The Sustainability Of Managed Systems
Published on 20 July 2009 in Sustainability and Communities
Introduction
The long-term viability of farming in Scotland depends on the sustainable management of our agricultural habitats. Over the past half a century, intensification of crop production has led to the systematic erosion of arable biodiversity and the degradation of arable habitats in many parts of the world. This has raised serious concerns about sustainability and long-term food security, particularly where intensive management has had negative impacts on the functioning of agricultural systems.
Arable sustainability is the ability of a system to maintain stable levels of food production and quality in the long term without escalating requirements for agrochemical inputs to regulate the system. To achieve this, the arable habitat should be able to support stable populations of a range of plants, invertebrates and microbes that perform essential system functions including decomposition and nutrient cycling, detoxification of chemical deposits, pollination and the control of crop pests and diseases. As biodiversity is lost and these processes degrade, ever more inputs are required to compensate.
Sustainable management of arable systems for both food security and a healthy environment must therefore achieve a balance between maximising crop production, conserving arable biodiversity and maintaining ecosystem functions.
Key Points
- Intensification of arable systems to maximise crop yields in the short-term is likely to cause degradation of the arable ecosystem and reduce the sustainability of food production in the long-term.
- A degraded arable ecosystem is less likely to be resilient to future climate change scenarios, particularly where these affect water availability, seasonal fluctuations in temperature, and pressure from new pests and diseases.
- Management practices to improve the sustainability of crop production include reduced tillage, the use of nitrogen-fixing legume plants and inputs of nutrients from renewable sources. These approaches also help mitigate the effects of climate change by reducing the production and emission of greenhouse gases.
- Sustainable management practices should be complemented by cultivation of suitable crop varieties. Crop varieties are being developed with traits for enhanced water and nutrient use efficiency, and pest and disease resistance. These can contribute to the environmental and economic sustainability of arable systems by reducing the dependence of crop yield on high levels of agrochemical inputs.
Research Undertaken
Current research at SCRI focuses on developing crops and crop management to enhance the sustainability of food production. Crop traits are being identified that can improve stress tolerance and the efficiency of water, light and nutrient resource use, all of which result in the opportunity for reducing chemical inputs and improving environmental and economic sustainability.
Image: Potato varieties from the CPC are screened for environmental traits.
Sustainable crop protection practices are also being developed that focus on environmentally benign and cost effective ways to reduce the incidence and severity of crop pests and diseases.
Image: New sources of aphid resistance within the Rubus genus are currently under investigation for their potential utility in future cultivars.
Finally, soil and weed management strategies are being investigated to determine the optimal combination of management and crop variety for high yields whilst maintaining the biophysical resilience and ecological sustainability of arable systems.
Image: Testing the impact of reduced tillage and the addition of compost and slurry on system resilience.
Do these strategies actually result in improved sustainability of the whole system at the field scale and in the long-term?
To find out, we are establishing a new experimental research platform at Balruddery Farm near Dundee, for long-term studies on arable sustainability. The Sustainability Research Platform is the first of its scale in the UK and will provide a test-bed for new management practices and ‘sustainable’ crop varieties developed at SCRI.
Image: Balruddery Farm.
A contiguous block of six fields, covering 40ha, has been set aside for the experimental platform. Each field will be divided in half to test the effect of our ‘sustainable’ cropping system (in one half) by comparison with current commercial practice (in the other half) on long-term trends in yield and system health.
The rotation will run over six years, including potatoes, winter wheat, winter oilseed rape, winter barley, field beans and spring barley. The sustainable treatment will include reduced tillage, reduced herbicide and pesticide inputs, and inorganic fertiliser replaced by compost, undersown legumes and green manures. Both conventional and sustainable treatments will be flexible enough to track changes in commercial management practices and developments in sustainable technologies over time.
The general hypotheses are that ‘sustainable’ management, in combination with new crop varieties, will:
- maintain yield quality and yield stability at lower levels of agrochemical inputs
- reduce GHG emissions and nutrient leaching from the system, and
- enhance soil quality and arable biodiversity.
To test these hypotheses we will measure the responses of the whole system to sustainable management over a range of different crop varieties throughout each growing season over the course of at least three rotation cycles. Measurements will be grouped into six research areas: carbon and nutrient dynamics, soil biophysics, community dynamics, pest and pathogen populations, crop yield and quality, and field margin biodiversity. Trade-offs between these components of the system will be assessed through empirical and mathematical modelling.
The platform will provide a resource for continued collaboration with scientists from the Scottish MRPs and international organisations, and a demonstration site for knowledge transfer, exchange and education activities, including specifically a resource for university undergraduate honours and postgraduate projects. In addition, links will be developed with existing long-term experimental platforms throughout Europe.
Policy Implications
A major obstacle to change towards more sustainable farming practices in Scotland is the short-term economic situation of farmers and their appreciation of the importance of the longer-term, wider-scale environmental impacts of arable intensification for maximising yield: you cannot manage for long-term environmental sustainability if your immediate situation is not economically viable; nor are you likely to forgo immediate profit if you are not convinced that there is a long-term benefit.
There are a number of ways to address these issues.
Provide evidence. We must be able to demonstrate the longer-term environmental and economic costs and benefits of any new 'sustainable' crop variety or management practice at a scale that is relevant to the commercial farming situation. Trade-offs between different components of the system are particularly important here, as interactions between different parts of the complex arable ecosystem may radically alter the results predicted by smaller-scale, shorter-term studies. To help provide this evidence, the Sustainability Research Platform is involving as many scientists as possible from different disciplines and will generate detailed long-term datasets on the whole arable ecosystem from soil health and biodiversity to economics and crop yield.
Exchange information. To be useful, this evidence needs to be available and relevant to farmers, agronomic advisors, agro-chemical companies and policy makers. It is therefore important to engage the farming community, industry and policy makers early on in the project design and provide regular feedback as the work progresses. This can help raise awareness of the issues surrounding sustainable agriculture and develop potential solutions.
Image: A knowledge exchange event at SCRI.
Develop policy. In the Scottish Executive's "Forward Strategy for Scottish Agriculture" (2006), it is recognised that there is a need to review the priorities and direction of Scottish Agriculture. In this strategy, it is stated that "the priority for future agri-environmental policy in Scotland is to tackle the potential tensions between economic, social and environmental aspects of sustainable development, while finding more ways to benefit all three". The research described here is finding ways to improve sustainability, particularly the environmental and economic aspects, but to have any effect the results need to be translated into government policy and farming practice. This will require a longer-term view of the impacts of crop production than is currently normal, and may require incentives to encourage farmers to risk potential short-term loss for long-term environmental and economic gain.
Author
Dr Cathy Hawes, SCRI champion for Sustainability Cathy.Hawes@scri.ac.uk
Topics
Sustainability and Communities
