Long-term experiment on sandy soil brings growers good yields and reduces environmental losses

Sometimes it is an almost impossible task for farmers who are growing arable crops or field vegetables on sandy soil. The government demands more sustainable production systems; i.e., lower emissions of pesticides and nutrients to the environment. And at the same growers are increasingly facing problems with pests and diseases while the organic matter content of their soil decreases. How should they set up their cropping system in such a way that they achieve good yields, with low emissions to the environment, and preserve their soil in such a way that they can continue to grow crops in the future?

Tackling problems simultaneously

Scientists of PPO are moving in to assist farmers. They are searching for possibilities to tackle all problems at the same time. Since 2006 they have been doing this on the Vredepeel experimental farm . Organic and conventional cultivation systems include ten different treatments, such as the use of green manure crops, compost or application of chitin, the main constituent of the hard parts of crustaceans.

On all treatments the scientists are recording the effect on pests and diseases and the use of fertilisers. Of the pests and diseases they in particular monitor the fungus Verticilium dahliae, which causes wilting disease, and the root lesion nematode Pratylenchus penetrans.

New detection methods

The researchers are not only comparing the effects of the different treatments. They are also developing new molecular techniques for detecting the pathogens and natural enemies that are present in the soil. Of course growers need to know exactly which pathogens are present in the soil to decide on the best measures to be taken in their own particular situation. There are, e.g., different green manure crops and different nematode species. A certain nematode multiplies in the presence of a particular green manure crop whereas it decreases when a different green manure crop is grown.

This research and advisory work is of course making use of knowledge from earlier PPO research and research by other research organisations. This means that growers now already need much less pesticides. And this new research contributes to a further reduction of the use of these products while at the same time maintaining quality and yield level of the crops.

Unique in the world

This research is unique in the world: no other sandy soil experiment in the world has been running for such a long time. This also makes it a popular place for other scientists to collect data. RIVM , the National Institute for Public Health and the Environment), e.g., is using the site to record data for the Landelijk Meetnet Bodemkwaliteit  (National Soil Quality Monitoring Network).