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1.
Abstract

Dicyandiamide (DCD) is a nitrification inhibitor that has been proposed for use in drill‐seeded rice. Immobilization of fertilizer NH4 +‐N by soil microorganisms under aerobic conditions has been found to be significantly enhanced in the presence of a nitrification inhibitor. The objective of this laboratory study was to determine if DCD significantly delayed nitrification of urea‐derived N, and if this enhanced immobilization of the fertilizer N in the delayed‐flood soil system inherent to dry‐seeded rice culture. Nitrogen‐15‐labeled urea solution, with and without DCD (1: 9 w/w N basis), was applied to a Crowley silt loam (Typic Albaqualf) and the soil was incubated for 10 weeks in the laboratory. The soil was maintained under nonflooded conditions for the first four weeks and then a flood was applied and maintained for the remaining six weeks of incubation. The use of DCD significantly slowed the nitrification of the fertilizer N during the four weeks of nonflooded incubation to cause the (urea + DCD)‐amended soil to have a 2.5 times higher fertilizer‐derived exchangeable NH4+‐N concentration by the end of the fourth week. However, the higher exchangeable NH4+‐N concentration had no significant effect on the amount of fertilizer N immobilized during this period. Immobilization of the fertilizer N appeared to level off during the nonflood period about the second week after application. After flooding, immobilization of fertilizer N resumed and was much greater in the (urea + DCD)‐amended soil that had the much higher fertilizer‐derived exchangeable NH4 +‐N concentration. Immobilization of fertilizer N appeared to obtain a maximum in the urea‐amended soil (18%) about two weeks after flooding and for the (urea + DCD)‐amended soil (28%) about four weeks after flooding.  相似文献   

2.
Summary The influence of the water regime on mineralization and immobilization of N and P was investigated in a calcareous sandy loam incubated with cattle, poultry and green manure (Sesbania aculeata), and wheat and rice straw in a pot experiment. At field capacity, N released from poultry and green manure during the first 4 weeks of incubation was 45% and 59%, respectively. During the next 12 weeks, only around 40% more organic N was mineralized from both sources. In contrast, addition of cattle manure resulted in a period of net N immobilization lasting up to 4 weeks. By the end of 16 weeks of incubation only about 19010 of the added N was mineralized. High rates of N immobilization were observed during the first 4 weeks of incubation of rice or wheat straw with C/N ratios of 78 and 85, respectively. The N mineralization kinetics of poultry and green manure and of untreated soil showed an initial fast reaction followed by a slow release of inorganic N and could be described by two simultaneous first-order reactions. Under waterlogged conditions mineralized N was lost simultaneously in significant amounts possibly through nitrification — denitrification reactions. At field capacity, the largest amount of Olsen P was accumulated in the soil amended with poultry manure, followed by cattle manure. Results from other treatments did not differ much from those of the untreated soil. About 15% of P from poultry manure was mineralized during the 1st week of incubation. In contrast to the field-capacity moisture regime, marked increases in Olsen P in the soils amended with green manure and crop residues were observed under water-logged conditions.  相似文献   

3.
An incubation experiment was conducted to study N2O emissions from a Typic Ustochrept, alluvial soil, fertilized with urea and urea combined with different levels of two nitrification inhibitors, viz karanjin and dicyandiamide (DCD). Karanjin [a furano-flavonoid, obtained from karanja (Pongamia glabra Vent.) seeds] and DCD were incorporated at rates of 5, 10, 15, 20 and 25% of applied urea-N (100 mg kg-1 soil), to the soil adjusted to field capacity moisture content. The highest N2O flux (366 µg N2O-N kg-1 soil day-1) was obtained on day 1 after incubation from soil fertilized with urea without any inhibitor. The presence of the inhibitors appreciably reduced the mean N2O flux from the urea-treated soils. The application of karanjin resulted in a higher mitigation of total N2O-N emission (92-96%) compared to DCD (60-71%). Rates of N2O flux ranged from 0.9 to 140 µg N2O-N kg-1 soil day-1 from urea combined with different levels of the two inhibitors (coefficient of variation=24-272%). Karanjin (62-75%) was also more effective than DCD (9-42%) in inhibiting nitrification during the 30-day incubation period.  相似文献   

