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1.
耕作措施对华北地区冬小麦田N2O排放的影响   总被引：2，自引：1，他引：1  
为研究不同耕作措施对冬小麦田N2O排放的影响以及探明N2O排放季节性波动的原因,该研究选取河北栾城县中国科学院农业生态系统试验站不同耕作处理下冬小麦田为研究对象,利用静态箱法测定翻耕秸秆还田（CT）、旋耕秸秆还田（RT）和免耕秸秆还田（NT）下冬小麦田N2O的排放。结果表明,耕作初期72 h翻耕、旋耕及免耕处理N2O排放总量分别为3.83、10.27、10.55 mg/m2。秸秆还田条件下,不同耕作措施冬小麦田N2O季节排放总量为：CT＞RT＞NT。CT、NT处理下N2O排放通量与0～20 cm各层次土壤温度呈极显著正相关。CT、NT处理表层0～5 cm土壤N2O排放通量与土壤充气孔隙度显著性负相关。NT处理土壤具有较高的C/N比,可能有利于减少N2O的排放。因此,华北冬小麦田采用NT能有效减少N2O排放。  相似文献   

2.
耕作措施对双季稻田CH4与N2O排放的影响   总被引：4，自引：8，他引：4  
随着全球气温的不断升高,温室气体减排成为研究的热点。该文旨在研究不同耕作措施下双季稻田CH4及N2O排放特征及其消长关系,为稻田温室气体减排及土壤固碳潜力评价提供依据。试验在湖南省宁乡县进行,通过静态箱法测定翻耕秸秆还田（CT）、旋耕秸秆还田（RT）、免耕秸秆还田（NT）的稻田CH4及N2O排放。结果表明：CH4排放主要来自于晚稻田,翻耕、旋耕和免耕晚稻田CH4排放分别占研究时段CH4排放的69%,67%,73%;各处理冬闲季CH4排放均不到研究时段排放量1%,冬闲CH4排放量为RT＞CT＞NT,差异显著;N2O排放时间变异性较大,早稻稻田N2O排放量为RT＞NT＞CT,晚稻稻田N2O排放量为NT＞RT＞CT,冬闲期各处理稻田N2O均为负排放;从研究时段排放量分析,翻耕秸秆还田有利于减少N2O排放,免耕秸秆还田有利于减少CH4排放;CH4与N2O排放呈显著负相关,冬闲季稻田CH4与N2O排放相关性不显著。总之,NT减少了CH4排放,虽N2O排放略有增加,但CH4与N2O引发的综合温室效应有所减弱。  相似文献   

3.
保护性耕作条件下小麦田N2O排放及影响因素研究   总被引：3，自引：0，他引：3  
采用静态箱—气相色谱法对保护性耕作和常规耕作小麦田的N_2O排放进行了原位测量,测量了土壤温度、水分、无机氮等相关影响因子。结果表明:(1)保护性耕作及常规耕作麦田N_2O的排放具有明显的季节性变化规律,各处理变化趋势较为一致。(2)N_2O的平均排放通量和季节排放量,除免耕秸秆还田外,保护性耕作与常规耕作差异显著。(3)在小麦生长季内,保护性耕作农田均表现为N_2O的排放源。(4)各处理N_2O季节排放量大小顺序为:耙耕秸秆还田(1.64 kg/hm~2)>旋耕秸秆还田(1.59 kg/hm~2)>常规耕作秸秆还田(1.48 kg/hm~2)>深松秸秆还田(1.42 kg/hm~2)>常规耕作无秸秆还田(1.34 kg/hm~2)>免耕秸秆还田(1.33 kg/hm~2),即,与常规耕作相比,保护性耕作(除免还)N_2O排放量增加。(5)温度是制约N_2O排放的关键因素,随着温度的升高N_2O表现出增加的趋势。(6)N_2O排放与水分、土壤无机氮含量无相关性。  相似文献   

4.
基于甘肃农业大学在定西市李家堡镇开展的保护性耕作长期定位试验,采用CO2分析仪、静态箱-气相色谱法对2011年度不同耕作措施下豆麦双序列轮作农田土壤CO2和N2O的排放通量进行全年连续观测。结果表明:测定期内不同耕作措施下豆麦双序列轮作农田土壤均表现为CO2源和N2O源;免耕不覆盖有利于降低两个序列土壤的CO2排放通量,免耕秸秆覆盖、免耕不覆盖和传统耕作+秸秆还田三种保护性耕作处理不同程度的减少了两个序列土壤的N2O排放通量;两个序列下CO2的相对增温潜势最大,W→P→W序列传统耕作+秸秆还田处理对温室效应贡献最多,相反免耕不覆盖处理能相对减少温室气体排放量,从而降低温室效应;P→W→P序列传统耕作不覆盖处理对温室效应的贡献最大,传统耕作+秸秆还田处理对温室效应贡献最小,对温室气体有减排效应。  相似文献   

