首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Modern light chestnut and chestnut soils and their analogues buried under steppe kurgans in the southeastern part of the Russian Plain were studied in order to determine the rates of the CO2 production by these soils under the native (with the natural moisture content) and moistened (60% of the total water capacity) conditions. It was found that the rates of the CO2 production by the soil samples in the native state are relatively close to one another and vary from 0.3 to 1.4 μg of C/100 g of soil/h. The rates of the CO2 production in the moistened state increased by two orders of magnitude for the modern surface soils and by an order of magnitude for the buried soils.  相似文献   

2.
This paper tracks the annual dynamics of carbon dioxide production (emission and profile concentration) by soils of the arboretum in the Moscow State University Botanical Garden that are planted with Siberian spruce and common pine. The high biological activity of the studied soils is caused by the high content of organic matter, slightly alkaline reaction, and good structure and texture. Differences in CO2 production by the soils of a spruce and pine forest (1.5–2 times higher in the latter) can be explained by different structures of soil profiles rather than a temperature regime. The seasonal dynamics of CO2 production are the same for both soils and associated with seasonal changes in climatic parameters. In the cold season, there is noticeable production of carbon dioxide by soils.  相似文献   

3.
The active layer thickness, CO2 emission, and contents of organic substances (including the total organic carbon, labile carbon, and the carbon of microbial biomass) in the soils of flat-topped peat mounds in the area of the Nadym Experimental Station in the north of Western Siberia (experimental site CALM R1) are characterized by considerable spatial variability. The low values of the CО2 emission are confined to the microelevations on the peatland surface. The high values of the emission (>200 mg CO2/(m2 h)) are typical of the soils with the highest content of the carbon of microbial biomass and the lowest content of the labile organic carbon. The soils of elevated flat-topped peat mounds statistically differ from the soils of waterlogged mires in the contents of total, labile, and microbial carbon and in the CO2 emission values. Though the soils of elevated flat-topped peat mounds are characterized by the high content of the carbon of microbial biomass (4260 ± 880 mg С/kg soil), the CO2 emission from them is low (158 ± 23 mg CO2/(m2 h)), which is explained by the structure of microbial communities in the cryogenic soils and by the effect of specific hydrothermic conditions.  相似文献   

4.
The transformation of humus substances resulting from artificial drainage of the surface-gleyed soddy-podzolic soils under conditions of pronounced microtopography and different agrogenic loads was studied. The studied soil characteristics included acid–base conditions, the content and group composition of humus, the ratios between the fractions of humus acids, and optical density of humic acids. The features attesting to humus degradation were found in the soils of microdepressions periodically subjected to excessive surface moistening, in the soils of different landforms upon the construction of drainage trenches, and in the plowed non-fertilized soils. The response of humus characteristics to the changes in the ecological situation in the period of active application of agrochemicals for reclamation of the agrotechnogenically disturbed soils was traced. It was shown that the long-term dynamics of the particular parameters of the biological productivity of the soil depend on the hydrological and agrogenic factors, as well as on the weather conditions.  相似文献   

5.
The studies of recent soils and paleosols buried under kurgans created in the periods of long-term aridization (3000–2000 BC) and climatic optimum (13th–14th centuries AD) were performed in steppes of the southeastern part of the East European Plain (Privolzhskaya Upland and Caspian Lowland) in order to determine the rate of carbon dioxide production by the soil samples at the natural moisture and after moistening up to 60% of the total moisture capacity. The CO2 emission from the samples of paleosols corresponding to the period of climatic aridization in the Lower Volga River at their natural moisture status was lower than that from the samples of background surface soils, whereas the CO2 emission from the samples of paleosols buried under optimum climatic conditions was higher than that from the samples of background surface soils. After moistening of the samples, the increase in the CO2 emission from the paleosol samples depended on the actual humidity of the climate in the corresponding period.  相似文献   

6.
In the humus horizon of soddy-podzolic soils of postagrogenic cenoses and primary forests, the contributions of the fungi and bacteria were determined by the selective inhibition of the substrate-induced respiration (SIR) by antibiotics; the basal (microbial) respiration and the net-produced nitrous oxide (N2O) were also determined. The procedure of the SIR separation using antibiotics (cycloheximide and streptomycin) into the fungal and bacterial components was optimized. It was shown that the fungi: bacteria ratio was 1.58, 2.04, 1.55, 1.39, 2.09, and 1.86 for the cropland, fallow, and different-aged forests (20, 45, 90, and 450 years), respectively. The fungal and bacterial production of CO2 in the primary forest soil was higher than in the cropland by 6.3 and 11.4 times, respectively. The production of N2O in the soils of the primary and secondary (90-year-old) forests (3 and 7 ng N-N2O/g soil per hour, respectively) was 2–13 times lower than in the postagrogenic cenoses, where low values were also found for the microbial biomass carbon (Cmic), its components (the Cmic-bacteria and Cmic-fungi), and the portion of Cmic in the organic carbon of the soil. A conclusion was drawn about the misbalance of the microbial processes in the overgrown cropland accompanied by the increased production of N2O by the soil during its enrichment with an organic substrate (glucose).  相似文献   