4.
甲烷（CH4）是一种强效温室气体,准确认识特定类型土壤CH4源汇特征及影响因子调控作用,对于提升土壤CH4吸收潜力以减缓全球气候变化具有重要意义。该研究以盐渍土为研究对象,在土壤室内培养试验中,设置了3个土壤含水率处理,分别为田间持水率（Field Capacity,FC）的50%（50%FC）,75% FC和100% FC;并在每个含水率下设置了6个含盐量处理,电导率分别为0.3、1.0、2.0、3.2、4.9和6.2 dS/m,研究不同土壤含水率和含盐量条件下盐渍土CH4吸收特征。在田间测坑试验中,观测了0.3、1.0和5.0 dS/m 3种含盐量土壤的CH4吸收特征及其对水分动态的响应。室内土壤培养试验结果表明,100%FC下6种盐分水平土壤CH4累积吸收量分别是75%FC下的1.08～1.39倍和50%FC的1.27～1.72倍,表明在田间持水率范围内,含水率升高促进了土壤CH4吸收;在3种含水率下,土壤CH4累积吸收量均随着处理含盐量升高而降低,6.2 dS/m最高含盐量处理的CH4累积吸收量相比0.3 dS/m最低含盐量处理显著降低了42.6%、52.3%和55.1%;相比50%FC、100%FC含水率下高含盐量对土壤CH4吸收具有更强的抑制作用,土壤含水率和含盐量对CH4吸收的影响存在显著的交互作用。田间测坑试验在野外田间条件下进一步验证了室内培养试验的结果,试验观测期内所有含盐量处理土壤CH4吸收速率均与土壤含水率呈显著正相关关系（P<0.01）;1.0和5.0 dS/m含盐量处理的累积CH4吸收量分别为0.3 dS/m非盐渍土处理的82.6%和59.8%,高含盐量抑制了土壤对CH4的吸收。研究结果表明盐渍土是CH4的汇,并受到土壤含水率和含盐量显著影响,在盐渍土开发利用中应考虑通过合理的水盐调控以提高土壤CH4汇的能力。  相似文献   

5.
The N mineralization rate in 11 soils was studied by aerobic incubation at 28°C and at a moisture content of 75% of field capacity for 2 weeks (short term) and 6 weeks (medium term). Relationships between the N mineralization indices for each period were evaluated. Ammonification largely predominated during the first 2 weeks of incubation, whereas nitrification was the predominant process between weeks 2 and 6. The net N mineralized in the different soils varied from 0 to 2.85% of the organic N after 2 weeks of incubation and from 0.32 to 3.36% of the organic N after 6 weeks of incubation, the mean values for each period being 0.82 and 1.51% of the organic N, respectively. The quantities of NH inf4 sup+ -N, NO inf3 sup- -N, and total inorganic N produced and the percentage of organic N mineralized after 2 weeks of incubation were highly and positively correlated with the coresponding values after 6 weeks of incubation. These results showed that either length of incubation could be used to determine the potential N mineralization capacity of the soils. Information obtained from two incubation periods was largely supplementary for the kinetic study of N mineralization, ammonification, and nitrification; therefore a medium-term incubation with intermediate measurements of N mineralization over a short term may be more useful than a single measurement using either of the two incubation periods.  相似文献   

