Implications of large‐scale miscanthus cultivation in water protection areas: A Life Cycle Assessment with model coupling for improved policy support

Abstract

Two major global challenges related to agriculture are climate change and the unbalanced nitrogen cycle. For both, national and international reduction targets have been defined to catalyse policy support for more sustainable farming systems. Miscanthus cultivation in water protection areas has been proposed as a contribution to achieving these targets. However, a thorough understanding of the underlying system dynamics at various spatial levels is required before recommendations for policy development can be provided. In this study, a model framework was established to provide economic and environmental indicator results at regional and sub‐regional levels. It presents a consequential Life Cycle Assessment coupled with an agro‐economic supply model (Economic Farm Emission Model) that simulates crop and livestock production, and an agricultural hydrology model (DAISY) that assesses effects on the nitrogen cycle. The framework is applied to Baden‐Württemberg, a federal state in southwest Germany with eight agro‐ecological regions. Scenarios investigating the differences between mandatory and voluntary miscanthus cultivation were also explored. While the results show the high potential of miscanthus cultivation for the reduction of greenhouse gas emissions (−16% to −724%), the potential to reduce nitrate leaching (−4% to −44%) is compromised in some sub‐regions and scenarios (+4% to +13%) by substantial effects on the crop rotation. Furthermore, the cultivation of miscanthus reduces gross margins in most sub‐regions (−0.1% to −9.6%) and decreases domestic food production (−1% to −50%). However, in regions with low livestock density and high yields, miscanthus cultivation can maintain or increase farmers' income (0.1%–5.8%) and improve environmental protection. The study shows that the heterogeneity of arable land requires a flexible promotion programme for miscanthus. Voluntary cultivation schemes were identified as most suitable to capture sub‐regional differences. Policies should address the demand for miscanthus, for example, support the development of regional value chains, including farmers, water suppliers and the biobased industry.

Comparative LCA studies of simulated HMF biorefineries from maize and miscanthus as an example of first‐ and second‐generation biomass as a tool for process development

“…Yield ranges shown typical for miscanthus cultivation in Southwest Germany were taken from own field trials (Weik et al, 2022). These are complemented with estimates on typical soil carbon sequestration associated with the cultivation of miscanthus on arable land.…”

“…Field emissions, including that is nitrous oxide, nitrate and phosphorus as well as heavy metals were modeled as suggested in Zampori and Pant (2019). Yield ranges shown typical for miscanthus cultivation in Southwest Germany were taken from own field trials (Weik et al, 2022). These are complemented with estimates on typical soil carbon sequestration associated with the cultivation of miscanthus on arable land.…”

An Adapted Indicator Framework for Evaluating the Potential Contribution of Bioeconomy Approaches to Agricultural Systems Resilience

“…Crop diversity, plant diversity Land/water/nutrient use efficiency Potential contribution of the BA Miscanthus mitigates leaching of nitrate to groundwater because it is deep rooting [ 239,240] and nitrogen fertilizer is generally unnecessary, except on soils of low fertility. N 2 O emissions from unfertilized miscanthus can be five times lower than from annual crops and up to 100 times lower than from intensive pasture.…”

Upscaling miscanthus production in the United Kingdom: The benefits, challenges, and trade‐offs

“…During the establishment phase, no significant difference was observed in N leaching between maize and miscanthus, but when mature, miscanthus decreased N leaching by 42% under fertilized conditions (224 kg N ha −1 ) and 82% when unfertilized (Studt et al., 2021). These characteristics make it a useful crop to include in water protection areas and as part of flood mitigation strategies, provided the variety used has a very low invasiveness risk to prevent escape along water courses (2.4) (Agostini et al., 2021; Ferrarini et al., 2017; Weik et al., 2022).…”

“…While larger field sizes lead to greater economies of scale, it has been shown that smaller plantations of less than 1 ha can provide reasonable gross margins and make use of 5 m wide buffer zones besides water courses where fertilizer applications are prohibited (Winkler et al., 2020). Strategically situating miscanthus stands or planting in strips has been suggested as a useful mechanism to help buffer against nutrient runoff and soil erosion (Agostini et al., 2015; Anejionu & Woods, 2019; Weik et al., 2022).…”