Prof. Guanghui Yu¹

¹Tianjin University, Tianjin, China

Intensive agriculture results in soil degradation, especially with the depletion of soil organic carbon (SOC). Application of organic fertilizers (e.g., animal manures) alone or combined with chemical fertilizers can alleviate soil degradation by increasing soil C while causing variations in soil hydrogen peroxide (H2O2) and iron availability. However, the underlying relationships among soil H2O2 production, iron availability and soil C storage following organic fertilization remain poorly understood. By combining results from three agroecosystem experiments from temperate northern to subtropical southern China with 25‒29 years of different fertilization treatments (no fertilization, Control; inorganic nitrogen, phosphorus and potassium fertilization, NPK; NPK plus manure, NPKM), here we show that NPK treatments increased soil H2O2 but decreased biodiversity (i.e., Shannon index) and SOC compared to NPKM treatments across all of the three fertilization sites. In all of the examined soils, the concentrations of H2O2 were approximately 0.7- to 7–fold higher under NPK treatment than under Control or NPKM treatments. The concentrations of H2O2 were significantly affected by the fertilization regimes (P < 0.001), experimental locations (P = 0.001) and their interaction (P = 0.01). Compared to Control and NPKM treatments, NPK treatment decreased Shannon index to the greatest extent (~1.5) at Qiyang site, followed by Jinxian (~0.6) and Gongzhuling (~0.3). There was a significant but negative correlation between soil H2O2 and Shannon index or mobilized iron, indicating that high biodiversity and high mobilized iron were beneficial to the decay of soil H2O2. Results from microcosm experiments support the field observations, implying the occurrence of microbial-mediated Fenton-like reactions or free-radical reactions was influenced by organic inputs. Together, these findings suggest that long-term manure inputs to soil initialize free-radical reactions by activating microbial communities and mobilizing iron, providing benefits for soil C stabilization and storage by increasing recalcitrance and SOC interactions.

Biography: Guanghui Yu, professor of Biogeoscience, Tianjin University. His specific research interests include: (1) Coupling Cycling of C and Fe in Soil. (2) Fungal-mineral Interfacial Processes.(3) Composting Process. He has published over 70 peer-reviewed English papers in international journals. He is currently the Associate Editor of 《Waste Management》and the Topic Editor of 《Frontiers in Environmental Science》.