摘要:针对西北绿洲灌区禾本科作物长期连作造成土壤质量下降问题，研究了不同绿肥还田利用方式对土壤团聚体组成、稳定性及土壤容重的影响。试验设绿肥覆盖免耕（NTG）、绿肥全量翻压（TG）、地上部移除根茬覆盖免耕（NT）、地上部移除根茬翻压（T）以及传统翻耕不复种绿肥（CT，对照）5个处理。两年结果表明，与CT相比，4种还田利用方式均可提升0~30 cm各土层土壤大团聚体含量、平均重量直径、几何平均直径与平均质量比表面积（P < 0.05）；与其他3种还田利用方式相比，NTG增幅最为显著。与CT相比，4种还田利用方式均可降低各土层团聚体分形维数（P < 0.05）；NTG处理和NT处理显著低于TG处理与T处理；与NT处理相比，NTG处理0~20 cm土层差异不显著，20~30 cm土层显著降低。与CT相比，翻压还田（TG和T）能够降低各土层土壤容重（P < 0.05），NT处理显著增加各土层土壤容重（P < 0.05），NTG处理仅在2019年0~10 cm和20~30 cm土层显著低于CT，其他不显著。相对于其他绿肥还田利用方式及传统翻耕不复种绿肥，麦后复种绿肥地表覆盖免耕是增加绿洲灌区农田0~30 cm土层土壤大团聚体形成及稳定性、降低土壤容重的适宜措施。
关键词:小麦-玉米轮作/
绿肥利用方式/
免耕/
土壤团聚体/
土壤容重
Abstract:Long-term continuous cultivation of gramineous crops can lead to soil quality degradation, thereby decreasing crop productivity. Optimization of the agronomic measures is a powerful way to improve soil physical and chemical properties, increase soil fertility, and enhance the sustainable development of agricultural production. The effects of different green manure utilization on the composition and stability of soil aggregates and soil bulk density were studied in this study to provide a theoretical and practical basis for improving the quality of farmlands in oasis irrigation areas. A field experiment was conducted in the oasis irrigation area in Northwest China to determine the composition and stability of soil aggregates and soil bulk density at 0-30 cm soil depth in maize farmlands in response to different green manure returning patterns. The green manure utilization patterns included: no tillage with the full quantity of green manure mulched on the soil surface (NTG), conventional tillage with the full quantity of green manure incorporated into the soil (TG), no tillage with root returning of green manure after removing the above-ground part of green manure (NT), conventional tillage with root returning of green manure incorporated into the soil after removing the above-ground part of green manure (T), and conventional tillage without green manure (CT) as the control. The results showed that the four green manure utilization patterns increased the soil macro-aggregate content, mean weight diameter, geometric mean diameter, and mean weight-specific surface area (P < 0.05) at 0-30 cm soil depth, compared to CT. Among the four green manure treatments, NTG had the most significant effects. However, different green manure utilization patterns significantly decreased the fractal dimension of soil aggregates (P < 0.05). Among the four green manure treatments, NTG and NT significantly decreased the fractal dimension of soil aggregates at 0-30 cm soil depth in comparison to TG and T. There was no significant difference in the fractal dimension of soil aggregates at 0-20 cm soil depth between NTG and NT treatments; however, NTG had a lower fractal dimension of soil aggregates at 20-30 cm soil depth than that of NT (P < 0.05). Compared to CT, TG and T significantly reduced the soil bulk density at 0-30 cm soil depth, but NT significantly increased the soil bulk density at each soil depth in the 0-30 cm soil layer (P < 0.05). NTG had significantly lower soil bulk density than CT at 0-10 cm and 20-30 cm soil depth in 2019, but the difference was not significant in 2018. Compared to the other green manure utilization patterns (TG, NT, and T) and conventional tillage without green manure treatment (CT), no tillage with the full quantity of green manure mulched on the soil surface treatment (NTG) increased the macro-aggregate content and stability of soil aggregates and reduced the soil bulk density at 0-30 cm soil depth.
Key words:Wheat-maize rotation/
Green manure utilization pattern/
No-tillage/
Soil aggregates/
Soil bulk density
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