7.
The contamination of soil with petroleum products is a major environmental problem. Petroleum products are common soil contaminants as a result of human activities, and they are causing substantial changes in the biological (particularly microbiological) processes, chemical composition, structure and physical properties of soil. The main objective of this study was to assess the impact of soil moisture on CO2 efflux from diesel-contaminated albic podzol soils. Two contamination treatments (3000 and 9000 mg of diesel oil per kg of soil) were prepared for four horizons from two forest study sites with different initial levels of soil water repellency. CO2 emissions were measured using a portable infrared gas analyser (LCpro+, ADC BioScientific, UK) while the soil samples were drying under laboratory conditions (from saturation to air-dry). The assessment of soil water repellency was performed using the water drop penetration time test. An analysis of variance (ANVOA) was conducted for the CO2 efflux data. The obtained results show that CO2 efflux from diesel-contaminated soils is higher than efflux from uncontaminated soils. The initially water-repellent soils were found to have a bigger CO2 efflux. The non-linear relationship between soil moisture content and CO2 efflux only existed for the upper soil horizons, while for deeper soil horizons, the efflux is practically independent of soil moisture content. The contamination of soil by diesel leads to increased soil water repellency.  相似文献   

8.
Parameters of biological activity (humus and microbial biomass reserves, potential intensity of the CO2 emission, and enzyme activity) have been determined in arable and natural chernozems on the plains of Kabardino-Balkaria as a part of the system for the ecological assessment of the state of the soil cover. Integral parameters of the eco-biological state of studied soils have been calculated on the basis of obtained data, and the level of changes in their total biological activity has been determined. A statistically significant decrease of the values of all the considered biological properties under the impact of tillage has been found. The data of two-way ANOVA suggest a stronger influence of agricultural management in comparison with genetic features of chernozems at the level of subtype. Differential approach is insufficient for evaluating the total level of soil biological activity, because there are many biological properties of soil, and the degrees of their changes in agrogenic soils are different. An integral approach has been used; it integrates the obtained data into a single integral assessment parameter. In arable soils, this integral parameter decreases by 39–46% and makes it possible to assess the degree of disturbance of the ecological functions of soils and their capacity for self-restoration.  相似文献   

9.
In the mineral horizons of the soils under different southern taiga forests (oak, archangel spruce, and aspen in the Kaluzhskie Zaseki Reserve of Kaluga region and the green moss spruce and spruce-broadleaved forests of the Zvenigorod Biological Station of Moscow State University in Moscow region), the carbon content in the microbial biomass (Cmic), the rate of the basal respiration (BR), and the specific microbial respiration (qCO2= BR/Cmic) were determined. The Cmic content was measured using the method of substrate-induced respiration (SIR). In the upper humus horizons of the soils, the Cmic content amounted to 762–2545 μg/g and the BR ranged from 1.59 to 7.55 μg CO2-C/g per h. The values of these parameters essentially decreased down the soil profiles. The portion of Cmic in the organic carbon of the humus horizons of the forest soils was 4.4 to 13.2%. The qCO2values increased with the depth in the soils of the Biological Station and did not change in the soils of the Reserve. The pool of Cmic and Corg and the microbial production of CO2 (BR) within the forest soil profiles are presented.  相似文献   

