9
Sustainable agriculture
Gordon Conway
I can't remember when or where I first met Richard Sandbrook and who introduced us. It was probably at Richard Macrory's house in the early 1980s, at a gathering of environmental types, most of whom seem to have turned up on Harley Davidsons. I am probably maligning a lot of people but it was several incarnations ago for me.
What I do clearly remember is that Richard and I hit it off from the start. Both of us were passionately committed to changing the world, at least in helping to change the developing world, in a way that married development, the alleviation of poverty and environmental protection. We also both had a strong sense of humour; we were collectors of human follies, particularly the follies of development experts (of the Evelyn Waugh Scoop variety). We were both, under our respectable exteriors, iconoclasts unwilling to accept the conventional wisdom whether from government servants, international bureaucrats or NGO activists. Scratch the surface and you will find that neither of us have changed that much.
At the time I was Professor of Environmental Technology at Imperial College in London. I had created the multi-disciplinary Centre for Environmental Technology at 48 Princes Gardens in South Kensington in the mid-1970s and, within the centre, had formed a small team of young people, with ecology or economics backgrounds, who were working on the theory and practice of sustainable agriculture. Richard suggested we should cooperate, which we did, and then in 1986 I moved full time to IIED on a sabbatical, taking some of the team with me – Jules Pretty, Jennifer McCracken and Melanie Salter. (If I remember correctly, Richard felt that I would benefit from the less rarified atmosphere of Bloomsbury. The downside was the Northern Line and having to find all my own money. Actually, not only my money but others’ as well. I do remember Doreen Ward, IIED's accountant, catching me on the stairs and saying there was not enough to pay everyone at the end of the month and would I go over to Washington and do a job for the World Bank and come back with a fistful of dollars. I have had a healthy respect for the realities of NGO life ever since.)
Many, today, exercise proprietorial claims over the concept of sustainable agriculture. The organic farming lobby, in particular, claims it as being synonymous with organic agriculture, and the mixture of fact and myth that that entails. I usually point to Varro, the second-century-BC Roman writer and estate owner, who refers to agriculture as an ‘Art and Science ... which teaches us what crops are to be planted in each kind of soil, and what operations are to be carried on, in order that the land may produce the highest yields in perpetuity.’ As is common in the best of Roman writing, the definition is clear, elegant and succinct.
For me it all began in the late 1970s with the work that Ian Craig, also from Imperial, and I were doing with a remarkable team of agricultural scientists at Chiang Mai University in northern Thailand (Benjavan and Kanok Rerkasem, Manu Seetisarn, Phrek Gypmantasiri, Aree Wiboonpongse and Laxmi Ganjapan were the prime movers at the university). They were remarkable in many ways – for their intellectual skills and curiosity, their commitment to interdisciplinarity and their ability to work as a team. They had a strong sense of humour and half of the team were women, both of which helped. I have never come across a team like it since. They are still together, with notable additions and some younger faculty, although sadly they are getting close to retirement.
What we did together has been written about elsewhere, but in essence we developed a technique called agroecosystem analysis as a tool for the holistic analysis of agricultural development. We defined agroecosystems as ‘ecological and socio-economic systems, comprising domesticated plants and/or animals and the people who husband them, intended for the purpose of producing food, fibre or other agricultural products’. We maintained that such agroecosystems had four distinctive properties – productivity, stability, equity and sustainability – and, most important, that these tended to be traded off against each other. For example, an agroecosystem with high sustainability might have low productivity and vice versa. The point of this analysis, although interesting in its own right as an academic exercise, was to help identify the key questions that would help design a development pathway in which the trade-offs between the properties could be minimized. The Chiang Mai team subsequently used the analysis to identify the key questions for the Chiang Mai valley and built a research programme on this.
The technique rapidly spread to other countries in Southeast Asia and in 1984 an Indonesian sister organization called Kelompok Penelitian Agro-Ekosistem held a conference in Java entitled ‘The Sustainability of Agricultural Intensification in Indonesia’. I think that can justifiably lay claim to being the first conference explicitly on sustainable agriculture.
