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| Effects of different moisture contents on nitrogen transformation and greenhouse gas emissions from uncultivated and cultivated cropland black soil |
| Received:March 28, 2025 |
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| KeyWord:soil moisture;agricultural management;black soil;N2O;CO2;nitrogen transformation |
| Author Name | Affiliation | E-mail | | LANG Man | Jiangsu Provincial University Key Laboratory of Agricultural and Ecological Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China
School of Ecology and Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China | | | WEI Shijing | School of Ecology and Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China | | | WEI Shaohua | School of Ecology and Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China | | | LI Dongling | School of Ecology and Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China | | | LI Ping | Jiangsu Provincial University Key Laboratory of Agricultural and Ecological Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China
School of Ecology and Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China | pli@nuist.edu.cn |
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| Abstract: |
| This study aimed at exploring the regularity of N transformation and greenhouse gas emissions from black soils under different moisture contents. A laboratory incubation experiment was conducted under 25 ℃ and 60%WHC or 90%WHC for 7 days to study the dynamic changes of inorganic N contents and the emissions of N2O and CO2 from uncultivated and cultivated cropland black soil. The results showed that the net N mineralization rate of black soil was significantly decreased after soil was cultivated, while the net nitrification rate was significantly increased（P<0.05）, the changes of soil moisture content had no effect on net N transformation rates for both soils（P> 0.05）. The CO2 emission rate of the uncultivated soil was significantly higher than that of the cultivated soil（P<0.05）, regardless of the soil moisture content, while the soil moisture effects on CO2 emission were depended on land-use type. When the moisture content in uncultivated soil increased from 60%WHC to 90%WHC, the CO2 emission was inhibited significantly, with the CO2 cumulative emission decreased from 82.52 mg·kg-1 to 69.32 mg·kg-1（P<0.05）, while the CO2 emission rates of cultivated soil under 60%WHC and 90%WHC were comparable, and no significant difference（P>0.05）was found for the CO2 cumulative emissions under the two moisture contents （57.62 mg·kg-1 and 59.18 mg·kg-1, respectively）. Land-use type, moisture content, and their interactions had significant effects on N2O emissions from soil（P<0.001）. The N2O emission rate of cultivated soil under 60%WHC was significantly higher than that of uncultivated soil（P<0.05）, with the N2O cumulative emission（4.20 μg·kg-1）was 1.45 times that of uncultivated soil（2.90 μg·kg-1）. The reverse was true when soil was incubated under 90%WHC, with the N2O cumulative emission of uncultivated soil（1 280.4 μg·kg-1）was 4.57 times that of cultivated soil（279.9 μg·kg-1）. Under the conditions of 60%WHC, N2O emission ratio of uncultivated and cultivated soils were between 0.013%-0.041%, indicating that N2O was mainly emitted from nitrification process. Under the conditions of 90%WHC, N2O emission ratio of uncultivated and cultivated soil were between 4.03%-10.00% and 0.021%-1.148%, respectively, indicating that N2O was mainly emitted from denitrification process. Our results indicated that long-term cultivation could lead to the decrease of pH and organic C content in black soil, thereby reducing the CO2 emission from microbial respiration and the ability of N mineralization. The large application of N fertilizer could promote the occurrence of nitrification and N2O emission under aerobic conditions, but when the water content increased, N2O emission maybe lower than that of uncultivated soil. |
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