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1.
Investigations of diurnal and seasonal variations in soil respiration support modeling of regional CO2 budgets and therefore in estimating their potential contribution to greenhouse gases. This study quantifies temporal changes in soil respiration and their driving factors in grassland and arable soils located in Northern Germany. Field measurements at an arable site showed diurnal mean soil respiration rates between 67 and 99 mg CO2 m–2 h–1 with a hysteresis effect following changes in mean soil temperatures. Field soil respiration peaked in April at 5767 mg CO2 m–2 day–1, while values below 300 mg CO2 m–2 day–1 were measured in wintertime. Laboratory incubations were carried out in dark open flow chambers at temperatures from 5°C to 40°C, with 5°C intervals, and soil moisture was controlled at 30%, 50%, and 70% of full water holding capacity. Respiration rates were higher in grassland soils than in arable soils when the incubating temperature exceeded 15°C. The respiration rate difference between them rose with increasing temperature. Monthly median values of incubated soil respiration rates ranged from 0 to 26.12 and 0 to 7.84 µg CO2 g–1 dry weight h–1, respectively, in grassland and arable land. A shortage of available substrate leads to a temporal decline in soil respiration rates, as indicated by a decrease in dissolved organic carbon. Temporal Q10 values decreased from about 4.0 to below 1.5 as temperatures increased in the field. Moreover, the results of our laboratory experiments confirmed that soil temperature is the main controlling factor for the Q10 values. Within the temperature interval between 20°C and 30°C, Q10 values were around 2 while the Q10 values of arable soils were slightly lower compared to that of grassland soils. Thus, laboratory studies may underestimate temperature sensitivity of soil respiration, awareness for transforming laboratory data to field conditions must therefore be taken into account.  相似文献   

2.
Soil respiration throughout an annual cycle was measured at three different stands in a tropical grassland situated at Kurukshetra at 29°58' N lat. and 76°51' E long. Rates of CO2 evolution were measured by alkali absorption using 13 cm dia × 23 cm aluminium cylinders inserted 10 cm into the ground. Both movable and permanently-fixed cylinders were used. The CO2 evolution rates for the three stands were: Stand I (dominated by Sesbania bispinosa) 49–358 mg CO2 m?2 h?1; Stand II (mixed grasses) 55–378 mg CO2m?2 h?1; and Stand III (dominated by Desmostachya bipinnata) 55–448 mg CO2 m?2 h?1. A positive significant relation existed between rate of CO2 evolution and soil water content (r = 0.59?0.740), and between soil respiration and temperature (r = 0.58?0.69). A statistical model developed on the basis of the relationship between CO2 evolution rates and certain abiotic environmental factors showed 69% comparability between the calculated and observed values of soil respiration. The contribution of root and root-associated microorganisms to total soil respiration was estimated at 42% using the relationship between root biomass and CO2 output from movable cylinders.  相似文献   

3.
The objective of this work was to provide evidence on the effects of faba bean (Vicia faba L.) and chickpea (Cicer arietinum L.) on the dynamics of soil N availability and yield parameters of wheat (Triticum turgidum L. var. durum) in a legume–wheat rotation in comparison with the effects of the more extensively studied common vetch (Vicia sativa L.). Soil samples were taken from field plots just before wheat sowing and incubated in the laboratory to assess N mineralization potential, soil respiration and N immobilization after incorporation of legume residues. Soil after vetch cultivation showed the highest residual N and mineralization potential (120 mg N kg?1 soil), the greatest CO2 release and the smallest N immobilization. Smaller mineral N release (80 mg N kg?1 soil) was shown by soil after faba bean cultivation, which, however, would be capable to support an average wheat production without fertilization. Soil after chickpea and wheat cultivation manifested no differences in residual N and mineralization or immobilization potential. Laboratory results were well correlated with grain yield and N uptake during the second season of rotation in the field. All legumes resulted in significant yield surpluses and provided N credit to the following unfertilized wheat.  相似文献   

