Effects of biochar combined with different nitrogen fertilization rates on turf quality and carbon footprint in a turf system

Biochar has been widely recognized for its potential to mitigate greenhouse gas emissions and enhance soil fertility through increased soil organic carbon (SOC) storage; however, systematic evaluations of carbon balance and ecological benefits in turf systems remain scarce. This study included eight treatments combining four N (nitrogen) rates (N 0 : 0, N 1 : 150, N 2 : 225, N 3 : 300) kg N ha -1 with two biochar practices (SB 0 : 0, SB:40) t ha -1 . The results showed that biochar application treatments (N 0 SB, N 1 SB, N 2 SB, and N 3 SB) reduced cumulative fluxes of soil N 2 O and CH 4 (global warming potential, GWP) by 17.37%, 26.62%, 32.73%, and 30.97%, net global warming potential (NGWP) 43.71%, 369.64%, 1046.17%, and 545.83%, and CF by 32.01%, 192.81%, 356.66%, and 253.34%, while increasing SOC sequestration by 129.20%, 138.61%, 133.89%, and 133.61%, total biomass by 3.99%, 14.22%, 15.51%, and 14.78%, and turf normalized difference vegetation index (NDVI) by -0.18%, 2.81%, 2.81%, and 1.89% compared to non-biochar treatments. Although biochar slightly increased ecosystem respiration, the effect was not significant ( p > 0.05). Notably, compared to N 3 SB, N 2 SB significantly reduced N 2 O by 12.85%, CH 4 by 11.47%, CF (carbon footprint) by 16.01%, and NGWP by 9.82%, while ecosystem respiration, SOC storage, turfgrass total biomass, and NDVI exhibited no significant differences between the two treatments. Overall, the co-application of biochar with 225 kg N ha -1 is a win−win strategy for reducing CF, enhancing carbon sequestration, and maintaining turf quality. • GHG emissions, SOC sequestration and turf quality of different turf managements were evaluated. • Biochar reduced carbon footprint by enhancing SOC sequestration and mitigating GWP. • Combining biochar with moderate nitrogen input (N 2 ) optimized carbon sequestration while maintaining turf growth and quality. • Excessive nitrogen (N 3 ) yielded no additional benefits over moderate levels, emphasizing the importance of balanced N management.