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| Effects of atmospheric CO2 enrichment and straw return on aggregate organic carbon in black soil |
| Received:August 05, 2022 |
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| KeyWord:CO2 concentration;straw return;soil aggregate;organic carbon;contribution rate |
| Author Name | Affiliation | E-mail | | YUE Ya | School of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China | | | XUE Haiqing | School of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China | | | FENG Qian | School of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China | | | MIAO Huan | School of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China | | | MIAO Shujie | School of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China | sjmiao2015@nuist.edu.cn | | QIAO Yunfa | School of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China | |
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| Abstract: |
| The responses of organic carbon distribution in soil aggregates to CO2 enrichment and straw return were studied to provide theoretical evidence for the carbon sequestration and mitigation of black soil. Based on the long-term CO2 enrichment experimental platform located in the black soil region of northeast China, four treatments were set. The treatments were the control（CK）, increasing CO2 concentration to 1 259.72 mg·m-3（EC）, straw returning（ST）, and increasing CO2 concentration combined with straw returning（EC+ST）. The results showed that the EC and ST treatments had no significant effect on the total soil organic carbon, whereas the EC+ST treatment increased total soil organic carbon by 3.09 g·kg-1（P<0.05）. The EC treatment had no significant effect on the proportion of soil aggregates, although the fractal dimension（D）increased by 0.06 and the stability of the soil aggregates decreased. Both the ST and EC + ST treatments increased the proportion of >0.5–1 mm macro-aggregates by 14.98 percentage points and 8.20 percentage points, respectively. In addition, the ST treatment reduced the proportion of ≤0.053 mm micro-aggregates by 12.88 percentage points, increased the number of waterstable aggregates（R0.25）by 0.14, and the average weight diameter（dMW）was increased by 0.08 mm, furthermore, D decreased by 0.11（P< 0.05）, and the stability of soil aggregates was enhanced, whilst the EC+ST treatment increased the proportion of >1 mm macro-aggregates by 4.07 percentage points, and also increased the dMW by 0.11 mm and increased the stability of soil aggregates. Compared with CK, the EC and EC + ST treatments increased the soil organic carbon content of ≤0.053 mm micro-aggregates by 0.66 g · kg-1 and 1.98 g · kg-1, respectively. In addition, the ST treatment increased the >1 mm macro-aggregate content of soil organic carbon by 0.55 g·kg-1, whilst >0.25–0.5 mm macro-aggregates decreased by 1.13 g·kg-1. In addition, the EC + ST treatment reduced > 1 mm macro-aggregates by 3.05 g·kg-1 （P<0.05）. EC treatment also increased the contribution of organic carbon of ≤0.053 mm micro-aggregates by 9.14 percentage points, compared to ST treatment, which decreased this by 10.54 percentage points. Furthermore, the organic carbon contribution rate of >0.5–1 mm macro-aggregates was increased by 14.35 percentage points, and the EC+ ST treatment increased the organic carbon contribution rate of both >1 mm macro-aggregates and >0.5 – 1 mm macro-aggregates by 3.25 percentage points and 6.74 percentage points, respectively. Additionally, >0.053–0.25 mm micro-aggregate organic carbon contribution rate was decreased by 5.82 percentage points. Straw returning could compensate for the adverse effects on the decrease of soil total organic carbon content and the deterioration of aggregate structure resulting from an increasing CO2concentration. Although the mineralization of straw returning releases CO2 into the atmosphere, it is still a potentially effective measure for increasing the content of organic carbon in black soil, and therefore should be applied in the black soil region of northeast China. However, the impacts of this CO2 released into the atmosphere and the greenhouse effect still need to be further studied. |
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