4.
为了研究黄淮海平原不同秸秆还田方式和施氮类型对夏玉米农田生态系统土壤呼吸的影响,于2010年6—10月,采用LI-COR-6400-09土壤气室连接红外线气体分析仪(IRGA)对玉米农田行间掩埋秸秆区的土壤呼吸作用进行了连续测定。结果表明,常规施肥下,玉米生育期内秸秆行间掩埋处理(ISFR)的平均土壤呼吸速率显著高于秸秆移除(NSFR)和秸秆覆盖(SFR)处理(P<0.05)。秸秆行间掩埋配合施用化学氮肥处理中,配施50.4 kg(N).hm 2处理(ISF3)的平均土壤呼吸速率为(178.85±46.60)mg(C).m 2.h 1,显著高于配施33.6 kg(N).hm 2处理(ISF2)的(124.11±23.18)mg(C).m 2.h 1(P<0.05)。秸秆行间掩埋配合施用鸡粪处理中,鸡粪施用量为33.6kg(N).hm 2(ISOM2)处理的平均土壤呼吸速率为(208.08±31.54)mg(C).m 2.h 1,施用16.8 kg(N).hm 2(ISOM1)和50.4 kg(N).hm 2(ISOM3)处理的为(135.07±21.97)mg(C).m 2.h 1、(171.43±43.31)mg(C).m 2.h 1,相比ISOM2处理,ISOM1和ISOM3处理的平均土壤呼吸速率降低了35.09%和17.61%。ISOM2处理玉米季CO2排放累积量为499.39 g(C).m 2,显著高于ISF2处理的297.86 g(C).m 2。秸秆行间掩埋配合施用化学氮肥对土壤呼吸速率的影响小于配合施用鸡粪的影响,配合施用16%总氮的鸡粪,即33.6 kg(N).hm 2时C/N比最适宜土壤微生物的代谢活动。  相似文献   

5.
Paclobutrazol is a plant growth regulator largely utilized in mango cultivation and usually applied directly to soil. The aim of this study was to examine the effect of paclobutrazol on soil microbial biomass, soil respiration and cellulose decomposition in Brazilian soils under laboratory conditions. Soil samples were collected from fields with and without a reported history of paclobutrazol application. A solution of paclobutrazol (8 mg of active ingredient kg?1 of soil) was added to soils, which were then incubated at 28 °C for 30 days. Paclobutrazol decreased soil microbial biomass, soil respiration and cellulose decomposition in soil with and without a report of paclobutrazol application, while significant increase was observed in the respiratory quotient (qCO2). Our results show that the soil microbiological attributes were negatively affected by paclobutrazol in short-term experiment.  相似文献   

6.
Soil heterotrophic respiration and its temperature sensitivity are affected by various climatic and environmental factors.However,little is known about the combined effects of concurrent climatic and environmental changes,such as climatic warming,changing precipitation regimes,and increasing nitrogen(N)deposition.Therefore,in this study,we investigated the individual and combined effects of warming,wetting,and N addition on soil heterotrophic respiration and temperature sensitivity.We incubated soils collected from a temperate forest in South Korea for 60 d at two temperature levels(15 and 20℃,representing the annual mean temperature of the study site and 5℃warming,respectively),three moisture levels(10%,28%,and 50%water-filled pore space(WFPS),representing dry,moist,and wet conditions,respectively),and two N levels(without N and with N addition equivalent to 50 kg N ha-1year-1).On day 30,soils were distributed across five different temperatures(10,15,20,25,and 30℃)for 24 h to determine short-term changes in temperature sensitivity(Q10,change in respiration with 10℃increase in temperature)of soil heterotrophic respiration.After completing the incubation on day 60,we measured substrate-induced respiration(SIR)by adding six labile substrates to the three types of treatments.Wetting treatment(increase from 28%to 50%WFPS)reduced SIR by 40.8%(3.77 to 2.23μg CO2-C g-1h-1),but warming(increase from 15 to 20℃)and N addition increased SIR by 47.7%(3.77 to 5.57μg CO2-C g-1h-1)and 42.0%(3.77 to 5.35μg CO2-C g-1h-1),respectively.A combination of any two treatments did not affect SIR,but the combination of three treatments reduced SIR by 42.4%(3.70 to 2.20μg CO2-C g-1h-1).Wetting treatment increased Q10by 25.0%(2.4 to 3.0).However,warming and N addition reduced Q10by 37.5%(2.4 to 1.5)and 16.7%(2.4 to 2.0),respectively.Warming coupled with wetting did not significantly change Q10,while warming coupled with N addition reduced Q10by 33.3%(2.4 to 1.6).The combination of three treatments increased Q10by 12.5%(2.4 to 2.7).Our results demonstrated that among the three factors,soil moisture is the most important one controlling SIR and Q10.The results suggest that the effect of warming on SIR and Q10can be modified significantly by rainfall variability and elevated N availability.Therefore,this study emphasizes that concurrent climatic and environmental changes,such as increasing rainfall variability and N deposition,should be considered when predicting changes induced by warming in soil respiration and its temperature sensitivity.  相似文献   

