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1.
The quantification of soil CO2 efflux is crucial for better understanding the interactions between driving variables and C losses from black soils in Northeast China and for assessing the function of black soil as a net source or sink of atmospheric CO2 depending upon land use.This study investigated responses of soil CO2 efflux variability to soil temperature interactions with diferent soil moisture levels under various land use types including grassland,bare land,and arable(maize,soybean,and wheat)land in the black soil zone of Northeast China.The soil CO2 effluxes with and without live roots,defined as the total CO2 efflux(FtS)and the root-free CO2 efflux(FrfS),respectively,were measured from April 2009 to May 2010 using a static closed chamber technique with gas chromatography.The seasonal soil CO2 fluxes tended to increase from the beginning of the measurements until they peaked in summer and then declined afterwards.The mean seasonal FtS ranged from 20.3±7.8 to 58.1±21.3 mg CO2-C m-2h-1 for all land use types and decreased in the order of soybean land>grassland>maize land>wheat land>bare land,while the corresponding values of FrfS were relatively lower,ranging from 20.3±7.8 to 42.3±21.3 mg CO2-C m-2h-1.The annual cumulative FtS was in the range of 107-315 g CO2-C m-2 across all land uses types.The seasonal CO2 effluxes were significantly(P<0.001)sensitive to soil temperature at 10 cm depth and were responsible for up to 62% of the CO2 efflux variability.Correspondingly,the temperature coefcient Q10 values varied from 2.1 to 4.5 for the seasonal FtS and 2.2 to 3.9 for the FrfS during the growing season.Soil temperature interacting with soil moisture accounted for a significant fraction of the CO2 flux variability for FtS (up to 61%) and FrfS (up to 67%) via a well-defined multiple regression model,indicating that temperature sensitivity of CO2 flux can be mediated by water availability,especially under water stress. 相似文献
2.
Understanding the factors affecting the CO 2 emission from agricultural practices is crucial for global warming.A study was performed in an apricot orchard field in the experimental farm of the Harran University,Southeast Turkey,to i) quantify weekly and seasonal variations of the CO 2 emissions from a Vertisol under apricot orchard;ii) evaluate the difference in CO 2 emission between the area under trees and rows;and iii) assess the relationships between the amounts of CO 2 emissions and environmental parameters for better use and management of the soils from the view point of carbon balance and flux in a semi-arid environment under drip irrigation.Soil CO 2 emission measurements were performed during May 2008 and May 2010,from both under tree crowns (CO 2-UC) and between tree rows (CO 2-BR),on a weekly basis in southeast Turkey with a semi-arid climate.CO 2 emissions were statistically correlated with weather and soil parameters such as air temperature,relative humidity,rainfall,soil water content,and soil temperature at various depths from 5 to 100 cm.The weekly emissions ranged from 82 to 1 110 kg CO 2 ha 1 week 1 and from 96 to 782 kg CO 2 ha 1 week 1 in CO 2-UC and CO 2-BR,respectively.Increase in CO 2 emission in the second year was due to increases in mean air and soil temperatures.The weekly and monthly cumulative CO 2 emissions were positively correlated with the air and soil temperatures.Multiple linear regression analysis explained 35% and 83% variations in average weekly and monthly CO 2 emissions,by using meteorological data.Including the interaction effects of meteorological parameters in regression equations nearly doubled the variance explained by the regression models.According to stepwise regression analysis,soil and air temperatures were found to have the most significant impact on the temporal variability of the soil CO 2 emission. 相似文献
3.