Although agroecosystem analysis was intended as a technique for identifying key research questions, we soon found that it had other uses not least, as we learned from a colourful experience in the Philippines, in dispute resolution. The US Agency for International Development (USAID) had constructed a small dam at the outlet of Lake Buhi in Bicol Province in order to provide irrigation water for downstream rice growers. But, as so often happens in such situations, the upstreamers did not like it, in fact were hopping mad – to the extent of getting the New People's Army (NPA) to stand armed on the dam to ensure that it did not function. In 1986 USAID asked IIED for help and Richard happily volunteered me. On arrival in Manila the USAID office provided us with a bulletproof car and pointed us in the right direction. We enlisted the help of Professor Percy Sajise of the University of the Philippines whose team was by this time expert in agroecosystem analysis. A week of mapping, diagram-making and interviewing provided a wealth of material that we then used for a workshop in a local hotel. The villagers, upstream and downstream, showed up, as did officials from the relevant Manila government agencies and also some representatives of the NPA. After three days of intensive argument around the maps and seasonal diagrams we had a resolution – involving staggered releases of the water – which seemed to leave everyone happy.
THE BREAKTHROUGH: PARTICIPATORY APPRAISAL
But it was two years later when we had moved to IIED that the breakthrough came. Like most breakthroughs, although it seemed revolutionary at the time, none of us could figure out why we had not thought of it before. The Swedish Red Cross, acting on behalf of the Ethiopian Red Cross, asked us to go to Wollo Province in Ethiopia to help them plan development priorities for the region which only four years before had suffered from a massive famine, killing nearly half the inhabitants. Jenny McCracken and I went, and with us, at the suggestion of the Swedish Red Cross, Robert Chambers of the Institute for Development Studies at Sussex.
Robert and I had known each other for some time but had never worked together. We started off with a degree of mutual suspicion and a major disagreement over who should use the single electric outlet in the room in Wollo we had been allocated. I wanted it to plug in my computer; Robert insisted that the priority was for his kettle to brew tea. We managed, with Jenny's help, to get that sorted out and then began to tackle the seemingly more difficult task of reconciling our agroecosystem analysis with Robert's skills in semi-structured interviewing. I was wedded to the discipline of maps and diagrams; Robert was insistent that it was only through free-flowing questions that one got at the truth. Of course, as was soon obvious, these approaches complemented one another and the workshop began in this way, with teams from the Red Cross and government agencies walking though the villages interviewing farmers and, at Robert's insistence, climbing to the tops of the hills to construct transects (it was one such climb that uncovered the existence of cultivated gully plugs, crucial to the agriculture yet ignored in the government's push to resettle everyone in the new villages in the valley bottoms).
The workshop was going well, apart from one day when Robert kept his team out way beyond curfew and we had to do some political smoothing. Then, about half-way through, Robert had a brainwave. Why, he asked, did the experts have to draw all the maps and ask all the questions? Why could the farmers not do this themselves?
From then on we increasingly involved the farmers in the exercise, not just as passive objects of investigation but also as genuine partners in the process of description and analysis. What they knew and how they expressed it, was a revelation for most of us. I remember sitting down with two farmers while they described, using a fascinating process of spatial and temporal mapping, the number of days of rain per month – for the previous ten years! One day Robert and I with our respective teams developed two different types of ranking procedures for the farmers to use. The purpose that day was to determine which trees they would like to plant (their priorities turned out to be very different from those of the forest department extension workers). Robert's technique was called matrix ranking and mine was pairwise ranking. To this day we argue their respective merits. Last year I got a kick, standing in a field in western Kenya, listening to a woman farmer rank the six different maize varieties in her trial plots. How long, I asked, have you been doing pairwise ranking? She gave me a withering look and replied ‘We have always done it in Kenya.’
A few weeks after the Wollo exercise, Jenny McCracken went to a coastal district of Gujarat in India and tried out a fully participatory exercise for the Aga Khan Rural Support Programme (India) (AKRSP(I)). When I asked her how it went, she said that on the final day of the work in one village, they held a meeting to discuss the analyses and, rather than the 60 or so villagers they had expected would attend, they were overwhelmed by a turn-out of 700! A key innovation from this work with AKRSP(I) was that the farmers not only played the main role in constructing the visual analyses, but they also took charge of presenting these analyses to the rest of the village. This meant that the village-level review had an altogether different dynamic than before, as the villagers were less deferential to their peers than they would have been to the ‘outside experts’, and were more apt to question and correct the findings.
In the same year Jules Pretty and I went to the Alpuri Valley in northern Pakistan to carry out a participatory exercise on behalf of the Swiss Development Corporation (SDC). SDC felt that the valley might be an appropriate setting for a fruit and vegetable development project. It is a somewhat inaccessible place, off the Swat Valley. With a small team of Pakistan agricultural and development experts we spent the first night in a Forest department guesthouse on the ridge high above the Alpuri valley. As was customary on these trips we listened to the BBC World Service which rewarded us with a reading of Kipling's poem about the six serving men – who, what, why, where, how and when. This was an ideal prompt for a discussion of interviewing techniques (we felt rather like partisans in occupied France who had just received a special coded broadcast from London's Bush House).
