改进密闭室抽气法以准确定量旱地土壤氨挥发  

Improving dynamic chamber method to accurate determine ammonia volatilization from upland soils

作　　者：钟光迪 任羡 潘珊珊 张翀 巨晓棠 ZHONG Guangdi;REN Xian;PAN Shanshan;ZHANG Chong;JU Xiaotang(School of Tropical Agriculture and Forestry,Hainan University,Haikou 570228,China)

机构地区：[1]海南大学热带农林学院,海口570228

出　　处：《农业环境科学学报》2024年第10期2434-2442,共9页Journal of Agro-Environment Science

基　　金：海南省自然科学基金项目(422RC597);国家自然科学基金项目(42207348);海南省重大科技计划项目(ZDKJ2021008);海南大学启动经费[KYQD(ZR)-20098,KYQD(ZR)-21028]。

摘　　要：密闭室抽气法被认为是定量土壤NH_(3)挥发较为可靠的方法,具有灵敏度高且成本低的优点。然而,大部分研究忽略了密闭室抽气法大气进气口NH_(3)浓度,可能会高估土壤NH_(3)挥发量,目前尚缺乏相关定量研究。本研究以华北冬小麦-夏玉米轮作为对象,对比分析了2019——2021年间冬小麦基肥(2次)、追肥(1次)、夏玉米四叶肥(2次)、夏玉米十叶肥(2次)共7次施肥后,改进密闭室抽气法前后测定农田土壤NH_(3)挥发的结果。改进前为包含大气背景NH_(3)的测定方法,为常规测定方法;改进后为扣除大气背景NH_(3)的测定方法,通过在田间加装3套采集距地面2.5 m高度大气的装置实现。结果表明:改进后的NH_(3)挥发通量(以N计)比改进前低0~0.23 kg·hm^(-2)·d^(-1)(0%~100%),平均值为0.06 kg·hm^(-2)·d^(-1)(33%),且37%的样本存在显著性差异(P<0.05,n=931)。改进后的NH_(3)挥发累积量比改进前低0.53~2.66 kg·hm^(2)(3%~53%),平均值为1.15 kg·hm^(-2)(29%),且47%的样本存在显著性差异(P<0.05,n=49)。改进前后NH_(3)挥发量(包括通量和累积量)存在显著差异的样本占比随着NH_(3)挥发量降低而升高。回归分析表明,改进前的NH_(3)挥发累积排放量可以用算式校正得到真实的NH_(3)累积排放量,校正式为y=0.94x-0.78(R2=0.99,P<0.01,n=49),其中y和x分别为校正后和校正前的NH_(3)挥发累积量,该算式可应用于华北土壤-作物体系NH_(3)挥发累积量的校正。综上,利用抽气法定量农田土壤NH_(3)挥发需要扣除大气背景NH_(3)以得到准确的测定结果,对于未扣除大气背景的旱地NH_(3)挥发累积量,可采用校正算式进行校正。The dynamic chamber method is considered a reliable approach to quantify soil ammonia(NH_(3))volatilization,with the advantages of high sensitivity and low cost.However,most researchers often ignore the atmospheric NH_(3) concentration from the inlet of the chamber,which may overestimate soil NH_(3) volatilization.However,the relevant quantitative studies are still lacking.This study took the winter wheat-summer maize rotation system in the North China Plain as an objective,compared NH_(3) volatilization measured before and after improvements of the dynamic chamber method using the data of seven fertilization events,which included basal fertilization and topdressing in winter wheat and four-and ten-leaf fertilization in summer maize.Before improvements,the obtained NH_(3) fluxes include atmospheric NH_(3) concentration,representing the conventional approach.After improvements,the atmospheric NH_(3) was excluded from the NH_(3) fluxes by installing three sets of devices for atmospheric collection at a height of 2.5 meters above ground.The results showed that the improved method had 0-0.23 kg·hm^(-2)·d^(-1)(0%-100%)lower NH_(3) fluxes(calculated on nitrogen)than before,with an average of 0.06 kg·hm^(-2)·d^(-1)(33%),and 37%of the samples showed significant differences(P<0.05,n=931).Moreover,the improved method had 0.53-2.66 kg·hm^(-2)(3%-53%)lower cumulative NH_(3) emissions than before,with an average of 1.15 kg·hm^(-2)·d^(-1)(29%),and 47%of the samples showed significant differences(P<0.05,n=49).The proportion of samples with significant differences in NH_(3) emissions between before and after improvements increased as NH_(3) emissions decreased.Regression analysis revealed that the cumulative NH_(3) emissions before improvements could be calibrated by the equation of y=0.94x-0.78(R^(2)=0.99,P<0.01,n=49),thus to obtain the real NH_(3) cumulative emissions,where y and x represent the cumulative NH_(3) emissions after and before calibration,respectively.This equation could be applied to the soil-crop systems

关 键 词：密闭室抽气法 大气背景氨 土壤氨挥发 华北平原 冬小麦-夏玉米轮作 

分 类 号：S151.9[农业科学—土壤学]