摘要:依托紫色土坡耕地长期施肥试验观测平台，研究生物炭、秸秆对紫色土坡耕地团聚体有机碳分布的影响。长期施肥试验处理包括不施肥（CK）、无机氮磷钾肥（NPK）、秸秆还田（RSD）、生物炭与无机氮磷钾配施（BCNPK）、秸秆与无机氮磷钾配施（RSDNPK）。利用湿筛法，进行土壤团聚体粒径分组，随后测定各粒径团聚体含量及其有机碳含量，并计算团聚体平均质量直径（MWD）和几何平均直径（GMD）。结果表明，RSD、RSDNPK和BCNPK处理的表层SOC含量比CK处理增加43.1%~90.5%，SOC储量提高65.1%~74.3%，其中RSDNPK处理、BCNPK处理较NPK处理SOC显著增加25.2%~33.1%（P < 0.05），SOC储量显著提高23.2%~30.0%（P < 0.05）。团聚体MWD和GMD均为RSD处理> RSDNPK处理> BCNPK处理> NPK处理> CK处理；RSD处理0.25~2 mm的团聚体含量高达45.5%，较CK处理提高57.7%；秸秆和生物炭配施处理（RSDNPK处理和BCNPK处理）0.25~2 mm的团聚体含量为41.3%~45.7%，而 < 0.053 mm粒径团聚体含量却降低54.1%~55.4%。NPK处理、RSD处理与CK处理的增长趋势相似，呈随团聚体粒径减小，团聚体有机碳含量先增大后减小，继而再增大的趋势；而RSDNPK、BCNPK处理则呈随粒径减小团聚体有机碳含量增加的趋势。生物炭和秸秆的施用能显著提升土壤有机碳含量，增强土壤结构稳定性，但生物碳的施用对提升土壤有机碳含量效果优于秸秆的施用，秸秆的施用对稳定土壤结构效果更优，因此生物炭和秸秆的施用可作为紫色土耕地土壤肥力维持和提升的有效管理措施。
关键词:土壤团聚体/
生物炭/
秸秆/
土壤有机碳/
紫色土
Abstract:The effects of biochar and straw application on the distribution of soil organic carbon (SOC) in purple soil aggregations of sloping uplands were explored from a long-term perspective. Five long-term fertilization treatments were included:no fertilizer (control, CK), mineral fertilizer application (NPK), crop straw residue application (RSD), a combined application of biochar and mineral fertilizer (BCNPK), and a combined application of crop straw residue and mineral fertilizer (RSDNPK). Soil samples were separated into > 2 mm large macroaggregates, 0.25-2 mm small macroaggregates, 0.053-0.25 mm microaggregates, and < 0.053 mm slit-clay microaggregates by sieving. The mass fraction of soil aggregations, organic carbon content, mean weight diameter, and geometric mean diameter of aggregations were measured. The results showed that the application of biochar and straw increased SOC content and stabilized the structure of aggregations compared with both CK and NPK treatments. In comparison with CK, SOC contents significantly increased by 43.1% under NPK treatment, 82.9% under RSD treatment, 79.1% under RSDNPK treatment, and 90.5% under BCNPK treatment. SOC stocks of topsoil increased significantly by 34.0% under NPK treatment, 68.2% under RSD treatment, 65.2% under RSDNPK treatment, and 74.3% under BCNPK treatment compared with CK treatment. In addition, the content of 0.25-2 mm aggregates of RSD treatment reached 45.5%, which was 57.7% higher than that of CK; more soil aggregations were concentrated on 0.25-2 mm aggregates. As compared with CK, the SOC content of 0.053-0.25 mm aggregates was reduced by straw and biochar treatments. The trends for NPK and RSD treatments were similar to those for CK, but RSDNPK and BCNPK treatment showed an increasing trend in organic carbon content in aggregates with decreased particle size. RSDNPK and BCNPK treatments significantly increased the SOC content and enhanced the stability of soil structure, but BCNPK treatment was superior to RSDNPK treatment in increasing SOC content, and RSDNPK treatment was more effective in stabilizing soil structure. BCNPK treatment and RSDNPK treatment are therefore effective management measures that can maintain and improve soil fertility of purple-soil-cultivated land.
Key words:Soil aggregates/
Biochar/
Crop straw/
Soil organic carbon/
Purple soil
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