The next morning we went down into the valley, marvelling at the fine chalet-like dwellings perched on the mountainsides. No wonder, we thought, that the Swiss felt it had promise! Our first interviews soon provided an explanation. Most of the men of the valley spent nine months of the year working in the coal-mines of Quetta. They were relatively well paid – hence the fine houses, and hence also a lack of interest in becoming fruit and vegetable garden-ers. It was a good lesson in the role of semi-structured interviewing. However, the exercise did provide another example of the value of participatory approaches, in this case leading to an agroecosystem mapping of the valley. Like so many participatory appraisal techniques, it was simple. We went to one village and asked them to describe how their village and its farmland differed from another village we could see across the valley; then we went to the other village and reversed the process. By the end of the week the valley was zoned, effectively by the farmers themselves.
These were some of the beginnings of what came to be known by a bewildering plethora of names, ‘participatory rapid rural appraisal’ by us at IIED, and later ‘participatory rural appraisal’, following parallel innovations by colleagues at the National Environment Secretariat, Kenya, and Clark University, USA. (Other names such as ‘participatory analysis and learning methods’ (PALM), ‘méthode accélére de recherche participative’ (MARP), reflected the different approaches that mushroomed at the time, driven by local needs and customs). Robert and I felt that it was crucial for this not to become a bureaucratized methodology, and set ourselves against manuals and textbooks. Instead, we established an informal newsletter, based at IIED, initially called RRA Notes. Later, the newsletter was renamed PLA Notes (PLA for ‘participatory learning and action’) in recognition of the widening array of participatory research and development approaches. The idea was to provide a forum for practitioners to describe their experiences and innovations and so disseminate good practice. We envisaged that new ideas reported from an African village one week would be tried out in an Asian village the next – and that has happened.
Today PLA Notes has an audience of several thousand individuals and institutions scattered throughout the world. Since its launch in 1988, 42 issues of the Notes have been published, documenting methodological challenges and innovations across a wide range of sectors and thematic areas, from community water management to participatory monitoring and evaluation, and from sexual and reproductive health to participatory urban appraisal.
Looking back, it is fair to say, the process has been a revolution. PLA embodies a set of methodologies, an attitude and a way of working which has finally challenged the traditional top-down process that has characterized so much development work. Participants from NGOs, government agencies and the research centres have rapidly found themselves, usually unexpectedly, listening as much as talking, experiencing close to first hand the conditions of life in poor households and changing their perceptions about the kinds of interventions and the research needs that are required. But, of course, it has not been without its problems. At times it has had the trappings of a fad. Banks and other aid agencies have inserted it as a requirement in project designs without ensuring just how genuine was the participatory element. In the beginning, some critics saw it primarily as an academic exercise. But the practical value soon became apparent, and hundreds, if not thousands, of development projects and programmes are demonstrably better for adopting the approach.
At IIED, however, PLA was only one of our preoccupations. We continued to be exercised by what is meant by sustainable agriculture. At the invitation of Johan Holmberg, then at the Swedish Agency for International Development (SIDA), we began a series of small bulletins that he christened Gatekeepers. The idea was to provide busy policy-makers and development experts with some windows into the theoretical and practical world of sustainable agriculture, emphasizing new findings in a clear and concise manner. The first, which Jenny and I wrote, described the findings of one of my then students, Michael Loevinsohn, that pesticide use on rice in the Philippines was apparently causing heavy mortality and morbidity among farm workers. That was Gatekeeper 1, issued in 1987, and the series has continued ever since, going out to several thousand policymakers, planners and academics in over 120 countries. Gatekeeper 100, entitled ‘Agri-Food Systems, Livelihoods and the Environment in a Globalizing World’, by members of the current Sustainable Agriculture team, was published in mid-2001.
We also continued to publish books and monographs. One important books was After the Green Revolution,1 which I co-authored with another IIED researcher Ed Barbier. He is a resource economist, now at York University; the discipline of combining agriculture, ecology and economics was a challenging experience. The other noteworthy book was Unwelcome Harvest: Agriculture and Pollution,2 authored by Jules and myself. It was a very large book (my wife irreverently referred to it as a very expensive doorstop), but to this day it is the only authoritative compendium of the polluting effects of agriculture.
