Dry-rewetting cycles regulate wheat carbon rhizodeposition,stabilization and nitrogen cycling |
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| Institution: | 1. Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA, USA;2. Natural Resources Ecology Laboratory, Department of Chemistry, Colorado State University, Fort Collins, CO, USA;3. Department of Ecology and Evolutionary Biology, Department of Earth System Science, University of California, Irvine, CA 92697-2525, USA;1. Key Laboratory of Mollisols Agroecology, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin 150081, China;2. School of Agriculture, Food & Wine, The University of Adelaide, Adelaide, South Australia 5005, Australia;1. Tiantong National Forest Ecosystem Observation and Research Station, Center for Global Change and Ecological Forecasting, Shanghai Key Lab for Urban Ecological Processes and Eco-restoration, Institute of Eco-Chongming, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China;2. State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province 210008, China;1. Department of Crop Production Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden;2. Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden;3. Department of Physical Geography and Quaternary Geology, Stockholm University, Sweden;4. Department of Biosystems Engineering & Soil Science, University of Tennessee, Knoxville, TN, USA;5. Nicholas School of the Environment, Duke University, Durham, NC, USA;6. Department of Civil and Environmental Engineering, Duke University, Durham, NC, USA;7. Department of Ecology, Evolution and Marine Biology, University of California at Santa Barbara, Santa Barbara, CA, USA |
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| Abstract: | Drying and rewetting of soil can have large effects on carbon (C) and nitrogen (N) dynamics. Drying-rewetting effects have mostly been studied in the absence of plants, although it is well known that plant–microbe interactions can substantially alter soil C and N dynamics. We investigated for the first time how drying and rewetting affected rhizodeposition, its utilization by microbes, and its stabilization into soil (C associated with soil mineral phase). We also investigated how drying and rewetting influenced N mineralization and loss. We grew wheat (Triticum aestivum) in a controlled environment under constant moisture and under dry-rewetting cycles, and used a continuous 13C-labeling method to partition plant and soil organic matter (SOM) contribution to different soil pools. We applied a 15N label to the soil to determine N loss. We found that dry-rewetting decreased total input of plant C in microbial biomass (MB) and in the soil mineral phase, mainly due to a reduction of plant biomass. Plant derived C in MB and in the soil mineral phase were positively correlated (R2 = 0.54; P = 0.0012). N loss was reduced with dry rewetting cycles, and mineralization increased after each rewetting event. Overall drying and rewetting reduced rhizodeposition and stabilization of new C, primary through biomass reduction. However, frequency of rewetting and intensity of drought may determine the fate of C in MB and consequently into the soil mineral phase. Frequency and intensity may also be crucial in stimulating N mineralization and reducing N loss in agricultural soils. |
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| Keywords: | Rhizodeposition Drought Carbon stabilization Plant–microbe interactions Rewatering Wheat |
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