5.
连续秸秆还田和免耕对土壤团聚体及有机碳的影响   总被引：10，自引：3，他引：7  
选取湖北省武穴市8年田间定位试验中的传统耕作(CT)、秸秆还田配合传统耕作(CTS)、免耕(NT)和秸秆还田配合免耕(NTS)4种处理,研究连续秸秆还田和免耕措施对表层(0—20cm)和亚表层(20—40cm)土壤团聚体稳定性及有机碳(SOC)的影响。结果表明:CTS、NT和NTS均显著增加了表层5mm水稳性团聚体的含量和团聚体平均重量直径(MWD),秸秆还田显著增加了亚表层土壤水稳性团聚体的MWD。与CT比较,CTS、NT、NTS处理的SOC含量分别增加20.83%,21.98%,32.76%。CTS和NTS处理显著提高了表层5,5~2,0.25mm团聚体中SOC含量,NT则显著提高了5,5~2mm团聚体中SOC含量;CTS显著增加了亚表层0.25 mm团聚体中SOC的含量。秸秆还田增加了表层土壤的碳(C)、氢(H)、氮(N)和氧(O)的含量,免耕降低了H的含量,增加了其他3种元素的含量,但是免耕处理增加了亚表层土壤中H的含量。NT和NTS处理较CT和CTS处理降低了土壤的H/C值,表明土壤的脂肪族成分在不断增加。秸秆还田主要增加了土壤中醇、酚类,芳香类,脂肪族化合物和碳水化合物的含量,而免耕主要增加脂肪族化合物的含量。这些有机组分的增加有助于团聚体稳定性的增强。  相似文献   

6.
不同管理措施对滨海盐渍农田土壤CO2排放及碳平衡的影响   总被引：1，自引：0，他引：1  
米迎宾  杨劲松  姚荣江  余世鹏 《土壤》2016,48(3):546-552
为探讨不同管理措施对滨海盐渍农田碳平衡的影响,本文通过玉米–小麦轮作试验,研究农田土壤的CO_2释放规律,及其农田碳收支状况。试验设计6个处理:1常规对照(CK);2有机肥常量(OF);3氮肥增施(NF);4秸秆还田(S);5有机肥加秸秆(OF+S);6免耕(NT)。研究表明,秸秆还田和有机肥的施用增加了土壤呼吸的强度,而免耕处理的CO_2平均释放量最低,不同处理下土壤呼吸总体表现为OF+SSOMNFCKNT。各处理土壤有机碳含量随着作物的收获逐渐升高,其中OF与NT增加最多,而增施氮肥处理并没有显著提高土壤的有机碳水平。各处理间的有机碳含量没有显著性差异。在两季作物种植结束后,各处理的碳输入均高于碳输出,均为碳净输入,表现出较强的碳汇特征。秸秆还田和单施有机肥的碳净输入均显著高于对照,可有效减缓因农田土壤CO_2排放而造成的全球气候变化问题。  相似文献   

7.
耕作措施和秸秆还田对双季稻田土壤氮渗漏的影响   总被引：5，自引：2，他引：3  
针对免耕稻田土壤物理性状的改变引起的土壤氮素淋洗问题,通过定位试验研究了不同耕作措施的稻田土壤氮素特征,为免耕稻田氮素的高效利用提供依据。研究在我国双季稻典型区湖南省宁乡县长期定位试验田进行,该试验地自2005年设置免耕秸秆还田（NT）、旋耕秸秆还田（RT）、翻耕秸秆还田（CT）和翻耕秸秆不还田（CT0）4种耕作处理,重复3次。使用定水头法分层测定0～80 cm土壤导水率,测定分析各处理80cm处土壤渗漏液铵态氮、硝态氮含量差异。研究结果表明,NT 0～80 cm土壤的饱和导水率较CT提高了63.14%,NT铵态氮、硝态氮渗漏量显著高于其他处理。秸秆还田措施使早稻耕作覆水初期渗漏水中硝态氮含量显著高于不还田处理。从全年淋失总量估算结果来看,各处理铵态氮渗漏量约是硝态氮的2倍。总之,相对于耕作处理,免耕会使氮素淋失量增加,而长期淹水条件下稻田铵态氮渗漏应得到更多的重视。  相似文献   

