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Search for feasible and sustainable measures
What are feasible and sustainable measures that can stimulate biodiversity? And how do we encourage farmers to actually include or introduce these measures on their farms? These were 2 key questions during the 'Boer Proof Nature' symposium that HAS Hogeschool Den Bosch and Bayer organized at the Forward Farm in Abbenes at the beginning of July.
"Farmers benefit most from nature that can take a beating; that's what we should focus on," says ecologist Henk Nijenhuis, one of the guest speakers at the symposium. Fellow ecologist Arjen de Groot of Wageningen UR believes that there is enough low-hanging fruit to make rapid progress in agrobiodiversity. "There is a lot of knowledge and we will have to transfer it to practice in a practical way."
'Farmer Proof Nature'
The first speaker is Henk Nijenhuis, polder ecologist. “We made up that word ourselves a few years ago,” he begins. "It not only means that I am an ecologist in a polder area, but it also stands for the verb to polder, or to discuss. I think that is at least as important. Nature is not an unambiguous concept, everyone has a different image or perception of it. we all talk about it all the time to avoid confusion of tongues."
According to Nijenhuis, nature measures on farms must above all be robust: they must have an effect without too much attention and time having to be devoted to them. In practice, this often involves well-chosen planting of trees, shrubs, grasses and flowers that suit the farm and the environment, taking into account the type of soil, the (changes in) groundwater level and the wind direction.
For example, the black poplar, aspen and fluttering elm thrive on the windier west side of the farm, while the hazel, sycamore maple and 2-post hawthorn do well on the leeward east side. On the warm south side, winter lime trees, summer oaks, wild apple and mirabelles fit, among other things, and on the cool and damp north side, black alder, wood willow and yellow dogwood.
Nijenhuis emphasizes that especially a combination of these trees is good for more biodiversity. "One tree is more of an early bloomer, which is beneficial for bees and other pollinators, while the other provides berries or fruits at times when birds can use them. That interaction is especially important."
Hedges, shrubs and plants
Hedges and shrubs (such as privet, field maple and hornbeam) can also make a nice contribution to biodiversity, he says. "They provide shelter for small animals and birds; they can scrounge around in it and use it as a refuge. For some birds (such as the sparrow) it is also a nice winter home." More diversity in plants and herbs also offers clear added value for nature, according to Nijenhuis.
He mentions the ivy, which produces many flowers with nectar in the autumn. "The food source is important for butterflies and insects." Sowing herbal mixtures also helps to increase biodiversity, although the right mixture must be used. "On the south side, meadow-herb mixtures are best, on the north side, mixtures for forest edges. For the other places, mixtures for shaded and nutrient-rich meadows are best."
In addition to trees, shrubs and plants, simple insect and bee hotels and ladybug hives can also help to make nature more diverse. "You only have to hang them up; that's all it is," says the polder ecologist. He also argues for not too neatly tidy yards "Leave some dead wood here and there; they provide shelter for birds and small mammals. Provide some loose, bare soil around the yard. These are places where soil-dwelling bees and bumblebees feel very much at home."
No Regret Measures
"Nowadays the contrasts between nature development and agriculture are magnified, while there are at least as many starting points for working together. That's what I want to talk about," Arjen de Groot of Wageningen Environmental Research kicks off. According to De Groot, there is enough low-hanging fruit that farmers can use to increase biodiversity on their farms.
He calls them 'no regret measures', which means that the costs remain limited, there is virtually no chance of undesirable side effects and the measures make an effective contribution to biodiversity. The first action should be aimed at preserving natural elements that already make a positive contribution to biodiversity, such as wooded banks, hedges, pools, ponds, ditch sides, old trees and areas with dead wood. "As a farmer you don't have to do anything about that, you just have to leave it for what it is."
Even simple measures such as installing a bee hotel or (even simpler) hanging up a bundle of bamboo sticks as a nesting place for bees hardly cost time and money. "It's about farmers seeing what is possible, so we have to bring the knowledge to the farm."
Disseminate practical knowledge
The ecologist advocates more projects that disseminate practical knowledge. He calls the project 'Kennisimpuls pollinators', which helps to increase knowledge about (wild) pollinators through practical networks and a helpdesk. "We notice that this concept is catching on; farmers are coming up with initiatives themselves to plant or sow small, unused corners or riparian zones with landscape elements that provide more biodiversity."
In the coming years, De Groot wants to move towards menus with which targeted choices can be made. "That may mean that flower edges become less colorful, but they become more useful for insects. Less spectacular species such as cow parsley and yarrow, but also clover and vetch have a good influence on insect abundance."
He also expects that the agriculturally unfortunate choices will become less common. "There are mixtures with wild carrots; they are not useful next to a plot with carrots, partly because they are a host plant for the carrot fly. There have been serious disappointments with them in the past."
Guide to more biodiversity
Finally, Tosca Smit, Barry van der Veeken and Youri van der Meer from HAS Hogeschool Den Bosch explained their updated (or rather: simplified) manual for agrobiodiversity. With this they build on earlier research by HAS students, which was much broader in scope, but therefore also less practical in nature.
With the manual (which has been tested on 3 arable farms), the 3 students hope to offer a tool that farmers can use to get a picture of the biodiversity on their farm in a relatively short time, based on a limited number of indicators.
