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| 稻油轮作秸秆还田下土壤铁氧化物对团聚体稳定性的影响 |
| Influences of iron oxides on aggregate stability with straw returning in a rice-rapeseed rotation system |
| 投稿时间：2025-03-05 |
| DOI：10.13254/j.jare.2025.0159 |
| 中文关键词: 秸秆还田，土壤团聚体，铁氧化物，络合铁，晶形铁氧化物 |
| 英文关键词: straw returning, soil aggregate, iron oxide, chelated iron, crystalline iron oxide |
| 基金项目:中国农业科学院创新工程项目（CAAS-CSAL-202302）；中央级公益性科研院所基本科研业务费专项（Y2025YC88） |
| 作者 | 单位 | E-mail | | 廖楚芊 | 南京林业大学生态与环境学院, 南京 210037
中国农业科学院农业资源与农业区划研究所/北方干旱半干旱耕地高效利用全国重点实验室, 北京 100081 | | | 刘淑军 | 中国农业科学院农业资源与农业区划研究所/北方干旱半干旱耕地高效利用全国重点实验室, 北京 100081
中国农业科学院衡阳红壤实验站/湖南祁阳农田生态系统国家野外科学观测研究站, 湖南 祁阳 426100 | | | 李冰洁 | 中国农业科学院农业资源与农业区划研究所/北方干旱半干旱耕地高效利用全国重点实验室, 北京 100081 | | | 黄晶 | 中国农业科学院农业资源与农业区划研究所/北方干旱半干旱耕地高效利用全国重点实验室, 北京 100081
中国农业科学院衡阳红壤实验站/湖南祁阳农田生态系统国家野外科学观测研究站, 湖南 祁阳 426100 | | | 段英华 | 中国农业科学院农业资源与农业区划研究所/北方干旱半干旱耕地高效利用全国重点实验室, 北京 100081 | duanyinghua@caas.cn | | 韩建刚 | 南京林业大学生态与环境学院, 南京 210037 | hanjiangang76@126.com | | 朱咏莉 | 南京林业大学生态与环境学院, 南京 210037 | |
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| 中文摘要: |
| 探明稻油轮作秸秆还田后土壤团聚体中铁氧化物形态与分布及其与团聚体稳定性的关系，并与双季稻模式下铁氧化物的分布特征进行比较，对于深入理解土壤结构形成机制具有重要意义。本研究依托起始于2016年的湖南祁阳稻油轮作长期定位试验，选取单施氮磷钾肥（NPK）、氮磷钾肥配施+水稻秸秆还田（NPKS1）、氮磷钾肥配施+水稻油菜秸秆均还田（NPKS2）3个处理，于2024年油菜收获后采集0~20 cm土层土样，采用湿筛法将土样筛分为大团聚体（>2 mm）、小团聚体（0.25~2 mm）、微团聚体（0.053~0.25 mm）和黏粉粒（<0.053 mm）共4个粒级，测定各粒级团聚体的质量百分比及铁氧化物含量及铁氧化物结合态有机碳含量，并分析铁氧化物含量与团聚体稳定性的关系。结果表明，与NPK相比，秸秆还田处理均显著提高了大团聚体质量百分含量，团聚体平均质量直径和几何平均直径分别显著提高38.8%~42.6%和42.2%~53.7%（P<0.05）。总的来说，秸秆还田后，土壤中络合铁含量显著提高47.8%~85.0%，晶形铁氧化物含量降低了13.4%~14.2%。与NPK相比，NPKS2处理下所有粒级团聚体中的络合铁含量均有显著增加，而晶形铁氧化物含量显著降低，非晶形铁氧化物含量仅在小团聚体中有显著增加。根据各粒级团聚体的质量百分比计算全土中团聚体铁氧化物含量发现，NPKS2较NPK处理络合铁含量显著增加了0.06~0.13 g·kg-1全土，非晶形铁氧化物含量仅在黏粉粒中有所降低，而在大团聚体中的晶形铁氧化物提高了0.61 g·kg-1全土，小团聚体和微团聚体中的晶形铁氧化物降低了2.92 g·kg-1全土和1.25 g·kg-1全土。对团聚体稳定性和铁氧化物含量的相关性分析发现，团聚体稳定性与大团聚体中的各粒级铁氧化物均呈正相关关系，与小团聚体中的晶形铁氧化物以及微团聚体中的络合铁氧化物和晶形铁氧化物均呈负相关关系。综上所述，稻油轮作模式下秸秆还田不仅提高了大团聚体的比例，还提高了各粒级团聚体中络合铁的含量，降低了团聚体中晶形铁氧化物的含量，特别是水稻油菜秸秆均还田处理效果更为显著。秸秆还田促进了小团聚体和微团聚体中晶形铁氧化物向络合铁的转化，增强了铁氧化物的活性并进一步提高了其结合有机碳的能力，这是土壤有机碳固存的机制之一。 |
| 英文摘要: |
| This study aims to explore the forms and distribution of iron oxides in soil aggregates after rice-rapeseed rotation with straw returning and their relationship with aggregate stability, and to compare the distribution characteristics of iron oxides with the double-cropping rice model. This is of great significance for a deeper understanding of the mechanism of soil structure formation. The experiment was based on the long-term positioning experiment of rice-rapeseed rotation in Qiyang, Hunan Province, which started in 2016. Three treatments were selected：single application of nitrogen, phosphorus and potassium fertilizers（NPK）, nitrogen, phosphorus and potassium fertilizers combined with rice straw returning（NPKS1）, and nitrogen, phosphorus and potassium fertilizers combined with returning of both rice and