Few studies are conducted to quantify the effects of enhanced N deposition on soil nitrous oxide (N2O) emission and methane (CH4) uptake in the meadow steppe of Inner Mongolia,China.A two-year field experiment was conducted to assess the effects of nitrogen (N) deposition rates (0,10,and 20 kg N ha-1 year-1 as (NH4)2SO4) on soil N2O and CH4 fluxes.The seasonal and diurnal variations of soil N2O and CH4 fluxes were determined using the static chamber-gas chromatography method during the two growing seasons of 2008 and 2009.Soil temperature,moisture and mineral N (NH4+-N and NO3--N) concentration were simultaneously measured.Results showed that low level of (NH4)2SO4 (10 kg N ha-1 year-1) did not significantly affect soil CH4 and N2O fluxes and other variables.High level of (NH4)2SO4 (20 kg N ha-1 year-1) significantly increased soil NO3--N concentration by 24.1％ to 35.6％,decreased soil CH4 uptake by an average of 20.1％,and significantly promoted soil N2O emission by an average of 98.2％.Soil N2O emission responded more strongly to the added N compared to CH4 uptake.However,soil CH4 fluxes were mainly driven by soil moisture,followed by soil NO3--N concentration.Soil N2O fluxes were mainly driven by soil temperature,followed by soil moisture.Soil inorganic N availability was a key integrator of soil CH4 uptake and N2O emission.These results suggest that the changes of availability of inorganic N induced by the increased N deposition in soil may affect the CH4 and N2O fluxes in the cold semi-arid meadow steppe over the short term. 相似文献
4.
水分状态、土壤类型和氮素种类对氧化亚氮和甲烷排放的影响 总被引：16，自引：0，他引：16
Specific management of water regimes, soil and N in China might play an important role in regulating N2O and CH4 emissions in rice fields. Nitrous oxide and methane emissions from alternate non-flooded/flooded paddies were monitored simultaneously during a 516-day incubation with lysimeter experiments. Two N sources （^15N-（NH4）2SO4 and ^15N-labeled milk vetch） were applied to two contrasting paddies： one derived from Xiashu loess （Loess） and one from Quaternary red clay （Clay）. Both N2O and CH4 emissions were significantly higher in soil Clay than in soil Loess during the flooded period. For both soil, N2O emissions peaked at the transition periods shortly after the beginning of the flooded and non-flooded seasons. Soil type affected N2O emission patterns. In soil Clay, the emission peak during the transition period from non-flooded to flooded conditions was much higher than the peak during the transition period from flooded to non-flooded conditions. In soil Loess, the emission peak during the transition period from flooded to non-flooded conditions was obviously higher than the peak during the transition period from non-flooded to flooded conditions except for milk vetch treatment. Soil type also had a significant effect on CH4 emissions during the flooded season, over which the weighted average flux was 111 mg C m^-2 h^-1 and 2.2 mg C m^-2 h^-1 from Clay and Loess, respectively. Results indicated that it was the transition in the water regime that dominated N2O emissions while it was the soil type that dominated CH4 emissions during the flooded season. Anaerobic oxidation of methane possibly existed in soil Loess during the flooded season. 相似文献
5.
中国西北地区膜下滴灌对棉田土壤CO2通量和浓度的影响 总被引：4，自引：0，他引：4
LI Zhi-Guo ZHANG Run-Hu WANG Xiu-Jun WANG Jie-Ping ZHANG Cui-Ping TIAN Chang-Yan 《土壤圈》2011,21(2):178-185
In northwestern China,there has been a change from traditional cultivation system (TC) with no mulching and flood irrigation to a more modern cultivation system (MC) using plastic film mulching with drip irrigation.A field study was conducted to compare soil CO 2 concentrations and soil surface CO 2 fluxes between TC and MC systems during a cotton growing season.CO 2 concentrations in the soil profile were higher in the MC system (3 107-9 212 μL L-1) than in the TC system (1 275-8 994 μL L-1) but the rate of CO 2 flux was lower in the MC system.Possible reasons for this included decreased gas diffusion and higher soil moisture due to the mulching cover in the MC system,and the consumption of soil CO2 by weathering reactions.Over the whole cotton growing season,accumulated rates of CO2 flux were 300 and 394 g C m-2 for the MC and TC systems,respectively.When agricultural practices were converted from traditional cultivation to a plastic film mulching system,soil CO 2 emissions could be reduced by approximately 100 g C m-2 year-1 in agricultural lands in arid and/or semi-arid areas of northern and northwestern China. 相似文献
6.