6.
The nitrogen (N) release from coated urea fertilizers (Arborite and ESN), traditional N fertilizers [urea, (NH2)2CO], and urea ammonium nitrate (UAN) [(NH2)2CO, NH4NO3] in three North Carolina (USA) soils was measured throughout a 12-week laboratory incubation. Treatments were N source and moisture level (60% and 80% of field capacity). In both the Candor and Cecil soils, 40% of the Arborite N had released by day 2 after addition to the soil. Maximum Arborite N release was achieved by week 6 for both soils. The ESN N release began between weeks 1 and 2, and maximum release was attained by week 6 for the Candor and by week 8 for the Cecil soil. The ESN reached 70% release on Portsmouth by week 8 and Arborite had an immediate release. Field studies of these coated ureas would be needed to determine if they are economically viable over more traditional N fertilizers in North Carolina.  相似文献   

7.
Transformation and effect of urea – dicyandiamide and ammonium sulphate – dicyandiamide products with ryegrass and rice The transformation of urea or ammonium sulphate fertilizers both in combination with dicyandiamide was tested in soil under aerobic conditions. Nitrification was determined after percolation and different incubation periods by measuring the amount of nitrate leached. The mineralisation of urea and ammonium sulphate in the fertile soil was relatively quick. However the addition of 5 to 10 % DCD of the total fertilizer-N inhibited vigorously the nitrification for 6 weeks, 20 % DCD even for 10 weeks. In this way the danger of nitrate leaching was greatly diminished and a slow and constant release of available nitrogen rendered. After a preceding aerobic incubation (up to 4 weeks), flooding and rice-seeding diminished the nitrogen losses by leaching and denitrification remarkably in the Ha/DCD – as well as AS/DCD-pots if compared to urea or ammonium sulphate alone. This effect was particulary clear after a 4 weeks incubation period. Therefore these urea – and ammonium sulphate-dicy-andiamide products guarantee a proper and constant N-nutrition of the rice plants and may decrease the N-losses caused by leaching and denitrification. Nitrogen fertilizers with nitrification inhibitors are of special interest for rice culture, because they allow a better timing of N-fertilizer application, rice seeding and water flooding and render a more economical utilization of nitrogen fertilizers.  相似文献   

8.
The effect of urea and urea mixed with different doses of two nitrification inhibitors, dicyandiamide (DCD) and karanjin [a furanoflavonoid, extracted from seeds of the karanja (Pongamia glabra Vent.) tree], on methane (CH4) consumption was examined in a Typic Ustochrept (alluvial inceptisol) soil, collected from a field under rice-wheat rotation. The soil, fertilized with urea (100 mg N kg-1 soil) and urea combined with different doses of the two inhibitors, DCD and karanjin (each added at 5%, 10%, 15%, 20% and 25% of applied N), was incubated at 25°C, at field capacity moisture content for 35 days. The methane consumption rate ranged between 0.2 and 1.7 µg CH4 kg-1 soil day-1 with little temporal variation (CV =10–31%). It was significantly higher in the control (no fertilizer-N) than other treatments except for a few cases, while total CH4 consumption in the incubation period was significantly higher in the control than other treatments. Methane consumption rate was found to be negatively and positively correlated with soil NH4 + and NO2 - + NO3 - content, respectively. Mean CH4 consumption rate, as well as total CH4 consumption, was lower on the addition of karanjin due to slower nitrification and higher conservation of NH4 + released from applied urea. Addition of urea led to a 17% reduction of total CH4 consumption while urea combined with karanjin and DCD had 50–64% and 19–34% reduction, respectively. Karanjin was a more effective nitrification inhibitor than DCD during the incubation period.  相似文献   

9.
Breakdown of Dicyandiamide in quartz sand and soils Under different moisture conditions the breakdown of dicyandiamide (DCD) was investigated in quartz sand with metal oxides and in soils. 1. In quartz sand without metal oxides DCD did not change over 100 days. 2. In the presence of amorphous Fe(III)-hydroxide DCD was transformed to guanylurea after 5 days to 50% and after 40 days to 90%. The transformation rate depended on the kind of metal oxides and increased with low humidity. Other metabolites were not detected in quartz sand medium. 3. In two soils (pH 6.5, 6.3; sandy silty loam and sand) the breakdown of DCD to guanylurea followed the same pattern, but continued to ammonium. About 20–70% of the added amount was transformed within 100 days. 4. With increasing soil moisture the transformation of DCD to guanylurea was slower, but the further breakdown to ammonium increased. 5. As long as DCD was present the formation of nitrate was blocked.  相似文献   

