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| Effects of addition of rice straw and rice straw biochar on soil organic carbon fractions and cumulative emissions of CH4 and CO2 in reddish paddy soil |
| Received:November 29, 2021 |
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| KeyWord:rice straw biochar;reddish paddy soil;particulate organic carbon;mineral-associated organic carbon;dissolved organic carbon;greenhouse gases |
| Author Name | Affiliation | E-mail | | LIAO Tianhuai | College of Applied Meteorology, Nanjing University of Information Sciences and Technology, Nanjing 210044, China | | | LI Huan | College of Applied Meteorology, Nanjing University of Information Sciences and Technology, Nanjing 210044, China | | | WANG Yanling | College of Applied Meteorology, Nanjing University of Information Sciences and Technology, Nanjing 210044, China | ylwang@nuist.edu.cn |
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| Abstract: |
| Clarifying the influence of rice straw biochar addition on soil organic carbon fractions and cumulative emissions of CH4 and CO2 and the associated underlying mechanisms could provide scientific basis for carbon sequestration and mitigation of CH4 and CO2 emissions in reddish paddy soil. In this study, a reddish paddy soil was used in an indoor incubation experiment with five soil amendment treatments:control (CK), rice straw (RS), and rice straw biochar prepared at 300, 400℃, and 500℃ (RSB300, RSB400, RSB500, respectively). These soil amendments were applied at the rate equivalent to 1% carbon addition to soil, based on soil weight. Differences in soil dissolved organic carbon (DOC), total organic carbon (TOC), free coarse particulate organic carbon (fcPOC), free fine particulate organic carbon (ffPOC), occluded particulate organic carbon (oPOC), free mineral-associated organic carbon (fMOC), and occluded mineral-associated organic carbon (oMOC) were analyzed after 0, 30 d, and 120 d of incubation. Correlations between cumulative emissions of CH4 and CO2 and various soil organic carbon fractions were also discussed. The results showed that DOC, TOC, fcPOC, ffPOC, oPOC, and fMOC contents were significantly increased in reddish paddy soil after rice straw biochar addition. With the increase in incubation time, oPOC and oMOC contents significantly increased, but fcPOC and fMOC contents significantly decreased. Compared with the CK treatment group, cumulative emissions of CH4 and CO2 in reddish paddy soil in the RS treatment group significantly and continuously increased. However, cumulative emissions of CO2 in reddish paddy soil in the RSB500 treatment group significantly decreased. In constrast, it increased in RSB300 and RSB400 treatment groups, with cumulative emission of CH4 in these treatment groups after 120 d of incubation increasing by 188.5% and 32.7%, respectively. Correlation analysis showed that cumulative emissions of CH4 and CO2 were significantly positively correlated with DOC, ffPOC, and fcPOC contents in reddish paddy soil after RS and RSB additions, but were mainly influenced by DOC and fcPOC (P< 0.01). Therefore, the addition of rice straw biochar can effectively improve the quantity and stability of soil organic carbon fractions in reddish paddy soil. Addition of rice straw biochar with pyrolysis at 500℃ exhibited the most remarkable inhibitory effect on cumulative emissions of CH4 and CO2 in this soil. |
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