Legacy effect of elevated CO2 and N fertilization on mineralization and retention of rice (Oryza sativa L.) rhizodeposit-C in paddy soil aggregates
Yuhong Li , Hongzhao Yuan , Anlei Chen , Mouliang Xiao , Yangwu Deng , Rongzhong Ye , Zhenke Zhu , Kazuyuki Inubushi , Jinshui Wu , Tida Ge
Soil Ecology Letters ›› 2022, Vol. 4 ›› Issue (1) : 78 -91.
Legacy effect of elevated CO2 and N fertilization on mineralization and retention of rice (Oryza sativa L.) rhizodeposit-C in paddy soil aggregates
• Elevated CO2 increased the amounts of rhizodeposits. • The turnover of rhizodeposits derived from N soil was faster than no N soil. • Rhizodeposits derived from elevated CO2 decomposed slower than from ambient air. • Microaggregates and silt-clay were the most and least affected fractions separately.
Rhizodeposits in rice paddy soil are important in global C sequestration and cycling. This study explored the effects of elevated CO2 and N fertilization during the rice growing season on the subsequent mineralization and retention of rhizodeposit-C in soil aggregates after harvest. Rice (Oryza sativa L.) was labeled with 13CO2 under ambient (400 ppm) and elevated (800 ppm) CO2 concentrations with and without N fertilization. After harvest, soil with labeled rhizodeposits was collected, separated into three aggregate size fractions, and flood-incubated for 100 d. The initial rhizodeposit-13C content of N-fertilized microaggregates was less than 65% of that of non-fertilized microaggregates. During the incubation of microaggregates separated from N-fertilized soils, 3%–9% and 9%–16% more proportion of rhizodeposit-13C was mineralized to 13CO2, and incorporated into the microbial biomass, respectively,, while less was allocated to soil organic carbon than in the non-fertilized soils. Elevated CO2 increased the rhizodeposit-13C content of all aggregate fractions by 10%–80%, while it reduced cumulative 13CO2 emission and the bioavailable C pool size of rhizodeposit-C, especially in N-fertilized soil, except for the silt-clay fraction. It also resulted in up to 23% less rhizodeposit-C incorporated into the microbial biomass of the three soil aggregates, and up to 23% more incorporated into soil organic carbon. These results were relatively weak in the silt-clay fraction. Elevated CO2 and N fertilizer applied in rice growing season had a legacy effect on subsequent mineralization and retention of rhizodeposits in paddy soils after harvest, the extent of which varied among the soil aggregates.
Rice rhizodeposits / Isotope labeling / Aggregates / Elevated carbon dioxide / Nitrogen fertilizer
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Higher Education Press
Supplementary files
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