共查询到20条相似文献,搜索用时 15 毫秒
1.
Abstract Nitrous oxide (N 2O) and methane (CH 4) fluxes from a fertilized timothy ( Phleum pratense L.) sward on the northern island of Japan were measured over 2?years using a randomized block design in the field. The objectives of the present study were to obtain annual N 2O and CH 4 emission rates and to elucidate the effect of the applied material (control [no nitrogen], anaerobically digested cattle slurry [ADCS] or chemical fertilizer [CF]) and the application season (autumn or spring) on the annual N 2O emission, fertilizer-induced N 2O emission factor (EF) and the annual CH 4 absorption. Ammonium sulfate was applied to the CF plots at the same application rate of NH 4-N to the ADCS plots. A three-way ANOVA was used to examine the significance of the factors (the applied material, the application season and the year). The ANOVA for the annual N 2O emission rates showed a significant effect with regard to the applied material ( P?= ?0.042). The annual N 2O emission rate from the control plots (0.398?kg N 2O-N ha ?1?year ?1) was significantly lower than that from the ADCS plots (0.708?kg N 2O-N ha ?1?year ?1) and the CF plots (0.636?kg N 2O-N ha ?1?year ?1). There was no significant difference in the annual N 2O emission rate between the ADCS and CF plots. The ANOVA for the EFs showed insignificance of all factors ( P?> ?0.05). The total mean?±?standard error of the EFs (fertilizer-induced N 2O-N emission/total applied N) was 0.0024?±?0.0007 (kg N 2O-N [kg N] ?1), which is similar to the reported EF (0.0032?±?0.0013) for well-drained uplands in Japan. The CH 4 absorption rates differed significantly between years ( P?= ?0.014). The CH 4 absorption rate in the first year (3.28?kg CH 4?ha ?1?year ?1) was higher than that in the second year (2.31?kg CH 4?ha ?1?year ?1), probably as a result of lower precipitation in the first year. In conclusion, under the same application rate of NH 4-N, differences in the applied materials (ADCS or CF) and the application season (autumn or spring) led to no significant differences in N 2O emission, fertilizer-induced N 2O EF and CH 4 absorption. 相似文献
2.
Abstract To determine the means and variations in CH 4 uptake and N 2O emission in the dominant soil and vegetation types to enable estimation of annual gases fluxes in the forest land of Japan, we measured monthly fluxes of both gases using a closed-chamber technique at 26 sites throughout Japan over 2 years. No clear seasonal changes in CH 4 uptake rates were observed at most sites. N 2O emission was mostly low throughout the year, but was higher in summer at most sites. The annual mean rates of CH 4 uptake and N 2O emission (all sites combined) were 66 (2.9–175) µg CH 4-C m ?2 h ?1 and 1.88 (0.17–12.5) µg N 2O-N m ?2 h ?1, respectively. Annual changes in these fluxes over the 2 years were small. Significant differences in CH 4 uptake were found among soil types ( P < 0.05). The mean CH 4 uptake rates (µg CH 4-C m ?2 h ?1) were as follows: Black soil (95 ± 39, mean ± standard deviation [SD]) > Brown forest soil (60 ± 27) ≥ other soils (20 ± 24). N 2O emission rates differed significantly among vegetation types ( P < 0.05). The mean N 2O emission rates (µg N 2O-N m ?2 h ?1) were as follows: Japanese cedar (4.0 ± 2.3) ≥ Japanese cypress (2.6 ± 3.4) > hardwoods (0.8 ± 2.2) = other conifers (0.7 ± 1.4). The CH 4 uptake rates in Japanese temperate forests were relatively higher than those in Europe and the USA (11–43 µg CH 4-C m ?2 h ?1), and the N 2O emission rates in Japan were lower than those reported for temperate forests (0.23–252 µg N 2O-N m ?2 h ?1). Using land area data of vegetation cover and soil distribution, the amount of annual CH 4 uptake and N 2O emission in the Japanese forest land was estimated to be 124 Gg CH 4-C year ?1 with 39% uncertainty and 3.3 Gg N 2O-N year ?1 with 76% uncertainty, respectively. 相似文献
3.