10.
The emission of CO2 from Galician (NW Spain) forest, grassland and cropped soils was studied in a laboratory experiment, at different temperatures (10-35 °C) and at moisture contents of 100% and 160% of the field capacity (FC) of each soil (the latter value corresponds to saturated conditions, and represents between 120% and 140% of the water holding capacity, depending on the soil). In the forest soil, respiration in the flooded samples at all temperatures was lower than that at 100% field capacity. In the agricultural (grassland and cropped) soils the emission was higher (particularly at the highest incubation temperatures) in the soils wetted to 160% of the field capacity than in those wetted to 100% of the field capacity. In all cases the emission followed first order kinetics and the mineralization constants increased exponentially with temperature. In the forest soil, the Q10 values were almost the same in the soils incubated at the two moisture contents. The grassland and cropped soils displayed different responses, as the Q10 values were higher in the soils at 160% than in those at 100% of field capacity. In addition, and particularly at the highest temperatures, the rate of respiration increased sharply 9 and 17 days after the start of the incubation in the grassland and in the cropped soil, respectively. The above-mentioned anomalous response of the grassland and cropped soils under flooding conditions may be related to the agricultural use of the soils and possibly to the intense use of organic fertilizers in these soils (more than 150 kg N ha−1 year−1 added as cattle slurry or manure, respectively, in the grassland and cropped soils). The observed increase in respiration may either be related to the development of thermophilic facultative anaerobic microbes or to the formation during the incubation period of a readily metabolizable substrate, possibly originating from the remains of organic fertilizers, made accessible by physicochemical processes that occurred during incubation under conditions of high moisture.  相似文献   

11.
Abstract

To determine the effect of incubation on DTPA‐extractable Fe, Zn, and Cu in soils with a wide pH range (4.2 ‐ 9.4) and to determine the nature of this effect, soils were incubated at field moisture capacity for 1 week with and without a sterilant (toluene). After incubation these soils as well as their air‐dry counterparts were analyzed for DTPA‐extractable Fe, Zn, and Cu.

Incubated soils were significantly lower in DTPA‐extractable Fe, Zn, and Cu than air‐dry soils over all soil pH values tested but there was no significant difference in mean values for incubated soils due to the addition of toluene. The results suggest that, upon incubation at field moisture capacity, the decrease in DTPA‐extractable Fe, Zn, and Cu observed was noa‐microbial in nature.  相似文献   

12.
Effect of dicyandiamide on the nitrification of liquid manure between late autumn and spring The influence of soil temperature on the nitrification of slurry manure with and without addition of the nitrification inhibitor dicyandiamide and the decomposition of dicyandiamide was tested in model experiments. 1. NH4-N of cattle slurry was completely nitrified within 10 or 30 weeks at 4°C or 0°C respectively in a growth chamber. The addition of dicyandiamide retarded the formation of NO3 in the first case for about 15 weeks (dicyandiamide was completely decomposed after 25 weeks), in the latter case for more than 30 weeks. 2. A simulation of field soil temperatures from October till May in an incubation trial resulted in full nitrification within four weeks, with dicyandiamide within 30 weeks. 3. Slurry mixed with soil, burried in polyethylene-bottles into the top soil of the open field, was nitrified until February when applied at the beginning of November, or until April when applied at the beginning of March. With DCD-addition, however, only one fourth of March-Slurry or hardly half of November-Slurry was nitrified. At the same time, in each case about 30% of the applied amount of DCD was still detectable.  相似文献   

