Biochar and mycorrhiza enhance soil carbon storage and reduce CO2 emissions in wastewater-irrigated turf

Irrigation with recycled wastewater can reduce freshwater demand and improve soil fertility, but it can also increase CO2 emissions from soil and contribute to global warming. This study investigated whether biochar and mycorrhiza can reduce CO2 emissions and enhance soil quality in wastewater-irrigated turf. A factorial experiment was conducted with four levels of biochar (0, 0.5, 1, and 1.5%), two mycorrhiza (with and without), and two types of irrigation water (freshwater and recycled wastewater). Soil CO2 and H2O emissions, moisture and temperature, and chemical and physical properties were measured for 3 months. Biochar and mycorrhiza treatments significantly reduced CO2 emissions by 19.4-45.0% compared to the control treatment. The combination of biochar at a 1.5% level with mycorrhiza had the highest emission-reducing effect. Biochar and mycorrhiza treatments also reduced H2O emissions by 8.1-14.6%, increased soil organic matter, carbon, and total nitrogen, regulated soil EC and pH, and improved soil porosity and aggregate stability. The results suggest that biochar and mycorrhiza can be effective strategies to mitigate CO2 emissions and improve soil quality in wastewater irrigation. The combination of biochar with mycorrhiza can have synergistic benefits for soil carbon storage and conservation.