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Abstract. Nitrogen (N) fertilizer inputs to agricultural soils area leading cause of nitrous oxide (N2O) emissions. Legume cover cropsare an alternative N source that can reduce agricultural N2O emissionscompared to fertilizer N. However, our understanding of episodic N2Oflux following cover crop incorporation by tillage is limited and hasfocused on single-species cover crops. Our study explores whether increasingcover crop functional diversity with a legume–grass mixture can reduce pulseemissions of N2O following tillage. In a field experiment, we plantedcrimson clover (Trifolium incarnatum L.), cereal rye (Secale cereal L.), a clover–rye mixture, and a no-covercontrol at two field sites with contrasting soil fertility properties inMichigan. We hypothesized that N2O flux following tillage of the covercrops would be lower in the mixture and rye compared to the clovertreatment because rye litter can decrease N mineralization rates. Wemeasured N2O for approximately 2 weeks following tillage to capturethe first peak in N2O emissions in each site. Across cover croptreatments, the higher-fertility site, CF, had greater cover crop biomass,2-fold-higher aboveground biomass N, and higher cumulative N2Oemissions than the lower-fertility site, KBS (413.4±67.5 vs. 230.8±42.5 g N2O-N ha−1; P=0.004). Therewas a significant treatment effect on daily emissions at both sites. AtCF, N2O fluxes were higher following clover than the control 6 d aftertillage. At KBS, fluxes from the mixture were higher than rye 8 and 11 dafter tillage. When controlling for soil fertility differences betweensites, clover and mixture led to approximately 2-fold-higher N2Oemissions compared to rye and fallow treatments. We found partial supportfor our hypothesis that N2O would be lower following incorporation ofthe mixture than clover. However, treatment patterns differed by site,suggesting that interactions between cover crop functional types andbackground soil fertility influence N2O emissions during cover cropdecomposition. 

Agricultural simplification continues to expand at the expense of more diverse forms of agriculture. This simplification, for example, in the form of intensively managed monocultures, poses a risk to keeping the world within safe and just Earth system boundaries. Here, we estimated how agricultural diversification simultaneously affects social and environmental outcomes. Drawing from 24 studies in 11 countries across 2655 farms, we show how five diversification strategies focusing on livestock, crops, soils, noncrop plantings, and water conservation benefit social (e.g., human well-being, yields, and food security) and environmental (e.g., biodiversity, ecosystem services, and reduced environmental externalities) outcomes. We found that applying multiple diversification strategies creates more positive outcomes than individual management strategies alone. To realize these benefits, well-designed policies are needed to incentivize the adoption of multiple diversification strategies in unison. 

Abstract The Kellogg Biological Station Long‐term Agroecosystem Research site (KBS LTAR) joined the national LTAR network in 2015 to represent a northeast portion of the North Central Region, extending across 76,000 km²of southern Michigan and northern Indiana. Regional cropping systems are dominated by corn (Zea mays)–soybean (Glycine max) rotations managed with conventional tillage, industry‐average rates of fertilizer and pesticide inputs uniformly applied, few cover crops, and little animal integration. In 2020, KBS LTAR initiated the Aspirational Cropping System Experiment as part of the LTAR Common Experiment, a co‐production model wherein stakeholders and researchers collaborate to advance transformative change in agriculture. The Aspirational (ASP) cropping system treatment, designed by a team of agronomists, farmers, scientists, and other stakeholders, is a five‐crop rotation of corn, soybean, winter wheat (Triticum aestivum), winter canola (Brassicus napus), and a diverse forage mix. All phases are managed with continuous no‐till, variable rate fertilizer inputs, and integrated pest management to provide benefits related to economic returns, water quality, greenhouse gas mitigation, soil health, biodiversity, and social well‐being. Cover crops follow corn and winter wheat, with fall‐planted crops in the rotation providing winter cover in other years. The experiment is replicated with all rotation phases at both the plot and field scales and with perennial prairie strips in consistently low‐producing areas of ASP fields. The prevailing practice (or Business as usual [BAU]) treatment mirrors regional prevailing practices as revealed by farmer surveys. Stakeholders and researchers evaluate the success of the ASP and BAU systems annually and implement management changes on a 5‐year cycle.