INTEGRATED AND COMPLEMENTARY APPROACHES
As I indicated at the beginning of this chapter, one of the problems of sustainable agriculture, as so often defined today, is that it means all things to all people. It has become an all-embracing term. Almost anything that is perceived as ‘good’ from the writer's perspective can fall under the umbrella of sustainable agriculture – organic farming, the small family farm, indigenous technical knowledge, biodiversity, integrated pest management, self-sufficiency, recycling, and so on. The problem with this is that it ignores the inevitable trade-offs in agricultural development – between productivity, equitability, stability and sustainability. Ignoring them is not only self-delusory, it is also dangerous since it lulls both expert and farmer alike into believing that the problem is solved and everyone is content.
The classic example of an approach to the trade-off issue is integrated pest management (IPM), which preoccupied me in the 1960s. Pesticides are frequently highly effective means of killing pests, and hence can be very productive, resulting in high and stable crop yields. But their use is often not sustainable – pests can evolve resistance and pesticides can wipe out the natural enemies of pests, so producing pest resurgences. Pesticides can also be inequitable in their effects – expensive to use and also hazardous, with the poor suffering most.
The alternatives may be better in some respects – biological control, or the use of cultural techniques such as intercropping – may be more sustainable, but they may be less effective. The trick in IPM is to combine these different techniques, making minimal use of safe pesticides, only when and where wanted, along with appropriate biological and cultural controls. There are now countless examples of IPM working in the developing world, the best known being the control of the brown planthopper in Indonesia. But it has taken the best part of 30 years for that to happen, in part because the trade-off question is still insufficiently addressed. For example, biological scientists find effective ways to control pests but often ignore the cost to farmers – especially the labour costs – and, as a consequence, the approach is simply not adopted on a wide enough scale.
An allied concept is integrated nutrient management (INM). In some respects this is an approach that is nearly a hundred years old. Farmers, soil scientists and agronomists have long known that organic matter – broken-down plant material and animal manure – is essential for healthy agriculture. When applied to and incorporated in the soil it creates a soil structure that allows for root development and the uptake of nutrients – both macro- and micro-nutrients. But organic matter is often relatively poor in the nutrients themselves. In some situations the nutrients can be created by nitrogen-fixing bacteria or blue-green algae. But the kind of high yields that developing-country farmers now need are, with a few exceptions, possible only with the application of synthetic fertilizers containing nitrogen, phosphorus and potassium and, where appropriate, micronutrients.
INM is an approach that recognizes this essential complementarity. Its greatest potential today lies in Africa. There are some who argue that what Africa needs to feed itself is organic farming. But this ignores the reality of current practices. In some respects, Africa is already following a form of organic farming. Pesticides are rarely used, and synthetic fertilizer inputs are only about 4 kilograms per hectare (compared with 42 kilograms per hectare in Asia). As a consequence, cereal yields average only 1 ton per hectare (yields comparable with those in Europe under the Roman Empire 2000 years ago) while in Asia the average is nearly three times more. Such low yields mean, in turn, that there is little organic matter to put back into the soil.
A case in point is production in Central Uganda of bananas, a key staple for many hundreds of years that is in severe decline, partly because of pests and diseases, but primarily because of the nutrient exhaustion of the soil. Bananas take out large quantities of potassium, and unless it is replaced yields inevitably fall. Over much of Africa the soil is being effectively mined in this way. (In parts of western Kenya the nitrogen is being removed at some 125kg/ha – equivalent to what European farmers regularly put on their land each year.)
Part of the problem is the cost of synthetic fertilizers. In countries such as Malawi the cost to poor farmers is many times greater than what European, or even Asian, farmers are paying. On average, fertilizer cost in Asia is equivalent to the price of 2-3 kilograms of grain, but 6–11 kilograms in Africa. It is not surprising that African farmers use so little fertilizer. Subsidies are part of the answer, at least until efficient small-scale private marketing systems are developed, but European and US governments, who subsidize their farmers to the tune of over $70 billion a year, have, through their influence on the World Bank and the IMF, insisted that fertilizer use should not be subsidized in the developing countries.
However, synthetic fertilizers, it must be stressed, are only part of the answer. The essence of INM is to use organic and inorganic techniques in partnership. Legumes, in particular, have been proven to contribute to high sustainable cereal yields. But again, the costs in labour and time have to be factored in. Far too often, experimental results are difficult for farmers to replicate. There is much talk today of the need for scaling-up of such approaches, but this can happen only if the demand and the feasibility are evident and can be easily built upon.
