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1.
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 CO2 and N2O 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 NH4 +-N concentrations, and soil pH. Biochar addition increased soil NO3 ?-N concentrations (p?=?0.004). Soil CO2 and N2O emission rates were increased by 40 (p?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?2 and N2O emissions and enhance soil C sequestration. However, the implications of the increased soil gross nitrification rate and NO3 ?-N in the biochar addition treatment for long-term NO3 ?-N dynamics and N2O emissions need to be further studied.  相似文献   

2.

Purpose

Genetic modification of Bt rice may affect straw decomposition and soil carbon pool under flood conditions. This study aims to assess the effects of cry gene transformation in rice on the residue decomposition and fate of C from residues under flooded conditions.

Materials and methods

A decomposition experiment was set up using 13C-enriched rice straws from transgenic and nontransgenic Bt rice to evaluate the soil C dynamics and CH4 or CO2 emission rates in the root and non-root zones. The concentrations and stable carbon isotope compositions of the soil organic carbon (SOC), dissolved organic carbon (DOC), microbial biomass carbon (MBC), CH4, and CO2 of the root and non-root zones were determined from 7 to 110 days after rice straw incorporation.

Results and discussion

Rice straw incorporation into soil significantly increased the SOC, DOC, and MBC concentrations and the CH4 and CO2 emission rates. The percentage of 13C-SOC remaining in the root zone was significantly lower than that in the non-root zone with rice straw decomposition. The DOC and MBC concentrations significantly increased in both the root and non-root zones between 0 and 80 days after rice straw incorporation. However, no significant differences were found after Bts (Bt rice straw added into soil) and Cks (nontransgenic Bt rice straw added into soil) incorporation in the root and non-root zones. This result may be attributed to the priming effects of sufficient oxygen and nutrients on straw degradation in the root zone.

Conclusions

Bt gene insertion did not affect the SOC, DOC, and MBC concentrations and the CH4 and CO2 emission rates in both the root and non-root zones. However, rice straw incorporation and root exudation significantly increased the SOC, DOC, and MBC concentrations and the CH4 and CO2 emission rates.  相似文献   

3.
不同秸秆还田年限对稻麦轮作系统温室气体排放的影响   总被引：4，自引：0，他引：4  
为揭示稻麦轮作系统不同秸秆还田年限下温室气体排放特征及减排调控机制,本研究采用大田小区试验,考察了稻麦轮作不同秸秆还田年限[空白对照(CK)、常规处理秸秆不还田(NT)、1年秸秆还田(SR1)和5年秸秆还田(SR5)]对CH4、CO2和N2O 3种温室气体排放规律的影响,同时测定了土壤固碳量,估算了秸秆焚烧产生的温室气体排放量,综合计算了4种处理对全球变暖的贡献。试验结果表明,SR1和SR5均显著提升CH4和CO2的排放通量,分别高出NT、CK处理73.52%、309.49%和13.29%、13.06%;同时显著降低N2O排放通量,较NT降低29.68%和42.55%;但SR1和SR5之间温室气体排放通量差异不显著;与NT相比,SR1和SR5可以显著提高土壤固碳量517.9%和709.03%,SR5土壤固碳量高出SR1达30.93%;NT秸秆焚烧产生的全球气温变暖贡献为9 698.49 kg(CO2-eqv)·hm?2,比CK高126.98%。综合分析温室气体排放、土壤固碳以及秸秆焚烧3个因素,SR1全球升温贡献最低,显著低于NT 4.72%。短期全量秸秆还田有助于降低总体温室气体排放,长期进行秸秆还田后降低幅度会逐步减小。  相似文献   

4.
Abstract

We studied the effect of crop residues with various C:N ratios on N2O 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 N2O, CO2 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 N2O and CO2 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 N2O and CO2 emissions in each treatment except WS, and correlations between CO2 flux and temperature in RS, soil NH+ 4-N and N2O flux in SSL and NR, soil NH+ 4-N and CO2 flux in SSL, and WSOC and CO2 flux in WS. The ratio of N2O-N/NO-N increased to approximately 100 in OL and SSL as N2O emissions increased. Cumulative N2O and CO2 emissions increased as the C:N ratio decreased, but not significantly. The ratio of N2O 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 CO2 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   

