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| Concentration and components of dissolved organic carbon in soil profiles after crop residues were incorporated into the topsoil |
| Received:August 10, 2018 |
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| KeyWord:dissolved organic carbon(DOC);concentration and composition;transfer and transformation;soil profile;crop residues incorporation into topsoil |
| Author Name | Affiliation | E-mail | | LI Bin-bin | Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China | | | WU Lan-fang | Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China | wulf@igsnrr.ac.cn |
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| Abstract: |
| Dissolved organic carbon(DOC)is regarded as one of the most important active components of soil organic carbon(SOC). Many studies have focused on the effects of field crop residue retention on DOC in topsoil. However, information regarding DOC in soil profiles is not available. To investigate DOC transfer in soil profiles after incorporation of crop residue into the topsoil, a field experiment was conducted at Yucheng Agricultural Experiment Station. The concentration and components of DOC in 0~40 cm soil profiles, in two treatments, i.e., with/without crop residue incorporation into topsoil, were analyzed. The concentration of DOC, the DOC/SOC ratio, components with the functional amine group(CO-NH)and aromatic compounds(C=C and benzene ring), as well as the average value of molecular weights of DOC compounds in the 0~40 cm of soil with crop residue incorporation were significantly higher than those in the soil without crop residue incorporation. Moreover, all values decreased with an increase in soil depth, and the differences between at 30~40 cm and 0~10 cm were significantly different. These results indicated that both the concentration and compounds of DOC are changed during leaching from the upper layers of soil to the lower levels and are affected by crop residue management. With the increase in soil depth, the concentration of DOC decreased and the composition of DOC became simple, whereas with the increase in crop residue incorporation, the concentration of DOC increased and the composition of DOC became more complex. DOC, DOC/SOC, amines and aromatic compounds in the soil with crop residue incorporation increased compared to those in soil without crop residue incorporation in the entire 0~40 cm soil profile; however, the difference between the two treatments decreased gradually with the depth of soil. Additionally, average molecular weight of DOC was higher in the soil because of crop residue incorporation, and this difference between the two treatments was obvious in the deeper layers. The results demonstrated that crop residues had a significant effect on DOC content and its distribution in the soil profile. |
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