Abstract Agricultural specialization has disconnected crop and livestock production in many farms and regions. As a result, crop farms are deficient in nitrogen to fertilize their crops, while livestock farms are deficient in proteins to feed their animals. The increased consumption of nitrogen rich input raised economics and environmental questions. In this study, we tested two mechanisms to reconnect crop and livestock production: increasing legume production and developing farm-to-farm exchanges of crops and manure. To do so, we developed the SYNERGY bio-economic model, which represents specialized farm types in a region and models exchanges between them. Applied to western France, it analyzes economic, technical and environmental impacts. When the legume share reached 10% of the region's area, legume production increased more on crop farms than on livestock farms and its use in feed was still limited. When farms could export more manure, legume production increased but N losses increased due to an intensification of pig production. This rebound effect offset the environmental benefits linked to the decrease in synthetic N fertilizers use. When local crop exchanges were possible, they remained limited and did not affect indicators. Thus, the two levers studied are insufficient to improve sustainability, mainly because of high livestock production.

中文翻译：

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SYNERGY：分析农场间交流和豆类生产以提高农业可持续性的区域生物经济模型

摘要 农业专业化使许多农场和地区的农作物和畜牧生产脱节。因此，农作物农场缺乏氮来为农作物施肥，而牲畜农场缺乏蛋白质来喂养他们的动物。富氮投入物消耗的增加引发了经济和环境问题。在这项研究中，我们测试了两种重新连接作物和畜牧生产的机制：增加豆类生产和发展农场与农场之间的作物和粪便交换。为此，我们开发了 SYNERGY 生物经济模型，该模型代表一个地区的专业农场类型并模拟它们之间的交流。应用于法国西部，它分析经济、技术和环境影响。当豆类份额达到该地区面积的10%时，农作物农场的豆类产量增长高于畜牧农场，但其在饲料中的使用仍然有限。当农场可以出口更多粪便时，豆类产量增加，但由于养猪生产集约化，氮损失增加。这种反弹效应抵消了与合成氮肥用量减少相关的环境效益。当当地作物交换成为可能时，它们仍然有限且不影响指标。因此，研究的两个杠杆不足以提高可持续性，主要是因为牲畜产量高。这种反弹效应抵消了与合成氮肥用量减少相关的环境效益。当当地作物交换成为可能时，它们仍然有限且不影响指标。因此，研究的两个杠杆不足以提高可持续性，主要是因为牲畜产量高。这种反弹效应抵消了与合成氮肥用量减少相关的环境效益。当当地作物交换成为可能时，它们仍然有限且不影响指标。因此，研究的两个杠杆不足以提高可持续性，主要是因为牲畜产量高。