10.
Response of methanogenesis and methanotrophy to elevated carbon dioxide (CO2) could be affected by changes in soil moisture content and temperature. In soil microcosms contained in glass bottles and incubated under laboratory conditions, we assessed the impact of elevated CO2 and temperature interactions on methanogenesis and methanotrophy in alluvial and laterite paddy soils of tropical origin. Soil samples were incubated at ambient (370 μmol mol−1) and elevated (600 μmol mol−1) CO2 concentrations at 25, 35 and 45 °C under non-flooded and flooded conditions for 60 d. Under flooded condition, elevated CO2 significantly increased methane (CH4) production while under non-flooded condition, only marginal increase in CH4 production was observed in both the soils studied and the increase was significantly enhanced by further rise in temperature. Increased methanogenesis as a result of elevated CO2 and temperature interaction was mostly attributed to decreased soil redox potential, increased readily mineralizable carbon, and also noticeable stimulation of methanogenic bacterial population. In contrast to CH4 production, CH4 oxidation was consistently low under elevated CO2 concentration and the decrease was significant with rise in temperature. The low affinity and high affinity CH4 oxidation were faster under non-flooded condition as compared to flooded condition. Admittedly, decreased low and high affinity CH4 oxidation as a result of elevated CO2 and temperature interaction was related to unfavorable lower redox status of soil and the inhibition of CH4-oxidizing bacterial population.  相似文献   

11.
Studies performed on dark gray loamy forest soils in an oak forest in the southern forest steppe and on sandy soddy-podzolic soil in a pine forest in the southern taiga showed that the annual emission of CO2 from the soil surface in the pine forest was 16.3 t CO2/ha, including 10.1 t CO2/ha due to root respiration and 6.2 t CO2/ha due to soil microbial respiration. In the southern forest steppe, the corresponding values were 17.8 t CO2/ha due to root respiration at the optimum water content (20%) and 28.3 t CO2/ha due to soil microbial respiration. With the insufficient soil water content (12.5%), 10.3 and 17.8 t CO2/ha were due to root respiration and soil microbial respiration, respectively. Under strong drought conditions (water content of 10%), the emission of CO2 decreased to 8.2 and 16.3 t/ha due to root respiration and soil microbial respiration, respectively.  相似文献   

12.
A high soil nitrogen (N) content in irrigated areas quite often results in environmental problems. Improving the management practices of intensive agriculture can mitigate greenhouse gas (GHG) emissions. This study compared the effect of maize stover incorporation or removal together with different mineral N fertilizer rates (0, 200 and 300 kg N ha?1) on the emission of nitrous oxide (N2O) and carbon dioxide (CO2) on a sprinkler-irrigated maize (Zea mays L.). The trail was conducted in the Ebro Valley (NE Spain) in a high nitrate-N soil (i.e. 200 g NO3–N kg?1). Nitrous oxide and CO2 emissions were sampled weekly using a semi-static closed chamber and quantified using the photoacoustic technique in 2011 and 2012. Applying sidedress N fertilizer tended to increase N2O emissions whereas stover incorporation did not have any clear effect. Nitrification was probably the main process leading to N2O. Denitrification was limited by the low soil moisture content (WFPS <?54%), due to an adequate irrigation management. Emissions ranged from ??0.11 to 0.36% of the N applied, below the IPCC (2007) values. Nitrogen fertilization tended to reduce CO2 emission, but only in 2011. Stover incorporation increased CO2 emission. Nitrogen use efficiency decreased with increasing mineral fertilizer supply. The application of N in high N soils of the Ebro Valley is not necessary until the soil restores a normal mineral N content, regardless of stover management. This will combine productivity with keeping N2O and CO2 emissions under control provided irrigation is adequately managed. Testing soil NO3 ?–N contents before fertilizing would improve N fertilizer recommendations.  相似文献   

13.
Elevated atmospheric CO2 concentration ([CO2]) may change litter chemistry which affects litter decomposability. This study investigated respiration and microbial biomass of soils amended with litter of Pinus densiflora (a coniferous species; pine) and Quercus variabilis (a deciduous species; oak) that were grown under different atmospheric [CO2] and thus had different chemistry. Elevated [CO2] increased lignin/N through increased lignin concentration and decreased N concentration. The CO2 emission from the soils amended with litter produced under the same [CO2] regime was greater for oak than pine litter, confirming that broadleaf litter with lower lignin decomposes faster than needle leaf litter. Within each species, however, soils amended with high lignin/N litter grown under elevated [CO2] emitted more CO2 than those with low lignin/N litter grown under ambient [CO2]. Such contrasting effects of lignin/N on inter- and intra-species variations in litter decomposition should be ascribed to the effects of other litter chemistry variables including nonstructural carbohydrate, calcium and manganese as well as inhibitory effect of N on lignin decomposition. The microbial biomass was also higher in the soils amended with high lignin/N litter than those with low lignin/N litter probably due to low substrate use efficiency of lignin by microbes. Our study suggests that elevated [CO2] increases lignin/N for both species, but increased lignin/N does not always reduce soil respiration and microbial biomass. Further study investigating a variety of tree species is required for more comprehensive understanding of inter- and intra-species variations of litter decomposition under elevated [CO2].  相似文献   