AbstractTo evaluate the hypothesis that plant-mediated oxygen supplies decrease methane (CH 4) production and total global warming potential (GWP) in a tropical peatland, the authors compared the fluxes and dissolved concentrations of greenhouse gases [GHGs; CH 4, carbon dioxide (CO 2) and nitrous oxide (N 2O)] and dissolved oxygen (DO) at multiple peatland ecosystems in Central Kalimantan, Indonesia. Study ecosystems included tropical peat swamp forest and degraded peatland areas that were burned and/or drained during the rainy season. CH 4 fluxes were significantly influenced by land use and drainage, which were highest in the flooded burnt sites (5.75 ± 6.66 mg C m ?2 h ?1) followed by the flooded forest sites (1.37 ± 2.03 mg C m ?2 h ?1), the drained burnt site (0.220 ± 0.143 mg C m ?2 h ?1), and the drained forest site (0.0084 ± 0.0321 mg C m ?2 h ?1). Dissolved CH 4 concentrations were also significantly affected by land use and drainage, which were highest in the flooded burnt sites (124 ± 84 μmol L ?1) followed by the drained burnt site (45.2 ± 29.8 μmol L ?1), the flooded forest sites (1.15 ± 1.38 μmol L ?1) and the drained forest site (0.860 ± 0.819 μmol L ?1). DO concentrations were influenced by land use only, which were significantly higher in the forest sites (6.9 ± 5.6 μmol L ?1) compared to the burnt sites (4.0 ± 2.9 μmol L ?1). These results suggest that CH 4 produced in the peat might be oxidized by plant-mediated oxygen supply in the forest sites. CO 2 fluxes were significantly higher in the drained forest site (340 ± 250 mg C m ?2 h ?1 with a water table level of ?20 to ?60 cm) than in the drained burnt site (108 ± 115 mg C m ?2 h ?1 with a water table level of ?15 to +10 cm). Dissolved CO 2 concentrations were 0.6–3.5 mmol L ?1, also highest in the drained forest site. These results suggested enhanced CO 2 emission by aerobic peat decomposition and plant respiration in the drained forest site. N 2O fluxes ranged from ?2.4 to ?8.7 μg N m ?2 h ?1 in the flooded sites and from 3.4 to 8.1 μg N m ?2 h ?1 in the drained sites. The negative N 2O fluxes might be caused by N 2O consumption by denitrification under flooded conditions. Dissolved N 2O concentrations were 0.005–0.22 μmol L ?1 but occurred at < 0.01 μmol L ?1 in most cases. GWP was mainly determined by CO 2 flux, with the highest levels in the drained forest site. Despite having almost the same CO 2 flux, GWP in the flooded burnt sites was 20% higher than that in the flooded forest sites due to the large CH 4 emission (not significant). N 2O fluxes made little contribution to GWP. 相似文献
4.
Wetlands are major natural sources of greenhouse gases (GHGs). In central and southern Africa, one of the most extensive wetlands are dambos (seasonal wetlands) which occupy 20–25% of land area. However, there are very little data on GHG methane (CH 4), carbon dioxide (CO 2) and nitrous oxide (N 2O) emissions from dambos, and this study presents the first estimates from dambos in Zimbabwe. The objective was to evaluate the effects of catena positions; upland, dambo mid-slope and dambo bottom, on GHG emissions along an undisturbed dambo transect. Methane emissions were ?0.3, 29.5 and ?1.3 mg m ?2 hr ?1, N 2O emission were 40.1, 3.9 and 5.5 µg m 2 hr ?1, while CO 2 emissions were 2648.9, 896.2 and 590.1 mg m ?2 hr ?1 for upland, mid-slope and bottom catena, respectively. Our results showed that uplands were important sources of N 2O and CO 2, and a sink for CH 4, while the dambo mid-slope position was a major source of CH 4, but a weak source of CO 2 and N 2O. Dambo bottom catena was weak source GHGs. Overall, dambos were major sources of CH 4 and weak sources of N 2O and CO 2.We concluded that, depending on catenal position, dambos can be major or minor sources of GHGs. 相似文献
5.
