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PURE NO MORE? SEED MIXTURES CUT CHEMICAL USE
One of the tragedies about the way the West Germans annexed East Germany was that the communist state's good features were jettisoned along with the bad. Agriculture was no exception. The GDR put a lot of resources into plant breeding and its barley varieties were grown throughout Europe. However, in East Germany itself, they were rarely grown by themselves. Instead, the state farms planted mixtures of the advanced barleys in their fields because this enabled them to avoid using fungicides which would have had to have been imported from the West for precious hard currency 23.
This use of barley mixtures was based on work carried out in the early 1970s at the Plant Breeding Institute in Cambridge in England by Martin Wolfe and John Barrett which showed that if three spring barley varieties were planted together, the plants were healthier than if each was grown apart. This, the researchers found, was because if one strain lacked resistance to a particular fungus, each stem was further from infected stems of the same variety and shielded from them by the resistant types. Moreover, although one of the components of the mixture might yield better than the other two in a particular year, it was impossible to predict which it would be and, consequently, the blend gave the highest, most stable yield from year to year.
Although some Danish farmers used this information and grew mixed crops successfully, barley mixtures never caught on in the West because the maltsters to whom all the best barley is sold refused to take them. Malting is harder to control if the seeds in a batch do not have the same properties and those in a blend obviously do not: they vary in size, nitrogen content and the length of time to germination. Western malting companies had no interest in overcoming this challenge whereas the East German maltsters did. As a result, 92% of the 350,000 hectares of spring barley grown in the GDR at the time of reunification was a mixture (the remaining 8% was used to grow pure seed for blending) and an estimated 400 tonnes less of fungicide was used each year. East Germany's valuable exports of malt and beer to the West were unaffected
"This national-scale German experiment was highly successful despite the fact that, as we discovered later, the crop diversity that they were using was much less than had been thought" Professor Wolfe told me in early 1995. "At the time of re-unification. the main problem was that the east German farmers had then to sell their harvested seed direct to, mainly, west German maltsters and brewers who paid higher prices but were not prepared to buy mixed seed. This forced the barley growers back to monoculture of the preferred quality varieties with application, once more, of expensive west German fungicides."24
According to Wolfe, who now works in the plant pathology department of the Federal Polytechnic in Zurich, some barley mixtures are still being grown in Germany to be sold to more open-minded maltsters and there is also some interest in wheat mixtures there. An estimated 100,000ha of wheat mixtures are already being grown in the US as a result of work by Dr. Chris Mundt and in Switzerland, where farmers are paid a subsidy not to use fungicides, insecticides and straw-shorteners on their crops, there has been a rapid and successful shift to the planting of mixtures of winter barley in those cantons where mixed seeds are available.
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| The Wolfes (photo: Patrick Whitefield, Permaculture Magazine) |
Wolfe hopes that plant breeders will now develop seed varieties specifically for mixing as he thinks that this would lead to considerable output gains. "Even more exciting could be selection of different species for positive interaction" he says. "This is because species mixtures have two principal advantages over variety mixtures. First, there would be no development of pathogen races able to attack the component species simultaneously because most, although not all, pathogen species are specialised to a single host species. Second, because different species utilise different factors in the environment, there is greater potential for 'complementation' among species than among varietes. We, and others, have had highly positive results with, for example, different forms of cereal/legume mixtures such as wheat and beans. Indeed, in the Third World, maize/beans is a very common crop and there is the well-established grass/clover mixture in Europe."
The ultimate mixed species cropping system is, of course, agroforestry. "My wife and I are now establishing four experimental agroforestry systems on a small farm in Suffolk as a long-term retirement project " Wolfe says. "One of our objectives is to indicate the possibilities for drawing people back to the countryside either directly to run such complex enterprises or indirectly to make use of their manifold products."
2002 Update by Caroline Whyte
Professor Wolfe's agroforestry farm at Wakelyn's has done very well in the past seven years. He is also involved with the Elm Farm Research Centre, and in fact, the research done at Wakelyn's is a collaborative effort with Elm Farm.
At the Wakelyn's farm, everything is grown amongst trees, with a complex rotation of crops. Wolfe explains that "the aim is to try and use biodiversity in all systems," as a way of promoting healthy plant development and discouraging pests and disease. The trees are all fairly young still - around 8 years old - and they are planted in North-South oriented rows to maximise the sunlight's passage into the area between the trees, where the other crops are planted. They are spaced 12 metres apart, which Wolfe thinks is a bit narrow for potential farm use - he recommends spacing them 24 metres apart instead. Some of the hardwoods could eventually grow big enough to block light from the smaller plants. But two of the species grown in other systems, willow and hazel, can be coppiced to allow more light to get through, and this has worked very well. Apple trees are also grown at the farm - they are interspersed among the other hardwoods in order to discourage the spread of pests and diseases among the apples, and Wolfe comments that this has been very effective.
The smaller crops are also grown in species mixtures - for example, cereals or vegetables are inter-cropped with clover, and wheat is mixed with beans. Within individual species there are experiments with variety mixtures, such as different varieties of wheat being mixed together, and different varieties of potato.
A third activity carried out at the farm is a new project on population breeding which is funded by a grant from the British government. The project is scheduled to last six years. The first stage, which has already been completed, is to take a range of different varieties of wheat and to intercross them in all combinations, creating a giant gene pool. Then, samples of the population will be grown on different sites so that they adapt to the specific environment of their site, effectively becoming landraces. The different samples can then be compared to each other to see how they have evolved and separated. Wolfe himself is growing a sample which he intends to compare with a sample grown by a neighbour of his, who is also a farmer but who farms conventionally rather than organically. It should be interesting to see the differences between the two samples.
Wolfe also hopes that this project will produce material quickly that can be used by organic farmers, because there is a dearth of appropriate varieties available to them at present. He comments that "we may have to develop a new legal framework for dealing with this new variable material". He is also involved in projects to try to involve farmers more directly in research. He points out that at present there is an unnecessary and unhealthy divide between the farming done by farmers and the agricultural research done by scientists. This divide only came about in the decades since World War II - historically farmers have always been very involved in experimenting with their crops. Although research institutes have often done valuable work, there is a tendency for them to focus too much on commercial opportunities because they can get royalties for variety production, and less on the actual needs of farmers. The current focus on GM crops is a good example of this.
Information about the Elm Farm Research Centre's work can be found on the Centre's website at www.efrc.com . The Soil Association's website (www.soilassociation.org) contains an interesting report on the detrimental effect that GM crops have had on farmer's incomes in the US and Canada.
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