土壤肥力与大气CO2浓度的升高对颤杨Populus tremuloides叶片、茎杆和根的暗呼吸的影响 总被引：3，自引：0，他引：3
An open-top chamber experiment was conducted at the University of Michigan Biological Station near Pellston,Michigan,USA,to study the effects of soil fertility and CO2 on leaf,sdtem and root dark respiration (Rd) of Populus tremuloides.Overall,area-based daytime leaf Rd(Rda) was significantly greater at elevated than at ambient CO2 in high-fertility soil,but not in low-fertility soil.Mass-based leaf Rd(Rdm) was overall greater for high-than for low-fertility soil grown trees at elevated,but not at ambient CO2 .Nighttime leaf Rda and Rdm were unaffected by soil fertility or CO2,nor was stem Rda ,which ranged from 1.0 to 1.4μmol m^-2s^-1 in the spring and 3.5 to 4.5μmol m^-2s^-1 in the summer.Root Rda was significantly higher in high-than in low-fertiliy soil,but was unaffected by CO2.Since biomass production of P.tremuloides will be significantly greater at elevated CO2 while specific Rd will either increase or remain unchanged,we predict that carbon loss to the atmosphere through respiration from this ecologically important species would increase at higher CO2.Soil fertility would also interact with elevated CO2 in affecting the carbon flow in the plant-soil-air system. 相似文献
7.
中国东北休闲期稻田温室气体排放 总被引：2，自引：0，他引：2
CH4, N2O and CO2 emissions from northeast Chinese rice fields were measured in the fallow season （November to March） to investigate the effects of freezing-thawing on the emissions. Both CH4 emission from and atmospheric CH4 oxidation by the soil occurred, but the flux was small. During the fallow season, rice fields acted as a minor source of atmospheric CH4, which accounted for about 1% of the CH4 emission during the rice growing period. The field was also a substantial source of atmospheric N20, which ranged between 40 to 77 mg m-2 and eu=counted for 40%-50% of the annual N20 emission. The largest N20 flux was observed in the thawing period during the fallow season. Laboratory incubation tests showed that the largest N20 flux came from the release of N20 trapped in frozen soil. Tillage and rice straw application （either mulched on the soil surface or incorporated in the soil） stimulated the CH4 and CO2 emissions during the fallow season, but only straw application stimulated N2O emission substantially. 相似文献
8.
LUXI－XI Y.BIOT 《土壤圈》1994,4(1):59-66
The effect of soil erosion on spring barley growth was studied on a deep loamy soil in East Anglia,England,in 1992,Soil erosion was simulated by three levels of soil desurfacing,7.5,18and 30cm with three replicates.Significant differences in crop height,ground cover and crop yield were observed between the three levels of desurfacing.Soil desurfacing also has a singnificant effect on soil moisture at the 20cm depth.The interaction between soil removal and crop performance affected soil moisture at the depths of 50 and 100cm,No significant differences were found in runoff and sediment etween the three topsoil removals due to very dry growing season.Regression equations were developed between spring barley yield and soil desurfacing Spring barley grain yield declined by 97.6kg/ha per cm soil desurfacing. 相似文献
9.
基于土壤剖面测定数据计算中国土壤有机碳贮量 总被引：10，自引：0，他引：10
Soil organic carbon (SOC) storage under different types of vegetations in China were estimated using measured data of 2 440 soil profiles to compare SOC density distribution between different estimates, to map the soil organic carbon stocks under different types of vegetation in China, and to analyze the relationships between soil organic carbon stocks and environmental variables using stepwise regression analyses. Soil organic carbon storage in China was estimated at 69.38 Gt (1015 g). There was a big difference in SOC densities for various vegetation types, with SOC distribution closely related to climatic patterns in general. Stepwise regression analyses of SOC against environmental variables showed that SOC generally increased with increasing precipitation and elevation, while it decreased with increasing temperature. Furthermore, the important factor controlling SOC accumulation for forests was elevation, while for temperate steppes mean annual temperature dominated. The more specific the vegetation type used in the regression analysis, the greater was the effect of environmental variables on SOC. However, compared to native vegetation, cultivation activities in the croplands reduced the influence of environmental variables on SOC. 相似文献
10.