Abstract We studied the effect of crop residues with various C:N ratios on N 2O emissions from soil. We set up five experimental plots with four types of crop residues, onion leaf (OL), soybean stem and leaf (SSL), rice straw (RS) and wheat straw (WS), and no residue (NR) on Gray Lowland soil in Mikasa, Hokkaido, Japan. The C:N ratios of these crop residues were 11.6, 14.5, 62.3, and 110, respectively. Based on the results of a questionnaire survey of farmer practices, we determined appropriate application rates: 108, 168, 110, 141 and 0 g C m ?2 and 9.3, 11.6, 1.76, 1.28 and 0 g N m ?2, respectively. We measured N 2O, CO 2 and NO fluxes using a closed chamber method. At the same time, we measured soil temperature at a depth of 5 cm, water-filled pore space (WFPS), and the concentrations of soil NH + 4-N, NO ? 3-N and water-soluble organic carbon (WSOC). Significant peaks of N 2O and CO 2 emissions came from OL and SSL just after application, but there were no emissions from RS, WS or NR. There was a significant relationship between N 2O and CO 2 emissions in each treatment except WS, and correlations between CO 2 flux and temperature in RS, soil NH + 4-N and N 2O flux in SSL and NR, soil NH + 4-N and CO 2 flux in SSL, and WSOC and CO 2 flux in WS. The ratio of N 2O-N/NO-N increased to approximately 100 in OL and SSL as N 2O emissions increased. Cumulative N 2O and CO 2 emissions increased as the C:N ratio decreased, but not significantly. The ratio of N 2O emission to applied N ranged from ?0.43% to 0.86%, and was significantly correlated with C:N ratio ( y = ?0.59 ln [ x] + 2.30, r 2 = 0.99, P < 0.01). The ratio of CO 2 emissions to applied C ranged from ?5.8% to 45% and was also correlated with C:N ratio, but not significantly ( r 2 = 0.78, P = 0.11). 相似文献
6.
Wood ash has been used to alleviate nutrient deficiencies and acidification in boreal forest soils. However, ash and nitrogen (N) fertilization may affect microbial processes producing or consuming greenhouse gases: methane (CH 4), nitrous oxide (N 2O) and carbon dioxide (CO 2). Ash and N fertilization can stimulate nitrification and denitrification and, therefore, increase N 2O emission and suppress CH 4 uptake rate. Ash may also stimulate microbial respiration thereby enhancing CO 2 emission. The fluxes of CH 4, N 2O and CO 2 were measured in a boreal spruce forest soil treated with wood ash and/or N (ammonium nitrate) during three growing seasons. In addition to in situ measurements, CH 4 oxidation potential, CO 2 production, net nitrification and N 2O production were studied in laboratory incubations. The mean in situ N 2O emissions and in situ CO 2 production from the untreated, N, ash and ash + N treatments were not significantly different, ranging from 11 to 17 μg N 2O m ?2 h ?1 and from 533 to 611 mg CO 2 m ?2 h ?1. However, ash increased the CH 4 oxidation in a forest soil profile which could be seen both in the laboratory experiments and in the CH 4 uptake rates in situ. The mean in situ CH 4 uptake rate in the untreated, N, ash and ash + N plots were 153 ± 5, 123 ± 8, 188 ± 10 and 178 ± 18 μg m ?2 h ?1, respectively. 相似文献
7.
The effect of controlled drainage on methane (CH 4) and nitrous oxide (N 2O) emissions from a paddy field under controlled irrigation (CI) was investigated by controlling the sub-surface drainage percolation rate with a lysimeter. CI technology is one of the major water-saving irrigation methods for rice growing in China. Water percolation rates were adjusted to three values (2, 5, and 8 mm d ?1) in the study. On the one hand, the CH 4 emission flux and total CH 4 emission from paddy fields under CI decreased with the increase of percolation rates. Total CH 4 emissions during the growth stage of rice were 1.83, 1.16, and 1.05 g m ?2 in the 2, 5, and 8 mm d ?1 plots, respectively. On the other hand, the N 2O emission flux and total N 2O emissions from paddy fields under CI increased with the increase of percolation rates. Total N 2O emissions during the growth stage of rice were 0.304, 0.367, and 0.480 g m ?2 in the 2, 5, and 8 mm d ?1 plots, respectively. The seasonal carbon dioxide (CO 2) equivalent of CH 4 and N 2O emissions from paddy fields under CI was lowest in the 2 mm d ?1 plot (1364 kg CO 2 ha ?1). This value was 1.4% and 19.4% lower compared with that in the 5 and 8 mm d ?1 plots, respectively. The joint application of CI and controlled drainage may be an effective mitigation strategy for reducing the carbon dioxide equivalents of CH 4 and N 2O emissions from paddy fields. 相似文献
8.