13.
双氰胺对不同质地红壤中碳酸氢铵的硝化抑制作用研究   总被引：2，自引：0，他引：2  
通过室内好气培养试验,研究了双氰胺(DCD)对施入不同质地红壤中碳酸氢铵的硝化抑制作用。结果表明,添加DCD明显提高了相应处理的铵态氮含量,降低了硝态氮含量。无论加入DCD与否,砂壤土中碳酸氢铵的硝化时间大约都需7周;轻粘土中碳酸氢铵的硝化时间为35.d,加入硝化抑制剂后硝化时间可延长2周;而中壤土中至培养结束时仍有较高的铵态氮,故铵的硝化时间有待进一步研究。DCD对碳酸氢铵的硝化抑制效果中壤土优于砂壤土、轻粘土;在砂壤土和轻粘土中,DCD对低浓度铵态氮处理的硝化抑制效果好;而在中壤土中对高浓度的抑制效果好。  相似文献   

14.
还田秸秆及其腐解产物的吸水能力研究   总被引：1，自引：0，他引：1  
[目的]研究水稻、小麦和油菜作物秸秆的腐解规律及其对秸秆吸水能力的影响,为农田秸秆资源有效利用和田间水分管理提供相应的理论依据。[方法]采用尼龙网袋法进行试验研究。[结果]在土壤水分饱和状态下,3种秸秆腐解速率均表现为前期快,后期缓慢的特点。培养结束(110d)时,水稻、小麦和油菜秸秆的累积腐解率分别为67.8%,55.5%和49.2%。光学显微镜结合红外光谱结果显示,与对照相比,水稻秸秆经过110d的腐解,其物质组成、化学结构和形貌特征均发生显著变化,小麦和油菜秸秆变化不明显。腐解0d时,水稻、小麦和油菜秸秆饱和吸水量依次分别为3.87,2.51,3.61g/g。随着秸秆组分、结构和形貌的变化,秸秆及其腐解产物饱和吸水量也有显著性差异。水稻秸秆在腐解15d时的饱和吸水量最大,为5.17g/g,之后其饱和吸水量逐渐下降并趋于稳定;小麦和油菜秸秆的饱和吸水量在腐解5d时达到最低值,分别为1.87,2.59g/g;之后其饱和吸水量逐渐增加。单位秸秆的吸水效果表明,3种作物秸秆在腐解初期的持水量最大,之后随着腐解时期的延长而有所降低。[结论]还田作物秸秆的吸水能力受到还田秸秆质量和腐解时期的双重影响,故在开展秸秆还田(尤其翻压)时,应注意秸秆含水量,还田时期和田间水分管理,降低由秸秆吸水产生的负面效应。  相似文献   

15.
Abstract

The potential for using dicyandiamide (DCD) to enhance yield of take‐all‐infested winter wheat (Triticum aestivum L.) was evaluated in six field experiments on four acid soils (pH 5.7–6.2). Ammonium and NO3 ‐ concentrations and NH4 +: NO3 ‐ ratios in 0–10 and 10–20 cm soil depths were measured for ten weeks after spring topdressing 180 kg N/ha as urea with 0, 13, or 27 kg DCD/ha. Nitrification was strongly inhibited for 6 to 10 weeks by either 13 or 27 kg DCD/ha. Averaged over the ten‐week sampling period, NH4 +: N03 ‐ ratios in the 0–10 cm depth of soil were 36: 1 for DCD‐treated plots as compared to 2: 1 for plots receiving only urea. Ratios in DCD‐treated plots were considerably wider than ratios associated with take‐all suppression (10: 1 to 3: 1) in earlier studies. Extractable NH4 + + NO3 ‐ concentrations in soil were high in DCD‐treated plots after 30 to 40 days, suggested that DCD had reduced crop uptake of N because of the lower mobility of NH4 + as compared to NO3 ‐. In four of the six studies, grain yields tended to be reduced by DCD. Results suggest that lower rates of DCD and/or application of some NO3 ‐ will be necessary if DCD is to be used as a tool for suppressing take‐all.  相似文献   