Maize(Zea mays L.), a staple crop in the North China Plain, contributing substantially to agricultural nitrous oxide(N_2O)emissions in this region. Many studies have focused on various agricultural management measures to reduce N_2O emissions. However, few have investigated soil N_2O emissions in intercropping systems. In the current study, we investigate whether maize-soybean intercropping treatments could reduce N_2O emission rates. Two differently configured maize-soybean intercropping treatments, 2:2 intercropping(two rows of maize and two rows of soybean, 2M2S) and 2:1 intercropping(two rows of maize and one row of soybean,2M1S), and monocultured maize(M) and soybean(S) treatments were performed using a static chamber method. The results showed no distinct yield advantage for the intercropping systems. The total N_2O production from the various treatments was 0.15 ± 0.04–113.85 ± 12.75 μg m~(-2) min~(-1). The cumulative N_2O emission from the M treatment was 16.9 ± 2.3 kg ha~(-1) over the entire growing season(three and a half months), which was significantly higher(P 0.05) than that of the 2M2S and 2M1S treatments by 36.6% and 32.2%, respectively. Two applications of nitrogen(N) fertilizer(as urea) at 240 kg N ha~(-1) each induced considerable soil N_2O fluxes. Short-term N_2O emissions(within one week after each of the two N applications) accounted for 74.4%–83.3% of the total emissions. Soil moisture, temperature, and inorganic N were significantly correlated with soil N_2O emissions(R~2= 0.246–0.365, n =192, P 0.001). Soil nitrate(NO_3~-) and moisture decreased in the intercropping treatments during the growing season. These results indicate that maize-soybean intercropping can reduce soil N_2O emissions relative to monocultured maize. 相似文献
11.
不同生物质炭输入水平下旱作农田温室气体排放研究 总被引：4，自引：0，他引：4
在陇中黄土高原干旱半干旱区,采用小区定位试验,对不同生物质炭输入水平下春小麦农田土壤温室气体(CO_2、N_2O和CH_4)的排放通量进行全生育期连续观测,并分析其影响因子。结果表明:6个生物质炭输入水平处理下[0 t·hm~(-2)(CK)、10 t·hm~(-2)、20 t·hm~(-2)、30 t·hm~(-2)、40 t·hm~(-2)、50 t·hm~(-2)],旱作农田土壤在春小麦全生育期内均表现为CH_4弱源、N_2O源和CO_2源。全生育期各处理CH_4平均排放通量依次为:0.005 7 mg·m~(-2)·h~(-1)、0.0047 mg·m~(-2)·h~(-1)、0.003 6 mg·m~(-2)·h~(-1)、0.003 3 mg·m~(-2)·h~(-1)、0.002 7 mg·m~(-2)·h~(-1)和0.000 4 mg·m~(-2)·h~(-1),N_2O平均排放通量依次为:0.230 5 mg·m~(-2)·h~(-1)、0.144 1 mg·m~(-2)·h~(-1)、0.135 3 mg·m~(-2)·h~(-1)、0.098 9 mg·m~(-2)·h~(-1)、0.125 0 mg·m~(-2)·h~(-1)和0.151 3mg·m~(-2)·h~(-1),CO_2平均排放通量依次为:0.449 2μmol·m~(-2)·s~(-1)、0.447 0μmol·m~(-2)·s~(-1)、0.430 3μmol·m~(-2)·s~(-1)、0.391 4μmol·m~(-2)·s~(-1)、0.408 0μmol·m~(-2)·s~(-1)和0.416 4μmol·m~(-2)·s~(-1)。土壤CH_4排放通量随生物质炭输入量的增加而减小;当生物质炭输入量小于30 t·hm~(-2)时,土壤N_2O、CO_2排放通量随其输入量增加而显著减小,但当其输入量超过30 t·hm~(-2)时,N_2O、CO_2排放通量则呈显著增大趋势。各处理在5~15 cm土层平均土壤温度差异显著(P0.05),在5~10 cm土层平均土壤含水量差异显著(P0.05),土壤温度及含水量受生物质炭影响明显;且CK处理不同土层的土壤温度及含水量波动最大,生物质炭输入可在一定程度上降低不同土层土壤的水热变化幅度;N_2O、CO_2排放通量与10~15 cm土层土壤温度呈显著性负相关,与20~25 cm土壤温度呈显著性正相关;CH_4平均排放通量与5~10 cm土层土壤温度呈显著性负相关,与其含水量呈显著性正相关;N_2O平均排放通量与15~20 cm土层土壤温度呈显著性正相关;CH_4、N_2O、CO_2平均排放通量与0~5 cm土层土壤水分呈显著性负相关。生物质炭的输入能够减小温室气体的排放,且会因其输入量的不同而异,因此适量应用生物质炭有利于旱作农田生育期内增汇减排。 相似文献
12.
