地表覆被对岩溶区鲜土无机三氮累积的影响  

Effects of Surface Vegetation on Inorganic Nitrogen Accumulation of Fresh Soil in Karst Area

作　　者：李仰征 何斌 杨梦 沈驰华 曹熙 彭建宇 高峰 王小二 LI Yangzheng;HE Bin;YANG Meng;SHEN Chihua;CAO Xi;PENG Jianyu;GAO Feng;WANG Xiaoer(School of Ecological Engineering,Guizhou University of Engineering Science,Bijie 551700,China)

机构地区：[1]贵州工程应用技术学院生态工程学院

出　　处：《环境科学与技术》2019年第6期44-51,共8页Environmental Science & Technology

基　　金：贵州省科技厅毕节市科技局贵州工程应用技术学院联合基金(黔科合LH字[2016]7064);国家星火计划项目(S2015F20047);贵州省重点学科生态学资助项目(黔学位合字ZDXK[2013]11)

摘　　要：通过对毕节市七星关区地表覆被差异明显的3个样地逐月采样,文章检测了土壤的铵态氮、亚硝态氮、硝态氮及有机质含量等指标,研究表明:(1)3个样地无机三氮季节差异明显,总体上表层土壤变异程度强于深层。凉亭样地为乔灌草地,植被覆盖良好,整个剖面年均有机质含量为最高,微生物底物充足导致铵态氮含量最大。3样地土壤有机质与铵态氮相关分析表征两者存在显著性相关(r2=0.549,p<0.05)。(2)对雨量充沛的中国南方区域新鲜土壤,其铵态氮均在夏季出现全年最低值,这主要是夏季强淋溶作用所致。而在北方非(弱)季风区,全年淋溶有限且夏季氨化作用强,铵态氮恰与南方相反,为全年高浓度时段。其他学者使用风干土此规律则被掩盖,这是因为矿质化作用会导致氮素出现流转。为精准评价原位土壤氮素含量应使用鲜土检测。(3)亚硝态氮全年最大的为农地鲜土,剖面均值达到2.39 mg/kg,最小的为撂荒疏草地。这与肥料施加和地表生物返还差异有关。3样地均在夏季出现了峰值,这除了与该季节腐殖质矿质化作用加强导致土壤转为弱碱性,进而为氨氧化细菌提供了游离氨基质有关,还受夏季土壤毛管孔隙长期被水充斥形成的微域缺氧环境,反硝化作用被激发、硝酸还原酶活性增大而亚硝酸还原酶活性被抑制等因素所制约。(4)3样地硝态氮含量曲线4月以后即表现显著下降态势,最低值出现在7月。这与硝态氮自身不易被土壤胶体吸附、春季以来逐步增强的淋溶和硝酸还原酶活性增大等因素有关。Three soil samples with different surface vegetation were taken monthly in Qixingguan District of Bijie City.The indexes of ammonium nitrogen,nitrite nitrogen,nitrate nitrogen and organic matter of soil were detected,and results showed that seasonal difference of inorganic nitrogen in three samples was obvious,and variation of inorganic nitrogen in the surface soil was more remarkable than the deeper.The ammonium nitrogen of fresh soils in Liangting was the highest than other samples,because its vegetation was consisted of trees,shrubs and grasslands so that the average annual organic content of whole soil section was the highest.The further reason was that microbial ammoniation was most efficient,due to sufficient substrate for ammonia oxidizing bacteria.The coefficient of correlation analysis between organic matter and ammonium nitrogen in each soil layer was correlated significantly(r2=0.549,p<0.05).The ammonium nitrogen of the fresh soil in southern China with abundant rainfall was the lowest in summer,which was mainly because of strong rain leaching in the season.However,the appearance was just opposite of that in the northern non-monsoon or weak monsoon region.Summer was the period of high ammonium nitrogen concentration because of efficient ammoniation and limited rain leaching throughout the year.If airdried soil was analyzed in the experiments,this law will be covered up.It is due to nitrogen element transfer will be produced with the period of air drying process.So fresh soil should be analyzed instead of air-dried soil in order to detect accurately various nitrogen forms of original soil.The largest concentration of fresh soil nitrite occurred in farmland in the whole year,the mean value of nitrite reached 2.39 mg/kg in soil profile,and the minimum value is appeared in uncultivated sparse grassland.The reason was related to the difference in the amount of fertilizer applied and surface biological return.The nitrite curve peaks of monthly time series occurred in summer.Specific reasons is included of vi

关 键 词：新鲜土壤 铵态氮 亚硝态氮 硝态氮 地表覆被 岩溶区 

分 类 号：X53[环境科学与工程—环境工程] S153[农业科学—土壤学]