生物质炭对强还原修复退化设施菜地土壤过程中NO3-去向影响及调控机制

Greenhouse soil degradation and soil borne disease is one of the restricted factor for sustainable development of the vegetable productions in Hainan province. Reductive soil disinfestation is an effective measure to solve this problem. However, reduction of soil NO3- during the reductive soil disinfestation may be accompanied some negative environmental effect, which may increase N2O emission and NO3- leaching. We suppose that if NO3- can be converted to N2 or ammonium or be adsorbed, which may reduce the negative environmental effects of RSD. Biochar has many advantages, including high porosity, high specific surface area and high pH, which may affect the RSD process. Therefore, In this study, laboratory, plot and field experiments were conducted to investigate the effect of biochar on reduction intensity, soil properties and N2O emission. In addition, the transformation of NO3- was also be investigated through routine analysis and 15N tracing technique. The microbiological mechanisms of N2O production pathway was also conducted through 15N tracing experiment and quantitative PCR and PCR-DGGE molecular ecology method. These results will provide the theory basis for the amendment of degraded vegetable soils and reducing negative environmental effects of reductive soil disinfestation.

设施土壤退化、土传病高发是限制海南蔬菜可持续发展的重要原因，而强还原方法是解决此问题的有效措施。然而，强还原处理退化土壤过程中硝态氮的还原可能增加N2O排放及NO3-淋溶。如果能将NO3-转化为N2或铵态氮或者吸附，将可能降低强还原过程产生的负面环境效应。生物炭具有多孔隙、高比表面积、高pH等优点，可能在强还原过程中发挥作用。本项目拟采用室内培养、盆栽及田间试验研究强还原过程中添加生物质炭对还原强度、土壤性质及N2O排放的影响；采用15N标记方法，通过通过测定NO3-在土壤各个氮库（有机氮、无机氮、N2O及N2）的分配，研究生物炭对强还原处理中硝态氮去向的影响；采用15N同位素标记法，结合定量PCR和PCR-DGGE等分子生态学手段，揭示生物质炭对强还原处理过程中N2O排放途径的影响及微生物学机制。最终为强还原方法的推广以及相应的减排措施的提出提供理论依据。

强还原方法是解决土壤退化、土传病高发的有效措施。然而，强还原处理退化土壤过程中硝态氮的还原可能增加N2O排放及NO3-淋溶。如果能将NO3-转化为N2或铵态氮或者吸附，将可能降低强还原过程产生的负面环境效应。生物炭具有多孔隙、高比表面积、高pH等优点，可能在强还处理过程中发挥作用。本项目选择退化设施菜地土壤，采用田间试验研究发现淹水条件下，紫花苜蓿与生物炭配施能够有效改良土壤，消除土壤积累的硝态氮和硫酸根，显著提高土壤pH，降低土壤EC，提高黄瓜产量。采用15N同位素标记法发现，淹水+生物炭处理后，土壤NO3-主要通过转化为N2损失。采用室内培养试验研究发现，淹水过程中，添加生物炭、秸秆或者二者混施均有助于减少淹水过程中的N2O排放，秸秆的减排效果优于秸秆+生物炭。本项目为强还原方法的推广以及相应的减排措施的提出提供理论依据。