Applications of dairy farm effluents to land may lead to ammonia (NH 3) volatilization and nitrous oxide (N 2O) emissions. Nitrogen (N) transformation process inhibitors, such as urease inhibitors (UIs) and nitrification inhibitors (NIs), have been used to reduce NH 3 and N 2O losses derived from agricultural N sources. The objective of this study was to examine the effects of amending dairy effluents with UI ( N-( n-butyl) thiophosphoric triamide (NBTPT)) and NI (dicyandiamide (DCD)) on NH 3 and N 2O emissions. Treatments included either fresh or stored manure and either fresh or stored farm dairy effluent (FDE), with and without NBTPT (0.25 g kg ?1 N) or DCD (10 kg ha ?1), applied to a pasture on a free-draining volcanic parent material soil. The nutrient loading rate of FDE and manure, which had different dry matter contents (about 2 and 11 %, respectively) was 100 kg N ha ?1. Application of manure and FDE led to NH 3 volatilization (15, 1, 17 and 0.4 % of applied N in fresh manure, fresh FDE, stored manure and stored FDE, respectively). With UI (NBTPT), NH 3 volatilization from fresh manure was significantly ( P?<?0.05) decreased to 8 % from 15 % of applied N, but the UI did not significantly reduce NH 3 volatilization from fresh FDE. The N 2O emission factors (amount of N 2O–N emitted as a percentage of applied N) for fresh manure, fresh FDE and stored FDE were 0.13?±?0.02, 0.14?±?0.03 and 0.03?±?0.01 %, respectively. The NI (DCD) was effective in decreasing N 2O emissions from stored FDE, fresh FDE and fresh manure by 90, 51 and 46 % ( P?<?0.05), respectively. All types of effluent increased pasture production over the first 21 days after application ( P?<?0.05). The addition of DCD resulted in an increase in pasture production at first harvest on day 21 ( P?<?0.05). This study illustrates that UIs and NIs can be effective in mitigating NH 3 and N 2O emissions from land-applied dairy effluents. 相似文献
9.
Biochar application can reduce global warming via carbon (C) sequestration in soils. However, there are few studies investigating its effects on greenhouse gases in rice ( Oryza sativa L.) paddy fields throughout the year. In this study, a year-round field experiment was performed in rice paddy fields to investigate the effects of biochar application on methane (CH 4) and nitrous oxide (N 2O) emissions and C budget. The study was conducted on three rice paddy fields in Ehime prefecture, Japan, for 2 years. Control (Co) and biochar (B) treatments, in which 2-cm size bamboo biochar (2 Mg ha ?1) was applied, were set up in the first year. CH 4 and N 2O emissions and heterotrophic respiration (Rh) were measured using a closed-chamber method. In the fallow season, the mean N 2O emission during the experimental period was significantly lower in B (67 g N ha ?1) than Co (147 g N ha ?1). However, the mean CH 4 emission was slightly higher in B (2.3 kg C ha ?1) than Co (1.2 kg C ha ?1) in fallow season. The water-filled pore space increased more during the fallow season in B than Co. In B, soil was reduced more than in Co due to increasing soil moisture, which decreased N 2O and increased CH 4 emissions in the fallow season. In the rice-growing season, the mean N 2O emission tended to be lower in B (?104 g N ha ?1) than Co (?13 g N ha ?1), while mean CH 4 emission was similar between B (183 kg C ha ?1) and Co (173 kg C ha ?1). Due to the C release from applied biochar and soil organic C in the first year, Rh in B was higher than that in Co. The net greenhouse gas emission for 2 years considering biochar C, plant residue C, CH 4 and N 2O emissions, and Rh was lower in B (5.53 Mg CO 2eq ha ?1) than Co (11.1 Mg CO 2eq ha ?1). Biochar application worked for C accumulation, increasing plant residue C input, and mitigating N 2O emission by improving soil environmental conditions. This suggests that bamboo biochar application in paddy fields could aid in mitigating global warming. 相似文献
10.