生物炭对干旱区绿洲农田土壤呼吸的影响 总被引：2，自引：0，他引：2
为探究不同粒径秸秆生物炭添加对绿洲农田土壤CO2排放及Q10的影响,以新疆典型绿洲农田土壤灰漠土为供试材料,采用室内土柱培养的方法,研究添加＞5、1～5、0.25～1和＜0.25mm共4种粒径棉花秸秆生物炭和葡萄藤生物炭对农田土壤CO2释放的影响。结果表明：（1）试验周期内（0～85d）,添加生物炭处理土壤呼吸速率呈先增加后降低的趋势,前10d土壤呼吸增速较高;添加生物炭的土壤呼吸速率（1.27μmol·m-2·s-1）高于不添加生物炭的对照处理（1.01μmol·m-2·s-1）,棉花秸秆生物炭处理土壤呼吸速率（1.43μmol·m-2·s-1）高于添加葡萄藤生物炭处理（1.08μmol·m-2·s-1）。培养期内土壤CO2累积过程符合一级反应动力学方程,生物炭添加改变了土壤CO2潜在排放量、周转速率和半周转期。（2）添加棉花秸秆和葡萄藤两种生物炭处理与土壤CO2累积排放量（y）分别符合y=7.51x+88.53和y=2.68x+75.85的线性关系（x为生物炭粒径）。（3）添加生物炭处理土壤呼吸速率与空气温度和土壤温度显著相关,棉花秸秆生物炭处理土壤呼吸速率与温度的相关性高于葡萄藤生物炭处理,土壤温度敏感系数随粒径的减小而增加。综合土壤呼吸速率和温度敏感系数考虑,建议绿洲农田施用1～5mm中等粒径生物炭。 相似文献
13.
Soil CO2 efflux, root mass, and root production were investigated in a humid temperate grassland of Japan over a growing season (Apr. to Sep.) of 2005 to reveal seasonal changes of soil CO2 efflux, to separate the respective contributions of root and microbial respiration to the total soil CO2 efflux, and to determine the environmental factors that control soil respiration. Minimal microbial respiration rate was estimated based on the linear regression equations between soil CO2 efflux and root mass at different experimental sites. Soil CO2 efflux, ranging from 4.99 to 16.29 μmol CO2 m-2 s-1, depended on the seasonal changes in soil temperature. The root mass at 0--10 cm soil depth was 0.82 and 1.27 kg m-2 in Apr. and Sep., respectively. The root mass at 0--10 cm soil depth comprised 60% of the total root mass at 0--50 cm soil depth. The root productivity at 0--30 cm depth varied from 8 to 180 g m-2 month-1. Microbial and root respiration rates ranged from 1.35 to 5.51 and 2.72 to 12.06 μmol CO2 m-2 s-1, respectively. The contribution of root respiration to the total soil CO2 efflux averaged 53%, ranging from 33% to 72%. The microbial respiration rate was exponentially related to soil temperature at 10 cm depth (R2 = 0.9400, P = 0.002, n = 6), and the root respiration rate was linearly related to the root production at 0--30 cm depth (R2 = 0.6561, P = 0.042, n = 6). 相似文献
14.
