Perennial forage systems enhance ecosystem quality variables compared with annual forage systems

Authors: IGBOKE, OGECHUKWU - North Dakota State University; BORTOLON, ELISANDRA - North Dakota State University; Ashworth, Amanda; TALLAKEN, JOE - University Of Minnesota; PICASSO, VALENTIN - University Of Minnesota; BERTI, MARISOL - North Dakota State University

Submitted to: Sustainability
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/16/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: As global challenges like climate change, biodiversity loss, and resource depletion increase, adopting more sustainable agricultural practices becomes imperative. Modern agriculture has been a driving force behind the unprecedented growth in global food production, but also raises concerns about environmental consequences. For the above reasons, there has been a growing interest in exploring sustainable alternatives to traditional annual cropping systems in recent years. One such promising solution is cropping systems diversification by integrating perennial forages into high-input, low-diversity cropping systems, however, environmental outcomes have largely not been explored. Researchers set out to evaluate environmental impacts of annual and perennial forage production (grain, pasture, silage, and hay) systems. Overall, this study found that perennial legumes or forages, in the form of crop rotations with annuals, and spatial diversity, such as intercropping multiple crop species with annuals, play a crucial role in fostering resilience and stability in agroecological systems. Consequently, perennial agriculture not only improves environmental services and nutrient circularity but also provides options for diversification by integrating livestock, manure applications, and other soil organic amendments while improving productivity under a changing climate.

Technical Abstract: As policymakers, farmers, and researchers strive to address the challenges posed by modern agriculture, a deeper understanding of how perennial forage cropping systems compare with conventional annual systems across key environmental impact categories can provide critical insights and become increasingly crucial for building a resilient and environmentally responsible agricultural future. In this study, a meta-analysis was conducted using a random effect model on empirical studies to determine the environmental impacts of annual vs. perennial forage production (grain, pasture, silage, and hay) management systems. Data of environmental impact categories of global warming potential or greenhouse gas emissions, fossil energy consumption, ozone layer depletion, abiotic depletion potential, ecotoxicity potential (terrestrial, freshwater, and marine), terrestrial acidification potential, and eutrophication potential (freshwater and marine) were extracted from original research peer-reviewed papers that included life cycle assessment. The system types considered included business as usual (BAU), only annual monoculture forages (as a control), BAU-improved, alternative, or aspirational system (AS), and diverse perennial circular system (DPCS). Overall, BAU exhibited an insignificant impact in ecotoxicity and eutrophication potential while maintaining a difference of 56%, 42, and 34% decrease in ecotoxicity, terrestrial acidification, and eutrophication potential, respectively, compared to DPCS. Also, BUA, BUA-improved, and AS were generally lower than DPCS because production methods for the alternative systems were closely related to BAU system. For this reason, integrating alfalfa (Medicago sativa; perennial) alfalfa-based systems into a diverse monoculture system improved all environmental categories devoid of net revenue losses. More so, DPCS with alfalfa legume diversification, through polyculture or intercropping, is a strategy that increases yields and income while improving nutrition, fostering resilience and stability, and providing ecosystem services.