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Session 9. Impacts of introducing service crops and
legumes in cropping systems 136
Agro-ecosystem services and drivers of variability in their delivery from legumes
in European cropping systems: a systematic review
Lenora Ditzler±1, Dirk van Apeldoorn∗1, Fernando Pellegrini2, Daniele Antichi3, Paolo Barberi2,
Walter Rossing1
1 Farming Systems Ecology Group, Wageningen University & Research, P.O. Box 430, 6700 AK Wageningen, The Netherlands
2 Group of Agroecology, Institute of Life Sciences, Scuola Superiore Sant'Anna, Piazza Martiri della Libertà 33, 56127 Pisa, Italy
3 Centre for Agri-environmental Research “Enrico Avanzi”, via Vecchia di Marina, 6, 56122, San Piero a Grado, Pisa, Italy
∗ Speaker
± Corresponding author: lenora1.ditzler[at]wur.nl
1 Introduction
The area of farmland under legume production in the European Union (EU) has steadily declined (with the notable exception of soya) in the last decades (FAOSTAT, 2018). Recently, it has been estimated that grain legumes occupy only 1.8% of arable land in the EU (Pelzer et al., 2017). This low percentage appears to indicate that despite the expected ecosystem service (ES) benefits of including legumes in cropping systems, various factors are dissuading farmers from doing so. Extension, policy, and marketing initiatives aimed at bolstering farmers’ uptake of legume crops require sound scientific evidence of the role and benefits of legumes in sustainable farm management. Gaining an overview of what is already known about ES delivered by legume crops can both feed these knowledge needs and direct new research.
2 Materials and Methods
Here we present findings from a systematic literature review on ES delivered by legumes in European cropping systems, which we conducted in response to an observed lack of such a review. Additionally, we systematically identify and characterize drivers of variability in the delivery of ES, also previously missing from the literature. Following the Prisma method (Moher, Liberati, Tetzlaff, & Altman, 2009), we compiled a literature database containing 132 documents reporting on ES delivered by legume crops and legume-based cropping systems in the EU. We then collected meta-data from each document, including details such as experiment location and design, method of legume inclusion, crops studied, and ES measured. Analysis of the meta-data were done on the basis of descriptive statistics (e.g. counts and associations between study locations, crop combinations, and ES measured) to illuminate trends, themes, and gaps in the literature. We examined a random subset of the database literature (3-5 papers measuring each ES) and recorded the direction of the effect on ES delivery observed by the incorporation of legumes and the reported sources of variability in this delivery.
3 Results
Our analysis revealed that much of the literature is concentrated around a relatively small combination of possible ES, crops, legume inclusion methods, and experiment locations (Figure 1). Papers on production-related services (namely yield and produce quality) were the most prevalent, and these primarily reported on cereal—grain legume intercrop systems, with experiments located in five main countries (France, Denmark, United Kingdom, Switzerland, and Italy). Furthermore, we found that the services for which there are apparent knowledge gaps in the literature (namely pest, weed, and disease suppression) are the same services that farmers involved in a large, legume-focused EU research project (LegValue) indicated they needed information on in order to more successfully incorporate legumes into their cropping systems. Notably lacking from the literature were studies conducted at the farm, landscape, and regional scale which could provide insight into ES operating beyond the plot level, for instance pollination or services with cultural value.
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Session 9. Impacts of introducing service crops and
legumes in cropping systems 137
Figure 1. Matrix of associations observed in the literature database between legume species and ecosystem service measured.
Dot color corresponds to the legume inclusion method (management practice) employed in the study. The larger the dot, the more studies on that combination.
A preliminary analysis of sources of variability showed that legumes can both enhance and detract from ES delivery, particularly for weed and disease suppression. This finding reinforces the need to focus research on these topics, as they are highly relevant for farmers considering new legume crops. Our survey of sources of variability also showed climate/environment, legume species and cultivar, and nitrogen fertilization (source, timing, and quantity) to be key drivers for many ES, indicating additional avenues for future research. Better understanding of sources of variability in ES delivery from legumes can be obtained through a quantitative meta-analysis of the literature in the database, for which an initial assessment identified 72 papers meeting inclusion criteria.
4 Discussion and Conclusions
The findings of this review point to an urgent need to extend and diversify research on ES from legumes to include those topics not yet well explored, rather than reinforcing known topic and context combinations. The apparent alignment between what farmers want to know and what is missing from the literature provides even more compelling stimulus to redirect research agendas and foster multi-actor engagement towards work that directly supports farmers in developing productive and sustainable legume-based cropping systems. References
FAOSTAT. (2018). Food and agriculture data. Retrieved from http://www.fao.org/faostat/
Moher, D., Liberati, A., Tetzlaff, J., & Altman, D. G. (2009). Preferred reporting items for systematic reviews and meta-analyses: The prisma statement. Annals of Internal Medicine, 151(4), 264-269.
Pelzer, E., Bourlet, C., Carlsson, G., Lopez-Bellido, R., Jensen, E., & Jeuffroy, M.-H. (2017). Design, assessment and feasibility of legume-based cropping systems in three European regions. Crop and Pasture Science, 68(11), 902-914.