黄土区夏闲期土壤呼吸变化特征及其影响因素 总被引：5，自引：0，他引：5
本文以1984年设立在黄土旱塬区长期田间定位试验为平台,于2009年采用动态密闭气室法(Li-8100,USA),监测了不同施肥措施下旱地冬麦种植系统中休闲期(7月至9月)土壤呼吸、10cm土层的温度和含水量变化,研究了休闲期土壤呼吸变化特征及其与环境因子的关系。结果表明:黄土旱塬农田休闲期土壤呼吸速率变化剧烈,最大值为5.05μmol m-2s-1,最小值为0.06μmol m-2s-1,平均值为2.00μmol m-2s-1,变异系数为116.5%;整个休闲期不同施肥处理的土壤呼吸速率大小为:化肥有机肥配施处理(NMP)有机肥处理(M)化肥氮磷处理(NP)化肥氮处理(N)和不施肥处理(CK);2009年7月7日至9月11日间NPM、M、NP、N和CK处理土壤CO2-C排放量分别为2.0、1.6、1.2、0.8和0.8 Mg hm-2;土壤呼吸与土壤水分为极显著抛物线关系(p0.01),可解释55%以上的土壤呼吸变异性;土壤呼吸与土壤温度呈显著线性相关(p0.01),但仅能解释呼吸作用变异性的19%~39%;土壤呼吸对耕作的响应强度与微生物量碳极显著线性正相关(p0.01),与土壤有机碳显著线性正相关(p0.05),与全氮、可溶性碳无明显关系(p0.05);降雨对土壤呼吸的促进或抑制主要取决于降雨前的土壤水分状况。长期水分亏缺降雨,降雨可明显促进土壤呼吸,而土壤水分充足时,降雨抑制土壤呼吸,其影响大小与土壤有机碳、全氮、土壤可溶性碳和微生物量碳密切相关。休闲期土壤呼吸受土壤水分、土壤干湿变化、土壤温度、翻耕及土壤有机碳水平等因素的影响。 相似文献
15.
采用开路式土壤碳通量测量系统于2010年3-10月在冬小麦-大豆轮作期对免耕与翻耕田土壤呼吸速率、5cm深土壤温度和湿度进行测定,以研究耕作措施对农田土壤呼吸的影响。结果表明,在冬小麦、大豆生长时段,免耕与翻耕田土壤呼吸速率的季节变化趋势基本一致。冬小麦生长时段免耕与翻耕田土壤呼吸速率的平均值分别为2.50±0.14和2.40±0.29μmol.m-2.s-1,大豆生长时段分别为2.82±0.28和3.50±0.52μmol.m-2.s-1。冬小麦生长时段免耕与翻耕田土壤呼吸无显著差异,但大豆生长时段二者存在显著差异(P<0.05),差异最明显的阶段在大豆开花期(7月下旬-8月中旬)。利用温度影响函数(指数函数)和湿度影响函数(二次函数)耦合的模拟模型进行土壤呼吸与土壤温度和湿度的回归分析,得出免耕条件下土壤温度和湿度可以共同解释25.3%的土壤呼吸变异(R2=0.253,P<0.05),翻耕条件下二者可以共同解释44.0%的土壤呼吸变异(R2=0.440,P<0.01)。可见,一方面,耕作措施对土壤呼吸的影响因种植作物而异,与翻耕相比,免耕显著降低了大豆田土壤呼吸,但对冬小麦田无显著影响;另一方面,免耕下土壤温度和湿度对土壤呼吸的影响比翻耕要小。 相似文献
16.
为研究模拟酸雨对冬小麦-大豆轮作农田土壤呼吸、硝化和反硝化作用的影响,在农田进行随机区组试验,布设4个区组,每块区组随机设置4个模拟酸雨处理,分别为去离子水A1（pH=6.7）、A2（pH=4.0）、A3（pH=3.0）、A4（pH=2.0）。采用LI-8100开路式土壤碳通量测量系统对不同酸雨强度的冬小麦-大豆轮作农田进行土壤呼吸速率观测,并采用气压过程分离技术（BaPS）测定不同酸雨处理的土壤CO2产生速率、硝化速率和反硝化速率。试验结果表明,冬小麦田各处理间土壤呼吸速率无显著差异（P〉0.05）;大豆田高强度模拟酸雨A4处理明显抑制了土壤呼吸作用（P〈0.05）。就冬小麦-大豆轮作生长季而言,各处理土壤呼吸速率无显著差异（P〉0.05）,其平均土壤呼吸速率分别为（2.26±0.11）、（2.31±0.20）、（1.91±0.09）、（2.03±0.17）μmol·m-2·s-1。冬小麦田A1、A3、A4处理间土壤CO2产生速率、硝化速率和反硝化速率均无显著性差异（P〉0.05）。高强度模拟酸雨抑制了大豆田土壤CO2产生速率;大豆田A1、A3、A4处理的硝化速率测定均值分别为（191.6±36.1）、（261.6±36.3）μg·kg-1·h-1和（255.2±45.1）μg·kg-1·h-1,这3个处理的反硝化速率均值分别为（172.8±19.8）、（216.0±45.7）μg·kg-·1h-1和（216.3±44.6）μg·kg-·1h-1。研究表明,模拟酸雨强度升高未显著影响冬小麦田土壤呼吸、硝化和反硝化作用;高强度模拟酸雨（pH=2.0）降低了大豆田土壤呼吸速率和CO2产生速率,但对土壤硝化和反硝化作用有促进作用。 相似文献
17.