7.
Land‐use change and soil management play a vital role in influencing losses of soil carbon (C) by respiration. The aim of this experiment was to examine the impact of natural vegetation restoration and long‐term fertilization on the seasonal pattern of soil respiration and cumulative carbon dioxide (CO2) emission from a black soil of northeast China. Soil respiration rate fluctuated greatly during the growing season in grassland (GL), ranging from 278 to 1030 mg CO2 m?2 h?1 with an average of 606 mg CO2 m?2 h?1. By contrast, soil CO2 emission did not change in bareland (BL) as much as in GL. For cropland (CL), including three treatments [CK (no fertilizer application), nitrogen, phosphorus and potassium application (NPK), and NPK together with organic manure (OM)], soil CO2 emission gradually increased with the growth of maize after seedling with an increasing order of CK < NPM < OM, reaching a maximum on 17 August and declining thereafter. A highly significant exponential correlation was observed between soil temperature and soil CO2 emission for GL during the late growing season (from 3 August to 28 September) with Q10 = 2.46, which accounted for approximately 75% of emission variability. However, no correlation was found between the two parameters for BL and CL. Seasonal CO2 emission from rhizosphere soil changed in line with the overall soil respiration, which averaged 184, 407, and 584 mg CO2 m?2 h?1, with peaks at 614, 1260, and 1770 mg CO2 m?2 h?1 for CK, NPK, and OM, respectively. SOM‐derived CO2 emission of root free‐soil, including basal soil respiration and plant residue–derived microbial decomposition, averaged 132, 132, and 136 mg CO2 m?2 h?1, respectively, showing no difference for the three CL treatments. Cumulative soil CO2 emissions decreased in the order OM > GL > NPK > CK > BL. The cumulative rhizosphere‐derived CO2 emissions during the growing season of maize in cropland accounted for about 67, 74, and 80% of the overall CO2 emissions for CK, NPK, and OM, respectively. Cumulative CO2 emissions were found to significantly correlate with SOC stocks (r = 0.92, n = 5, P < 0.05) as well as with SOC concentration (r = 0.97, n = 5, P < 0.01). We concluded that natural vegetation restoration and long‐term application of organic manure substantially increased C sequestration into soil rather than C losses for the black soil. These results are of great significance to properly manage black soil as a large C pool in northeast China.  相似文献   

8.
The emission of carbon dioxide (CO2) from podzols (Albic Podzols (Arenic)) and the factors controlling its spatiotemporal variability in the forest ecosystems of the Pasvik Reserve in the Kola Subarctic are characterized. Relatively favorable climatic conditions beyond the polar circle in summer are responsible for intensive soil respiration. The type of forest affects the emission of CO2 from the soil surface. The lowest rate of the CO2 emission is typical of the soils under lichen pine forest (105–220 mg C/(m2 h) or 180 g C/m2 during the summertime). Higher rates are observed for the soils under green moss pine (170–385 mg C/(m2 h) or 360 g C/m2 during the summertime) and birch (190–410 mg C/(m2 h) or 470 g C/m2 during the summertime) forests. This may related to a higher contribution of root respiration (44, 88, and 67%, respectively). Soil respiration and the contribution of root respiration to it increase with an increase in the canopy density; mass of small roots; microbial biomass; depth of the stony layer; soil moistening; and the contents of available carbon, nitrogen, phosphorus, and potassium compounds. At the same time, they decrease with an increase in the portion of lichens in the ground cover. The seasonal dynamics are characterized by the CO2 emission maximums in the summer and fall and minimum in the spring. The daily dynamics are smoothed under conditions of the polar day.  相似文献   

