| Effects of straw returning amount on stability of soil aggregates and organic carbon content in dryland wheat field of the Loess Plateau |
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| DOI：10.7606/j.issn.1000-7601.2022.02.28 |
| Key Words: straw returning amount soil aggregates soil organic carbon dryland wheat field |
| Author Name | Affiliation | | WANG Yongdong | College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou, Gansu 730070, China | | WU Jun | College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou, Gansu 730070, China
Gansu Provincial Key Laboratory of Arid Land Crop Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China | | CAI Liqun | College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou, Gansu 730070, China
Gansu Provincial Key Laboratory of Arid Land Crop Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China
Gansu Engineering Research Center for Agricultural Water\|saving, Lanzhou, Gansu 730070, China | | ZHANG Renzhi | College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou, Gansu 730070, China
Gansu Provincial Key Laboratory of Arid Land Crop Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China
Gansu Engineering Research Center for Agricultural Water\|saving, Lanzhou, Gansu 730070, China |
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| Abstract: |
| This study aimed to investigate the effects of straw returning on stability of soil aggregates and organic carbon in the dry farmland of the Loess Plateau in central Gansu. Different straw returning experiments were conducted in Lijiapu Town, Dingxi City, Gansu Province in 2019. The two straw types were wheat and corn, and the straw returning amount included 0 (CK), 3 500 kg·hm-2 (low amount), 7 000 kg·hm-2 (medium amount) and 14 000 kg·hm-2 (high amount). The results showed that soil mechanically stable aggregates were >0.25 mm aggregates as the main aggregates, and the particle size gradually increased with the deepening of soil layer, while that of water\|stable aggregates were the opposite. When compared the treatment of straw returning to the field with no returning to the field, the contents of <0.25 mm mechanical stability and water stability aggregates decreased by 3.53%~21.74% and 2.73%~8.95%, respectively. The average weight diameter MWD and geometric average diameter GMD of soil mechanical stability aggregates increased by 16.29% and 30.12%, respectively, while that of water stability aggregates increased by 20.93% and 12.12%, respectively. The aggregate fragmentation rate PAD decreased by 2.53%~13.23%. The effect of medium straw was the best, and the effect of corn straw was more significant than that of wheat straw. Straw returning increased soil organic carbon content, and the higher the amount of straw returning on the soil surface, the more significant the improvement effect on soil organic carbon became. Compared with CK, the soil organic carbon content in high amount of corn straw returning to the field was significantly increased by 31.37%. In the subsoil, the medium wheat straw returning and high corn straw returning significantly increased soil organic carbon content by 29.85% and 36.31%, respectively, when compared with CK. The results of correlation and multiple regression analysis showed that soil organic carbon had a significant positive correlation with the stability index of mechanically stable aggregates, and extremely significant positive correlation with the stability index of water\|stable aggregates. However, there was an extremely significant negative correlation between aggregate fragmentation rate and soil organic carbon. The fitting equation of soil organic carbon and water\|stable aggregate GMD was the most suitable to describe the relationship between soil organic carbon and the stability of soil aggregates. In conclusion, the optimum amount of corn straw returning was 7 000 kg·hm-2 for effectively improving the structure of soil aggregates, soil carbon sequestration potential and soil quality. |
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