不同利用方式红壤氮素矿化、硝化和反硝化特征及参数估算

发布时间：2018-09-13 07:29

【摘要】：土壤氮循环是陆地生态系统氮素循环的重要组成部分。土壤理化性质和利用方式会影响到土壤矿化、硝化和反硝化作用过程,从而影响到土壤的供氮能力与温室气体排放。因此土壤氮素的矿化作用、硝化作用和反硝化作用过程、影响因素及其模拟、预测,历来是土壤科学和环境科学关注的热点问题。比较分析不同利用方式土壤的矿化、硝化和反硝化作用,准确定量模拟土壤氮素矿化过程,探讨其影响机理,研究其预测方程,有助于分析土壤氮素转化效率和预测土壤温室气体排放,对于提高土壤氮素管理水平具有重要意义。以亚热带典型红壤区湖南省金井镇小流域为研究对象,在研究比较五种不同利用方式(菜地、稻田、荒地、林地和茶园)土壤氮素状况的基础上,采用淹水培养法研究了不同利用方式土壤的矿化、硝化和反硝化作用特征及影响机理；并分别利用动力学模型拟合比较,通过多元回归建立了土壤基本理化性质与拟合参数的估算方程。主要研究结果如下：(1)采用连续淹水培养法研究了不同利用方式土壤氮素矿化特征。研究表明,不同利用方式土壤的矿化氮累积量差异较大,稻田菜地荒地林地茶园,其中稻田土壤的矿化氮累积量最高(219.27 mg/kg),是其他利用方式土壤的2-6倍；且氮素快速矿化主要在培养前7天,之后逐渐平缓,并在28天趋于稳定。应用氮矿化模型对氮矿化作用进行了拟合。结果表明,单氮库和双氮库模型均能较好拟合氮矿化作用,拟合效果差异不明显。应用两种模型拟合的氮矿化势都与土壤全氮、土壤微生物生物量碳、土壤微生物生物量氮、pH、碱解氮有显著相关性；仅利用土壤微生物生物量碳及pH两变量就能较好地预测氮矿化势,且土壤微生物生物量碳相对pH对氮素矿化动力学参数估算具有更关键作用。(2)采用连续淹水培养法研究了不同利用方式土壤氮素硝化特征。研究表明,不同利用方式土壤硝化氮累积量差异显著,菜地茶园荒地稻田林地,其中菜地土壤的硝化氮累积量最高,为其他利用方式的10-60倍；不同利用方式土壤的硝化速率大小与硝化氮累积量一致,菜田土壤最快,林地土壤最慢；且硝化氮前五天累积速率缓慢,而后快速增长,可能由于土壤pH值较低的缘故,直到培养结束土壤硝化作用也未曾趋于平稳。应用零级动力学模型能很好的拟合土壤硝化氮累积速率,拟合的氮硝化氮累积速率与土壤微生物生物量磷、pH有显著相关性；利用土壤微生物生物量磷及pH两变量能较好地预测氮矿化势和矿化速率常数。(3)采用连续淹水培养法研究了不同利用方式土壤氮素反硝化特征。研究表明,不同利用方式土壤的反硝化氮累积量差异明显,其大小依次为稻田土壤菜地土壤荒地土壤林地土壤茶园土壤,其中稻田土壤的反硝化氮累积量最高(330.83mg/kg),是其他利用方式土壤的3-8倍；且氮素快速反硝化主要在培养前7天,之后逐渐平缓,并在28天趋于稳定。应用一级动力学模型能较好的拟合氮反硝化作用。应用一级动力学模型拟合的氮反硝化势与土壤全氮、有机质、土壤微生物生物量碳、土壤微生物生物量氮、碱解氮有显著相关性；氮反硝化速率常数与土壤微生物生物量磷有显著相关性；仅利用土壤微生物生物量碳就能很好地预测氮反硝化势,利用土壤微生物生物量磷和砂粒含量能较好的预测土壤反硝化速率常数。
[Abstract]:Soil nitrogen cycling is an important component of nitrogen cycling in terrestrial ecosystems. Soil physicochemical properties and utilization patterns can affect soil mineralization, nitrification and denitrification processes, thereby affecting soil nitrogen supply capacity and greenhouse gas emissions. Soil mineralization, nitrification and denitrification under different land use patterns are comparatively analyzed, and the process of soil nitrogen mineralization is simulated quantitatively and accurately. The mechanism of soil nitrogen mineralization is discussed, and the prediction equation is studied. It is helpful to analyze soil nitrogen conversion efficiency and predict soil greenhouse. Gas emissions are of great importance to improving soil nitrogen management. Taking Jinjing Town watershed in subtropical typical red soil region of Hunan Province as an example, the nitrogen status of soil under five different land use patterns (vegetable field, paddy field, wasteland, forest land and tea garden) was studied by submerged culture method. The characteristics of soil mineralization, nitrification and denitrification and their influencing mechanism were studied. The estimation equations of soil basic physical and chemical properties and fitting parameters were established by multiple regression through fitting comparison of dynamic models. The results showed that the accumulation of mineralized nitrogen in the paddy field was the highest (219.27 mg/kg), which was 2-6 times higher than that in other land use types. The rapid mineralization of nitrogen mainly occurred 7 days before cultivation, then slowed down gradually and became stable in 28 days. The