两种轮作模式下秸秆还田对土壤呼吸及其温度敏感性的影响 总被引：2，自引：0，他引：2
通过分析不同作物轮作模式下秸秆还田对土壤呼吸及其温度敏感性的影响,为深入探究关中地区农田生态系统碳循环提供理论依据。试验设置于陕西省杨凌地区,在2012年10月至2014年9月期间以冬小麦-夏玉米轮作模式和冬小麦-夏大豆轮作模式作为研究对象,分别设置秸秆还田(SM)和秸秆不还田(NS)两个处理,测定分析不同处理下土壤呼吸、土壤温度及土壤含水量的变化趋势和差异,并估算土壤呼吸的温度敏感性(Q_(10))。结果表明:土壤呼吸存在明显的季节变化,在作物生育期大部分时间内,SM处理的土壤呼吸速率均显著高于NS处理(P0.05),且SM处理的作物生育期土壤呼吸平均速率及土壤呼吸累计排放量也极显著高于NS处理(P0.01);不同作物生育期土壤呼吸平均速率依次为夏玉米夏大豆冬小麦,土壤呼吸总量表现为冬小麦夏玉米夏大豆、冬小麦-夏玉米轮作冬小麦-夏大豆轮作。冬小麦-夏玉米轮作与冬小麦-大豆轮作的土壤温度间存在差异;其中,在冬小麦生育前期,冬小麦-夏玉米轮作的土壤温度显著高于冬小麦-大豆轮作;第2季夏玉米生育期内5 cm深度的土壤温度显著低于同季的夏大豆;相比NS处理,SM处理能提高冬季土壤的温度,并降低春季和夏季的土壤温度;在高温少雨的时期内,SM处理能够提高0~30 cm土壤的平均含水量,不同的前茬作物引起两种轮作模式中冬小麦耕作层土壤含水量间明显的差异,夏玉米耕作层土壤含水量显著高于夏大豆。相关分析表明,土壤呼吸与5 cm和10 cm土壤温度均存在极显著的正相关性,且与5 cm土壤温度的相关性更好;但土壤呼吸与0~30 cm的土壤平均含水量无显著相关性。5 cm和10 cm土壤温度变化能够分别解释土壤呼吸变化的64.6%~67.3%和51.5%~59.6%。整个研究周期内,温度敏感性(Q_(10))为1.70~2.01,冬小麦-夏玉米轮作的温度敏感性显著高于冬小麦-大豆轮作,且同一轮作模式下SM处理的温度敏感性显著低于NS处理。因此,秸秆还田能够提高农田的土壤呼吸作用,降低土壤呼吸的温度敏感性,同时能够调节土壤的水热状况。 相似文献
18.
模拟增温增雨对克氏针茅草原土壤呼吸的影响 总被引：1，自引：0，他引：1
利用开顶式生长室（OTC）于2011年7-9月和2012年5-9月两个植物生长季在以克氏针茅（Stipa krylovii）为主要建群种的典型草原进行模拟增温和增雨的控制试验,以探讨增温和增雨及其交互作用对内蒙古克氏针茅（S.krylovii）草原土壤呼吸的影响。结果表明：（1）土壤呼吸速率日内变化和逐日变化均呈单峰曲线趋势,全天15：00达到最高值（2.26μmol·m-2·s-1）,生长季8月初达到最高值（5.51μmol·m-2·s-1）。9：00-11：00土壤呼吸速率能较好代表全天24h均值。（2）与对照相比,增温1.91℃使土壤呼吸速率降低19.0%,且白天降幅大于夜间。增雨20%使土壤呼吸速率较对照增加18.6%。而增温增雨（气温增加1.64℃,降雨量增加20%）处理下,土壤呼吸速率较对照增加13.0%。（3）土壤呼吸速率与土壤含水量、土壤温度均具有显著相关关系。约79%的土壤呼吸速率是由土壤温度和土壤含水量共同决定的,其中以土壤含水量为主（R2=0.797,P〈0.001）。气温升高使土壤含水量降低,间接导致土壤呼吸速率下降。研究结果可为典型草原科学应对气候变化和草地畜牧业可持续发展提供依据。 相似文献
19.