Abstract To assess their impacts on net global warming, total greenhouse gas emissions (mainly CO 2, N 2O and CH 4) from agricultural production in arable land cropping systems in the Tokachi region of Hokkaido, Japan, were estimated using life cycle inventory (LCI) analysis. The LCI data included CO 2 emissions from on-farm and off-farm fossil fuel consumption, soil CO 2 emissions induced by the decomposition of soil organic matter, direct and indirect N 2O emissions from arable lands and CH 4 uptake by soils, which were then aggregated in CO 2-equivalents. Under plow-based conventional tillage (CT) cropping systems for winter wheat, sugar beet, adzuki bean, potato and cabbage, on-farm CO 2 emissions from fuel-consuming operations such as tractor-based field operations, truck transportation and mechanical grain drying ranged from 0.424 Mg CO 2 ha ?1 year ?1 for adzuki bean to 0.826 Mg CO 2 ha ?1 year ?1 for winter wheat. Off-farm CO 2 emissions resulting from the use of agricultural materials such as chemical fertilizers, biocides (pesticides and herbicides) and agricultural machines were estimated by input–output tables to range from 0.800 Mg CO 2 ha ?1 year ?1 for winter wheat to 1.724 Mg CO 2 ha ?1 year ?1 for sugar beet. Direct N 2O emissions previously measured in an Andosol field of this region showed a positive correlation with N fertilizer application rates. These emissions, expressed in CO 2-equivalents, ranged from 0.041 Mg CO 2 ha ?1 year ?1 for potato to 0.382 Mg CO 2 ha ?1 year ?1 for cabbage. Indirect N 2O emissions resulting from N leaching and surface runoff were estimated to range from 0.069 Mg CO 2 ha ?1 year ?1 for adzuki bean to 0.381 Mg CO 2 ha ?1 year ?1 for cabbage. The rates of CH 4 removal from the atmosphere by soil uptake were equivalent to only 0.020–0.042 Mg CO 2 ha ?1 year ?1. From the difference in the total soil C pools (0–20 cm depth) between 1981 and 2001, annual CO 2 emissions from the CT and reduced tillage (RT) soils were estimated to be 4.91 and 3.81 Mg CO 2 ha ?1 year ?1, respectively. In total, CO 2-equivalent greenhouse gas emissions under CT cropping systems in the Tokachi region of Hokkaido amounted to 6.97, 7.62, 6.44, 6.64 and 7.49 Mg CO 2 ha ?1 year ?1 for winter wheat, sugar beet, adzuki bean, potato and cabbage production, respectively. Overall, soil-derived CO 2 emissions accounted for a large proportion (64–76%) of the total greenhouse gas emissions. This illustrates that soil management practices that enhance C sequestration in soil may be an effective means to mitigate large greenhouse gas emissions from arable land cropping systems such as those in the Tokachi region of northern Japan. Under RT cropping systems, plowing after harvesting was omitted, and total greenhouse gas emissions from winter wheat, sugar beet and adzuki bean could be reduced by 18%, 4% and 18%, respectively, mainly as a result of a lower soil organic matter decomposition rate in the RT soil and a saving on the fuels used for plowing. 相似文献
11.
AbstractForest fires can change the greenhouse gase (GHG) flux of borea forest soils. We measured carbon dioxide (CO 2), methane (CH 4) and nitrous oxide (N 2O) fluxes with different burn histories in black spruce ( Picea mariana) stands in interior Alaska. The control forest (CF) burned in 1920; partially burned (PB) in 1999; and severely burned (SB1 and SB2) in 2004. The thickness of the organic layer was 22 ± 6 cm at CF, 28 ± 10 cm at PB, 12 ± 6 cm at SB1 and 4 ± 2 cm at SB2. The mean soil temperature during CO 2 flux measurement was 8.9 ± 3.1, 6.4 ± 2.1, 5.9 ± 3.4 and 5.0 ± 2.4°C at SB2, SB1, PB and CF, respectively, and differed significantly among the sites ( P < 0.01). The mean CO 2 flux was highest at PB (128 ± 85 mg CO 2-C m ?2 h ?1) and lowest at SB1 (47 ± 19 mg CO 2-C m ?2 h ?1) ( P < 0.01), and within each site it was positively correlated with soil temperature ( P < 0.01). The CO 2 flux at SB2 was lower than that at CF when the soil temperature was high. We attributed the low CO 2 flux at SB1 and SB2 to low root respiration and organic matter decomposition rates due to the 2004 fire. The CH 4 uptake rate was highest at SB1 [–91 ± 21 μg CH 4-C m ?2 h ?1] ( P < 0.01) and positively correlated with soil temperature ( P < 0.01) but not soil moisture. The CH 4 uptake rate increased with increasing soil temperature because methanotroph activity increased. The N 2O flux was highest [3.6 ± 4.7 μg N 2O-N m ?2 h ?1] at PB ( P < 0.01). Our findings suggest that the soil temperature and moisture are important factors of GHG dynamics in forest soils with different fire history. 相似文献
12.
Increasing greenhouse gas emissions from anthropogenic activities continue to be a mounting problem worldwide. In the semi-natural Miscanthus sinensis Andersson; grasslands of Aso, Kumamoto, Japan, which have been managed for thousands of years, we measured soil methane (CH 4) and nitrous oxide (N 2O) emissions before and after annual controlled burns. We estimated annual soil carbon (C) accumulation, and CH 4 and N 2O emissions induced by biomass burning in 2009 and 2010, to determine the impacts of this ecosystem and its management on global warming. Environmental factors affecting soil CH 4 and N 2O fluxes were unknown, with no effect of annual burning observed on short-term soil CH 4 and N 2O emissions. However, deposition of charcoal during burning may have enhanced CH 4 oxidation and N 2O consumption at the study site, given that emissions (CH 4: ?4.33 kg C ha ?1 yr ?1, N 2O: 0.17 kg N ha ?1 yr ?1) were relatively lower than those measured in other land-use types. Despite significant emission of CH 4 and N 2O during yearly burning events in early spring, the M. sinensis semi-natural grassland had a large annual soil C accumulation, which resulted in a global warming potential of ?4.86 Mg CO 2eq ha ?1 yr ?1. Consequently, our results indicate that long-term maintenance of semi-natural M. sinensis grasslands by annual burning can contribute to the mitigation of global warming. 相似文献
13.
