Conservation agriculture as a promising trade-off between conventional and organic agriculture in bundling ecosystem services

Summary

Agriculture is a human activity that receives the most direct benefits from ecosystem services (ES) while it is one of the most influent on their sustainability and is also directly impacted by global changes. One main challenge for future agroecological systems is thus to encourage the co-occurrence of multiple services both to agriculture and from agriculture. In this article, we questioned through a large-scale study, the ability of conservation agriculture to support not only supporting services related to soils, as it was originally designed for, but also overall biotic potential for multiservice agriculture. We assessed the expression levels of ES from and to agroecosystems (input and output services respectively) within 5 crop management systems, comparing different forms of conservation, organic and conventional agricultures. Fifty winter wheat and fava bean fields in southwestern France were monitored for 17 ES: seven input services (either supporting or regulating) and ten output services (either provisioning or out of direct agricultural income). Observed co-variations and antagonisms between services occurred only for input services and were related to services based on mobile agents or soil properties. Regarding pest regulations, opposite responses were observed between aphids and bruchids, attributed to contrasted responses of the pests to habitat diversity and especially notable in fields under conservation agriculture. As to soil quality, conservation agriculture exhibited significantly higher levels of soil structure stability than conventional and organic systems but slightly lower water infiltration. For output services, our results showed that crop production was not jeopardized by conservation agriculture practices with, for instance, no significant differences in levels of winter wheat yields between systems based on direct seeding or plowing. Organic agriculture however improved crop health regarding diseases but significantly decreased yields. However, high variability in level of expression of output services in conservation agriculture was observed, with both highest and lowest rated fields observed under direct seeding management for provisioning services. These variations can be attributed mainly to system immaturity regarding both ecological processes and farmers' expertise. Finally, one unexpected outcome of the study was that negative impacts of intensive agricultural practices appeared to be mitigated by elements of production situation such as presence of livestock and clayey soils. Overall, the study provides a detailed illustration of the potential for conservation agriculture to address the apparent antagonism between productivity and environmental performances.