16. October 2007 11:00
Making more hay – what farmers can learn from ecology
Farmers all over Europe could get higher yields and fewer weeds in their intensive grasslands, if they planted more species. A new European study has shown that this basic ecological pattern holds true for planted pastures.
It is now well established in biodiversity science that when you lose species from an ecosystem, it becomes less productive. Simple communities, with only one or two species, cannot grow as much biomass as combinations of species. So why do farmers who grow grasses for animal food persist in planting only one or two species of grass, when they could get a higher yield by planting a few extra species? Perhaps ecological research does not seem relevant to farmers, who work with highly artificial plant communities, mostly monocultures. A research project involving more than 20 European countries, coordinated by the European Science Foundation (ESF), has bridged the gap, and demonstrated that the effect can work for farmers too.
The research had a similar set up to other large-scale ecological experiments looking at how important the number of species is to the working of ecosystems. It was the largest ever experiment of its kind and was carried out by scientists from 26 different universities and research institutes under the umbrella of the European Science Foundation’s EuroDIVERSITY Programme. There were 28 sites, dotted all across Europe, from the far north to the hot, dry south. At each site, experimental plots were planted with different combinations of four species that farmers of the region are familiar with. In central Europe, they were red clover, white clover, rye grass and cock’s foot, another grass. Some plots had just one species, some had equal quantities of all four species, and some had a different balance, such as mostly one species and smaller amounts of the others.
The big difference, compared to the ecological experiments, is that the plots were treated as they are on farms. They were fertilised, they were harvested by machine and yields were calculated in tonnes per hectare, instead of the normal grams per square metre. “If you want to communicate to farmers, you have to speak their language,” says John Finn, an ecologist from the Teagasc Environment Research Centre in Ireland, who presented these results to a conference of European biodiversity scientists in early October.
The results show that on average, if you plant four species instead of one, you get an additional 3.5 tonnes per hectare of food for your livestock. You also get fewer weeds in the field. At most sites, the yield from a mix of species exceeded the yield from a monoculture of the most productive plant, an effect known in ecology as ‘overyielding’. And the best mix uses equal quantities of each of the four plants.
“Large areas of Europe are covered with intensive grasslands,” says Finn. He argued that if these grasslands had four plant types, instead of one or two, there would be definite benefits for wildlife. “The research showed that more insects associate with the species-rich swards.” More insects means more food for wild birds and small mammals.
There is still work to do, to convince farmers. The scientists now have to find out how the quality of the forage changes if you add more species, and how the mixtures do when their environment is tough, as it often is in Mediterranean countries. “Our biggest challenge, though, is to communicate the results to agronomists and advisory agencies, so that their advice to farmers might incorporate these results,” says Finn.
Information for Editors:
- This work was part of a project called COST Action 852, funded under the European Commission’s COST programme and completed in 2006.
- The research is described in the following publication, which also contains a full list of participating institutes: Kirwan et al., (2007). Evenness drives consistent diversity effects in intensive grassland systems across 28 European sites. Journal of Ecology 95: 530-530.
- For more information on this research, or to arrange an interview, contact John Finn (john.finn[at]teagasc.ie, tel: 00 353 53 9171273).
- The work was presented at the first European Science Foundation EuroDIVERSITY conference, held in Paris from 3-5 October 2007. EuroDIVERSITY brings together scientists studying biodiversity from different angles. It allows those working in very disparate areas, such as microbes, oceans, and grasslands, to network and collaborate. It also encourages the study of the social and economic aspects of biodiversity change. For more information see www.esf.org/eurodiversity.
Media contact:
- Dr. Inge JonckheereE-Mail