5.
Abstract

To evaluate the carbon budget in soils under different cropping systems, the carbon dioxide (CO2) flux from soils was measured in a total of 11 upland crop fields within a small watershed in central Hokkaido over the no snow cover months for 3 years. The CO2 flux was measured using a closed chamber method at bare plots established in each field to estimate soil organic matter decomposition. Temporal variation in instantaneous soil CO2 fluxes within the sites was mainly controlled by soil temperature and moisture. Annual mean CO2 fluxes and cumulative CO2 emissions had no significant relationship with soil temperature and moisture (P > 0.2). However, there was a significant quadratic relationship between annual mean CO2 flux or cumulative CO2 emission and soil clay plus silt content (%) (R2 = 0.72～0.74, P < 0.0003). According to this relationship, the optimum condition for soil CO2 emission is at a clay plus silt content of 63%. The cumulative CO2 emission during the no snow cover season within each year varied from 1,159 to 7,349 kg C ha?1 at the different sites. The amount of crop residue carbon retained in the soils following a cropping season was not enough to offset the CO2 emission from soil organic matter decomposition at all sites. As a consequence, the calculation of the soil carbon budget (i.e. the difference between the carbon added as crop residues and compost and the carbon lost as CO2 from organic matter decomposition) ranged from –7,349 to –785 kg C ha?1, except for a wheat site where a positive value of 4,901 kg C ha?1 was observed because of a large input of organic carbon with compost. The negative values of the soil carbon budget indicate that these cropping systems were net sources of atmospheric CO2.  相似文献   

6.
Purple soils (Eutric Regosols) are widely distributed in humid subtropical Southwest China. They are characterized by high nitrification activities, with risks of severe NO3? leaching. Incorporation of crop residues is considered an effective method to reduce NO3? loss. In the present study, we compared the effects of alfalfa, rice straw, and sugarcane bagasse on gross N transformation turnover in a purple soil (purple soil, pH 7.62) compared with those in an acid soil (acid soil, pH 5.26), at 12 h, 3 months, and 6 months after residue incorporation. The gross N transformation rates were determined by 15N tracing. All tested crop residues stimulated the gross N mineralization rates, but reduced the net mineralization rates in both soils at 12 h after residue incorporation; however, the extent of the effect varied with the crop residue qualities, with rice straw having the strongest effects. Crop residues reduced net nitrification rates by depressing gross autotrophic nitrification rates and stimulating NO3? immobilization rates in the purple soil, particularly after rice straw incorporation (net nitrification rate decreased from 16.72 mg N kg?1 d?1 in the control to ??29.42 mg N kg?1 d?1 at 12 h of residue incorporation); however, crop residues did not affect the gross autotrophic nitrification rates in the acid soil. Crop residue effects subsided almost completely within 6 months, with sugarcane bagasse showing the longest lasting effects. The results indicated that crop residues affected the N transformation rates in a temporal manner, dependent on soil properties and residue qualities.  相似文献   

7.
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   

8.
Wheat (Triticum aestivum L.) residues and nitrogen (N) management are the major problems in the southern part of Iran where irrigated wheat–cotton (Gossypium hirsutum L.)–wheat rotation is a common practice. A 2-year (2009–2011) field experiment was conducted as a split plot design with four replications at a cotton field (Darab), Fars Province, Iran, to determine the influence of different rates of wheat residue (0%, 25%, 50%, and 75%) incorporation and N rates (150, 200, 300, and 400 kg ha?1) on weed suppression, yield, and yield components of cotton. Results showed that a higher residue incorporation and a lower N rate improved weed suppression in both years. For treatments receiving 150 kg N ha?1 and 75% of wheat residues (2250 kg ha?1), weed biomass and density were significantly lower compared to treatments receiving 400 kg N ha?1. The highest cotton lint yield (about 2400–2700 kg ha?1) was obtained by 300 kg N ha?1 in the absence of residue application, in both years. Incorporation of 25% of wheat residue (750 kg ha?1) and application of 300 kg N ha?1 are recommended to guarantee an optimum level of cotton lint yield and weed suppression in a wheat–cotton–wheat rotation in this region.  相似文献   

