Ecosystem Services and Disservices Are Bundled in Simple and Diverse Cover Cropping Systems

Abstract

C over crops are widely used to improve soil quality, weed management , pest regulation, nutrient cycling, and crop yield (Snapp et al., 2005; Blanco-Canqui et al., 2015; CTIC, SARE, and ASTA, 2016). This array of ecosystem services suggests that cover crops are "multifunctional, " although current knowledge is primarily derived from studies of single or disciplinary-focused subsets of services (Schipanski et al., 2014). Furthermore, processes that enable cover crop multifunctionality are not well understood. Increasing cover crop diversity, for example, can enhance multifunctional-ity (Finney and Kaye, 2017), but not all services respond in the same manner (Finney et al., 2016). Cover crops can also introduce disservices, leading to an outcome worse than not planting a cover crop (Finney et al., 2016). Managing cover crops for multifunctionality requires knowledge of how service interactions are influenced by species identity and diversity (Carpenter et al., 2009). Interactions arise when the provisioning of one service leads to changes in another or when the same factor drives a change in multiple services, leading to co-occurring or "bundled" services (Bennett et al., 2009; Raudsepp-Hearne et al., 2010; Storkey et al., 2015; Finney et al., 2016). As one example of linked services, high nitrogen (N) retention in grass cover crops can lead to low N supply (low residue mineralization) and low yields in the subsequent cash crop (Finney et al., 2016; White et al., 2017). Common approaches to analyzing multifunctionality do not highlight interactions that lead to service synergies or trade-offs. Multifunctionality is typically calculated as an average of standardized values (Maes et al., 2012; Byrnes et al., 2014; Storkey et al., 2015; Finney and Kaye, 2017). Yet, averaging masks how individual services respond to diversity because increases and decreases in individual services can average each other out (Byrnes et al., 2014). Here, we evaluate cover crop multifunctionality based on eight ecosystem services measured for three consecutive years in 10 cover crop treatments using Abstract: Agroecosystems are increasingly expected to provide multiple ecosystem services. We tested whether and how cover crop selection (identity and number of species) affects provisioning of multiple services (multifunctionality). In a 3-yr study of 10 cover crop treatments and eight ecosystem services, certain services consistently co-occurred. One such service "bundle" included cover crop biomass production, weed suppression, and nitrogen retention. Another set of bundled services included cash crop production, nitrogen supply, and profitability. We also identified trade-offs: as some services increased, other disservices arose, limiting multifunctionality. However, functionally diverse mixtures ameliorated disservices associated with certain monocultures, thereby increasing cover crop multifunctionality. Core Ideas • Cover crop monocultures and mixtures support multiple ecosystem services. • Service interactions can lead to bundling, or co-occurrence, of certain services. • Service interactions also create trade-offs among services and disservices. • Cover crop mixtures can mitigate disservices to increase multifunctionality. Abbreviations: PCA, principal components analysis.