact.
At the landscape scale
- The re-integration of arable and livestock production in ways that reduce the need for external inputs of nutrients and the production of potentially polluting waste materials
- The intensive and multi-functional environmental management of a small percentage of uncropped land in more productive and intensively farmed areas to sustain the biodiversity necessary to support agricultural production and provide other cultural and regulatory ecosystem services.
- Land sharing techniques that balance agricultural production against other ecosystem services such as carbon storage and biodiversity conservation in less productive extensively farmed areas
- The recognition that the optimal mix of ecosystem services that can be delivered by any particular land parcel will vary according to its physical characteristics and geographical location, suggesting that there is a need to develop new policy instruments to encourage optimal patterns of land management rather than always seeking to maximise the economic returns from agricultural production.
- Agro-ecology has some useful insights to bring to the development of new agricultural systems, but it doesn’t have all the answers. The development of such systems will require close collaboration with agricultural scientists, practising farmers, social scientists, economists and politicians.
Ideas to explore further with practitioners and agricultural scientists
Several speakers at the conference stressed that, in seeking to promote changes to agricultural systems, it is very important not to imply that agro-ecology has found a series of answers that the farming industry should simply take away and put into practice. Instead the need is to engage with mainstream agricultural scientists, agronomists, agricultural economists and with practising farmers and to understand their concerns and aspirations. From a shared understanding of the problem, it may then be possible to jointly develop new and innovative agricultural systems with the potential to be profitable and resilient as well as to allow for higher productivity and reduced adverse environmental impact.
This process of engagement could be framed as building on the report of the Defra-sponsored Green Food Group, which reported in July 2012 (Defra 2012). This report aimed to scope out how the goals of improving the environment and increasing food production might be reconciled. It included members from agriculture, food and environmental interests and it covered a number of farming sectors, geographical areas and food products. Much useful discussion was had, but the timetable was too short for potential solutions and complex interrelationships to be explored in detail.
As suggested by Joern Fischer, the discussion could be focused primarily on land scarcity, specifically on how we might produce more and impact less within the existing productive agricultural area. The areas explored during this conference which are directly relevant to this topic and which could form the basis for a constructive discussion about how they might be incorporated into future commercial agricultural practice include:
- The greater use of legumes to substitute for or supplement manufactured nitrogen fertiliser and to benefit soil structure (e.g the work reported by Stobart and Iannetta).
- Using mycorrhizae to improve resource use efficiency in crop plants (e.g. the work reported by Brito)
- How semi-natural habitats might be engineered to produce ecosystem services such as pollination and pest control that are as useful as possible to commercial agriculture (e.g. the work reported by Stoate, Siriwardina and Boatman).
- How livestock and arable farming might be commercially re-integrated at a landscape scale (e.g. the work reported by Watson).
- How novel systems such as agroforestry might be made commercially viable in a European context.
It might be wise to leave aside for the moment the wider questions about how to achieve the optimal balance of ecosystem services from land.
Ideas to explore further with other decision takers
This will depend in large part on the outcome of the dialogue with the practitioners, since this may well identify areas that require R&D funding to develop. However, the wider question of how to ensure the optimal use of land to produce the full range of ecosystem services is one where the role of Government at national and EU level is central. In this discussion it is important to bear in mind the risk that well-intentioned but ill-thought through policy interventions may cause perverse effects such as the displacement of food crops by biofuels mentioned by Bill Sutherland.
Boatman N. 2013. To what extent should environmental conservation be integrated with agricultural production? Aspects of Applied Biology 121, Rethinking Agricultural Systems in the UK pp 117-124
Brito I, Carvalho M, Alho L, Caseirio M, Goss M J. 2013. Practical exploitation of mycorrhizal fungi in agricultural systems. Aspects of Applied Biology 121, Rethinking Agricultural Systems in the UK pp 25-30
Defra 2012. Green food project conclusions, July 2012
Fischer J, Abson D J, Van Butsic, Chappell M J, Ekroos J, Hanspach J, Kuemmerle T, Smith H G, Von Wehrden H. 2013. Land sparing versus land sharing: moving forward. Aspects of Applied Biology 121, Rethinking Agricultural Systems in the UK pp 105-107
Foresight 2011. The Future of Food and Farming: Final Project Report. The Government Office for Science, London.
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Siriwardena G M. 2013. What if we designed farmed landscapes for birds? Aspects of Applied Biology 121, Rethinking Agricultural Systems in the UK pp 59-65
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Stoate C, Szczur J. 2013. An ecosystem services approach to productive land management in a farm-scale catchment. Aspects of Applied Biology 121, Rethinking Agricultural Systems in the UK pp 35-42
Waterhouse A, Ricci P. 2013. Choices in intensity of management in beef production farms: impacts on food production, carbon emissions and biodiversity potential. Aspects of Applied Biology 121, Rethinking Agricultural Systems in the UK pp 89-96
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Westaway S, Wolton R, Smith J, Wolfe M. 2013. Hedges: an ecological approach to biofuel production. Aspects of Applied Biology 121, Rethinking Agricultural Systems in the UK pp 89-96
Wolfe M, Smith J. 2013. Darwin, diversity and future land use. Aspects of Applied Biology 121, Rethinking Agricultural Systems in the UK pp 11-16