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

Source abstract

Abstract 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 (N 2 O) 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 N 2 O emissions. This study aimed to assess the impact of 11 conventional and alternative lawn management practices, on carbon dioxide (CO 2 ) and N 2 O 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 N 2 O 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 CO 2 and N 2 O emissions. Lawns mowed once a year emitted 1.5 times less CO 2 (752 mg CO 2 m − 2 h − 1 ) than conventional lawns mowed weekly and receiving mineral fertilizer (1147 mg CO 2 m − 2 h − 1 ). The results suggest that mineral fertilization should be replaced by organic alternatives to reduce N 2 O 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.