Speaker
Description
Introduction
Sustainable cropping systems are deemed multifunctional, i.e., supplying sufficient agricultural products while maximizing eco-environmental and socio-economic benefits. Researchers have made considerable efforts to develop cropping systems towards multi-attribute sustainability either by diversifying crop rotations (Liang et al., 2023) or ameliorating management practices (Chen et al., 2014). However, few studies investigate the sustainability benefits of cropping systems by integrating these two approaches, leaving the potential scope for improvement across multiple sustainability objectives unknown. To fill this gap, we proposed a model-aided method for designing and evaluating all agronomically feasible crop rotations furnished with the optimal management regime for specific agricultural regions, which enables stakeholders to grasp the whole picture of improvement potential and possible trade-offs across farming sustainability objectives.
Methods
Our modelling framework for designing sustainable cropping systems comprises four parts: 1) Rotation generation module, 2) Yield estimation module, 3) Management optimization module, and 4) Indicator assessment module. Initially, the model generates all feasible rotations based on a predefined list of candidate crops and rotation rules (Dogliotti et al., 2004). Next, it calculates the yield of each crop in the rotations, considering the attainable yield level and crop succession-induced yield-reducing factors. An optimal management regime is then devised for each crop to close the yield gap associated with crop management with more efficient resource use, incorporating three advanced agronomic strategies including the integrated soil-crop system management (Chen et al., 2014), the steady-state N balance fertilization (Yin et al., 2021), and manure substitution. With crop input-output data obtained from above steps, the model quantifies the sustainability indicator performance of rotations in socio-economic, human-nutrition, eco-environmental terms. We illustrate this framework by exploring promising cropping systems in terms of 11 sustainability objectives for the North China Plain where cropland is predominantly covered by the highly intensified wheat-maize double cropping.
Results
Relative to the currently dominant intensified wheat-maize system, optimized management can increase gross margin by 47%, and dietary energy and zinc yield by 19% while mitigating groundwater depletion, aquatic eutrophication, and greenhouse gas emission by 45-75% albeit with a 12% increase in economic risk. However, this cereal-based system did not produce vitamin C and had low agrobiodiversity. The model generated 3,684 optimally managed alternative rotations, of which 2801 (76%) are Pareto-optimal in terms of 11 objectives. Although no single alternative outperformed the intensified wheat-maize in all objectives simultaneously particularly due to higher labor use and economic risks, these rotations presented considerable benefits in gross margin, vitamin C output and eco-environmental indicators. On average, Pareto-optimal rotations had more than twice the gross margin and agrobiodiversity, and 36-64% lower groundwater depletion, aquatic eutrophication and greenhouse gas emission compared to the intensified wheat-maize system, while 405, 612 and 2421 (16%, 22% and 86%) of them supplied more dietary energy, zinc, and vitamin C than the wheat-maize respectively. On the other hand, trade-offs were evident between gross margin and economic risks/labor use, and between gross margin/dietary energy yield and eco-environmental benefits.
Discussion
Combining rotation diversification and management optimization holds promise for improving multi-attribute sustainability. While optimizing management alone for the dominant wheat-maize system could deliver multiple wins in productivity, profitability and eco-environmental performance, it failed to address objectives that require the inclusion of non-cereal species, e.g., vitamin C production and agrobiodiversity. Moreover, optimally managed diversified rotations could offer opportunities to further enhance the benefit for each sustainability objective compared to the wheat-maize system. Given that no single rotation performed best across all objectives, implementing various promising rotations with the optimized wheat-maize system in the future farming landscapes could better reconcile stakeholders' sustainability demands. This modeling framework is flexible for application in other agricultural regions with appropriate adaptations.
References
Dogliotti, S., et al., 2003. ROTAT, a tool for systematically generating crop rotations. Eur. J. Agron. 19, 239–250.
Liang, Z., et al., 2023. Designing diversified crop rotations to advance sustainability: A method and an application. Sustain. Prod. Consum. 40, 532–544.
Chen, X., et al., 2014. Producing more grain with lower environmental costs. Nature 514, 486–489.
Yin, Y., et al., 2021. A steady-state N balance approach for sustainable smallholder farming. Proc. Natl. Acad. Sci. 118, e2106576118.
| Keywords | Multi-attribute agricultural sustainability; Cropping system redesign; Trade-offs; Synergies; ROTAT model |
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