8.
通过设置在甘肃省定西市李家堡镇的保护性耕作措施长期定位试验,共设4个处理（T：传统耕作;NT：免耕无覆盖;TS：传统耕作＋秸秆还田;NTS：免耕＋秸秆覆盖）,采用春小麦豌豆双序列轮作（即小麦→豌豆→小麦和豌豆→小麦→豌豆,本文中所指春小麦地、豌豆地分别指2008年种植春小麦、豌豆的轮作次序）,于2008年3月中旬对春小麦、豌豆双序列轮作下的土壤有机碳、全氮、土壤微生物量碳及土壤微生物量氮含量进行了采样测定。结果表明,经过7a的轮作后,两种轮作次序下,0-30cm土层中土壤有机碳、全氮、土壤微生物量碳、土壤微生物量氮含量均有在免耕＋秸秆覆盖、传统耕作＋秸秆还田处理较免耕不覆盖、传统耕作处理高的趋势,且其含量均随着土壤深度的增加而降低。其中,土壤微生物量碳含量在两种轮作次序下的排序均为：免耕＋秸秆覆盖（NTS）〉传统耕作＋秸秆还田（TS）〉免耕不覆盖（NT）〉传统耕作（T）;而土壤微生物量氮含量在春小麦地和豌豆地的排序则分别表现为：免耕＋秸秆覆盖（NTS）〉传统耕作＋秸秆还田（TS）〉传统耕作（T）〉免耕不覆盖（NT）和免耕＋秸秆覆盖（NTS）〉传统耕作＋秸秆还田（TS）〉免耕不覆盖（NT）〉传统耕作（T）。同时,微生物量碳、微生物量氮与有机碳和全氮均呈显著正相关,说明提高土壤有机质、全氮含量的保护性耕作模式有利于土壤微生物量碳与氮的积累。  相似文献   

9.
田间定位试验开始于2008年,共设置秸秆还田翻耕（cT＋）、无秸秆翻耕（CT-）、秸秆还田免耕（NT＋）和无秸秆免耕（NT-）四个处理。利用静态箱——气相色谱法,测定分析了2010-2011年度和2012-2013年度两个小麦生长季内土壤coz排放、土壤DOC含量及土壤有机质含量的动态变化。结果表明：两个小麦生长季内土壤coz排放规律基本一致,从当年小麦出苗到越冬土壤C02排放量下降,第二年小麦返青后,士壤CO：排放量开始上升,到开花期达到排放高峰,其后开始下降直至小麦成熟。各处理2010-2011年、2012-2013年度土壤C02平均排放通量分别为：CT＋246．44、273．94mg·m^-2．h～,CT-183．54、212．57mg·m^-2．h^-1,NT＋188．41、200．06mg·m^-2·h^-1,NT-179．66、179．10mg·m^-2·h^-1。土壤DOC含量的动态变化表现为在一定范围内上下波动,各处理2010-2011年、2012-2013度年土壤DOC平均含量分别为：CT＋0．601、0．467g·kg^-1;CT-0．530、0．377g·kg^-1;NT＋0．621、0．544g·kg^-1;NT-0．528、0．402g·kg^-1。方差分析表明．秸秆还田能增加土壤CO2排放、DOC含量和有机质含量;翻耕能增加土壤CO2排放,对DOC含量和有机质含量无显著影响;免耕减少土壤C02排放,对DOC含量无显著影响,能增加土壤有机质含量。相关分析表明,土壤CO2排放与DOC含量动态变化没有显著相关关系,土壤CO2排放总量与土壤有机质含量正相关,DOC含量和土壤有机质含量无明显相关关系。  相似文献   

10.
不同耕作措施对雨养冬小麦碳足迹的影响   总被引：2，自引：1，他引：2  
为了解不同耕作管理措施对我国北方旱作农田作物生产生命周期内生产资料及生产过程碳排放足迹的影响,在山西省临汾市尧都区连续15年保护性耕作长期定位试验基地,利用静态箱-气相色谱法连续两年测定了不同秸秆管理和耕作措施(秸秆不还田旋耕、秸秆还田旋耕、秸秆覆盖免耕)下,旱作冬小麦田N_2O周年排放通量,并对不同耕作管理措施的生产资料和生产过程中的碳排放进行全面分析与计算,以估算不同耕作措施的碳足迹。结果表明:1)秸秆覆盖免耕和秸秆不还田旋耕条件下旱作冬小麦田N_2O年度累积排放量较秸秆还田旋耕分别平均减少19.2%和18.9%;2)旱作冬小麦在秸秆覆盖免耕条件下产量最高;3)旱作农田碳足迹中氮肥生产、农田N_2O直接排放和柴油消耗排放占到总排放足迹的90%以上;4)秸秆覆盖免耕较其他耕作方式的碳足迹低,两年试验期间,较秸秆还田旋耕处理碳足迹分别低11.0%和6.9%,较秸秆不还田旋耕处理碳足迹分别低7.9%和8.3%。5)在半干旱地区,秸秆覆盖免耕处理单位产量碳足迹最低,是本研究中低碳低排的推荐措施。本研究结果可为旱作农田以低碳减排为目标的可持续发展提供科学依据。  相似文献   

