岩溶区农业种植对土壤有机氮矿化的影响  

Effects of agricultural cultivation on soil organic nitrogen mineralization in karst regions

作　　者：文冬妮 杨程[2] 杨霖 秦兴华 孟磊[1] 何秋香 朱同彬[3] Christoph Müller WEN Dongni;YANG Cheng;YANG Lin;QIN Xinghua;MENG Lei;HE Qiuxiang;ZHU Tongbin;Christoph Müller(College of Tropical Crops,Hainan University,Haikou,Hainan 570228,China;Jiangsu Institute of Geological Survey,Nanjing,Jiangsu 210018,China;Institute of Karst Geology,CAGS/Key Laboratory of Karst Dynamics,MNR&GZAR,Guilin,Guangxi 541004,China;Department of Plant Ecology,Justus-Liebig University Giessen,Heinrich-Buff-Ring 26,35392 Giessen,Germany)

机构地区：[1]海南大学热带作物学院,海口570228 [2]江苏省地质调查研究院,南京210018 [3]中国地质科学院岩溶地质所/自然资源部、广西岩溶动力学重点实验室,广西桂林541004 [4]Department of Plant Ecology,Justus-Liebig University Giessen,Heinrich-Buff-Ring 26,35392 Giessen,Germany

出　　处：《中国岩溶》2020年第2期189-195,共7页Carsologica Sinica

基　　金：国家自然科学基金(41771340,41877348);中国地质科学院岩溶地质研究所基本科研业务费项目(2020003)。

摘　　要：土壤有机氮矿化是供应无机氮的主导过程,研究其变化对于认识土壤氮素有效性和指导氮肥施用具有重要意义。本研究分别在云南建水、蒙自和勐腊岩溶区选取脐橙地、玉米地和橡胶地作为研究对象,并以临近未受人为扰动的草地或原始林地作为对照,采用15N同位素标记方法,研究了岩溶区草地或原始林地开垦种植农作物后石灰土有机氮矿化(MNorg)速率变化,并区分了易分解有机氮矿化(MNlab)和难分解有机氮矿化(MNrec)对MNorg的贡献。结果表明,原始林地土壤MNorg(8.94 mg N∙kg^-1 d^-1)显著高于草地(1.41~2.46 mg N·kg^-1 d^-1),且均以MNlab为主。其中,草地MNlab对MNorg贡献率可达80.6%~93.1%,而在原始林地中该贡献率达到62.2%。岩溶区草地或林地开垦种植经济作物显著降低MNorg速率,其MNorg速率为0.53~0.89 mg N∙kg^-1 d^-1,下降比例达62.5%~90.1%。这种差异主要受MNlab和MNrec影响,由草地开垦种植脐橙和玉米后土壤MNorg下降主要归于MNlab速率下降,而MNrec并未发生显著变化;原始林地开垦种植橡胶后土壤MNorg下降主要归于MNlab和MNrec速率的共同下降。岩溶区草地或原始林地开垦种植农作物后土壤有机碳、全氮、全磷、全钙和全镁含量及土壤田间持水量、pH、阳离子交换量均显著降低,且与土壤MNorg和MNlab呈显著正相关,表明农业种植对土壤理化性质的改变是影响矿化速率的重要因素。The mineralization of organic N dominates the production of inorganic N,therefore,it is of great significance to study the change of soil N availability and to guide N fertilization.Soil samples under navel orange,corn and rubber plantations were collected in karst regions of Jianshui,Mengzi and Mengla,Yunnan Province,respectively,and the adjacent undisturbed grassland and natural forest were sampled as control.The 15N tracing technique was used to investigate the changes in the mineralization rate of organic N to NH4+(MNorg)in calcareous soi when grassland or natural forest was converted to croplands in karst regions,and the contributions of the mineralization of labile organic N(MNlab)and recalcitrant organic N(MNrec)to MNorg were quantified.The results showed that MNorg rate in forest soils(8.94 mg N·kg^-1d^-1)was significantly higher than that in grassland soils(1.41-2.46mg N·kg^-1d^-1).Soil MNlabdominated MNorg,accounting for 80.6%-93.1%of MNorg in grassland soils and 62.2% in forest soils,respectively.Soil MNorg was significantly reduced to 0.53-0.89 mg N·kg^-1d^-1 during the conversion of grassland or forest to cropland,with a decreased ratio of 62.5%-90.1%.When grassland was converted to navel orange or corn plantations,MNlab rather than MNrec was responsible for the decreased MNorg.However,the decreased MNorg was mainly attributed to the simultaneous decline in MNlab and MNrec when natural forest was converted to rubber plantation.The contents of soil organic carbon,total N,total phosphorus,total calcium and tota magnesium,as well as pH,CEC and WHC were significantly reduced during the conversion of grassland or natural forest to cropland in karst regions,all of which were positively correlated with soil MNorg and MNlab,indicating that the changes in soil physical and chemical properties during agricultural cultivation was an important factor affecting MNorg.

关 键 词：岩溶区 农业种植 15N标记 矿化速率 易分解有机氮 

分 类 号：S153.6[农业科学—土壤学]