9.
Forested peatlands contain large pools of terrestrial carbon. As well as drainage, forest management such as fertilizer application can affect these pools. We studied the effect of wood ash (application rates 0, 5 and 15 t ha?1) on the heterotrophic soil respiration (CO2 efflux), cellulose decomposition, soil nutrients, biomass production and amount of C accumulated in a tree stand on a pine‐dominated drained mire in central Finland. The ash was spread 13 years before the respiration measurements. The annual CO2 efflux was statistically modelled using soil temperature as the driving variable. Wood ash application increased the amounts of mineral nutrients of peat substantially and increased soil pH in the uppermost 10 cm layer by 1.5–2 pH units. In the surface peat, the decomposition rate of cellulose in the ash plots was roughly double that in control plots. Annual CO2 efflux was least on the unfertilized site, 238 g CO2‐C m?2 year?1. The use of wood ash nearly doubled CO2 efflux to 420–475 g CO2‐Cm?2 year?1 on plots fertilized with 5–15 t ha?1 of ash, respectively. Furthermore, ash treatments resulted also in increased stand growth, and during the measurement year, the growing stand on ash plots accumulated carbon 11–12 times faster than the control plot. The difference between peat C emission and amount of C sequestered by trees on the ash plots was 43–58 g C m?2, while on the control plot it was 204 g C m?2. Our conclusion is that adding wood ash as a fertilizer increases more C sequestration in the tree stand than C efflux from the peat.  相似文献   

10.
Lime is a common amendment to overcome soil acidity in agricultural production systems. However, plant root effects on lime and soil carbon (C) dynamics in acidic soils under varied temperature remain largely unknown. We monitored root effects of soybean on the fate of lime applied to an acidic soil at 20 and 30°C in growth chambers. Soil respired CO2 was continuously trapped in columns without and with plants until the final stage of vegetative growth. Lime‐derived CO2 was separated from total respired CO2 based on δ13C measurements in CO2. Leaching was induced at early and late vegetative growth stages, and the leachates were analysed for dissolved organic (DOC) and inorganic C (DIC) concentrations. Soil respiration significantly increased with lime addition at both temperatures (p < 0.001). The presence of soybean doubled the recovery of lime‐derived CO2‐C at 20°C at the early growth stage; however, by the end of the experiment, the contribution of lime‐derived CO2‐C to soil respiration was negligible in all treatments, indicating that the contribution of lime to soil respiration was shortlived. In contrast, DIC and DOC concentrations in leachates remained elevated with liming and were greater in the presence of soybean. We observed no main temperature effects and no interactive effects of temperature and soybean presence on lime‐derived CO2‐C, DIC and DOC. These results highlight the role of plant‐modulated processes in CO2 release and C leaching from lime in acidic soils, whereas an increase in temperature may be less important. Temperature and plant roots alter the rate of key processes controlling C dynamics in a limed acidic soil. Lime‐derived CO2‐C, DIC and DOC increased more in the presence of plants than with increased temperature. Root effects are more important than temperature for inorganic and organic carbon dynamics in limed acidic soils.  相似文献   

