Professor Xinhua He^1,2, Ms Rong Huang¹, Mr Dong  Tian¹, Mr Jiang Liu¹, Mr Sheng Lv¹, Mr Ming Gao¹

¹Centre of Excellence for Soil Biology, College of Resources & Environment, Southwest University, Beibei, China, ²School of Biological Sciences, University of Western Australia, Perth, Australia

How to link soil carbon (C) sequestration or restoration with straw utilization is an enormous challenge for agriculture. The addition of straw-based organic matters including fresh straw, decomposed straw or straw-derived biochar to soil can alter soil C pools. To understand the potential of soil C sequestration and dynamics after the addition of straw and/or straw-derived biochar, an in situ mesocosm experiment in purple soil (Eutric Regosol) was performed under five treatments: (1) no straw/biochar control (CT), (2) straw only (ST), (3) straw with a straw-decay bacterium (STDB), (4) biochar only (BC) and (5) straw plus biochar (STBC). Carbon dioxide (CO2) flux from soil, soil organic C (SOC), labile organic C (LOC), and soil aggregate associated OC were analyzed within a dryland rapeseed/maize cropping system. Results showed that soil CO2 flux increased with the addition of straws (ST, STBC and STDB), but decreased under BC because its lower LOC, particularly the microbial biomass C fraction in LOC. The combined application of STDB increased percentage of macro-aggregates (>2mm and 0.25-2mm). Meanwhile, both the decomposition of organic matter and the CO2 flux were increased. The 0.053-0.25mm aggregates under BC had the highest fine intra-aggregate particulate organic C (iPOC), which promoted C sequestration. However, the higher coarse-iPOC in >2mm and 0.25-2mm aggregates under ST and STDB promoted SOC decomposition and also CO2 flux. Compared with all three straw treatments (ST, STBC and STDB), the sole biochar addition improved the physical protections for SOC from soil aggregates, but reduced CO2 flux, while increased net C sequestration without significant decreases of crop yields and net primary productivity. Our results demonstrated differential responses of soil C pool and aggregates associated organic C to straw and/or straw-derived biochar addition while providing insights into the potential for soil C sequestration or restoration by using agriculture based organic materials.

Biography:

Xinhua is currently a Professor and Director of Centre of Excellence for Soil Biology at Southwest University, Chongqing China (2015-). He has held a PhD in Plant Ecophysiology from University of Queensland, Australia since 2002, and then worked as a Postdoctoral Fellow at UC Davis and University of Tokyo, Senior Research Scientist at USDA and University of Western Australia.

During the past 20 years, Xinhua has focused on carbon/nitrogen movement in agricultural and natural ecosystems, roles of soil beneficial microbes in plant ecophysiology and soil structural stability and health, nano-minerals complexation in the preservation of soil organic matter under contrasting fertilizations. Xinhua is currently exploring emerging technologies including stable isotopes of 13C and 15N, Pyrosequencing, Electron Microscopy, Nano-scale Secondary Ion Mass Spectrometry (nano-SIMS), and Synchrotron Radiation Facility, etc., to address above-mentioned topics in a variety of plant-microbial-soil systems under global environmental change scenarios.

Currently Xinhua has >200 publications including 3 books, 26 book chapters and >170 papers in a variety of journal including Agri Ecosyst Environ, Biol Fert Soils, Biogeosciences, Glob Biogeochem Cy, Nature Commu, Nature Geosci, New Phytologist, Plant Soil, SBB, Trends Ecol & Evol, Trends Plant Sci, Tree Physiol, etc. (see https://www.researchgate.net/profile/Xinhua_He3). At present Xinhua has presented >100 talks at various universities and international conferences and his research has been viewed by 70,000 times by >4,000 readers from the Mendeley data base. Xinhua has been servicing as a Section Editor for Plant and Soil (2015) and an Associate Editor Soil Research (2019) and a regular peer reviewer for >100 journals and funding bodies (ARC, GRDC, BBSRC sLOLA, NSF, NSFC, USDA and NOW) around the world.