PurposeThe purposes of this study were to analyse the spatiotemporal variations in greenhouse gas diffusive fluxes at the sediment–water interface of sewage-draining rivers and natural rivers, and investigate the factors responsible for the changes in greenhouse gas diffusive fluxes. Materials and methodsGreenhouse gas diffusive fluxes at the sediment–water interface of rivers in Tianjin city (Haihe watershed) were investigated during July and October 2014, and January and April 2015 by laboratory incubation experiments. The influence of environmental variables on greenhouse gas diffusive fluxes was evaluated by Spearman’s correlation analysis and a multiple stepwise regression analysis. Results and discussionSewage-draining rivers were more seriously polluted by human sewage discharge than natural rivers. The greenhouse gas diffusive fluxes at the sediment–water interface exhibited obvious spatiotemporal variations. The mean absolute value of the CO2 diffusive fluxes was seasonally variable with spring>winter>fall>summer, while the mean absolute values of the CH4 and N2O diffusive fluxes were both higher in summer and winter, and lower in fall and spring. The annual mean values of the CO2, CH4 and N2O diffusive fluxes at the sewage-draining river sediment–water interface were ??123.26?±?233.78 μmol m?2 h?1, 1.88?±?6.89 μmol m?2 h?1 and 1505.03?±?2388.46 nmol m?2 h?1, respectively, which were 1.22, 4.37 and 134.50 times those at the natural river sediment–water interface, respectively. The spatial variation of the N2O diffusive fluxes in the sewage-draining rivers and the natural rivers was the most significant. As a general rule, the more serious the river pollution was, the greater the diffusive fluxes of the greenhouse gases were. On average for the whole year, the river sediment was the sink of CO2 and the source of CH4 and N2O. There were positive correlations among the CO2, CH4 and N2O diffusive fluxes. The main influencing factor for CO2 and N2O diffusive fluxes was the water temperature of the overlying water; however, the key factors for CH4 diffusive fluxes were the Eh of the sediment and the NH4+-N of the overlying water. ConclusionsRiver sediment can be either a sink or a source of greenhouse gases, which varies in different levels of pollution and different seasons. Human sewage discharge has greatly affected the carbon and nitrogen cycling of urban rivers. 相似文献
14.
Agricultural soil is a major source of nitrous oxide (N 2O), and the application of nitrogen and soil drainage are important factors affecting N 2O emissions. This study tested the use of polymer-coated urea (PCU) and polymer-coated urea with the nitrification inhibitor dicyandiamide (PCUD) as potential mitigation options for N 2O emissions in an imperfectly drained, upland converted paddy field. Fluxes of N 2O and methane (CH 4), ammonia oxidation potential, and ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) abundances were monitored after the application of PCU, PCUD, and urea to upland soil. The results showed that urea application increased the ammonia oxidation potential and AOB and AOA abundances; however, the increase rate of AOB (4.6 times) was much greater than that of AOA (1.8 times). These results suggested that both AOB and AOA contributed to ammonia oxidation after fertilizer application, but the response of AOB was greater than AOA. Although PCU and PCUD had lower ammonia oxidation potential compared to urea treatment, they were not effective in reducing N 2O emissions. Large episodic N 2O emissions (up to 1.59 kg N ha ?1 day ?1) were observed following heavy rainfall 2 months after basal fertilizer application. The episodic N 2O emissions accounted for 55–80 % of total N 2O emissions over the entire monitoring period. The episodic N 2O emissions following heavy rainfall would be a major source of N 2O in poorly drained agricultural fields. Cumulative CH 4 emissions ranged from ?0.017 to ?0.07 kg CH 4 ha ?1, and fertilizer and nitrification inhibitor application did not affect CH 4 oxidation. 相似文献
15.