11.
The absorption and transport of Na and Cl from 0.1 mM and 10 mM 22Na labelled NaCl or 36Cl labelled KCl were examined in 15 days old seedlings of 3 cultivars of rice differing in their tolerance to salinity. Furthermore, the effects of 10, 100 and 1000 ppm (N)2S on their uptake were studied. It was found that in general, the salt‐tolerant cultivars BR and PNL‐1 absorbed more Na and translocated a lesser proportion of it to the shoot, compared to the salt‐sensitive IR‐8, from 0.1 mM NaCl. The presence of (N)2S reduced the uptake of Na in all the cultivars. It was also found that the presence of 100 ppm K, KN or NNreduced Na absorption from 0.1 mM NaCl significantly in all the cultivars, and the translocation to shoot in BR‐ Chloride transport from 0.1 mM NaCl was reduced by (N)2S in all the cultivars. The 3 cultivars differed significantly in the rates of absorption and transport of Na and Cl. The results indicate that PNL‐1 which is a cross of IR‐8 X BR, has inherited the salt tolerance trait from BR. Lower rates of Na translocation to the shoot can be used as an index of salt tolerance in rice.  相似文献   

12.
我国酸性硫酸盐土壤中铁锰形态转化及迁移   总被引：7，自引：0，他引：7  
刘兆辉  王遵亲 《土壤学报》1994,31(4):376-384
酸性硫酸盐土壤酸性很强，有机质含量高，造成了这种土壤所特有的铁锰淋洗、转化和迁移规律。研究结果表明：在酸性硫酸盐土壤中全铁含量较低，一般在３５－５０ｇ／ｋｇ（以Ｆｅ２Ｏ３计），全锰含量也低，一般在０．２５－０．５５ｇ／ｋｇ（以ＭｎＯ计），一般滩涂中全铁大于６０ｇ／ｋｇ，全锰大于１ｇ／ｋｇ。酸性硫酸盐土壤中，铁的游离度较小，一般在３７－７０％，铁的活化度较大，一般在８－２０％，而滩涂中铁的游离度一般  相似文献   

13.
Recently conventional chemical analyses were mostly replaced by instrumental analysis. Although results from both methods were examined in details after the samples had been solubilized or extracted by appropriate techniques, the solubilization method was considerably altered so as to be convenient for the following analysis. In atomic absorption spectrophotometry (AAS), for example, fusion technique was mostly inadequate because of the higher salts concentration in the obtained solution. The use of H2SO4 must also be avoided in acid digestion for SO4 2- precipitates with Sr2+ or La3+ which must be added to eliminate interferences in the succeeding procedure. Therefore, it is essential to consider the whole scheme including sample treatments to evaluate the suitability of instrumental analysis. In this experiment, the suitability of the methods which have been employed in our laboratory was examined by analyzing 9 rock standards.  相似文献   

14.
We examined the potential of a subsoil to denitrify nitrate under optimal anaerobic conditions in a laboratory-based incubation when supplied with a range of C substrates of increasing recalcitrance. Both topsoil and its associated subsoil were supplied with nitrate and either glucose, starch or cellulose. Microbial respiration and the evolution of N2O and N2 were measured. The subsoil supported low amounts of microbial activity and responded only to the glucose treatment; with less than one-fifth of the N2O production measured in the top soil. Overall, our findings demonstrated that the denitrification potential of this particular subsoil is relatively low and that only simple carbohydrates could be utilised readily by the resident microorganisms.  相似文献   

15.
Abstract

The availability of soil Mn to corn in relation to extractability of soil Mn by EDTA, Mg(NO3)2, CH3COONH4, hydroquinone, H3PO4, and NH4H2PO4 as affected by liming was evaluated under field conditions on a single soil type. EDTA, Mg(NO3)2 and CH3COONH4‐extractable Mn were related inversely to available Mn. No useful relationships were found between hydroquinone, H3PO4, and NH4H2PO4‐extractable soil Mn and Mn uptake by sweet corn.  相似文献   

