稻田转为菜地初始阶段温室气体排放特征  

Greenhouse Gas Emission During the Initial Years After Rice Paddy Conversion to Vegetable Cultivation

作　　者：邬磊 何志龙[2] 汤水荣 吴限 张文菊[1] 胡荣桂[2] WU Lei;HE ZhiLong;TANG ShuiRong;WU Xian;ZHANG WenJu;HU RongGui(Institute of Agricultural Resources and Regional Planning,Chinese Academy of Agricultural Sciences,Beijing 100081;College of Recourses and Environment,Huazhong Agricultural University,Wuhan 430070;College of Tropical Crops,Hainan University,Haikou 570228)

机构地区：[1]中国农业科学院农业资源与农业区划研究所,北京100081 [2]华中农业大学资源与环境学院,武汉430070 [3]海南大学热带作物学院,海口570228

出　　处：《中国农业科学》2020年第24期5050-5062,共13页Scientia Agricultura Sinica

基　　金：国家自然科学基金(41907093);中央公益性科研院所基本科研业务费专项(1610132019013)。

摘　　要：[目的]近年来,随着我国社会经济的快速发展和人们生活水平的提高及膳食结构的改善,越来越多的稻田被转为蔬菜种植,影响了土壤碳氮转化过程及其引起的温室气体排放。因此有必要探究稻田转为蔬菜种植,特别是该土地利用方式转变初始阶段的温室气体(CH4和N2O)排放特征及其关键影响因素。[方法]试验选取了长期种植水稻的双季稻田,将其中一部分转为蔬菜种植,另一部分继续种植水稻,每个处理设置了3个重复,按照当地常规模式进行管理。采用静态暗箱一气相色谱法连续3年进行田间原位观测,比较分析稻田和由稻田转变的菜地CH4和N2O排放特征及其年际变化差异,明确稻田转为菜地初始阶段CH4和N2O排放的关键影响因素。[结果]稻田是重要的CH4排放源,其第一年的排放强度(183.91 kg CH4-C·hm^-2·a^-1)明显低于后续两年(241.56-371.50 kg CH4-C·hm^-2·a^-1),这主要归功于后两年降雨量的增加引起了土壤水分含量的升高。稻田转为菜地显著减少了CH4排放,减少量相当于稻田CH4年累积排放量的83%-100%。菜地第一年的CH4累积排放量(31.22 kg CH4-C·hm^-2)显著高于第二年(0.45 kg CH4-C·hm^-2)和第三年(0.89 kg CH4-C·hm^-2),表明稻田转菜地对CH4排放的影响具有时间滞后效应。稻田是弱的N2O排放源(1.35-3.49 kg N2O-N·hm^-2·a^-1),其转为菜地显著增强了N2O排放。菜地第一年的N2O累积排放量(95.12 kg N2O-N·hm^-2)显著高于第二年(38.28 kg N2O-N·hm^-2)和第三年(40.07 kg N2O-N·hm^-2)。菜地土壤异养呼吸对N2O排放的影响在第一年明显高于第二、三年,表明稻田转为蔬菜种植的第一年,有机质矿化对N2O排放有重要贡献。在100年尺度CO2当量下,稻田转为蔬菜种植第一和第二年的综合增温潜势(GWP)相对于稻田分别显著增加了390%和98%,主要是由于增加的N2O增温潜势超过了减少的CH4增温潜势。但是,稻田转为菜地的第三年,菜地的[Objective]In recent years,with the rapid development of social economy,the improvement of people’s living standards and shifting diets and the increasing demands of vegetables result in a considerable share of rice paddy fields conversion to vegetable production in China,thus influencing soil carbon and nitrogen cycling and associated greenhouse gas(GHG)emissions.Therefore,it is necessary to investigate the impacts of land-use conversion from rice into vegetable cultivation on methane(CH4)and nitrous oxide(N2O)emissions and their key regulating factors,particularly during initial period upon conversion.[Method]In this study,six rice paddies subjected to long-term double-rice planting were chosen,and the half of them were converted into vegetable cultivation(Veg)and the remaining still for rice production(Rice),with three replicates of each treatment.The Veg and Rice were managed according to local practices.The fluxes of CH4 and N2O from the rice paddy and converted vegetable fields were measured with static chambers from December 2012 to December 2015,so as to investigate the characteristics and inter-annual variation of CH4 and N2O emissions and to identify the key factors regulating the two GHGs during the initial period upon conversion.[Result]Rice paddy acted as an important source of CH4,and CH4 emission was significantly lower in the first year(183.91 kg CH4-C·hm^-2.a^-1)relative to the later two years(241.56-371.50 kg CH4-C·hm^-2-a^-1),mainly attributed to enhanced precipitation increasing soil water content during the latter two years.Conversion from rice to vegetable cultivation substantially reduced CH4 emission from Veg by 83%-100%as compared to Rice over the study period.Annual CH4 emissions from Veg were significantly higher in the first year(31.22 kg CH4-C-hm^-2)relative to any later years(0.45-0.89 kg CH4-C·hm^-2),suggesting that this land-use conversion had strong legacy effect on CH4 emission.Paddy soil acted as a minor source of N2O(1.35-3.49 kg N2O-N-hm^-2·a^-1).Rice conversion to veget

关 键 词：稻田 菜地 土地利用方式 CH4 N2O 综合增温潜势 

分 类 号：S181[农业科学—农业基础科学]