16.
【目的】本研究旨在明确硝化抑制剂对稻田土壤氮素周转的影响,探讨抑制剂提高氮肥利用率及微生物响应机理。【方法】以草甸黑土发育的水稻土为研究对象,进行了两组培养试验 (25℃),培养周期均为150天。共设4个处理:1) 不施肥 (CK);2) 单施尿素 (Urea);3) 尿素 + 双氰胺 (Urea + DCD);4) 尿素 + 3, 4-二甲基吡唑磷酸盐 (Urea + DMPP)。一组试验从培养第1天起,抽取气体样品,用气相色谱法测定N2O排放量。另一组试验从培养第1天直到结束,取土样测定氨氧化细菌和氨氧化古菌数量,采用荧光定量PCR等技术测定nirK基因和nirS基因拷贝数,用常规方法测定土壤无机氮含量。【结果】施用尿素显著增加了N2O排放量,其中85%的N2O排放发生在培养开始后的前两周内。Urea + DMPP处理土壤NH4+浓度在前23天稳定在较高水平,与Urea处理相比,N2O减排率为78.3%,Urea + DCD处理为21.6%。Urea + DMPP处理排放系数为0.05%,Urea + DCD为0.18%,Urea + DMPP处理显著低于Urea + DCD处理。施用尿素培养,土壤氨氧化细菌 (AOB) 数量显著增加而氨氧化古菌 (AOA) 数量则显著减少。添加DCD和DMPP能显著抑制AOB的数量,但对AOA没有影响。培养第3、30和90天,Urea + DMPP处理土壤中的AOB数量显著低于Urea + DCD处理的30%、56%和60%。对于反硝化细菌来说,所有处理中的nirK基因拷贝数均显著高于nirS基因拷贝数。添加DMPP在培养第3和30天显著减少了含nirK和nirS基因的反硝化细菌数量,而添加DCD对两类反硝化细菌数量无明显作用。【结论】东北黑土水稻生产中,硝化抑制剂DMPP降低N2O排放量和排放系数的效果显著好于DCD,因为DMPP在培养后的30天内,可以显著抑制氨氧化细菌繁衍,降低反硝化细菌数量,从而起到减少N2O排放、提高肥料利用率的作用。  相似文献   

17.
In a laboratory incubation study, the periodic changes in different chemical fractions of copper (Cu) in three sludge-amended soil types (acidic sandy clay loam, neutral clay loam and alkaline clay loam) of varying soil reaction were monitored under field capacity and flooding moisture regime over 16 months. The water soluble and exchangeable fraction of Cu was very low (≤1% of total Cu) in all three soil types. At the end of incubation (16 months), the sodium acetate extractable (carbonate sorbed)- and residual-Cu fractions transformed into Fe-Mn oxide fraction, irrespective of moisture regime in all three soil types. However, the extent of transformation varied among soils.  相似文献   