14.
In two layers of the humus horizons in soddy-podzolic soils of different biogeocenoses (Kostroma oblast) representing a succession series, the carbon content in the microbial biomass (Cmic) was determined using the method of substrate-induced respiration and the rate of microbial CO2 production (basal respiration, BR). The Cmic content was from 110 to 755 μg/g soil, and the BR was from 0.40 to 2.52 μg CO2-C/g/h. A gradual increase in the Cmic content and BR was found in the following sequence: cropland—fallow (7-year-old)—young (20- and 45-year-old) forests—secondary and native (primary) forests (90- and 450-year-old, respectively). In the litter, the Cmic content was higher in the 45-year-old forest than in the secondary and native forests: 10423, 6459, and 4258 μg C/g of substrate, respectively. The portion of Cmic in the soil organic carbon content in the upper layer of the soils studied varied from 1.3 to 5.4%; its highest value was in the soils under the secondary and native forests. The pool of microbial biomass carbon and the microbial CO2 production in the upper 25-cm layer of the soils were calculated.  相似文献   

15.
Seasonal changes of the soil CO2 concentration and the rate of CO2 fluxes emission from the soil formed on the sediments of the former Lake Texcoco, which occupied a significant part of the Mexico Valley until the mid-17th century, were studied. The soils (Fluvic Endogleyic Phaeozems) were characterized by a low CO2 fluxes rate, which is related to their high alkalinity. The mean values of soil respiration were 6.0–14.1 mg C/(m2 h) depending on vegetation type, which corresponds to 60–157 g C/(m2 yr). The contribution of plants to the CO2 fluxes insignificantly varied by seasons and depended on the species composition of vegetation. The soil CO2 concentration and soil respiration in eucalypt (Eucalyptus globulus Labill.) plantation were two times higher than those in the grass–subshrub area, the ground cover of which consisted of Distichlis spicata (L.) Greene and Suaeda nigra (Raf.) J.F. Macbr. species. This can be related to the significant volumes of gas production during the respiration of eucalypt roots and associated rhizosphere community. The contribution of the root systems of grass cover to the soil CO2 fluxes in eucalypt plantation slightly varied within the year and was equal to 24% on the average. In the grass–subshrub area, its value varied from 41% in the cold season to 60% in the warm season. The spatial variability of soil CO2 concentration and its flux rate to the atmosphere was due to the differences in plant species composition and hydrothermal conditions, and their temporal trend was closely related to the seasonal accumulation of plant biomass and soil temperature.  相似文献   

16.
Response of N2 fixation to elevated CO2 would be modified by changes in temperature and soil moisture because CO2 and temperature or water availability has generally opposing effects on N2 fixation. In this study, we assessed the impacts of elevated CO2 and temperature interactions on nitrogenase activities, readily mineralizable C (RMC), readily available N (NRN) contents in an alluvial and a laterite rice soil of tropical origin. Soil samples were incubated at ambient (370 μmol mol-1) and elevated (600 μmol mol-1) CO2 concentration at 25oC, 35oC, and 45oC under non-flooded and flooded conditions for 60 days. Elevated CO2 significantly increased nitrogenase activities and readily mineralizable C in both alluvial and laterite soils. All these activities were further stimulated at higher temperatures. Increases in nitrogenase activity as a result of CO2 enrichment effect over control were 16.2%, 31.2%, and 66.4% and those of NRN content were 2.0%, 1.8%, and 0.5% at 25oC, 35oC and 45oC, respectively. Increases in RMC contents were 7.7%, 10.0%, and 10.6% at 25°C, 35°C and 45°C, respectively. Soil flooding resulted in a more clear impact of CO2 enrichment than the non-flooded soil. The results suggest that in tropical rice soils, elevated CO2 increased readily available C content in the soil, which probably stimulates growth of diazotrophic bacteria with enhanced N2 fixation and thereby higher available N.  相似文献   

17.
The volcanic soils of Kamchatka are characterized by low and very low values of their potential potassium buffer capacity. The largest amount of readily exchangeable potassium (-ΔK 0) is observed in the surface layers of the natural soils and is due to the active biogenic accumulation. The soddy horizons have a high content of strongly fixed potassium (K X ). The main factors determining the content of the labile potassium and its mobility are the contents of physical clay, humus, and exchangeable potassium. The extremely nonuniform distribution of all the potassium status parameters throughout the soil profile reflects the discrete character of the volcanic pedogenesis. The low values of the potential buffer capacity for the potassium (PBCK) at the high values of the equilibrium potassium potential (AR 0) and the medium content of the labile potassium in the light-textured synlithogenic soils simultaneously indicate both the good potassium supply of the plants and the incapability of the soils to resist potassium exhaustion under agricultural production conditions for a long time.  相似文献   

18.

