秸秆还田下稻虾共作模式对稻田土壤有机碳矿化的影响

Impact of Rice-Crayfish Integrated System under Straw Returning on Soil Organic Carbon Mineralization in Paddy Field

    摘要
  • 摘要:
    目的 稻虾共作模式是一种以种稻为中心，稻草还田淹水养虾为特点的复合生态系统，为探究秸秆还田下稻虾共作模式在淹水养虾和湿润种稻两种土壤水分条件下对稻田土壤有机碳矿化的影响。
    方法 基于江汉平原低湖区稻虾共作长期定位试验，以冬泡 + 秸秆不还田（W）、冬泡 + 秸秆还田（WS）和冬泡 + 养殖克氏原螯虾 + 秸秆还田（WSC）的土壤为研究对象，分析0 ~ 10 cm和10 ~ 20 cm土层土壤活性碳组分含量，采用室内25℃恒温模拟培养法，研究两种水分条件（W1：70%田间持水量；W2：浅层淹水1.5 cm）下土壤有机碳矿化速率、累积矿化量和矿化强度，利用一级动力学方程拟合土壤潜在可矿化有机碳量、有机碳库的周转速率常数和半周转期。
    结果 ①冬泡 + 养殖克氏原螯虾 + 秸秆还田处理提高了0 ~ 20 cm土层总有机碳含量。②淹水条件提高了0 ~ 20 cm土层土壤潜在矿化有机碳量C0和有机碳库的周转速率常数k。③相对于冬泡 + 秸秆还田处理，冬泡 + 秸秆还田 + 养殖克氏原螯虾处理在土壤含水量为70%田间持水量条件下降低了0 ~ 20 cm土层有机碳的矿化强度，而淹水条件下则显著增加了0 ~ 10 cm土层土壤有机碳累积矿化量和矿化强度，提高了土壤有机碳的潜在可矿化量C0和T1/2半周转期。
    结论 秸秆还田下稻虾共作模式（冬泡 + 养殖克氏原螯虾 + 秸秆还田）提高了土壤总有机碳含量，增强了淹水条件下表层土壤的有机碳矿化作用，降低了土壤含水量70%田间持水量条件下有机碳矿化作用，增强了土壤固碳能力。

     

    Abstract:
    Objective A Rice-Crayfish Integrated System, centered on rice cultivation with straw returning and crayfish farming in flooded fields, is a compound ecosystem. This study aimed to explore the impact of this system under two soil moisture conditions (flooded crayfish farming and moist rice cultivation) on soil organic carbon SOC) mineralization in paddy fields.
    Method Based on long-term experiments in the low lake area of Jianghan Plain, three treatments were set up: winter flooded fallow + no straw returning(W), winter flooded fallow + straw returning (WS), winter flooded fallow + crayfish cultivation + straw returning(WSC). Active carbon fractions in 0-10 cm and 10-20 cm soil layers were analyzed. Using a 25°C constant-temperature indoor simulation culture method, SOC mineralization rates, cumulative mineralization, and intensity were investigated under two moisture conditions (W1:70% field capacity; W2:1.5 cm shallow flooding). A first-order kinetic model was used to amount of potential mineralization C0, constant mineralization rate k, and half turnover period T1/2.
    Result ① The winter flooded fallow + crayfish cultivation + straw returning treatment increased the total SOC in the 0-20 cm soil layer. ② Flooding (W2) increased the amount of potential mineralization and constant mineralization rate in the 0-20 cm soil layer. ③ Compared to winter flooded fallow + straw returning, the winter flooded fallow + crayfish cultivation + straw returning treatment decreased the mineralization intensity of SOC in the 0-20 cm soil layer at 70% field capacity, while significantly increasing the cumulative mineralization and mineralization intensity of SOC in the 0-10 cm layer under flooding conditions, raising the amount of potential mineralization and the half turnover period of SOC.
    Conclusion increased The total organic carbon was increased, the mineralization of organic carbon was enhanced in the surface soil under shallow flooding conditions, and the mineralization was reduced at 70% field capacity, and the soil carbon sequestration capacity was enhanced in Rice-Crayfish integrated System (winter flooded fallow + crayfish cultivation + straw returning).

     

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