These were the kinds of issues we debated during the two years of my stay at IIED. They continued after I left. Jules Pretty took over the team for a couple of years, producing an excellent book, Regenerating Agriculture3 that persuasively argues the case for the role of indigenous resources in agriculture. This was followed by another book, The Living Land,4 with a focus on agricultural systems in industrialized countries. Jules then became Professor of Environment and Society at the University of Essex where he has recently produced an important review of more than 200 sustainable agriculture programmes worldwide. These programmes and projects include organic farming, strictly defined, but also IPM and INM approaches. As he demonstrates, together these have been adopted at a phenomenal rate over the last decade. The combined area within such programmes is now 29 million hectares, up from only about half a million hectares in 1990. The current total is about 3 per cent of the agricultural area of developing countries.
As I was leaving IIED, Ian Scoones, another of the Imperial College team, joined the programme and continued his work on the ecological and socio-economic approaches to range management by pastoral communities in Africa. In this he teamed up with Camilla Toulmin and the Drylands Programme at IIED. He is now at the Institute of Development Studies (IDS) in Sussex, and has several important books to his name, including Range Ecology at Disequilibrium,5 and Living with Uncertainty6. Jenny McCracken stayed at IIED until 1991 before going to work in Washington DC, partly with the World Bank. She is now a freelance consultant in Switzerland, working with a number of different international development institutions.
After Jules Pretty left IIED at the end of 1996, John Thompson took over the leadership of the group, which was renamed the Sustainable Agriculture and Rural Livelihoods (SARL) Programme, and established a multi-disciplinary team of six researchers and four information and communications specialists. It has continued to prosper, focusing on the political ecology of agri-food systems in both developing and industrialized countries. Today, SARL maintains an integrated programme of collaborative research, information exchange, and advocacy and advisory support with partners on six continents.
As for myself, I left IIED in 1989 to take up the post of Representative for the Ford Foundation in New Delhi. There I managed to find some time to continue the IIED work, especially during the year when Robert Chambers was in Hyderabad. On holiday at Kulu in the Himalayan foothills we produced an IDS discussion paper on the topic of sustainable livelihoods – arguing against the sectoral approach to alleviating poverty and instead taking a holistic perspective that saw people's livelihoods as the basis is for integrated development. For a short conceptual paper it has had considerable impact. Many aid agencies (including the Rockefeller Foundation!) now take sustainable livelihoods as their basic paradigm.
From India I moved to Sussex in 1992 to become Vice-Chancellor of the University of Sussex. Very little of my time was taken up with issues of sustainable agriculture – except for one important period when I headed a small committee to produce a new vision for the Consultative Group on International Agricultural Research (CGIAR). The vision – which eventually became a book, The Doubly Green Revolution7 – owed much to the IIED work. It called for a new agricultural revolution for the developing world, which was as productive as the old Green Revolution, but sustainable, equitable and environmentally friendly.
In 1998 I took over as President of the Rockefeller Foundation in New York. A major theme of the Foundation is Food Security, especially for Africa, and a great deal of the $30 million plus that we spend annually on this topic goes in grants to universities, research institutions and NGOs, primarily in the developing countries, who are working on techniques of IPM, INM and other related approaches to productive, sustainable and equitable agriculture.
To the traditional concerns of sustainable agriculture is now added the challenge of biotechnology and, in particular, genetically modified (GM) crops. I want to finish by discussing briefly some of these issues. At the Foundation we have spent the last ten years funding the training of Asian scientists in rice biotechnology. It has been a highly successful programme and there must now be nearly 1000 biotechnologists working on rice and other crops in universities and research institutes in countries such as China, the Philippines, Vietnam, India and Thailand. Now we are turning our attention to Africa, and at the same time trying to move forward the intense public dialogue that revolves around GM crops.
We acknowledge that biotechnology approaches raise many legitimate questions. There are many potential hazards; some real, others imaginary. These need addressing by clear trials subject to public scrutiny, in both developed and developing countries. But there are also many potential benefits, especially relevant to creating more sustainable and equitable agricultural systems. For example, there is already evidence from China and Mexico of dramatic reductions in pesticide use following the introduction of ‘Bt’ cotton (incorporating the Bacillus thuringiensis gene). In the US, Roundup Ready soybean, in addition to significantly reducing farmers’ costs ($0.75 billion per year in the US), is resulting in less herbicide pollution of rivers, and, more important, the widespread adoption of various no-till rotations that are helping soil conservation.