18.
A sandy clay loam soil was used to study the effect of (a) urea application at rates equivalent to 250, 500, 1000 and 2000 ppm-N, at moisture content level of 100 % WHC, and (b) soil moisture levels of 30, 60 and 100 % of the WHC in addition to water-logging conditions, when urea was applied at the rate of 500 ppm-N, on urea-N transformations. In both cases, the incubation took place at 30°C and lasted for 6 weeks. The experiments were carried out in a closed system daily aerated. Complete hydrolysis of the added urea was attained after 1, 2 and 3 weeks for 250, 500 and 1000 ppm urea-N, respectively. Six weeks incubation period was not enough for full hydrolysis of the 2000 ppm urea-N. The rate of urea hydrolysis increased linearly for urea concentration up to 1000 ppm N. This concentration must have been sufficient to saturate the urease present in the soil used. The peak of NON was higher the higher the rate of urea applied. Delay of the nitrate formation was always accompanied by the accumulation of nitrites. At the end of the experiment, the nitrate-N formed represented 93,90,77 and only 20 % of the initially applied nitrogen for 250, 500, 1000 and 2000 ppm-urea-N, respectively. The rate as well as the total ammonia loss increased with increasing the rate of urea application. No appreciable differences were observed in urea hydrolysis due to the variations in moisture levels within the range of WHC. Under water-logging conditions, urea hydrolysis was slower and extended to the 6th week, also the rate of urea hydrolysis was no more than 50 % of the rate produced in moisture treatments within WHC. NON accumulation persisted for one week in the moisture levels within the range of WHC, while it continued in the water-logged treatment till the end of the experiment. Nitrate formation was slightly favoured at 100 % WHC and decreased somewhat with lowering the soil moisture levels. However, it was completely inhibited under water-logging conditions. Ammonia volatilization was not markedly affected by moisture levels within WHC, however, the water-logged treatment showed the highest total loss.  相似文献   

19.
采用恒温土壤培养实验的结果表明,尿素在滇池北岸蔬菜地土壤中转化速率非常快,培养3天尿素水解了90%左右。施用硫磺2周后,土壤pH从8.15下降到7.5左右,施S0对减少土壤氨挥发可能是有利的。DCD对尿素在土壤中水解具有显著抑制作用,但S0、DCD对尿素水解协同效应不明显,主要是由于该类型土壤中尿素水解和S0分解不同步,前者显著快于后者。为了发挥施S0在减少氮素流失效果,建议S0施用时间比尿素早2周左右。S0施用能显著延缓土壤铵态氮的硝化作用。因此,S0与DCD合理配合施用,对减少氮素向滇池水体迁移可能具有实践意义。  相似文献   

20.
硝化抑制剂对毛竹林土壤N_2O排放和氨氧化微生物的影响   总被引：4，自引：3，他引：1  
为了探索硝化抑制剂在毛竹生产中的施用技术,通过培养试验研究3,4-二甲基吡唑磷酸盐(DMPP)和双氰胺(DCD)两种硝化抑制剂对毛竹林施用尿素后土壤N2O排放、氮素转化和相关氨氧化细菌(AOB)、氨氧化古菌(AOA)群落结构和丰度的影响。试验设(1)对照(CK)、(2)单施尿素(Urea)、(3)尿素+1%DMPP(DMPP占总N的1%,下同);(4)尿素+1.5%DMPP;(5)尿素+10%DCD;(6)尿素+15%DCD等6个处理,测定N2O的排放动态以及气体排放转折点时的土壤特征指标。结果表明:与单施尿素相比,160 d的时间内两种DMPP用量处理的土壤N2O累积排放减排幅度均为54%,而10%DCD和15%DCD处理的土壤分别减少28%和41%。DMPP和DCD处理50 d和90 d时土壤的NH4+-N含量均显著高于(p0.05)单施尿素处理,而NO3--N含量和表观硝化率则恰好相反,但两种抑制剂间无差异。DMPP处理的AOB群落结构的变化从10 d开始显现,至50 d和90 d时仍保持明显的抑制状态,而DCD处理则至90 d时抑制作用基本消失。单施尿素AOB功能基因(amo A)的丰度均显著高于硝化抑制剂处理(90 d时尿素+10%DCD处理除外);在整个培养期内,尿素和对照土壤的AOA群落结构相似,硝化抑制剂反而增加了AOA功能基因的丰度,表明硝化抑制剂对AOA丰度无明显抑制作用。即两种硝化抑制剂主要通过抑制AOB起作用;调节土壤p H至中性范围,并在1%DMPP施用条件下,硝化抑制剂的抑制效果最显著。  相似文献   

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