水稻秸秆/根系添加对稻田红壤发生层颗粒态及矿物结合态有机碳的影响

Effect of Rice Straw or/and Root Additions on the Particulate- and Mineral- Associated Organic Carbon in the Pedogenic Horizon of Paddy Red Soils

    摘要
  • 摘要:
      目的  基于室内培养试验，明确等碳量添加水稻秸秆（S）、根系（R）或二者混合物（S + R）对稻田红壤不同发生层中颗粒态有机碳和矿物结合态有机碳的影响。
      方法  以稻田红壤（20 ~ 30年）氧化还原层1（Br1）、犁底层（Ap2）及水耕表层（Ap1）的土壤为材料，基于等碳量添加S、R及S + R的培养试验，分析了水稻秸秆与根系添加到供试土壤30、60、120和210天时，各发生层土壤中总有机碳、游离态颗粒有机碳、闭蓄态颗粒有机碳及矿物结合态有机碳的变化差异与影响因素。
      结果  等碳量添加S、R或S + R均可显著增加稻田红壤各发生层土壤总有机碳、游离态颗粒有机碳、闭蓄态颗粒有机碳及矿物结合态有机碳含量。但随着培养时间的延长，各发生层土壤总有机碳、闭蓄态颗粒有机碳和矿物结合态有机碳含量均呈显著降低趋势，而游离态颗粒有机碳含量则呈显著增加趋势。R或S + R处理的土壤总有机碳增加量均高于S处理，且Br1层土壤总有机碳的增加量显著高于Ap1和Ap2层。
      结论  水稻秸秆与根系还田利于稻田红壤有机碳的增加，而将水稻秸秆和根系的混合物深还至Br1层（20 ~ 40 cm）对稻田红壤有机碳量的增加效果更好。

     

    Abstract:
      Objective  Effect of rice straw or/and rice root additions on the particulate organic carbon and mineral-associated organic carbon in pedogenic horizon of paddy red soil were investigated based on the incubation experiment in the lab.
      Method  Soil samples were separately collected from the redox layer 1(Br1), plough bottom layer (Ap2) and hydroponic surface layer (Ap1) across the paddy red soil profile, which was located at the Sunjia Watershed, Jiangxi Province, China. Rice straw (S), rice root (s) and their mixture (S + R) were added into the tested soils based on equal carbon content, and they were cultured 210 days. The total organic carbon (TOC), particulate organic carbon (fPOC), occluded particulate OC (oPOC) and mineral bound OC (MOC) were gradually extracted by Sixs’ method after 30, 60, 120 and 210 days of incubation.
      Result  Additions of rice straw (S), rice root (R) and their mixture (S + R) with equal carbon content could significantly increase the TOC, fPOC, oPOC and MOC in Ap1, Ap2 and Br1 layers of paddy red soil. With the extension of culture time, theTOC, oPOC and MOC in all pedogenic horizons were significantly decreased , while the fPOC was significantly increased. The increments of TOC in treatments of R and S + R were obviously higher than that in treatment S; and the increment of TOC in Br1 soil was also significantly higher than that in Ap1 and Ap2 soils.
      Conclusion  In practical agricultural production, the mixture of rice straw and root should be returned deeply to the Br1 layer (20-40 cm) of paddy red soil, those could effectively improve the soil organic carbon sequestration.

     

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