9.
This study evaluated the effects of rice straw and water regimes on CH4 and N2O emissions from paddy fields for two rice growing seasons (summer 2014 and spring 2015). Water regimes included alternating wet–dry irrigation (AWD) maintained at three levels (–5 cm, – 10 cm and –15 cm) in comparison to continuous flooding irrigation (CF). Rice straw (5 t ha–1) was incorporated into the top soil (0 – 15 cm), distributed and burned in situ. Results showed that using burned in situ rice straw was found to reduce seasonal cumulative CH4 emission (24–34% in summer; 18–28% in spring), N2O emission (21–32% in summer; 22–29% in spring) and lower rice yield (8–9%) than rice straw incorporation into top soil. AWD methods reduced the amount of CH4 production (22.6–41.5%) and increased N2O emission (25–26%) without any decrease in rice yield. Rice straw incorporation into the top soil with AWD had higher water productivity (23–37%) than rice straw when burned in situ with CF. The results conclude that AWD and rice straw management can be employed as mitigation strategy for CH4 and N2O emissions from paddy fields in Central Vietnam.  相似文献   

10.
A 56-day aerobic incubation experiment was performed with 15-nitrogen (N) tracer techniques after application of wheat straw to investigate nitrate-N (NO3-N) immobilization in a typical intensively managed calcareous Fluvaquent soil. The dynamics of concentration and isotopic abundance of soil N pools and nitrous oxide (N2O) emission were determined. As the amount of straw increased, the concentration and isotopic abundance of total soil organic N and newly formed labeled particulate organic matter (POM-N) increased while NO3-N decreased. When 15NO3-N was applied combined with a large amount of straw at 5000 mg carbon (C) kg?1 only 1.1 ± 0.4 mg kg?1 NO3-N remained on day 56. The soil microbial biomass N (SMBN) concentration and newly formed labeled SMBN increased significantly (P < 0.05) with increasing amount of straw. Total N2O-N emissions were at levels of only micrograms kg?1 soil. The results indicate that application of straw can promote the immobilization of excessive nitrate with little emission of N2O.  相似文献   

11.
应用静态明箱-气相色谱法对4 个施氮肥水平N0 [0 kg(N)·hm-2]、N200 [200 kg(N)·hm-2]、N400 [400kg(N)·hm-2]、N600 [600 kg(N)·hm-2]的夏玉米-冬小麦季轮作体系2008~2010 年的土壤温室气体(CH4、CO2 和N2O)排放通量进行研究, 同时观测5 cm 土层土壤温度并记录降水量。结果表明: 太行山前平原冬小麦-夏玉米轮作农田生态系统为CH4 吸收汇, CO2 和N2O 排放源。随着氮肥施入量的增加土壤对CH4 的吸收速率降低, 而CO2 和N2O 的排放速率增加。冬小麦季施氮处理土壤对CH4 的吸收速率显著低于无氮肥的N0 处理, 而N600处理土壤CO2 和N2O 排放速率显著高于N0 处理(P<0.05)。施肥和灌溉会直接导致土壤CO2 和N2O 的排放通量增加, 同时土壤对CH4 的吸收峰值减小。土壤温度升高和降水量增加以及干湿交替加剧均会造成N2O 和CO2排放速率增加。同时在持续干燥和低温条件的冬季不施氮处理观测到土壤对N2O 的吸收现象。N0、N200、N400 和N600 处理土壤CH4 年排放总量(kg·hm-2·a-1)分别为-1.42、-0.75、-0.82、-0.92(2008~2009 年)和-2.60、-1.47、-1.35、-1.76(2009~2010 年), N0、N200、N400 和N600 处理土壤CO2 年排放总量(kg·hm-2·a-1)分别为15 597.6、19 345.6、21 455.9、29 012.5(2008~2009 年)和10 317.7、11 474.0、13 983.5、20 639.3(2009~2010年), N0、N200、N400 和N600 处理土壤N2O 年排放总量(kg·hm-2·a-1)分别为1.05、2.16、5.27、6.98(2008~2009年)和1.49、2.31、4.42、5.81(2009~2010 年)。  相似文献   