Since the development of effective N 2O mitigation options is a key challenge for future agricultural practice, we studied the interactive effect of tillage systems on fertilizer-derived N 2O emissions and the abundance of microbial communities involved in N 2O production and reduction. Soil samples from 0–10 cm and 10–20 cm depth of reduced tillage and ploughed plots were incubated with dairy slurry (SL) and manure compost (MC) in comparison with calcium ammonium nitrate (CAN) and an unfertilized control (ZERO) for 42 days. N 2O and CO 2 fluxes, ammonium, nitrate, dissolved organic C, and functional gene abundances (16S rRNA gene, nirK, nirS, nosZ, bacterial and archaeal amoA) were regularly monitored. Averaged across all soil samples, N 2O emissions decreased in the order CAN and SL (CAN?=?748.8?±?206.3, SL?=?489.4?±?107.2 μg kg ?1) followed by MC (284.2?±?67.3 μg kg ?1) and ZERO (29.1?±?5.9 μg kg ?1). Highest cumulative N 2O emissions were found in 10–20 cm of the reduced tilled soil in CAN and SL. N 2O fluxes were assigned to ammonium as source in CAN and SL and correlated positively to bacterial amoA abundances. Additionally, nosZ abundances correlated negatively to N 2O fluxes in the organic fertilizer treatments. Soils showed a gradient in soil organic C, 16S rRNA, nirK, and nosZ with greater amounts in the 0–10 than 10–20 cm layer. Abundances of bacterial and archaeal amoA were higher in reduced tilled soil compared to ploughed soils. The study highlights that tillage system induced biophysicochemical stratification impacts net N 2O emissions within the soil profile according to N and C species added during fertilization. 相似文献
16.
Yak and Tibetan sheep graze extensively on natural grasslands in the Qinghai-Tibetan Plateau, and large amounts of excrement are directly deposited onto alpine grasslands. However, information on greenhouse gas (GHG) emissions from this excrement is limited. This study evaluated the short-term effects of yak and Tibetan sheep dung on nitrous oxide (N 2O), methane (CH 4), and carbon dioxide (CO 2) emissions from alpine steppe soil at a water holding capacity (WHC) of 40 or 60 % and from alpine meadow soil at a WHC of 60 or 80 % under laboratory conditions. Cumulative N 2O emissions over a 15-day incubation period at low soil moisture conditions ranged from 111 to 232 μg N 2O–N kg soil ?1 in the yak dung treatments, significantly ( P?<?0.01) higher than that of sheep dung treatments (28.7 to 33.7 μg N 2O–N kg soil ?1) and untreated soils (1.04–6.94 μg N 2O–N kg soil ?1). At high soil moisture conditions, N 2O emissions were higher from sheep dung than yak dung and non-treated soils. No significant difference was found between the yak dung and non-treated alpine meadow soil at 80 % WHC. Low N 2O emission in the yak dung treatment from relatively wet soil was probably due to complete denitrification to N 2. Yak dung markedly ( P?<?0.001) increased CH 4 and CO 2 emissions, likely being the main source of these two gases. The addition of sheep dung markedly ( P?<?0.001) elevated CO 2 emissions. Dung application significantly ( P?<?0.01) increased global warming potential, particularly for alpine steppe soil. In conclusion, our findings suggest that yak and Tibetan sheep dung deposited on alpine grassland soils may increase GHG emissions. 相似文献
17.
Application of crop residues and its biochar produced through slow pyrolysis can potentially increase carbon (C) sequestration in agricultural production systems. The impact of crop residue and its biochar addition on greenhouse gas emission rates and the associated changes of soil gross N transformation rates in agricultural soils are poorly understood. We evaluated the effect of wheat straw and its biochar applied to a Black Chernozemic soil planted to barley, two growing seasons or 15 months (at the full-bloom stage of barley in the second growing season) after their field application, on CO 2 and N 2O emission rates, soil inorganic N and soil gross N transformation rates in a laboratory incubation experiment. Gross N transformation rates were studied using the 15N isotope pool dilution method. The field experiment included four treatments: control, addition of wheat straw (30 t ha ?1), addition of biochar pyrolyzed from wheat straw (20 t ha ?1), and addition of wheat straw plus its biochar (30 t ha ?1 wheat straw + 20 t ha ?1 biochar). Fifteen months after their application, wheat straw and its biochar addition increased soil total organic C concentrations ( p?=?0.039 and <0.001, respectively) but did not affect soil dissolved organic C, total N and NH 4 +-N concentrations, and soil pH. Biochar addition increased soil NO 3 ?-N concentrations ( p?=?0.004). Soil CO 2 and N 2O emission rates were increased by 40 ( p?0.001) and 17 % ( p?=?0.03), respectively, after wheat straw addition, but were not affected by biochar application. Straw and its biochar addition did not affect gross and net N mineralization rates or net nitrification rates. However, biochar addition doubled gross nitrification rates relative to the control ( p?0.001). Our results suggest that land application of biochar, as opposed to the application of the raw wheat straw, could suppress CO 2 and N 2O emissions and enhance soil C sequestration. However, the implications of the increased soil gross nitrification rate and NO 3 ?-N in the biochar addition treatment for long-term NO 3 ?-N dynamics and N 2O emissions need to be further studied. 相似文献
18.
