Critical factors contributing biodiversity in arable farming

Introduction

Biodiversity is decreasing alarmingly worldwide and also in the Netherlands. Although the causes of this are multiple, it becomes clear that the strong intensification of agriculture is primarily responsible for this. In the Netherlands, agriculture, in addition to original nature reserves, made an important contribution to biodiversity until the 2nd World War. However, after this war, biodiversity decreased sharply due to the intensification of Dutch agriculture, especially through the use of artificial fertilizers, pesticides and crop protection products. This is even more the case in the Netherlands than in most other Western European countries.

The need for change, transition to a more sustainable system is urgently needed and is widely recognized. That is why more sustainable production methods are also being sought with less or no use of artificial fertilizers and pesticides. In addition to 'normal' extensification (e.g. less artificial fertilizers and lower livestock densities), new forms of agriculture are being developed, such as agroforestry and strip cropping, which lead to more biodiversity. Another important possibility to improve biodiversity within the agricultural system is the application of ecological structures. Many studies have shown that all these forms contribute to improved biodiversity of agriculture.

However, for farmers who want to contribute to biodiversity on their farm, it is still difficult to determine what the most suitable and best options are. Research does not yet sufficiently show what the underlying mechanisms are of various possible measures that lead to the greatest 'yield' for biodiversity. This is also a problem for the Dutch government.

In the Netherlands and other EU countries, there are all kinds of subsidy schemes for various measures, but in arable farming these are mainly action-oriented and not result-oriented. Many studies have shown that the action-oriented schemes generally yield little result. In fact, that should be the starting point.

In the Netherlands, work is currently being done on a system of KPIs (Key Performance Indicators) in the Biodiversity Monitor Arable Farming. The system of KPIs that has now been developed is certainly an improvement because the expected result has a greater chance of success, but it is not yet a panacea because the intended biodiversity improvement itself is not measured. Research also shows that more insight is needed into the actual relationship between the KPI scores and biodiversity in the field and into the critical factors and mechanisms that lead to more biodiversity on farms.

Project description

In order to achieve the overarching goal, 5 research questions are formulated:

1. What scores do 20-25 arable farms that work with crop diversity (strip cultivation and conventional farms within CropMix and beyond) have for the 8 KPIs (Key Performance Indicators within the Biodiversity Monitor Arable Farming) and how are these related to the measured biodiversity at plot level?
2. What are the synergistic factors and mechanisms that lead to more biodiversity at plot level (in the soil, in terms of insects, birds and plants) with different types (widths) of strip cultivation?
3. What are the critical factors and mechanisms that lead to more biodiversity (in the soil, in terms of insects, birds and plants) at plot level when adding different types of ecological structures to strip cultivation and to monocultures?
4. Investigating experiences of pioneers (farmers) in applying measures/methods mentioned under 2 and 3 to increase/enlarge biodiversity.
5. Which biodiversity KPIs can be added to the Biodiversity Monitor Arable Farming and can also serve as a tool for farmers in choosing the best development measures to increase biodiversity on their farm?

Ad 1. Within the Biodiversity Monitor Arable Farming, 8 performance indicators have been developed. In the study, all these indicators will be calculated for 20-25 farms. In addition, biodiversity will be measured on a number of representative plots and at the existing ecological structures per farm.

The data collection will take place over a period of 3 years (2025-2027) so that any special (weather) conditions can be included. Per plot and per type of ecological structure, we look at the biodiversity in and on the soil, flying insects, plants and birds. A measurement program has been set up for this purpose per biodiversity category

The absolute and relative biodiversity may provide starting points for identifying critical factors and mechanisms that lead to more biodiversity on arable farms. These factors may then be useful for designing critical performance indicators for biodiversity within the Biodiversity Monitor Arable Farming

Ad 2. With regard to the second research question, the following methodology is applied: the biodiversity of different forms of strip cropping (different widths of strips and differences in crop diversity) is investigated on three arable farms. The biodiversity measurements are the same as under 1 (see above).

The different types of strip cropping are then compared with each other and with a comparable plot without strip cropping (monoculture). By including the local circumstances in the research in all situations, an attempt is made to identify the critical factors that increase biodiversity. From there, the underlying mechanisms that are important for increasing biodiversity are also described.

These factors may then be useful for designing critical performance indicators for biodiversity within the Biodiversity Monitor Arable Farming

Ad 3. With regard to the third research question, the following methodology is applied: biodiversity is measured on 2 monoculture farms and on 3 strip cropping farms where there is a combination with different types of ecological structures. The biodiversity measurements are the same as under 1 (see above). Subsequently, the effects on biodiversity of monocultures in combination with ecological structures are compared with strip cropping + ecological structures (see under chapter 2) and with monocultures alone. From there, the underlying mechanisms that are important for working on increasing biodiversity can also be described.

We will compare the biodiversity of different combinations of strip cropping and monocultures with ecological structures. We will also compare the effects of different forms of ecological structures. The absolute and relative biodiversity may offer starting points for identifying critical factors and mechanisms that lead to more biodiversity on arable farms. These factors may then be useful for designing critical performance indicators for biodiversity within the Biodiversity Monitor Arable Farming

Ad 4. ​​The following methodology will be used with regard to the fourth objective: interviews will be conducted with 20-25 farmers who have been working with (different types of) strip cropping or with combinations of monocultures/strip cropping and ecological structures for a number of years about their experiences. These oral surveys will further explore the effects of various measures on biodiversity (as they perceive them) and socio-economic aspects. Discussions will also be held with them about which possible KPIs for biodiversity could be included in the BMA. These surveys will be processed and qualitative conclusions will be drawn from them and possible KPIs for biodiversity will be established (in accordance with the systematics of the Biodiversity Monitor Arable Farming)

Ad 5. Based on the results and outcomes of the 4 sub-studies above, proposals will be made to add some critical performance indicators for biodiversity to the BMA. These proposals will be discussed with experts and the team that developed the BMA. Hopefully, definitive conclusions can be drawn from this about adding these KPIs to the BMA.

The results and the biodiversity KPIs will also be used to design a tool for arable farms so that they are better able to choose the best development measures for them that lead to greater biodiversity on their farms and for which a reasonable compensation is available from various subsidy schemes.

Project leader

This project is led by Wim van Hooff, PhD candidate

wim.vanhooff@wur.nl