Wetenschap - 8 juli 2010

Goodbye to a constructive mid-fielder

Herman van Keulen, expert in the field of crop growth, animal production and sustainable land use, is one of the founders of production ecology. His simulation models are used all over the world but he prefers to stay out of the limelight. He retired last week.

Herman van Keulen (65) grew up on a mixed farm in Twente: five hectares with cows, pigs, chickens and grain.
Later, in the course of his career as production ecologist, he came across many of these sorts of farms in Africa and Asia. How can such farms raise their production? What is the potential growth of crops, depending on the weather, the soil and the management strategies of the farmer? It was to answer these questions that Van Keulen applied knowledge about plants, soils, rainfall and business management in a simulation model. He supervised more than 50 PhD students and is a big name in agronomics internationally. Last Thursday, he gave his valedictory lecture.
That does not mean he has stopped working though. Among Van Keulen's current projects is research for the Gates Foundation on whether water-saving rice production methods harm soil fertility. In the Netherlands he is involved in Wageningen UR's De Marke experimental farm, where research is being done on how dairy farmers can farm in a way that is both productive and environmentally friendly. He is also active in the 'Cows and Opportunities' network that grew out of this, and he wrote the EU research proposal that the farm is now based on.
Van Keulen is a product of the Cees de Wit school and one of the founders of production ecology. He worked with researchers such as Rudy Rabbinge, Frits Penning de Vries, Henk Breman and Jan Goudriaan to develop models for predicting plant growth and crop yields under a range of different environmental conditions. He developed Bacros, a programme for stimulating crop growth, and he thought up the 'tipping bucket' model for describing the behaviour of water in soils. This concept is still in use thirty years down the line. Van Keulen developed from a soil scientist into an expert on crop growth, animal production systems and eventually sustainable land use.

Waste paper
And yet Van Keulen is not a celebrity Wageninger. People who know him say that is because he did not develop his own line of research. Van Keulen is a generalist rather than a specialist. What is more, he does not seek out media attention, for example for his vision on sustainable agriculture and the world food supply issue. In the nineteen nineties he was professor of Animal Production Systems for five years, but was happier after that as professor without a chair at Plant Production Systems under Rudy Rabbinge and then Ken Giller. 'Herman is good at supervising PhD researchers, but he is not a manager', says Rabbinge. Van Keulen is a member of the SKV football club, where he is not on the board but helps his fellow club member collect waste paper.
'He knows his stuff, he works hard and he writes a lot of articles', says Prem Bindraban, who got his PhD under Van Keulen's supervision and later went on to become his boss. 'And he is a walking library. If you ask him a question about energy stores in the wheat stalk, he will know the author of a seminal article on the topic from 1975. He keeps up with publications very well.' His room was chock-full of literature and cuttings - until the move to the Radix building. 'Then he had to tidy up. That was tough for him', says Martin van Ittersum of Plant Production Systems.
Red pen
The red pen with which Van Keulen corrected the drafts of scientific articles is famous. 'I got my papers back covered in red ink', remembers Bindraban. 'It was only a couple of years ago that I got a publication back with hardly any red pen on it. That felt like a tremendous victory.' All his PhD students are familiar with Van Keulen's red pen, but his critiques are highly valued. 'He is a highly motivated perfectionist, but easy to get along with, very diligent and loyal to students and staff', says Van Ittersum.
Thirty years ago, Van Keulen and his Wageningen colleagues discovered in Mali that it was not water that was the limiting factor for agriculture in the Sahel, but nutrients in the soil. That came as a surprise to many agronomists.  But, many years and many African PhDs later, Van Keulen believes that you cannot improve agriculture with fertilizer alone. 'Even if you make fertilizer free, it won't improve the incomes of farmers in Mali. That was an eye-opener for Herman', says development economist Arie Kuijvenhoven. 'The farmers there engage in agriculture to survive. The Sahel is not suitable for sustainable agriculture.'
Kuijvenhoven got to know Van Keulen in 1987, when a group of Wageningers set out to develop an integral system analysis for agriculture. 'Production ecologists were homing in on the square metre scale, and only saw the physiological limitations on crop yields', recalls Kuijvenhoven. 'We combined those with the behavioural and marketing options farmers had. Do they have credit and access to markets? What happens to prices when production goes up? What is the infrastructure like? This left only a couple of option for limitations on growth, and we came to understand better why farmers often didn't invest in raising production.' It was a highly educational meeting, as Van Keulen explained in his lecture. 'Interdisciplinary research is an absolute must, and I have learned a great deal from it.'
Strikers
Van Keulen's bio-economic models brought fame to Wageningen, Kuijvenhoven explains. 'The International Food Policy Research Institute has been using the Wageningen model for years.' In that group Kuijvenhoven's fast talking and Van Keulen's solid work complemented each other very well. 'I made sure we got the money from The Hague; he took care of the contents of the proposal. We could not have achieved so much as a team without him. He is the creative mid-fielder without whom the strikers can't score the goals.'
Van Keulen's integrative models are used worldwide by other researchers. During his lecture he showed an illegal copy of one of his early model studies: 'no wonder Pudoc publishers went bust.' But the models also make it possible to show farmers and policymakers the choices they have. 'We have the potential to feed the world,' says Van Keulen, 'but the soil quality and the water supplies are getting worse. On top of that, agrobiodiversity is falling and we are losing six million hectares of forest every year. If politicians don't make choices, we won't achieve any of our goals. We need a paradigm shift if we are going to improve the quality of natural resources.' Just like Joop van Lenteren in his farewell lecture two weeks ago, Van Keulen also spoke in favour of population policies to stem the growth in the world population. 'There is a limit to what the earth can provide for the population', he said.
Van Keulen's quotable quotes:
'If you agree, you soon won't have anything more to say'
'Fame is nice, but mainly when you are playing klaverjassen.'
'If you can't convince someone, at least sow doubt in his mind.
'If I had to finish all my work I'd go to bed after I get up.'

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