16.
Abstract

Forest fires can change the greenhouse gase (GHG) flux of borea forest soils. We measured carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) 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 CO2 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 CO2 flux was highest at PB (128 ± 85 mg CO2-C m?2 h?1) and lowest at SB1 (47 ± 19 mg CO2-C m?2 h?1) (P < 0.01), and within each site it was positively correlated with soil temperature (P < 0.01). The CO2 flux at SB2 was lower than that at CF when the soil temperature was high. We attributed the low CO2 flux at SB1 and SB2 to low root respiration and organic matter decomposition rates due to the 2004 fire. The CH4 uptake rate was highest at SB1 [–91 ± 21 μg CH4-C m?2 h?1] (P < 0.01) and positively correlated with soil temperature (P < 0.01) but not soil moisture. The CH4 uptake rate increased with increasing soil temperature because methanotroph activity increased. The N2O flux was highest [3.6 ± 4.7 μg N2O-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   

17.
The emission of acidifying compounds to air in the Netherlands, expressed as acidifying equivalents, consisted in 1992 mainly of NOX (45%), NH3 (35%) and SO2 (20%). Transportation, agriculture and large combustion plants each contributed about 30% to the national total emission of acidifying compounds. The emissions from transportation activities mainly consisted of NOX, while in agriculture NH3 emission strongly dominated. Combustion processes in large combustion plants resulted both in SO2 emissions (especially from refineries) and NOX emissions (especially from public power plants). The total emission of acidifying substances decreases steadily in the Netherlands. The emission in 1992 was 24% lower than in 1985. It is expected to decrease further in future. The emission levels in 1992 and 1993 still are more than twice as high as the emission objective for the year 2000, set by Dutch environmental policy.  相似文献   

18.
The mechanism of SO2 inhibition of photosynthesis in intact leaves of tomato and maze was studied to evaluate SO2 inhibition of photorespiration. Leaf tissues were fumigated with SO2 under photorespiratory (low CO, and/or high O, concentrations) and non-photo-respiratory conditions. When tomato leaf disks were fumigated with 10 ppm SO2 at 2, 21 and 100° o O., SO2 inhibited photosynthesis at 2% O2 in the same degrees as at 21% O2. SO2 inhibition of photosynthesis was depressed at higher CO2 concentrations when the disks were fumigated with SO2 at different CO2 concentrations. High CO2 concentrations also reduced the photosynthesis inhibition of maize leaf disks. These results suggest that SO2 inhibits photosynthesis through other mechanisms than photorespiration inhibition and confirm the view that SO2 competes with CO2 for the carboxylating enzymes in photosynthesis  相似文献   

19.
本文研究水热条件渐变的地带性土壤中Ｇ１、Ｇ２组胶散复合体有机、无机物的化学组成及其结合特点。结果表明：Ｇ２组中铁有积累现象，游离态铁、铝氧化物含量为Ｇ２＞Ｇ１，但均随土壤类型变化。松结态腐殖质（Ｈ１）为Ｇ１＞Ｇ２，紧结态腐殖质（Ｈ３）则为Ｇ１＜Ｇ２。可提取腐殖质中，松、稳结态腐殖质之比值Ｈ１／Ｈ２和胡敏酸、富里酸之比值ＨＡ／ＦＡ，除个别土壤之外，都相关不大。Ｇ１、Ｇ２两组复合体中都含有一定数量的络  相似文献   

20.
In the C2H2-C2H4 assay for measurement of heterotrophic N2 fixation in water-logged soils, the diffusion of C2H2 into the soil and the recovery of C2H4 from it are critical factors regulating the assay result. To establish an C2H2-C2H4 assay technique suitable for waterlogged soils, the C2H2-reducing activities (ARA), assayed by varying the method of assay gas filling, the pC2H2 of the assay gas, the duration of assay incubation and of soil vibration before the gas sampling, were compared.

A maximum ARA was measured when the following set of procedures were applied to the soil sample in assay flasks: 1) a 4-fold repetition of I-min evacuation under 0.01 atmospheric pressure and the subsequent I-min filling under 1 atmospheric pressure with assay gas at pC2H2 of 0.1 atm, 2) an assay incubation for 3 hr, and 3) a sampling of an aliquot of the headspace gas after strongly vibrating the flask for 1 min.

The ARA measured by this technique was several times larger than those measured by the techniques hitherto applied, and corresponded to an almost 80% of the V max of the sample. This technique was, therefore, proposed for the assay of heterotrophic N2 fixation in waterlogged soils.

A striking depression of ARA in the soil sample prepared with agitation indicated that a microbial ecosystem established in the soil should be kept as undisturbed as possible throughout the C2H2-C2H4 assay.  相似文献   

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