Rice rhizodeposits affect organic matter priming in paddy soil: The role of N fertilization and plant growth for enzyme activities, CO2 and CH4 emissions

Carbon dioxide (CO2) and methane (CH4) production in paddy soils play a crucial role in the global carbon (C) cycle and greenhouse gas emissions. A rhizosphere priming effect (RPE) may change these emissions, but the relationships between RPE, CH4 emission, and the effect of N fertilization are unknown. We investigated the RPE on CO2 and CH4 emissions and their dependence from N fertilization in a13CO2 continuous labelling experiment by partitioning total CO2 and CH4 derived from roots and soil organic matter (SOM). Because of plant-derived CO2, rice plants strongly increased total CO2 emission compared to that from unplanted soil. SOM-derived CO2 and CH4 increased in the presence of roots but decreased after N fertilization. The RPE for CO2 at an early growth stage (≤40 days) was negative: −1.3 and −1.9 mg C day−1 kg−1 soil without and with N fertilization, respectively. However, 52 days after transplanting, RPE for CO2 got to positive. The RPE for CH4 increased gradually up to 1.6 and 0.5 mg C day−1 kg−1 soil at the end of the experiment without and with N fertilization, respectively. Moreover, the RPE for CH4 got half of the RPE for CO2 after 64 days showing the relevance of CH4 emissions for greenhouse gases balance and C cycling in paddy ecosystems. The RPE for CO2 and CH4 emissions increased with microbial biomass content and activities of xylanase and N-acetylglucosaminidase. Supporting the results to RPE, the enzyme activities decreased with N fertilization, suggesting that reduced N limitation decreased microbial potential to mine N from SOM. In conclusion, for the first time we showed that root-microbial interactions stimulated SOM mineralization in rice paddies through rhizosphere priming effects not only for CO2 but also for CH4, but the RPE decreased with N fertilization. © 2017 Elsevier Ltd

Zhu Z.1, 2 , Ge T.1, 2 , Liu S.1, 2 , Hu Y.1, 2 , Ye R.3 , Xiao M.1, 2 , Tong C.1, 2 , Kuzyakov Y. 1, 4, 5, 6 , Wu J.1, 2
Elsevier Ltd
  • 1 Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan, 410125, China
  • 2 Changsha Research Station for Agricultural and Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan, 410125, China
  • 3 Department of Plant and Environmental Sciences, Pee Dee Research and Education Center, Clemson University ClemsonSC 29506, United States
  • 4 Department of Soil Science of Temperate Ecosystems, Department of Agricultural Soil Science, University of Göttingen, Göttingen, 37077, Germany
  • 5 Agro-Technology Institute, RUDN University, Moscow, Russian Federation
  • 6 Institute of Environmental Sciences, Kazan Federal University, Kazan, 420049, Russian Federation
Ключевые слова
C and N cycles; CH4 production; Enzyme activity; N fertilization; Rhizosphere priming effect; Rice paddy
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