12.
基于2009-2011年田间试验, 研究了黄土旱塬区不同秸秆覆盖措施下冬小麦农田土壤呼吸和小麦产量变化, 计算了生产每千克籽粒产量下土壤CO2的释放量, 并以此比较了处理间的经济 环境效益值。试验包括4个处理: 无覆盖对照(CK)、全年9 000 kg·hm-2秸秆覆盖(M9000)、全年4 500 kg·hm-2秸秆覆盖(M4500)和夏闲期秸秆覆盖(SF)。结果表明: 冬小麦生育期内土壤CO2累积释放量在处理间无显著差异, 但第1年生育期为14.92~17.43 t(CO2)·hm-2, 显著高于第2年[12.95~13.69 t(CO2)·hm -2](P<0.05), 处理和年份的交互作用不显著。与CK(产量5.03 t·hm-2)相比, 秸秆覆盖降低了作物产量, 其中M9000 (4.71 t·hm-2)与CK差异显著。经济 环境效益值计算结果显示, 冬小麦生育期内生产每千克籽粒释放2.96~3.16 kg CO2, 处理间无显著差异。从各处理平均值看, 小麦产量以及经济 环境效益值均存在显著的年际差异, 降水偏少的第1年度作物产量(4.60~4.98 t·hm-2)显著低于降水相对丰富的第2年度(4.50~5.47 t·hm-2), 但经济 环境效益值(3.03~3.69 kg·kg 1、2.45~2.88 kg·kg-1)结果相反。处理和年份对作物产量和经济 环境效益值具有显著的交互影响, 在缺水年份秸秆覆盖能够提高作物产量, M9000处理具有最优的经济 环境效益; 而在丰水年份, 秸秆覆盖导致产量显著下降, CK具有更好的经济 环境效益。  相似文献   

13.
Abstract

To assess their impacts on net global warming, total greenhouse gas emissions (mainly CO2, N2O and CH4) 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 CO2 emissions from on-farm and off-farm fossil fuel consumption, soil CO2 emissions induced by the decomposition of soil organic matter, direct and indirect N2O emissions from arable lands and CH4 uptake by soils, which were then aggregated in CO2-equivalents. Under plow-based conventional tillage (CT) cropping systems for winter wheat, sugar beet, adzuki bean, potato and cabbage, on-farm CO2 emissions from fuel-consuming operations such as tractor-based field operations, truck transportation and mechanical grain drying ranged from 0.424 Mg CO2 ha?1 year?1 for adzuki bean to 0.826 Mg CO2 ha?1 year?1 for winter wheat. Off-farm CO2 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 CO2 ha?1 year?1 for winter wheat to 1.724 Mg CO2 ha?1 year?1 for sugar beet. Direct N2O emissions previously measured in an Andosol field of this region showed a positive correlation with N fertilizer application rates. These emissions, expressed in CO2-equivalents, ranged from 0.041 Mg CO2 ha?1 year?1 for potato to 0.382 Mg CO2 ha?1 year?1 for cabbage. Indirect N2O emissions resulting from N leaching and surface runoff were estimated to range from 0.069 Mg CO2 ha?1 year?1 for adzuki bean to 0.381 Mg CO2 ha?1 year?1 for cabbage. The rates of CH4 removal from the atmosphere by soil uptake were equivalent to only 0.020–0.042 Mg CO2 ha?1 year?1. From the difference in the total soil C pools (0–20 cm depth) between 1981 and 2001, annual CO2 emissions from the CT and reduced tillage (RT) soils were estimated to be 4.91 and 3.81 Mg CO2 ha?1 year?1, respectively. In total, CO2-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 CO2 ha?1 year?1 for winter wheat, sugar beet, adzuki bean, potato and cabbage production, respectively. Overall, soil-derived CO2 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   