11.
Soil management practices that result in increased soil carbon (C) sequestration can make a valuable contribution to reducing the increase in atmospheric CO2 concentrations. We studied the effect of poultry manure, cattle slurry, sewage sludge, NH4NO3 or urea on C cycling and sequestration in silage grass production. Soil respiration, net ecosystem exchange (NEE) and methane (CH4) fluxes were measured with chambers, and soil samples were analysed for total C and dissolved organic C (DOC). Treatments were applied over 2 years and measurements were carried out over 3 years to assess possible residual effects. Organic fertilizer applications increased CO2 loss through soil respiration but also enhanced soil C storage compared with mineral fertilizer. Cumulative soil respiration rates were highest in poultry manure treatments with 13.7 t C ha?1 in 2003, corresponding to 1.6 times the control value, but no residual effect was seen. Soil respiration showed an exponential increase with temperature, and a bimodal relationship with soil moisture. The greatest NEE was observed on urea treatments (with a CO2 uptake of ?4.4 g CO2 m?2 h?1). Total C and DOC were significantly greater in manure treatments in the soil surface (0–10 cm). Of the C added in the manures, 27% of that in the sewage pellets, 32% of that in the cattle slurry and 39% of that in the poultry manure remained in the 0–10 cm soil layer at the end of the experiment. Mineral fertilizer treatments had only small C sequestration rates, although uncertainties were high. Expressed as global warming potentials, the benefits of increased C sequestration on poultry manure and sewage pellet treatments were outweighed by the additional losses of N2O, particularly in the wet year 2002. Methane was emitted only for 2–3 days on cattle slurry treatments, but the magnitudes of fluxes were negligible compared with C losses by soil respiration.  相似文献   

12.
Abstract

This study investigated whether small additions to soil of primary paper-mill sludge, a wood fibre residue from paper production (fibre sludge), caused temporary N immobilization and thereby reduced the amount of inorganic nitrogen leached from agricultural land. This was achieved by measuring respiration and immobilization of N in incubation studies at 8°C, with fibre sludge added at rates varying from 63 to 1000?mg?C?kg?1 soil. Glucose added at rates of 63–250?mg?C?kg?1 soil was used as a reference. Respiration in soil after glucose addition followed an exponential course with the highest rates on days 2–4. During this period maximum peaks of net N immobilization were measured. Even addition of only 63?mg glucose-C?kg?1 soil caused significant immobilization of N in soil. Fibre sludge additions to soil caused lower respiration activities, characterized by two initial peaks followed by somewhat higher respiration rates during the remaining incubation than for glucose. It was likely that hemicellulose, which amounted to 14% of the total C, was the initial available energy source in the sludge as concentrations of water-soluble C were very low. Addition of at least 250?mg?C?kg?1 soil as fibre sludge was required to cause significant N immobilization in soil corresponding to 5?kg?N?ha?1. Both nitrate and ammonium were immobilized. Relating maximum N immobilization data during days 2 to 10 to corresponding respiration data for glucose and fibre sludge revealed that microbes utilised similar amounts of C per unit N immobilized. On average, 175.6±74.8?mg CO2-C were respired to immobilize 1?mg?N and the relationship between C respiration and N immobilization was linear (R 2=0.984). To make soil application of fibre sludge a realistic counter-measure against N leaching from agricultural soils, pre-treatment is necessary to increase the content of energy readily available to microbes.  相似文献   

13.
Soil cultivation changes and usage of agricultural wastes can have profound impacts on greenhouse gas (GHG) emission from soil. In this study, the effects of soil cultivation and organic amendment on GHG emission were investigated using aerobic incubation. Surface soil (0–20 cm) from (1) rice–legume consecutive rotation (Rice) and (2) recently (<3 years) converted from rice field to plastic-covered intensive vegetable and flower production (VegC) were collected in Kunming, P.R. China. Rose (Rosa rugosa Thunb.) residues and cattle manure were applied at 5% by weight. Results indicated that N2O and CO2 fluxes were significantly influenced by soil cultivation, organic amendment, incubation time and their interaction (p <0.05). Applying cattle manure increased, while rose residue decreased, cumulative N2O emissions from soil (84 days). Rose residue application significantly increased cumulative CO2 emissions with peak values of 6371 (Rice) and 7481 mg kg?1 (VegC), followed by cattle manure addition figure of 2265 (VegC) and 3581 mg kg?1 (Rice). Both were significantly higher (p <0.05) than the un-amended Control at 709 (VegC) and 904 mg kg?1 (Rice). Our study demonstrates that a low C/N ratio in cattle manure is better than a high C/N ratio in rose residue in regard to reducing the global warming potential of agricultural soil.  相似文献   