rapeseed straws（NPKS2）. Soil samples from the 0-20 cm layer were collected after rapeseed harvest in 2024. The samples were sieved into four particle sizes by wet sieving method：large aggregates（>2 mm）, small aggregates（0.25-2 mm）, micro-aggregates（0.053-0.25 mm）, and clay-silt particles（<0.053 mm）. The mass percentage of each particle size aggregate, the content of iron oxides and the content of iron oxide-bound organic carbon were determined. The relationship between iron oxide content and aggregate stability was analyzed. The results showed that compared with NPK, the mass percentage of large aggregates in the straw returning treatments was significantly increased, and the average mass diameter and geometric mean diameter of aggregates were significantly increased by 38.8% to 42.6% and 42.2% to 53.7%（P<0.05）, respectively. Overall, the content of chelated iron in the soil significantly increased by 47.8% to 85.0%, while the content of crystalline iron oxides decreased by 13.4% to 14.2%. Compared with NPK, the content of chelated iron in all particle size aggregates in the NPKS2 treatment significantly increased, while the content of crystalline iron oxides significantly decreased. The content of amorphous iron oxides only significantly increased in small aggregates. The content of iron oxides in aggregates was calculated based on the mass percentage of each particle size aggregate in the whole soil. It was found that the content of chelated iron in NPKS2 significantly increased by 0.06 g·kg-1 to 0.13 g·kg-1 in the whole soil compared with NPK. The content of amorphous iron oxides only decreased in clay-silt particles, while the content of crystalline iron oxides in large aggregates increased by 0.61 g·kg-1 in the whole soil, and the content of crystalline iron oxides in small aggregates and micro-aggregates decreased by 2.92 g·kg-1 and 1.25 g·kg-1 in the whole soil, respectively. Correlation analysis between aggregate stability and iron oxide content showed that aggregate stability was positively correlated with all levels of iron oxides in large aggregates, and negatively correlated with crystalline iron oxides in small aggregates and chelated and crystalline iron oxides in micro-aggregates. In conclusion, straw returning in the rice-rapeseed model not only increased the proportion of large aggregates, but also increased the content of chelated iron in aggregates of all particle sizes and decreased the content of crystalline iron oxides in aggregates, especially in the NPKS2 treatment. Therefore, straw returning may promote the transformation of crystalline iron oxides in small aggregates and micro-aggregates into chelated iron, enhance the activity of iron oxides and further strengthen their ability to bind organic carbon, which may be one of the mechanisms of soil organic carbon sequestration. |
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