Redefining the field to mobilize three-dimensional diversity and ecosystem services on the arable farm

Lenora Ditzler,Dirk F.Van Apeldoorn,Rogier P.O Schulte,Pablo Tittonell,Walter A.H Rossing

doi:10.1016/j.eja.2020.126197

Abstract

In this article we explore the concept and implications of three-dimensional (spatial, temporal, and genetic) in-field crop diversification to inform systems redesign towards ecological intensification. We first present a conceptual framework for classifying diversity in arable contexts. We then apply the framework to analyse two long-term systems experiments in The Netherlands where spatial and genetic diversity measures were implemented via strip and mixed intercropping with the aim to increase ecosystem service delivery: incidence and spreading rate of late blight (Phytophthora infestans) in potato (Solanum tubersosum L.), and biocontrol control potential in wheat (Triticum aestivum L.). In the case of late blight, potatoes planted in strips had significantly lower disease incidence than the monoculture reference across all years, and adding cultivar mixing within the strip was more powerful in mitigating late blight than spatial diversification alone. In the case of biocontrol in wheat, strips supported significantly larger (for all but one taxonomic group) and significantly more diverse epigeic natural enemy populations than the sole culture reference in all years. However, the addition of species mixing within strips did not further increase biocontrol indices compared to sole-wheat strips. These results imply that compromises between management complexity and ecosystem service enhancement are achievable through strip cropping, an operable practice with current machinery, and one that does not require a thorough reconfiguration of the production system. The three-dimensional diversity framework proved useful for unpacking experimental outcomes in terms of diversity-mediated mechanisms, however it requires further development before it can be used to facilitate multi-objective optimization.

Highlights

In arable farming, the field is an important management unit which shapes how a farmer conceptualizes and executes cultivation activities
When the two treatment factors were differentiated as separate fixed factors in the linear mixed model, the post-hoc pairwise comparisons showed that rate of disease spread was significantly lower in the mixed-cultivar treatments compared to the monocultural REF (p = 0.0238), and that only the narrower strip width (3 m, spatial factor) showed significantly lower disease spread compared to the REF treatment (p = 0.0087)
We hypothesized that activating di versity in multiple dimensions at once would multiply the ecosystem service benefits, of pest and disease regulation, and tested this hypothesis with two examples of strip and mixed intercropping in the Netherlands

Summary

Introduction

The field is an important management unit which shapes how a farmer conceptualizes and executes cultivation activities. In Europe as in other parts of the world, the initiation of agricultural industrialization efforts post-WWII (in part supported by land reallotment and consolidation policies) led to a change in the size, composition, and configuration of arable fields as farms adapted to accommodate larger farm machinery, a drive to specialize, and the de mands of new economies of scale (Jepsen et al, 2015). In combination with how a farmer manages it, field size, composi tion, and configuration dictate what effect arable farming has on the delivery of various ecosystem (dis)services (Fahrig et al, 2015; Sirami et al, 2019). A monocultural approach to arable agriculture enables farmers to treat entire fields, no matter how big, as a single unit of management where cultivation tasks may be executed with efficiency by large-scale machinery. While heralded as technological breakthroughs that helped reduce hunger worldwide (i.e. the Green Revolution), it is known that widespread applications of synthetic fertilizers and crop protection products, together with concurrent agricultural landscape simplifica tion, have contributed to a cascade of failing ecosystem controls and the overstepping of multiple planetary boundaries (Campbell et al, 2017; Kinzig et al, 2006)

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