14.
Solar vegetable greenhouse soils show low soil organic carbon content and thus also low rates of soil respiration. Processing vegetable residues to biochar and mixing biochar with maize straw might improve soil respiration and increase soil organic carbon stocks, while preventing the spread of soil-borne diseases carried by vegetable residues. In an incubation experiment, we tested how additions of maize straw (S) and biochar (B) added in varying ratios (100S, 75S25B, 50S50B, 25S75B, 100B and 0S0B (control)) affect soil respiration and fraction of added C remaining in soil. Daily CO2 emissions were measured over 60 days incubation, the natural abundance of 13C in soil and in the added biochar and maize straw were analysed. Our result shows that (a) soil CO2 emissions were significantly increased compared to soil without the straw additions, while addition of biochar only decreased soil respiration; (b) cumulative CO2 emissions decreased with increasing ratio of added biochar to maize straw; (c) the abundance of soil 13C was significant positively correlated with cumulative CO2 emissions, and thus with the ratio of straw addition. Our results indicate that incorporation of maize straw in greenhouse soils is a meaningful measure to increase soil respiration and to facilitate greenhouse atmosphere CO2 limitation while producing vegetables. On the other hand, additions of biochar from vegetable residues will increase soil organic carbon concentration. Therefore, the simultaneous application of maize straw and biochar obtained from vegetable residues is an effective option to maintain essential soil functions for vegetable production in sunken solar greenhouses.  相似文献   

15.
Microbial biomass, respiratory activity, and in‐situ substrate decomposition were studied in soils from humid temperate forest ecosystems in SW Germany. The sites cover a wide range of abiotic soil and climatic properties. Microbial biomass and respiration were related to both soil dry mass in individual horizons and to the soil volume in the top 25 cm. Soil microbial properties covered the following ranges: soil microbial biomass: 20 µg C g–1–8.3 mg C g–1 and 14–249 g C m–2, respectively; microbial C–to–total organic C ratio: 0.1%–3.6%; soil respiration: 109–963 mg CO2‐C m–2 h–1; metabolic quotient (qCO2): 1.4–14.7 mg C (g Cmic)–1 h–1; daily in‐situ substrate decomposition rate: 0.17%–2.3%. The main abiotic properties affecting concentrations of microbial biomass differed between forest‐floor/organic horizons and mineral horizons. Whereas microbial biomass decreased with increasing soil moisture and altitude in the forest‐floor/organic horizons, it increased with increasing Ntot content and pH value in the mineral horizons. Quantities of microbial biomass in forest soils appear to be mainly controlled by the quality of the soil organic matter (SOM), i.e., by its C : N ratio, the quantity of Ntot, the soil pH, and also showed an optimum relationship with increasing soil moisture conditions. The ratio of Cmic to Corg was a good indicator of SOM quality. The quality of the SOM (C : N ratio) and soil pH appear to be crucial for the incorporation of C into microbial tissue. The data and functional relations between microbial and abiotic variables from this study provide the basis for a valuation scheme for the function of soils to serve as a habitat for microorganisms.  相似文献   

16.
Twenty plots (20 m2 each) were selected in coniferous and mixed forests of the industrial Vologda district and the Vytegra district without developed industries in Vologda region. In March, snow cores corresponding to the snow cover depth were taken on these plots. In August, soil samples from the 0- to 20-cm layer of litter-free soddy-podzolic soil (Albic Retisol (Ochric)) were taken on the same plots in August. The content of mineral nitrogen (Nmin), including its ammonium (NH+4) and nitrate (NO-3) forms, was determined in the snow (meltwater) and soil. The contents of total organic carbon, total nitrogen, and elements (Al, Ca); pH; particle size distribution; and microbiological parameters―carbon of microbial biomass (Cmic) and microbial respiration (MR)―were determined in the soil. The ratio MR/Cmic = qCO2 (specific respiration of microbial biomass, or soil microbial metabolic quotient) was calculated. The content of Nmic in meltwater of two districts was 1.7 mg/L on the average (1.5 and 0.3 mg/L for the NH+4 and NO–3 forms, respectively). The annual atmospheric deposition was 0.6–8.9 kg Nmin/ha, the value of which in the Vologda district was higher than in the Vytegra district by 40%. Reliable correlations were found between atmospheric NH+4 depositions and Cmic (–0.45), between NH+4 and qCO2 (0.56), between atmospheric NO-3 depositions and the soil NO-3 (–0.45), and between NO-3 and qCO2 (–0.58). The content of atmospheric Nmin depositions correlated with the ratios C/N (–0.46) and Al/Ca (–0.52) in the soil. In forests with the high input of atmospheric nitrogen (>2.0 kg NH+4/(ha yr) and >6.4 kg Nmin/(ha yr)), a tendency of decreasing Cmic, C/N, and Al/Ca, as well as increasing qCO2, was revealed, which could be indicative of deterioration in the functioning of microbial community and the chemical properties of the soil.  相似文献   