Soil temperature plays an important role in organic matter decomposition, thus likely to affect ammonia and gaseous emission from land application of manure. An incubation experiment was conducted to quantify ammonia and greenhouse gas (GHG) (N 2O, CO 2 and CH 4) emissions from manure and urea applied at 215?kg N ha ?1 to Fargo-Ryan silty clay soil. Soil (250?g) amended with solid beef manure (SM), straw-bedded solid beef manure (BM), urea only (UO), and control (CT) were incubated at 5, 10, 15, and 25 °C for 31 days at constant 60% water holding capacity (WHC). The cumulative GHGs and NH 3 emission generally increased with temperature and highest emission observed at 25 °C. Across temperature levels, 0.11–1.3% and 0.1–0.7% of the total N was lost as N 2O and NH 3, respectively. Cumulative CO 2 emission from manure was higher than UO and CT at all temperatures ( P?<?0.05). Methane accounted for <0.1% of the total C (CO 2?+?CH 4) emission across temperatures. The Q 10 values (temperature sensitivity coefficient) derived from Arrhenius and exponential models ranged 1.5–3.7 for N 2O, 1.4–6.4 for CO 2, 1.6–5.8 for CH 4, and 1.4–5.0 for NH 3. Our results demonstrated that temperature significantly influences NH 3 and GHG emissions irrespective of soil amendment but the magnitude of emission varied with soil nutrient availability and substrate quality. Overall, the highest temperature resulted in the highest emission of NH 3 and GHGs. 相似文献
19.
AbstractThe effects of nitrogen (N) and sulfur (S) deposition on methane (CH 4) and nitrous oxide (N 2O) emissions under low (10 cm below soil surface) and high (at soil surface) water tables were investigated in the laboratory. Undisturbed soil columns from the alpine peatland of the Tibetan Plateau were analyzed. CH 4 emission was higher and N 2O emission was lower at the high water table than those at the low water table regardless of nutrient application. Addition of N (NH 4NO 3 (ammonium nitrate), 5 g N m ?2) decreased CH 4 emission up to 57% and 50% at low and high water tables, respectively, but correspondingly increased N 2O emission by 2.5 and 10.4 times. Addition of S (Na 2SO 4 (sodium sulfate), 2.5 g S m ?2) decreased CH 4 and N 2O emission by 64% and 79% at the low water table, respectively, but had a slightly positive effect at the high water table. These results indicated that the responses of CH 4 and N 2O emissions to the S deposition depend on the water table condition in the high-altitude peatland. 相似文献
20.
Drainage of peatlands affects the fluxes of greenhouse gases (GHGs). Organic soils used for agriculture contribute a large proportion of anthropogenic GHG emissions, and on-farm mitigation options are important. This field study investigated whether choice of a cropping system can be used to mitigate emissions of N 2O and influence CH 4 fluxes from cultivated organic and carbon-rich soils during the growing season. Ten different sites in southern Sweden representing peat soils, peaty marl and gyttja clay, with a range of different soil properties, were used for on-site measurements of N 2O and CH 4 fluxes. The fluxes during the growing season from soils under two different crops grown in the same field and same environmental conditions were monitored. Crop intensities varied from grasslands to intensive potato cultivation. The results showed no difference in median seasonal N 2O emissions between the two crops compared. Median seasonal emissions ranged from 0 to 919?µg?N 2O?m ?2?h ?1, with peaks on individual sampling occasions of up to 3317?µg?N 2O?m ?2?h ?1. Nitrous oxide emissions differed widely between sites, indicating that soil properties are a regulating factor. However, pH was the only soil factor that correlated with N 2O emissions (negative exponential correlation). The type of crop grown on the soil did not influence CH 4 fluxes. Median seasonal CH 4 flux from the different sites ranged from uptake of 36?µg CH 4?m ?2?h ?1 to release of 4.5?µg?CH 4?m ?2?h ?1. From our results, it was concluded that farmers cannot mitigate N 2O emissions during the growing season or influence CH 4 fluxes by changing the cropping system in the field. 相似文献
|