14.
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 (CH4) and nitrous oxide (N2O) 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. CH4 and N2O emissions and heterotrophic respiration (Rh) were measured using a closed-chamber method. In the fallow season, the mean N2O 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 CH4 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 N2O and increased CH4 emissions in the fallow season. In the rice-growing season, the mean N2O emission tended to be lower in B (?104 g N ha?1) than Co (?13 g N ha?1), while mean CH4 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, CH4 and N2O emissions, and Rh was lower in B (5.53 Mg CO2eq ha?1) than Co (11.1 Mg CO2eq ha?1). Biochar application worked for C accumulation, increasing plant residue C input, and mitigating N2O 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   

15.
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 (CH4) and nitrous oxide (N2O) emissions before and after annual controlled burns. We estimated annual soil carbon (C) accumulation, and CH4 and N2O 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 CH4 and N2O fluxes were unknown, with no effect of annual burning observed on short-term soil CH4 and N2O emissions. However, deposition of charcoal during burning may have enhanced CH4 oxidation and N2O consumption at the study site, given that emissions (CH4: ?4.33 kg C ha?1 yr?1, N2O: 0.17 kg N ha?1 yr?1) were relatively lower than those measured in other land-use types. Despite significant emission of CH4 and N2O 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 CO2eq 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   

16.
Abstract

As a means of economic disposal and to reduce need for chemical fertilizer, waste generated from swine production is often applied to agricultural land. However, there remain many environmental concerns about this practice. Two such concerns, contribution to the greenhouse effect and stratospheric ozone depletion by gases emitted from waste‐amended soils, have not been thoroughly investigated. An intact core study at Auburn University (32 36′N, 85 36′W) was conducted to determine the source‐sink relationship of three greenhouse gases in three Alabama soils (Black Belt, Coastal Plain, and Appalachian Plateau regions) amended with swine waste effluent. Soil cores were arranged in a completely random design, and treatments used for each soil type consisted of a control, a swine effluent amendment (112 kg N ha?1), and an ammonium nitrate (NH4NO3) fertilizer amendment (112 kg N ha?1). During a 2‐year period, a closed‐chamber technique was used to determine rates of emission of nitrous oxide (N2O)–nitrogen (N), carbon dioxide (CO2)–carbon (C), and methane (CH4)–C from the soil surface. Gas probes inserted into the soil cores were used to determine concentrations of N2O‐N and CO2‐C from depths of 5, 15, and 25 cm. Soil water was collected from each depth using microlysimeters at the time of gas collection to determine soil‐solution N status. Application of swine effluent had an immediate effect on emissions of N2O‐N, CO2‐C, and CH4‐C from all soil textures. However, greatest cumulative emissions and highest peak rates of emission of all three trace gases, directly following effluent applications, were most commonly observed from sandier textured Coastal Plain and Appalachian Plateau soils, as compared to heavier textured Black Belt soil. When considering greenhouse gas emission potential, soil type should be a determining factor for selection of swine effluent waste disposal sites in Alabama.  相似文献   

17.
探讨秸秆还田与施氮对高纬度黑土区春玉米产量与温室气体排放特性的影响,对促进粮食增产和降低环境代价具有重要意义。本研究通过位于黑土区的大田定位试验,利用静态箱-气相色谱计数方法,在秸秆还田与不还田和3个氮素用量(纯N:120 kg·hm~(-2),240 kg·hm~(-2)和300 kg·hm~(-2))条件下,研究了春玉米不同生育时期农田土壤CO2、N2O和CH4综合温室效应与排放强度,以及土壤过氧化氢酶和脲酶活性的变化。结果表明:无秸秆还田时,高氮用量处理春玉米产量最高;秸秆还田后,中等氮用量处理(240 kg·hm~(-2))春玉米产量最高,且与无秸秆还田的高氮处理间无显著差异。无秸秆还田时,随施氮量增加,CO2、N2O和CH4排放量均显著提高,综合温室效应和土壤温室气体排放量与强度显著增加(P0.05);增施氮肥配合秸秆还田,增加了CO2和N2O的排放量,而土壤CH4的碳汇功能增强,温室气体排放量与强度未显著提高(P0.05)。无秸秆还田,增施氮肥降低了土壤过氧化氢酶活性但提高了土壤脲酶活性;而秸秆还田使得增施氮肥引起的土壤过氧化氢酶活性降低的幅度加大但土壤脲酶活性提高的幅度变小。因此,秸秆还田后配合中等用量氮处理(240 kg·hm~(-2))玉米产量最高,且能够抑制单纯增施氮肥对综合温室效应和土壤温室气体排放强度的促进作用,推荐在生产中参考使用。  相似文献   