17.
The development of soil respiration was investigated from the beginning of secondary succession of a newly-exposed rubble-dump cover with and without additional management. Special interest was paid to the influence of soil temperature and soil moisture. CO2-concentrations were measured every 2 weeks for 3 yr in the field by using an air current method with conical chambers and infrared gas analysis. No significant influence of soil moisture conditions (range of soil moisture 4–80 kPa soil water suction) on respiration rates was found. Carbon dioxide evolution generally followed soil temperature patterns in both ecosystems and showed a positive correlation with temperature T at 5 cm depth (mgCO2m?2h?1 = a + b (T°C)2). Moreover both plots showed the same tendency of increasing soil respiration during the first 3 yr after reclamation, in spite of great differences in vegetation structure and coverage. This change in soil respiration rates describes the succession of soil microflora.  相似文献   

18.
Soil respiration of a desert soil was measured at the New Mexico State University Ranch in Southern New Mexico. Respiration rates were highest during late July and August after summer rains. Soil respiration data were used to estimate soil organic matter turnover which was 54 yr using summer data and 20 yr using both summer and winter data. The long turnover estimate for summer measurements resulted from temperatures above optimum in June and July. Diurnal soil respiration was also measured after a simulated 2.54 cm rain event. For both wetted and dry soils, temperature controlled the patterns of soil respiration with an optimum of near 41°C. Activation energy values decreased from 84.91 to 39.5 kJ mol?1 when the soil was wetted. A light-dark container method was tested as a possible means of estimating algal uptake of CO2, however, the method was not feasible for desert soils.  相似文献   

19.
Soil carbon dioxide (CO2) respiration is one of the important soil health parameters that provides a general assessment of soil microbial activity and soil quality. Soil respiration rates, however, have not been widely applied in soil testing protocols mainly because the traditional methods are either inconvenient, technically cumbersome or too expensive. Currently, only two methods are available for a true real-time soil respiration rate determination (<2 h): the infrared gas analyzer (IRGA) and the microrespirometer (MR or MicroRes®) methods. We analyzed the real-time soil respiration rates of 20 soil samples from fifteen states after various periods of incubation using the IRGA method and the MR method. The measured soil respiration rates ranged from 0.4 µL CO2/h/g to 9.0 µL CO2/h/g. Both methods show precision in soil respiration determinations (CV = 12.7% and 11.9%, respectively). Comparison of the results between the IRGA and MR methods indicates high degrees of agreement (r2 = 0.914). This study shows that the MR method is a simpler and more cost-effective alternative for real-time soil respiration rate determinations.  相似文献   

20.
Fly ash and biosolid wastes can be mixed and applied to soil as a means of disposal. A significant decline in soil respiration following waste application indicates restricted activities of functional microbial populations. Weathering decreases salinity and neutralizes alkalinity in fly ash, but there is little information on the effects of unweathered fly ash and biosolid mixtures on soil carbon (C) mineralization. The objective of this study was to determine the effects of a weathered fly ash–limestone scrubber residue (LSR) mixed with an aerobically digested biosolid on soil respiration in a laboratory incubation study. Biosolids significantly increased carbon dioxide (CO2) production (p < 0.05), but up to 6.75% (w/w) fly ash did not. Mean total C mineralization was 770 mg CO2‐C kg?1 soil in the control and 3,810 mg CO2‐C kg?1 soil in the 6.75% (w/w) biosolid treatment. Fly ash with neutral pH and low salinity appears unlikely to affect soil and biosolid C mineralization.  相似文献   

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