results showed that the single nitrogen pool and the double nitrogen pool models could fit the nitrogen mineralization well, and the fitting effect was not significant. The nitrogen mineralization potential fitted by the two models was significantly correlated with soil total nitrogen, soil microbial biomass carbon, soil microbial biomass nitrogen, pH and alkaline hydrolyzable nitrogen. Soil microbial biomass carbon and pH were used to predict nitrogen mineralization potential, and the relative pH of soil microbial biomass carbon played a more important role in estimating the kinetic parameters of nitrogen mineralization. (2) Nitrification characteristics of soil under different land use patterns were studied by continuous submergence culture. Nitrogen accumulation in vegetable tea garden wasteland paddy forest land was the highest, which was 10-60 times higher than that of other utilization methods; the nitrification rate of different utilization methods was the same as that of nitrification nitrogen accumulation, vegetable field soil was the fastest, woodland soil was the slowest; and the accumulation rate of nitrification nitrogen was slow five days before and then fast Soil nitrification did not tend to be stable until the end of cultivation because of the low pH value of soil. The zero-order kinetic model can well fit the accumulation rate of soil nitrification nitrogen. The fitting accumulation rate of nitrogen nitrification nitrogen has a significant correlation with soil microbial biomass phosphorus and pH. Phosphorus and pH could better predict nitrogen mineralization potential and rate constants. (3) The denitrification characteristics of soils under different land use patterns were studied by using continuous submergence culture method. The results showed that the denitrification nitrogen accumulation of soils under different land use patterns was significantly different, and the denitrification nitrogen accumulation was in turn the size of soil tea in paddy soil, vegetable soil, wasteland soil and woodland soil. Among garden soils, paddy soils had the highest denitrification nitrogen accumulation (330.83 mg/kg), which was 3-8 times that of other soils. Rapid denitrification mainly occurred 7 days before cultivation, then gradually slowed down and stabilized in 28 days. The first-order kinetic model could better fit the nitrogen denitrification. Nitrogen denitrification potential was significantly correlated with soil total nitrogen, organic matter, soil microbial biomass carbon, soil microbial biomass nitrogen and alkaline hydrolyzable nitrogen; nitrogen denitrification rate constant was significantly correlated with soil microbial biomass phosphorus; soil microbial biomass carbon alone could predict nitrogen denitrification potential well, and soil microbial biomass nitrogen denitrification potential could be utilized. Biomass phosphorus and sand content can better predict soil denitrification rate constant.
【学位授予单位】：中南林业科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X144

【参考文献】