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Semelhante a Martin Wolfe Appg24 Feb2010
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Martin Wolfe Appg24 Feb2010
- 1. Farming for the Future – the Agroecological Approach Martin Wolfe The Organic Research Centre – Elm Farm, at Wakelyns Agroforestry, Fressingfield, Suffolk, UK
- 2. Agricultural Revolution - from 1700 to 1900, leading to and driven by the Industrial Revolution and the Enclosures Tools : soluble, synthetic fertilisers, pesticides, farm machinery – and the use of clover - particularly in the Norfolk Four-Course Rotation (wheat-barley-turnips-clover; imported from Flanders)
- 3. But Darwin was barely heard ........... The drive was to MONOCULTURE - and the loss of biodiversity - and this monoculture drive was exported all over the world - A schism between agriculture and the natural world was created which grew, and grew......
- 4. Wheat monoculture in space and time
- 5. Problems with Monoculture 1: loss of biodiversity and thus of ecosystem services – and of resilience Provisioning (food and water, materials, energy); Regulating (carbon sequestration, climate regulation, decomposition and detoxification, purification of water and air, pests and diseases, pollination); Supporting (nutrient dispersal and cycling, seed dispersal, primary production); Cultural (aesthetic, recreational and other benefits)
- 6. Problems with Monoculture 2: cereal powdery mildew – a serial spore-producer
- 7. The yield stability of a variety mixture
- 9. Wheat population in a hardwood alley
- 10. We need to re-integrate Agriculture and the Natural World -and the best way? AGROFORESTRY - the integration of tree management into agriculture
- 13. Winter wheat and hazel in 2006
- 14. Clover ley in 2008
- 15. Potatoes in 2009
- 16. Continuous winter wheat on 50 ha. 10-11 t/ha – mostly needed to pay for the synthetic inputs Continuous winter wheat on 50 ha. 10-11 t/ha – mostly needed to pay for the synthetic inputs
- 17. Surveying the food web ..........diverse hardwoods and hidden ley Highly diverse outputs – no external inputs except for some diesel
- 18. The Balance Sheet Monoculture Eco-agroforestry Artificial inputs High Low Outputs High, simple High, complex Labour Low High Resilience Low High Biodiversity Low High Sustainability Low High
Notas do Editor
- Many of the tools and synthetic fertilisers with which we are now familiar had their origins in this period. Systemic pesticides came later. All of the developments focused on replacement of labour and development of monocultures with higher yields and greater convenience for harvesting and processing. Since that time, use of the Norfolk four-course rotation, or similar, has almost disappeared.
- Opportunities for industrial processing and distribution of produce and 'value-added' derivatives were seized on – which fed back on the farming systems, promoting even more monoculture. The strength of this drive to monoculture and the concomitant massive reductions in biodiversity and ecosystem services caused the developing schism between nature and agriculture to widen increasingly quickly. It was, of course, during the Agricultural Revolution that Darwin published the 'Origin of Species', which showed how the Natural World had developed on the basis of abundant biodiversity. Darwin's explanations included examples from agriculture, from the rapidly disappearing time when biodiversity was accepted as the basis for farming practices.
- What we now see commonly in eastern England is vast areas of wheat monoculture. This 50 hectare field produces about half a billion identical wheat heads, often the same type in successive years. But this could also be soya bean in Latin America or oil palm in Indonesia. Having obliterated most of the local biodiversity, such monocultures are dependent on massive inputs of a wide range of chemical 'supports', all based, for their production and distribution, on large amounts of fossil energy, at a rough ratio of 10 calories in for every 1 calorie of energy produced.
- In the public eye, based on colourful televison documentaries, loss of biodiversity through agricultural development tends to be equated with, for example, the loss of habitat for the orang-outang, or a particular 'red list' bird or wild orchid. What needs to be made more clear, is that loss of biodiversity on the scales involved means loss of a wide range of organisms from the microscopic to the massive that are all involved in the provison of ecosystem services – those services provided by the natural world to keep itself, which includes us, alive, healthy and evolving.
- The impact of large-scale monoculture on the displaced biodiversity is complex. For example, a single variety (all identical plants) may be used on tens or hundreds of thousands of hectares, which means that a genotype of the pathogen able to grow on one of those plants will have access to all. Furthermore, the fungus itself evolved in nature, which means that it was faced continuously with diversity problems – surrounding plants would have been genetically different, perhaps different species. In other words, the probability of a single spore released by the pathogen being able to start a new infection would have been extremely low. For this reason, such pathogens evolved the ability to produce vast numbers of spores, just to survive. In a monoculture, of course, the probability of survival of each spore is several orders of magnitude higher, so rapid epidemic development follows. One response to this problem in industrialised agriculture, has been to develop and extend the use of fungicides. Because the fungicides are used as 'monocultures' they are also prone to being overcome by newly selected forms of the pathogen. The other approach is more breeding of resistant monocultures, leading to a 'boom and bust' cycle as each new variety is overcome sooner or later. Some now propose the use of GM varieties to provide resistance without the use of fungicide. But this is still a continuation of the monoculture approach, and only for a single character.