Purpose

Agricultural practises impact soil properties and N transformation rate, and have a greater effect on N2O production pathways in agricultural soils compared with natural woodland soils. However, whether agricultural land use affects N2O production pathways in acidic soils in subtropical regions remains unknown.

Materials and methods

In this study, we collected natural woodland soil (WD) and three types of agricultural soils, namely upland agricultural (UA), tea plantation (TP) and bamboo plantation (BP) soils. We performed paired 15N-tracing experiment to investigate the effects of land use types on N2O production pathways in acidic soils in subtropical regions in China.

Results and discussion

The results revealed that heterotrophic nitrification is the dominant pathway of N2O production in WD, accounting for 44.6 % of N2O emissions, whereas heterotrophic nitrification contributed less than 2.7 % in all three agricultural soils, due to a lower organic C content and soil C/N ratio. In contrast, denitrification dominated N2O production in agricultural soils, accounting for 54.5, 72.8 and 77.1 % in UA, TP and BP, respectively. Nitrate (NO3 ?) predominantly affected the contribution from denitrification in soils under different land use types. Autotrophic nitrification increased after the conversion of woodland to agricultural lands, peaking at 42.8 % in UA compared with only 21.5 % in WD, and was positively correlated with soil pH. Our data suggest that pH plays a great role in controlling N2O emissions through autotrophic nitrification following conversion of woodland to agricultural lands.

Conclusions

Our results demonstrate the variability in N2O production pathways in soils of different land use types. Soil pH, the quantity and quality of organic C and NO3 ? content primarily determined N2O emissions. These results will likely assist modelling and mitigation of N2O emissions from different land use types in subtropical acidic soils in China and elsewhere.
  相似文献   

19.
The results of long-term (1992–2005) monitoring of the carbon compounds transformation in soils of forest- steppe agroecosystems polluted by heavy metals in the Baikal region in the years different from the “climatic norm” are discussed. The influence of environmental factors on the functioning of microbial community was estimated by the Cmicr content and CO2 emission. The changes in the ecophysiological parameters (Cmicr/Corg and C-CO2/Cmicr, mg/(g h) related to the availability of the substrate and intensity of carbon (re)immobilization in different soils revealed the differences in the formation of a stable microbial community dependent on the environmental factors, especially in anomalous years. The use of a systemic approach and analysis of the carbon compounds transformation based on the proportion between the flows of net-mineralized and (re)immobilized carbon (NM: RI) allowed to evaluate integrally the functioning regime of the agroecosystems and the ecological impact on them. The differences in the functioning of agroecosystems on different heavy metal-polluted soils identified on the background of climatic changes are suitable for forecasting the current state and development of agroecosystems. For agroecosystems of this region, C-CO2 emission was estimated for the first time; it was more intense from the soils with the high humus content than from the soils poor in humus (141 and 101 g C/m2, respectively).  相似文献   

20.
Field estimation of the microbial biomass of soils derived from natural and anthropogenic parent materials Whereas the estimation and evaluation of physical and chemical soil properties is possible with the use of widely accepted methods, there is still no procedure with respect to microbiological parameters. Therefore, our objective was to develop a field procedure for estimating the integral parameter ”︁microbial biomass”. For this purpose, microbial biomass data (Cmic in dry matter) of soils developed in natural parent materials from 116 sites in Germany and abroad were analyzed. Additionally, Cmic in 33 German soils developed in anthropogenic parent materials was determined. In the soils under consideration, Cmic varied between 100 and 4000 kg ha—1 in the upper 30 cm. For soils of natural substrates statistical relations between Cmic and the humus and clay content as well as pH were derived. From these parameters which are combined as the diagnostic characteristics of humus a simple procedure for estimating Cmic of arable soils was developed. For soils developed in anthropogenic parent materials, however, an estimation procedure was developed that uses the nature of the parent material and the degree of soil development. To evaluate the estimated amount of Cmic, a frame consisting of 6 classes is proposed: < 200 kg ha—1 (= very low), 200—400 kg ha—1 (= low), 400—800 kg ha—1 (= moderate), 800—1600 kg ha—1 (= medium), 1600—3200 kg ha—1 (= high), and > 3200 kg ha—1 (= very high).  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号