Minimizing N2O and CO2 emissions from urban lawns through sustainable management strategies

Lawns, which can represent up to 50–70% of urban green spaces, provide key ecosystem services. However, their greenhouse gas (GHG) emissions depend strongly on management practices. Conventional practices—such as mineral fertilization and irrigation—increase soil nitrous oxide (N2O) emissions and contribute to the carbon footprint of lawns. In contrast, alternative approaches—such as organic fertilization, reduced mowing frequency, and recycling of grass clippings and tree litter on soil surface—may improve carbon storage and reduce GHG emissions. However, litter decomposition may also lead to N2O emissions. This study aimed to assess the impact of 11 conventional and alternative lawn management practices, on carbon dioxide (CO2) and N2O emissions, with a particular focus on comparing the effects of mineral and organic fertilization. GHG fluxes were measured in spring, summer, and autumn, and analyzed in relation to soil temperature, moisture and mineral nitrogen concentrations. Organic fertilization induced 8.1 times less cumulative N2O emissions (2–5 mg N m− 2) than mineral fertilization (34–70 mg N m− 2). Recycling of grass clippings and tree litter on soil surface did not increase CO2 and N2O emissions. Lawns mowed once a year emitted 1.5 times less CO2 (752 mg CO2 m− 2 h− 1) than conventional lawns mowed weekly and receiving mineral fertilizer (1147 mg CO2 m− 2 h− 1). The results suggest that mineral fertilization should be replaced by organic alternatives to reduce N2O emissions, and that spring applications should be delayed or avoided to enhance N use efficiency. Furthermore, reducing mowing frequency and recycling litter on lawns appear to be sustainable alternatives, as they have a low potential for GHG emissions while also supporting soil fertility, carbon storage, water cycling, and biodiversity.