设施菜田土壤pH和初始C/NO_3~–对反硝化产物比的影响  

Effects of p H and initial labile C/NO_3~– ratio on denitrification in a solar greenhouse vegetable soil

作　　者：曹文超[1] 郭景恒[1] 宋贺[2] 刘骕 陈吉吉 王敬国[1] 

机构地区：[1]中国农业大学资源与环境学院,北京100193 [2]安徽农业大学农学院,安徽合肥230036

出　　处：《植物营养与肥料学报》2017年第5期1249-1257,共9页Journal of Plant Nutrition and Fertilizers

基　　金：国家自然科学基金项目(41230856;41301258)资助

摘　　要：【目的】设施菜田土壤反硝化作用是N_2O排放和氮素损失的重要途径。本研究通过室内厌氧培养试验,在不同p H和初始C/NO_3~–条件下,比较设施菜田土壤反硝化氮素气体排放及产物比的变化特征。【方法】以设施菜田土壤为研究对象,通过添加一定量低浓度的酸碱溶液调节土壤p H分别为酸性、中性和碱性条件,调节后的实测p H分别为5.63、6.65和7.83;同时以谷氨酸钠作为有效性碳,除未添加有效性碳作为对照处理(CK)外,其他有效性碳与硝酸盐(C/NO_3~–)的比值分别调节为5∶1、15∶1和30∶1,三种p H条件下均设置4个C/NO_3~–水平,每个水平3次重复。利用自动连续在线培养系统(Robot系统),在厌氧条件下监测不同处理土壤产生的N_2O、NO、N_2和CO2浓度的动态变化,通过计算N_2O/(N_2O+NO+N_2)指数估算反硝化过程N_2O的产物比。【结果】增加土壤的p H能显著减少设施菜田土壤N_2O和NO的产生量,酸性(p H 5.63)土壤的N_2O、NO产生量峰值在不同初始C/NO_3~–比下均显著高于中性(p H 6.65)和碱性(p H 7.83)土壤(P<0.05)。中性和碱性土壤在高C/NO_3~–下有利于减少反硝化过程N_2O的产生,而酸性土壤条件下差异并不显著。中性土壤条件下增加有机碳含量会降低NO产生量,而在酸性和碱性土壤上有机碳的添加对NO产生量没有显著影响。土壤p H和初始C/NO_3~–比对土壤N_2O的产生有极显著的交互效应(P<0.001)。酸性和中性土壤上添加有机碳能够显著增加土壤N_2的产生速率(P<0.05),且与对照相比,不同p H的土壤添加有机碳后均显著促进反硝化过程中N_2O向N_2的转化。在不同初始C/NO_3~–下碱性土壤的CO2产生量显著高于酸性和中性土壤,同时与对照相比,添加有机碳显著增加了土壤的CO2产生量(P<0.05)。酸性土壤的N_2O产物比在不同初始C/NO_3~–下均极显著高于碱性土壤(P<0.01),且不同初始C/NO_3~–下的土壤N_2O产物比随p H�[ Objectives ] Denitrification is one of predominant process for N2O emission from solar greenhouse vegetable soils. An anoxic incubation experiment was conducted to explore effects of soil pH and initial labile C/NO3^- ratio on nitrogen gaseous emissions （i.e. N2O, NO and N2） and the N2O product during the denitrification in a solar greenhouse vegetable soil. [ Methods ] A typical greenhouse vegetable soil in Shouguang City was selected for the study, and soil pH was adjusted to acidic, neutral and alkaline by adding a certain amount of low concentration of acid （0.1 mol/L HCI） or alkaline （0.1 mol/L NaOH） solution. The final soil pH values were 5.63, 6.65 and 7.83 （adjusted）, respectively. Sodium glutamate （C5H8NO4Na） was added as a labile organic carbon source, and the ratios of initial labile C to NO3^- were adjusted to 5 ： 1, 15 ： 1 and 30 ： 1 by adding different amounts of sodium glutamate and no sodium glutamate addition in the control （CK）. Four levels of initial labile C/NO3^- ratios were set up in the three soils with different pH, and there were three replicates in each level. A robotized incubation system was used to monitor the kinetics of gaseous products （NzO, NO, N2, and CO2） of denitrification under anoxic conditions and to estimate the N2O product ratio of denitrification by calculating Index N2O/（N2O ＋ NO ＋ N2）. [ Results ] The increase in soil pH significantly reduced N2O and NO production in the soil, and the peak values of N2O and NO production the alkaline and neutral soils with different initial C/NO8 in the acidic soil were significantly higher than those of ratios （P 〈 0.05）. With the increase of initial labile C, the production of N2O was reduced in the neutral and alkaline soils, but kept unchanged in the acidic soil. The addition of sodium glutamate reduced NO emission in the neutral soil. However, there were no differences in NO production in other pH levels. A significant interaction on N2O production was observed between soil pH and i

关 键 词：反硝化 pH C/NO3^– N2O 日光温室 

分 类 号：S153[农业科学—土壤学] S626[农业科学—农业基础科学]