摘要
紫花苜蓿(Medicago sativa)作为黄土高原退耕还林主要草种,其种植面积日益扩大。本研究依托布设在黄土高原雨养农业区不同种植年限的苜蓿栽培试验,分析不同种植年限苜蓿草地(14、12、5 a)土壤温室气体(CO2、N2O和CH4)排放特征的影响,同时从土壤温度、含水量及酶活性的角度探究不同种植年限苜蓿对以上温室气体的影响机制。结果表明,黄土高原苜蓿地为CO2和N2O的排放源,CH4的吸收汇;在测定期内CO2排放速率表现为6月最高,1月最低;N2O排放速率表现为7月最高,12月最低;CH4吸收速率表现为7月最高,3月最低。CO2累计排放量表现为5 a>14 a>12 a,5 a苜蓿地较12 a苜蓿地和14 a苜蓿地分别显著增加16.60%、13.01%(P<0.05);N2O累计排放量表现为14 a>12 a>5 a,不同处理间差异不显著(P>0.05);CH4累计吸收量表现为5 a>12 a>14 a,各处理间差异显著。分析综合增温潜势发现5 a苜蓿地增温潜势显著高于12 a和14 a苜蓿地。逐步回归分析表明,CO2排放通量主要影响因素为土壤温度和水分(R^2=0.870),N2O排放通量主要影响因素为土壤温度(R^2=0.930),CH4排放通量主要影响因素为土壤温度和脲酶含量(R^2=0.962)。
Alfalfa is the main grass species in the farmlands returned to forests in Loess Plateau,whose planting area has been expanding.The experiment relied on the alfalfa(Medicago sativa)cultivation with different planting years(14,12,and5 a)in Loess Plateau.The objective of this study was to determine the effects of different planting years on soil greenhouse gas(CO2,N2O,and CH4)emission of alfalfa,and we discuss the main mechanisms underlying the effects of soil temperature,soil moisture,and enzyme activities under different treatments on soil greenhouse gas emission.The results showed that all the treatments showed source effects for atmospheric CO2 and N2O,but sink effects for atmospheric CH4;the flux of CO2 peaked in June and bottomed in January,whereas the flux of N2O peaked in July and bottomed in December,and the flux of CH4 peaked in July and bottomed in March.According to the planting years,the amount of total CO2 emission showed a pattern of 5 a>14 a>12 a;Compared with 12 and 14 alfalfa planting years,the CO2 emission of 5 alfalfa planting years increased significantly by 16.60%and 13.01%,respectively.Total N2O emission showed a pattern of 14 a>12 a>5 a,but there was no difference among the treatments.CH4 absorption showed a pattern of 5 a>12 a>14 a,in opposite correlation with the increase in alfalfa planting years.The warming potential under 5 a was higher than those under 12 a and 14 a.Stepwise regression analysis results showed that the flux of CO2 was significantly affected by soil temperature and moisture(R^2=0.870),that of N2O was significantly affected by soil temperature(R^2=0.930),and the flux of CH4 was significantly affected by soil temperature and urease(R^2=0.962).
作者
张耀全
邓长芳
罗珠珠
牛伊宁
李玲玲
蔡立群
谢军红
马欣
ZHANG Yaoquan;DENG Changfang;LUO Zhuzhu;NIU Yining;LI Lingling;CAI Liqun;XIE Junhong;MA Xin(Resources and Environmental Faculty of Gansu Agricultural University,Lanzhou 730070,Gansu,China;Gansu Key Laboratory of Aridland Crop Science,Lanzhou 730070,Gansu,China)
出处
《草业科学》
CAS
CSCD
2020年第1期30-40,共11页
Pratacultural Science
基金
国家自然科学基金(41461067、31860364)
甘肃省科技计划项目(18JR3RA175)
