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

Abstract

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 (N₀: 0, N₁: 150, N₂: 225, N₃: 300) kg N ha⁻¹ with two biochar practices (SB₀: 0, SB:40) t ha⁻¹. The results showed that biochar application treatments (N₀SB, N₁SB, N₂SB, and N₃SB) reduced cumulative fluxes of soil N₂O and CH₄ (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 N₃SB, N₂SB significantly reduced N₂O by 12.85 %, CH₄ 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.