In the developing countries there is considerable potential for pest- and disease-resistant GM crops, especially as part of IPM programmes. Control of the weed Striga that causes enormous damage in parts of Africa, could be aided in this way. Higher soil nutrition helps, and there is promise in cultural control methods, for example, intercropping with the legume Desmodium, but it may not be enough. Another alternative may be herbicide treatment of the seed, but this will require herbicide-resistant cereals. Another is to transfer, using a biotechnology approach, Striga resistance to maize from sorghum or from wild maize relatives. It is a complex problem and there will be no simple magic bullet but biotechnology could play an important role in an integrated programme.
Many of these benefits are some way off, but other techniques of biotechnology – particularly tissue culture and marker-aided selection – are already producing real benefits in farmers’ hands. Pioneering work in Kenya and Uganda involving local universities and government research institutes has produced bananas, using tissue culture, that are free of viruses and other pests and diseases. Farmers are setting up their own nurseries in villages and selling on the banana suckers to their neighbours.
Most exciting, however, has been the development of the new rices at the West Africa Rice Development Association (WARDA), based in Côte d'Ivoire. Rice consumption is growing dramatically in West Africa, partly fuelled by population growth, partly by increasing consumer demand. But local production is falling even further behind demand. The region is importing about half of its requirements, some 3.5 million tons at a cost approaching 1 billion dollars.
But now WARDA has achieved the daunting task of crossing the African rice species (Oryza glaberrima) with the Asian species (Oryza sativa). The crossing is difficult, because of the high incidence of resulting sterility. But the application of embryo-rescue tissue culture has overcome the problem, and the use of another advanced technique of biotechnology, anther culture, has enabled WARDA scientists to fix some 3000 new rice lines resulting from the crossing, backcrossing and subsequent selection.
The rices have many of the characteristics of their African ancestors. They grow well in drought-prone, upland conditions and their early vigorous growth crowds out the weeds that ordinarily require vast amounts of labour for their removal. They are resistant to local pests and disease, tolerant of poor nutrient conditions and mineral toxicity. But as they mature they take on some of the characteristics of their Asian ancestors, producing full panicles of non-shattering grain, and they are ready for harvesting in about 100 days.
Under low inputs they yield up to 3 tons per hectare, and with high inputs up to 5 tons (current average yields in the region are barely above 1 ton). WARDA has also brilliantly combined the high science of biotechnology with a central role for farmer participation. Given the great diversity of African ecologies, the traditional top-down extension approach is inappropriate. In several countries, farmers are conducting their own farm trials of over 300 of the new lines. Dissemination of the new seed is also relying on the traditional village systems of barter and sales among farmers. As a consequence the spread of the varieties is very rapid.
In Guinea, some 160 farmers evaluated the first new lines in 1997, just a year after they were produced at WARDA. With World Bank assistance, 20,000 hectares were planted in Guinea in 2000, and this year it will approach 90,000 hectares. Guinea's increased rice tonnage will save some $13 million in import costs.
In many respects this is the Doubly Green Revolution in action. It marries the best of modern science with genuine farmer participation in a way that is highly productive, sustainable, equitable and environmentally friendly. The sustainable agriculture programme at IIED can claim no direct credit, but many of the concepts, ideas and techniques that we developed have become part of the agricultural mainstream and helped to inspire and shape efforts such as this. We can be reasonably proud of ourselves – not a bad job!
NOTES
1Conway, Gordon and Edward Barbier (1990) After the Green Revolution, Earthscan, London.
2Conway, Gordon and Jules Pretty (1991) Unwelcome Harvest: Agriculture and Pollution, Earthscan, London.
3Pretty, Jules (1995) Regenerating Agriculture: Policies and Practice for Sustainability and Self-Reliance, Earthscan, London.
4Pretty Jules (1998) The Living Land, Earthscan, London.
5Behnke Jnr, Roy H, Scoones Ian and Carol Kerven (eds) (1993) Range Ecology at Disequilibrium: New Models of Natural Variability and Pastoral Adaptation in African Savannas, Earthscan, London.
6Scoones, Ian (ed.) (1993) Living with Uncertainty, IT Publications, London.
7Conway, Gordon (1995) The Doubly Green Revolution, Comstock/ Cornell Paperbacks, Cornell University Press.