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| Effects of shredded straw and burned straw returning to the field on soil porosity and organic carbon in cultivated layer of calcareous purple soil |
| Received:August 16, 2021 |
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| KeyWord:straw;returning shredded;returning burned;soil pore;soil organic carbon |
| Author Name | Affiliation | E-mail | | WANG Yue | Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China
College of Resources, Sichuan Agricultural University, Chengdu 611130, China | | | KUANG Fuhong | Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China | kuangfuh@imde.ac.cn | | MA Shenglan | Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China | | | WANG Yanqiang | Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China | | | LI Lan | College of Resources, Sichuan Agricultural University, Chengdu 611130, China | | | TANG Jialiang | Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China | | | ZHU Bo | Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China | |
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| Abstract: |
| To clarify the effects of different long-term straw-returning methods on soil pores and organic carbon in the cultivated layer of calcareous purple soil in the hilly area of the central Sichuan Basin, in-situ monitoring and computed tomography were used to determine the organic carbon concentration and storage, and pore characteristics of soil in the cultivated layer of the following treatments:RMW0 (summer maize-winter wheat rotation, without straw returned to the field), RMWshred(summer maize-winter wheat rotation, 50% straw shredded and returned to the field), and RMWburn(summer maize-winter wheat-straw rotation, 50% straw burned and returned to the field). The results showed that the total porosity of cultivated layer soil was significantly increased by both the RMW shred and RMWburn treatments, while the corresponding bulk densities were decreased. The macroporosity of cultivated layer soil in RMW burn was 2.7 times higher than that of RMWshred. Compared with RMW0, the RMWshred and RMWburn treatments could effectively improve the centralized distribution of soil macropores and make the distribution of interlayer macropores more uniform. The quantities of pores in all three treatments were dominated by equivalent pore diameters of 100~500 μm. The RMWshred and RMWburn treatments optimized the pore number ratio and volume ratio of different equivalent pore diameters in the cultivated layer of soil, with the RMW shred treatment having a superior effect. RMWburn was beneficial for increasing the number of >1 000 μm equivalent pores in the cultivated layer of soil, while the average diameter of >1 000 μm pores in the cultivated layer of soil under the RMWshred tended to be smaller. The mean throat cross-sectional area, mean throat cross-sectional shape factor and mean pore shape factor of RMWshred and RMWburn were lower than those of RMW0. Long-term straw returning to the field caused the pore space of the cultivated soil to change in a direction favorable for water and fertilizer retention, and the water and fertilizer retention ability of RMWshred was better than that of RMWburn. After 15 years of continuous straw returning, the soil organic carbon concentration only increased significantly in the RMWshred treatment. Based on a comprehensive comparison of the differences between the two straw-returning treatments, in terms of improving pore characteristics and carbon sequestration in the cultivated soil layer in the hilly area of the central Sichuan Basin, long-term returning of shredded straw is more conducive to improving soil pore characteristics and more effective in accumulating soil organic carbon than long-term returning of burned straw, making it more sustainable option for the green development of agriculture in the hilly area of the central Sichuan Basin. |
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