18.
In an incubation experiment with flooded rice soil fertilized with different N amounts and sampled at different rice stages, the methane (CH4) and carbon dioxide (CO2) production in relation to soil labile carbon (C) pools under two temperature (35°C and 45°C) and moisture (aerobic and submerged) regimes were investigated. The field treatments imposed in the wet season included unfertilized control and 40, 80 and 120 kg ha?1 N fertilization. The production of CH4 was significantly higher (27%) under submerged compared to aerobic conditions, whereas CO2 production was significantly increased under aerobic by 21% compared to submerged conditions. The average labile C pools were significantly increased by 21% at the highest dose of N (120 kg ha?1) compared to control and was found highest at rice panicle initiation stage. But the grain yield had significantly responded only up to 80 kg ha?1 N, although soil labile C as well as gaseous C emission was noticed to be highest at 120 kg ha?1 N. Hence, 80 kg N ha?1 is a better option in the wet season at low land tropical flooded rice in eastern India for sustaining grain yield and minimizing potential emission of CO2 and CH4.  相似文献   

19.
The association between the responses of microbial activity and residue decomposition to elevated atmospheric [CO2] under field conditions in Australian cropping systems is unknown. We measured soil CO2 emission and decomposition of wheat and field pea residues in a wheat cropping system in the field using the Australian Grains Free-Air CO2 Enrichment (AGFACE) facility in Horsham, Victoria. Elevated [CO2] (550 μmol mol−1) increased soil CO2 emission by 41%, but did not affect the percentage of the original mass or C remaining for either type of residue throughout the experimental period. Our findings suggest that the rates of residue decomposition and residue C mineralization in this semi-arid wheat cropping system were not affected by elevated [CO2] despite higher microbial activity. This has major implication for the C sequestration potential of semi-arid cropping systems under future CO2 climates.  相似文献   

20.
Abstract

To evaluate the effect of increasing forest disturbances on greenhouse gas budgets in a taiga forest in eastern Siberia, CO2, CH4 and N2O fluxes from the soils were measured during the growing season in intact, burnt and clear-felled larch forests (4–5 years after the disturbance). Soil temperature and moisture were higher at the two disturbed sites than at the forest site. A 64–72% decrease in the Q 10 value of soil CO2 flux from the disturbed sites compared with the forest site (5.92) suggested a reduction in root respiration and a dominance of organic matter decomposition at the disturbed sites. However, the cumulative CO2 emissions (May–August) were not significantly different among the sites (2.81–2.90 Mg C ha?1 per 3 months). This might be because decreased larch root respiration was compensated for by increased organic matter decomposition resulting from an increase in the temperature and root respiration of invading vegetation at the disturbed sites. The CH4 uptake (kg C ha?1 per 4 months [May–September]) at the burnt site was significantly higher (–0.15) than the uptake at the forest (–0.045) and clear-felled sites (0.0027). Although there were no significant differences among the sites, N2O emission (kg N ha?1 per 4 months) was slightly lower at the burnt site (0.013) and higher at the clear-felled site (0.068) than at the forest site (0.038). This different influence of burning and tree felling on CH4 and N2O fluxes might result from changes in the physical and chemical properties of the soil with respect to forest fire.  相似文献   

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