Science - September 2, 2004

PRI part of big weed project

Researchers help Chinese to reduce crop spraying

Plant Research International is to help China to reduce its use of chemical weed killers. In a project worth a total of eight million euros, the MLHD method for more effective use of herbicides, that was developed in Wageningen, will be adapted for use in maize, wheat and soya cultivation in four provinces.

At first glance the part of the Wageningen weed experts in the new project looks modest. The researchers will receive a mere half a million euros for their contribution to the project. ‘The Chinese are clever negotiators and most of the work will be done by Chinese researchers. Our contribution is confined to supplying expertise and supervising the research,’ confirms Dr Bert Lotz, leader of the Applied ecology cluster at Plant Research International (PRI). He regards the project first and foremost as an investment in the future. ‘The half million is useful for our turnover, but perhaps more important is that we have a foot in the door, we will become known and can show that we work internationally with Wageningen expertise. If the project is successful then we can look forward to bigger prospects. Everything is big in China and agriculture is an enormous growth market there. If you can corner a share of that market now it should lead to big things in the future. At the same time, there’s also a lot we can learn from the Chinese, in terms of new crops and weed varieties. It’ll open up a whole new world for us.’

 

His recent visit to China has left a deep impression on Lotz, especially when it comes to the developments in agriculture that are taking place there. The project in which the MLHD method will be introduced was officially launched in Beijing this summer. It is financed by the Dutch development finance organisation FMO-NIO and the Chinese ministry of agriculture. The original proposal was submitted by a company in Delft, EARS, which will also coordinate the project. Other participants are the Dutch consultants DLV Adviesgroep and the Chinese-Dutch consultants HOFUNG.

 

MLHD stands for Minimum Lethal Herbicide Dose, and the method is a relatively simple way of determining the lowest possible effective dosage of herbicide. It works best for photosynthesis-inhibiting herbicides and consists of three steps. First the quantity and development stage of the weed in the field is determined. Then there are tables that indicate how much herbicide is required. Two days after application the effect of the herbicide is checked. A chlorophyll fluorescence meter measures whether the rate of photosynthesis has decreased sufficiently that the weeds will die. ‘You can’t see this just by looking at the plants, but by measuring you can see whether you need to apply more herbicide,’ explains Dr Corne Kempenaar, the MLHD project leader.

 

Tests carried out in the Netherlands show that this economical but effective form of spraying can lead to a thirty to forty percent reduction in herbicide use. Kempenaar: ‘If you compare the amount used with the recommended dosages on the packet then the reductions are even bigger. The extra knowledge gained by measuring means you can apply lower dosages without running into problems. What we do is make use of the slack in the system, so it’s possible to fine-tune the amount of herbicide used without running too high a risk. The problem with herbicides is that they also affect the crops, but this method keeps crop yields up.’ The MLHD method requires a bit of practice to start with, but one the farmer knows how to use it, he only needs about an hour per field. The costs of the handy measuring instrument developed by EARS and PRI and A&F are also quickly earned back in herbicide savings.

 

In the Netherlands the method has now been refined for beets, potatoes, flax, onions, green beans and maize. This month a researcher from Plant Research International will go to China to help set up the bench-mark tests for the three crops selected (maize, wheat and soya) under the prevailing conditions. Lotz: ‘At this point we can build on the research we did here at the end of the nineties, so we don’t have to repeat the laboratory work in China. This year we’ll start with greenhouse experiments, and go over to field testing next year already.’

 

Herbicide application is also related to the weather conditions, and the MLHD method can be linked to the Crop and weather information system GEWIS, which was also developed at Wageningen UR.   Gewis indicates the optimal moment for application on the basis of information on the current weather conditions and the short-term forecast. After the field tests, the following two years will be used to introduce the new technology in four provinces in China. Lotz is optimistic that the new technique will be adopted: ‘The Chinese are very open to new technology and China has a very good knowledge infrastructure. It is also the biggest herbicide user in the world, and as a result is now experiencing considerable problems with pollution of groundwater. Lotz: ‘There’s still a whole world to conquer over there.’ /GvM

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