生物质炭对菜地土壤氮素流失的阻控及其影响机理研究

High rate of nitrogen (N) fertilizer is applied to achieve high vegetable yield in recent years. The long-term excessive N fertilization not only lowers the vegetables quality, but also lead to the greater pollution risk of both water and atmospheric environment. Therefore, in view of the lack of N loss control technology in vegetable field, the proposed study aims to investigate the effect of N uptake and loss in a typical vegetable field in south China by applying biochars with a large specfic surface area and high adsorption capability to soils under laboratory and field conditions. Laboratory studies will be conducted to investigate the effects of biochar porosity, application rates and aging process on the effectiveness of adsorption of NO3- and NH4+ to soils amended with biochars. The impacts of biochar type and application methodon the soil N leaching, ammonia volatilization and N2O emission will be carried out in a field experiment where typical local vegetable varieties and conventional rotation systems will be employed. These studies will help us reveal the influence of biochar properties and the application methods on the migration and transformation of fertilizer-deruved N, and its environmental fate. The proposed study will provide theoretical foundation and technical support for reducing N loss from vegetable fields and promoting eco-environmental quality.

近年来蔬菜的增产主要依靠氮肥的大量投入，长期过量施肥不仅使得蔬菜品质下降，同时盈余氮素流失后对水体和大气带来较大的环境风险。针对当前菜地氮流失阻控技术匮乏的现状，本项目拟采用室内模拟与田间试验相结合的实验方法，选用比表面积较大、吸附性能强的生物质炭作为土壤改良剂，遵循当地主要蔬菜品种及习惯轮作制度，研究生物质炭的施用对南方菜地土壤氮素吸收利用和流失的影响。通过吸附-解吸附试验阐明生物质炭孔隙度、用量、老化时间对无机氮吸附能力的影响及其之间潜在的相互关系，采用田间试验探讨不同温度制备的生物质炭,生物质炭一次施入与分批多次施入及其施用量对硝态氮淋失、氨挥发和氧化亚氮释放的影响效果，从而揭示生物质炭施用对菜地土壤氮循环的影响。本项目的实施将有助于评价生物质炭施用对菜地氮素迁移转化的长期环境效应，为缓解我国菜地土壤氮流失、提高生态环境质量提供理论基础和技术支撑。

近年来，在通过增施氮肥达到作物增产目的的同时，随之而来的环境问题也日益严重，过量施用氮肥带来了水体富营养化、土壤氨挥发和N2O排放等问题。本项目采用猪炭和竹炭作为土壤改良剂，研究生物质炭的施用对南方菜地土壤氮素吸收利用和流失的影响。. 通过吸附-解吸附试验阐明了生物质炭种类、用量、老化时间对NH4+-N吸附能力的影响。结果表明，对于不同培养周期的竹炭处理，5%添加量下的土壤对铵态氮的吸附效果均优于1%添加量处理；而对于猪炭，在培养15 d时，5%添加量处理下土壤对铵态氮的吸附量较大，而在培养60 d时，1%添加量处理下土壤对铵态氮的吸附量较大。. 通过田间试验探讨了不同种类的生物质炭，生物质炭一次施入与分批多次施入及其施用量对氧化亚氮、二氧化碳排放和氨挥发的影响效果。结果表明，与不施炭对照相比，竹炭处理可使两季空心菜和小青菜土壤N2O和CO2累积排放量显著降低，且一次施用处理优于分批施用。一次性施用20 t hm-2竹炭处理在抑制土壤N2O和CO2排放方面的效果优于猪炭。此外，猪炭和竹炭处理显著(P＜0.05)降低了两茬空心菜季土壤氨挥发，而对小青菜季土壤氨挥发没有显著性影响。与对照相比，一次性施用20 thm-2猪炭处理下空心菜-小青菜轮作周期土壤氨挥发总损失降低了41.0%。与竹炭相比，猪炭对土壤氨挥发的抑制效果更佳。. 通过培养试验研究了竹炭和稻草炭对菜地土壤理化性质和重金属（Cd、Cu、Pb和Zn）生物有效性的影响。结果表明，添加稻草炭可显著提高土壤pH、电导率、CEC和有效磷含量等理化性质，且随施用量增加效果更明显。与竹炭相比，稻草炭对降低土壤中重金属有效性的效果更好，而竹炭和稻草炭对土壤中有效态Cu和Pb的固定效果优于Cd和Zn。总体而言，稻草炭在提高土壤质量方面的效果优于竹炭，且细粒径和高用量处理效果优于粗粒径和低用量处理。. 本项目的实施将有助于评价生物质炭施用对菜地氮素迁移转化的长期环境效应，为缓解我国菜地土壤氮流失、提高生态环境质量提供理论基础和技术支撑。