利用长期定位试验研究了太湖地区不同施肥处理下油菜生长期间水稻土CO2排放通量,耕作方式为水稻-油菜轮作,并对CO2排放通量和土壤（5cm）温度、土壤水分含量进行了回归模拟。结果表明,不同施肥处理平均土壤呼吸CO2排放速率在49．37～85．97CO2-Cmg·m^-2·h^-1之间,与不施肥处理相比,长期施用肥料显著提高了土壤呼吸CO2排放速率,且在油菜的两个生育期,施肥对土壤呼吸释放CO2的促进作用,花角期显著高于角果发育成熟期。相关分析表明,土壤呼吸CO2排放强度与土壤水分、土壤温度有显著的正相关关系。通过计算Q10,无肥处理（NF）较其他肥料处理（CF、CFM、CFS）对土壤温度有更大的敏感性。 相似文献
20.
黄土区退耕草地合理放牧可减少土壤CO2排放和土壤侵蚀 总被引：1，自引：1，他引：0
【目的】在退耕草地实施合理放牧,有助于减少土壤CO2排放、 减缓土壤侵蚀。为验证此假设,本研究选择黄土高原渭北旱原坡地,建立退耕草地放牧、 退耕草地不放牧和传统农业耕作三种处理的对比试验小区,定量研究了退耕草地合理放牧相对于退耕草地在减少土壤CO2排放和土壤侵蚀的作用及其影响因素,为探寻在我国西部退耕还草区实施畜牧业生产与环境保护的协调发展模式提供科学依据。【方法】在建立的退耕草地放牧、 退耕草地不放牧和传统农业耕作3种处理的试验小区,利用LI-8100 碳通量自动测量仪原位监测植物生长期(4~8月)和放牧前后土壤CO2排放速率的变化,同时利用时域反射仪(TDR)测定表层0—10 cm土壤含水量,用地温表测定土壤表层2 cm和5 cm的温度。利用环境放射性核素 7Be示踪技术监测较大降雨事件引起的土壤侵蚀速率,同时取样测定侵蚀区土壤有机碳含量,比较不同处理小区侵蚀导致的土壤有机碳流失量。【结果】观测期间,3种处理CO2平均排放速率大小顺序为退耕草地[3.69±0.39 μmol/(m2·s)]退耕草地放牧[3.00±0.44 μmol/(m2·s)]传统农耕地[1.99±0.22 μmol/(m2·s)],坡耕地退耕还草后土壤CO2排放增加了85%,而合理放牧使退耕草地土壤CO2排放量减少了19%。放牧后退耕草地土壤CO2排放速率平均减少了11%,减少值在2% ~ 41%之间。观测期内,退耕草地放牧后土壤侵蚀速率比农耕地和退耕草地分别减少了93% 和77%。坡耕地退耕还草后土壤CO2排放增加主要由于草被植物引起土壤有机碳储量增加和土壤侵蚀强度减小,放牧后退耕草地土壤CO2排放减少主要与动物踩踏引起土壤容重明显增加及草类植被地上部分向土壤中输入的有机碳的减少有关。水分、 温度影响因子无法解释3种处理间土壤CO2排放差异。【结论】合理放牧不仅能显著减少退耕草地土壤CO2排放,而且可以有效控制退耕草地土壤和有机碳侵蚀流失。放牧期间动物的踩踏作用引起草地土壤容重显著增加是退耕草地土壤CO2排放量和土壤侵蚀速率减少的主要原因。本研究结果揭示,在我国黄土高原和类似的退耕还草地区实施合理放牧既可以促进当地畜牧业生产,又能控制土壤侵蚀和减少CO2的排放,是一种值得探究的草地可持续发展管理模式。 相似文献