Mediterranean cropping systems, characterised by continuous cereal cropping, are largely dependent on synthetic inputs, such as N fertilisers. On the other hand, they face difficult pedoclimatic conditions, exacerbated by climate change. Diversification is seen as a way to increase cropping systems resilience. The aim of this study was to co-design diversified cropping systems based on the expertise of local stakeholders and co-assess their performance, using modelling data. Our case study is the Ebro valley in Spain, a Mediterranean area with great potential for diversification, particularly where irrigation is available. Two workshops were organized to i) define the reference system in the study area and its limitations ii) co-design diversified systems to overcome these limitations and iii) co-assess reference and diversified systems. Between the two workshops, the STICS soil-crop model was calibrated with local experimental data, enabling to simulate the inter-annual (2000–2021) agronomic and environmental performance of the reference and diversified systems. An economic analysis was conducted. Stakeholders evaluated all economic, agronomic and environmental aspects. The reference system was a continuous winter cereal crop based on synthetic N fertilisation and intensive tillage. The four diversified co-designed systems consisted in introducing pea and/or rapeseed every 2 or 4 years, reducing tillage and partially replacing synthetic N fertilisation with locally sourced livestock manure. Simulation results showed that wheat and barley grain yields remained stable with diversification. Pea and rapeseed yields were lower in rotations where both were introduced compared to when each was the only break crop over 4 years. At the system level, protein yield remained stable with diversification, however, energy yield decreased by 20 % when break crops were introduced twice and by 10 % when introduced once. Gross margins improved with diversification only when pea was introduced once (12 %), mainly due to reduced expenses (-31 %), while incomes remained stable compared to RCS. However, incomes decreased by 5 % when rapeseed was introduced once, and by 10 % when both break crops were introduced. Unexpectedly, environmental performance deteriorated with diversification, with increased N losses through ammonia volatilisation and nitrate leaching in the years following pea and rapeseed cropping, due to greater N availability in the soil. An increased use of pesticides was predicted by the stakeholders in diversified systems, where the environmental impacts were exacerbated with the higher presence of break crops. The reference system presented slightly lower N availability and increased soil organic carbon storage. Overall, the approach proved useful in identifying a diversification strategy that improved agronomic and economic performance, with the system including pea once every four years being the most efficient. However, the environmental trade-offs associated with the increased presence of pea and rapeseed in the crop rotation must be considered in order to mitigate the environmental risks.

中文翻译：

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共同设计的多样化地中海种植系统的绩效：混合利益相关者的知识和建模数据


地中海种植系统的特点是连续种植谷物，在很大程度上依赖于合成投入，例如氮肥。另一方面，他们面临着因气候变化而加剧的艰难的土壤气候条件。多样化被视为提高种植系统弹性的一种方式。本研究的目的是根据当地利益相关者的专业知识共同设计多样化的种植系统，并使用建模数据共同评估其绩效。我们的案例研究是西班牙的埃布罗河谷，这是一个具有巨大多样化潜力的地中海地区，特别是在有灌溉的地方。组织了两次研讨会，以 i）定义研究领域的参考系统及其局限性 ii）共同设计多元化系统以克服这些局限性 iii）共同评估参考和多元化系统。在两次研讨会之间，STICS 土壤作物模型使用当地实验数据进行了校准，从而能够模拟参考系统和多样化系统的年际（2000-2021）农艺和环境绩效。进行了经济分析。利益相关者评估了所有经济、农艺和环境方面。参考系统是基于合成氮肥和精耕细作的连续冬季谷物作物。四个多样化的共同设计系统包括每 2 或 4 年引入豌豆和/或油菜籽、减少耕作以及用当地牲畜粪便部分取代合成氮肥。模拟结果表明，小麦和大麦籽粒产量保持稳定且多样化。与 4 年内唯一中断作物时相比，豌豆和油菜籽轮作产量较低。 在系统水平上，蛋白质产量随着多样化而保持稳定，然而，当引入两次休息作物时，能量产量下降了20%，当引入一次时，能量产量下降了10%。仅当豌豆推出一次时（12%），毛利率才随着多元化而改善，主要是由于费用减少（-31%），而与 RCS 相比，收入保持稳定。然而，当引进一次油菜籽时，收入下降了 5%，当引进两种休耕作物时，收入下降了 10%。出乎意料的是，环境绩效随着多样化而恶化，在豌豆和油菜种植后的几年里，由于土壤中氮的有效性增加，氨挥发和硝酸盐浸出导致氮损失增加。多元化系统中的利益相关者预计农药的使用会增加，其中更多的休耕作物会加剧对环境的影响。参考系统的氮利用率略低，土壤有机碳储存量有所增加。总体而言，该方法被证明有助于确定可改善农艺和经济绩效的多样化战略，其中每四年一次包括豌豆的系统是最有效的。然而，为了减轻环境风险，必须考虑与轮作中豌豆和油菜籽增加相关的环境权衡。