1b: Managing functional biodiversity for sustainable crop production

1b:     Managing functional biodiversity for sustainable crop production

Conveners:     Merel Hofmeijer (Farming Systems Ecology, Wageningen University)

                        Jonne Rodenburg (Crop Systems Analysis, Wageningen University)

                        Felix Bianchi (Farming Systems Ecology, Wageningen University)

1. Abundance of aphid natural enemies on flowering service plants is associated with aphid prey and floral resources

Mengxiao Sun, Bing Liu, Felix Bianchi, Wopke van der Werf and Yanhui Lu, State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China; Centre for Crop Systems Analysis, Wageningen University & Research, Wageningen, The Netherlands  Farming Systems Ecology, Wageningen University & Research, Wageningen, The Netherlands

Natural enemies of agricultural pests rely on alternative prey and floral resources that may be scarce in intensively managed agricultural landscapes. Flowering service plants can provide food resources, but context-specific information on suitable plant species and plant traits that are attractive and supportive to natural enemies are often lacking. We assessed aphid natural enemies on 39 service plant species in Korla, Xinjiang, China, in 2020 and 2021 by visual counts and sweepnetting. Flowering period, corolla type, and extrafloral nectar were evaluated as possible predictors of natural enemy attraction. Gossypium hirsutum, Melilotus officinalis, Medicago sativa, Anethum graveolens, and Foeniculum vulgare attracted many natural enemies, but some also hosted pest aphids. Ladybeetles consistently responded to extrafloral nectar and open corollas, while responses of other natural enemies varied. Our findings suggest that service plants hosting non-crop-infesting aphids can be useful for habitat management programs aiming to conserve natural enemies.

2. Exploring potential success factors for soil multifunctionality: the effects of farm management intensity, organic farming, soil life and soil carbon

Sophie van Rijssel, Guusje Koorneef, Ciska Veen, Mirjam Pulleman, Ron de Goede, Rob Comans, Wim van der Putten & Kyle Mason-Jones, Soil Chemistry Group, Wageningen University & Research, Wageningen, The Netherlands; Soil Biology Group, Wageningen University & Research, Wageningen, The Netherlands

The simultaneous delivery of multiple soil functions is essential to achieve high crop yields with lower environmental impact. We investigated what factors affect this so-called soil multifunctionality in 57 Dutch fields under organic and conventional arable farming. We measured 9 soil function indicators to obtain the multifunctionality score, and collected information on land management. We show that increasing management intensity is associated with declining soil multifunctionality across all fields, whereas multifunctionality was not related with organic vs. conventional farming. We also explored how soil life and soil organic carbon can underlie management effects. We characterized the species composition and abundance of soil microbial community with 15 parameters, and soil carbon quantity and quality with 16 parameters. We found that bacterial biomass and total soil organic carbon content, respectively, were the strongest biotic and abiotic predictors of soil multifunctionality. This research supports the development of ecological practices for sustainable crop production.

3. The effect of strip cropping on weed communities in cereals in the Netherlands

Esther Moinat, Merel Hofmeijer, Farming Systems Ecology Group, Wageningen University & Research, Wageningen, The Netherlands

The simplification of cropping systems has led to decreased weed diversity. Diverse weed communities can deliver agroecosystem services, contributing to the overall resilience of a cropping system. A way to foster weed diversity is through crop diversification, such as strip cropping. This study aimed to explore the effect of strip cropping on weed communities in cereals, compared to a monoculture. The weed community was assessed on 20 farm locations throughout the Netherlands. Weed transects were placed in the monoculture, the middle of the strip and the edge of the strip. The weed transects were surveyed on species richness, weed density and weed cover. The results show that strip cropping significantly increases species richness, weed density and weed cover compared to a monoculture in conventionally managed systems, but not in organically managed systems. Whether the change in species composition results in, for example, a less competitive community, has yet to be explored.

4. Exploring the impact of strip cultivation on weed seed predation

Amandrie Louw, lammert Bastiaans, Merel Hofmeijer, Niels Anten, Centre for Crop Systems Analysis, Wageningen University & Research, Wageningen, The Netherlands; Farming Systems Ecology, Wageningen University & Research, Wageningen, The Netherlands

Strip cultivation is an intercrop system whereby multiple crops in alternating strips are grown together on the same land resulting in higher levels of crop diversity. While this practice demonstrated improvement of pest and disease suppression in crops, its effect on weed pressure is less well understood. This study aimed to investigate if the increased spatial diversity following from strip cropping enhances weed seed predation, aiding the management of weed populations. The experimental design within two location, Wageningen and Lelystad, included faba bean–pumpkin and cabbage–oats cropping pairs in strips against the respected monocrops, as a control. Chenopodium quinoa seeds were put on seed exposures in caged and uncaged setups to quantify seed predation. Significant differences were observed between caged and uncaged seed exposures. Our result indicated that strip cropping within oats, pumpkin and faba bean supported higher seed predation than monocropping across locations, highlighting the role of crop arrangement in seed predation dynamics.

       5. Investigating interactions of habitat configuration and pesticide hazard for crop pollination to improve agroecological measures

Swantje Gebhardt, Copernicus Institute of Sustainable Development, Utrecht University

Natural landscape elements that are intended as pollinator refuges in intensively managed agricultural landscapes can become overexposed to pesticides and lose their benefit to crop pollination. We modelled the spatial processes of pesticide exposure in habitats and the subsequently reduced pollination services for a set of artificial landscapes that varied in habitat amount, land use clustering, and mortality hazard arising from pesticides applied on crops. Through this systematic approach, we found that in landscapes with limited habitat amount and hazardous pesticide use, pollination services can be safeguarded by compact patches of habitat, whereas more dispersed habitat achieves better pollination when pesticide hazard is lower. We further showed the importance of pollinator resources at different foraging ranges and strategic allocation of buffer areas to reduce pesticide exposure. Our results inform landscape management for crop pollination to consider spatial processes to design more effective habitat restoration and pesticide reduction measures.