Sustainable intensification strategies seek to increase production while decreasing the environmental footprint of agricultural systems. In the Upper Mississippi River Basin, relay cropping of a winter oilseed crop between corn and soybean has gained interest for its potential to increase total yields and revenue while providing the environmental benefits of winter cover. In a six-year field study in central Iowa, a basic corn-soybean rotation was compared with a corn-winter camelina-soybean relay cropping system for crop yields, nitrate losses in drainage, and nitrous oxide (N₂O) emissions from soil. Despite filling a niche as an overwintering crop with the potential to assimilate soil nitrogen, nitrate loads in drainage were not reduced in the camelina relay cropping system. Over the course of the study, management changes to support the camelina crop tripled cumulative N₂O emissions during the camelina-soybean phase, from 3.57 kg N₂O-N ha^-1 in the basic corn-soybean rotation to 12.2 kg N₂O-N ha^-1 in the camelina relay system. Most of the increased emissions in the camelina system were associated with peak emissions events following tillage and starter fertilizer application in the fall and during the spring thaw, which may point to risks of exacerbating greenhouse gas emissions during fall management of a relay crop. Corn and soybean yields were decreased in the relay cropping system by 9.8 % and 23.3 %, respectively, as a result of management changes to the system and interspecific competition. However, combined grain dry weight of soybean and the camelina oilseed crop were similar to the soybean yield in the basic corn-soybean rotation. These findings highlight the need for careful evaluation and optimization of sustainable intensification systems to ensure environmental and production goals are met.

可持续集约化战略旨在增加产量，同时减少农业系统的环境足迹。在密西西比河流域上游，在玉米和大豆之间进行冬季油籽作物的接力种植已引起人们的兴趣，因为它有可能增加总产量和收入，同时提供冬季覆盖的环境效益。在爱荷华州中部进行的一项为期六年的田间研究中，比较了基本的玉米-大豆轮作与玉米-冬季亚麻荠-大豆轮作系统的作物产量、排水中的硝酸盐损失和一氧化二氮（N ₂O) 土壤排放。尽管作为一种具有同化土壤氮潜力的越冬作物填补了生态位，但在亚麻荠种植系统中，排水中的硝酸盐负荷并未减少。在研究过程中，为支持亚麻荠作物而进行的管理改变使亚麻荠-大豆阶段的累积 N _{2 O 排放量增加了两倍，从基本玉米-大豆轮作中的 3.57 kg N 2} O-N ha ^-1增加到 12.2 kg N ₂ O-N ha ^-1在亚麻荠接力系统中。亚麻荠系统中大部分增加的排放与秋季耕作和施肥后和春季解冻期间的排放峰值事件有关，这可能表明在接力作物的秋季管理期间加剧温室气体排放的风险。由于系统管理变化和种间竞争，轮作系统的玉米和大豆产量分别下降了 9.8% 和 23.3%。然而，大豆和亚麻籽作物的组合谷物干重与基本玉米-大豆轮作中的大豆产量相似。这些发现强调了对可持续集约化系统进行仔细评估和优化的必要性，以确保实现环境和生产目标。