- A simple answer, known for a long time, which we developed further at the Plant Breeding Institute in Cambridge, is to grow physical mixtures of a few varieties each with different resistance characters. This mimics the natural world, reducing the probabiity of spore survival and the rate of epidemic development. The problem for the pathogen can be made much more difficult by changing the composition of the mixtures over years and locations. However, by using different varieties in the mixture, many characters additional to disease resistance may be affected. In this example, which represents a common result, the yields of each of the three varieties used vary unpredictably from year to year in different directions. The mixture, on the other hand, is much more stable with little variation from year to year.
- This approach was taken up on a national scale in the former German Democratic Republic for the spring barley crop, with outstanding success. Close collaboration among pathologists, breeders, quality experts and advisers ensured that the mixtures grown controlled the disease while providing high yields and good quality malt and beer. With the collapse of the country in 1989, however, the whole system was swept away in favour of a return to massive monoculture and the re-introduction of large-scale fungicide application. The teams that had organised the mixture approach were devastated. Our own view, given the success of the variety mixtures, was that we should be able to go much further by using populations of wheat and other crops, in which all plants are genetically different rather than identical so that a wide range of variable problems can be dealt with simultaneously.
- The wheat population trial in this example is growing in an alley cropping system integrated with a range of seven different hardwood tree species. The variability in the wheat is evident; it comes from genetic segregation among 190 crosses involving 20 different wheat parents bred over the past 80 years. As expected, the populations, like the mixtures, show greater consistency of performance over a range of different environments (locations and years) than their parent varieties. The extent of this consistency and its value is being analysed in current field trials.
- This example illustrates the potential value of integrating annual and perennial crops to provide genetic variation both within and between crops within a small space. This is referred to as agroforestry, although our particular interest is in eco-agroforestry, which is a way of maximising the agro-ecological approach to the system. By appropriate design and management, it represents a highly productive way of re-integrating agriculture and the natural world, to get away from the 'parks versus prairies' mentality.
- There are many potential advantages of such systems, as shown. Of major importance are three factors: a) such systems are often ancient in origin and still widespread and effective in many areas of the world (including parts of Europe) where monoculture and industrialised agriculture have not yet penetrated, b) where trials have been carried out on their productivity, they frequently show a Land Equivalent Ratio in excess of 1.2. This means that to obtain the same total output of crop and tree products from separate areas of those crops and trees, would need 1.2 times as much land. Moreover, such separated production would lose many of the other advantages associated with the agroforestry. c) because of the interactions among all of the components including those in the biodiversity encouraged by agroforestry, the inputs required to achieve such high productivity are solar radiation, air, water, soil and labour. There are disdavantages, of course, mostly related to inconvenience, relative to monoculture, for cultivation and harvesting. These can be dealt with easily. New skills are required for managing complex systems, and more labour; both of these could be regarded as disadvantages or advantages.
- Wakelyns Agroforestry is my own farm in the north-east of Suffolk. It occupies 23 ha with a range of alley cropping systems. These are largely hardwood trees (including fruit and nut-bearing species) or coppice trees (hazel or willow) which provide wood-chip heating for the farmhouse. The alleys are 12 or 18m wide and occupied by an organic crop rotation which includes field trials on a range of topics including development of wheat populations (Defra-funded Wheat breeding Link and EU-funded SOLIBAM – strategies for organic and low-input breeding and management). The Defra-funded LEGLINK project is analysing the potential for a complex mixture of useful legume species to replace monocultural use of white or red clover. The APPG would be welcome to visit.
- Wheat field trials growing in a hazel alley. In this particular year, with no inputs other than the previous ley crop, the wheat yields were similar to national average yields for 'conventional' monoculture wheat crops.
- Potato crop in 2009 following the ley crop shown in the previous slide. The potatoes are planted as a coarse mosaic of several different varieties. Blight started in July in the westernmost alley. From that initial infection, there was a clear gradient of decreasing infection from west to east due largely to the effect of the hazel hedges interfering with spread of blight pathogen spores from west to east.
- The neighbouring crops are large-scale wheat monocultures with some rape and occasional sugar beet. Wheat yields are high but most of the returns are needed to pay for the inputs of approximately 30 different chemicals applied to the crop at different stages. Biodiversity is poor.
- The 'technology' in this east-west view of Wakelyns' hardwood alley cropping, is being used by one of a pair of barn owls that were breeding on the site. They were popular representatives of the 'peak' of the food webs in the agroforestry systems.
- Regrettably, the differences between the two systems are not recognised in real value terms but only in terms of the cash value of commodity production. Society needs the commodity , but, increasingly, it needs the other outputs, resilience, biodiversity and sustainability, together with a reduction in artificial inputs. Unfortunately, this is not yet recognised so that the eco-agroforester does not receive a proper reward for the system that has a higher long-term value for society.