Effect of Salinity and Nitrogen Status on Nitrogen Uptake by Tall Fescue Turf

ABSTRACT

Nitrogen (N) absorption is inhibited by root zone salinity, which could result in increased NO₃ leaching. Conversely, N absorption is enhanced by moderate N deficiency. Because turfgrasses are grown under N-limiting conditions, it is important to understand the interactive effects of salinity and N deficiency on N uptake. This study examined the effect of N status (replete versus deficient) and salinity on N (¹⁵NO₃ and ¹⁵ NH₄) uptake and partitioning by tall fescue (Festuca arundinacea Schreb.). Two cultivars (‘Monarch’ and ‘Finelawn I’) were grown in nutrient solution culture. Treatments included N level (100% or 25% of maximum N demand) and salinity (0, 40, 80, and 120 meq L^?1) in a factorial arrangement. Absorption of NO₃ and NH₄ was greater in low-N than in high-N cultures, but was reduced by salinity under both N treatments. Salinity reduced partitioning of absorbed N to leaves and increased retention in roots. These results suggest that turfgrass managers should consider irrigation water quality when developing their fertilizer program.     

不同盐分和氮肥水平对菠菜水分及氮素利用效率的影响

采用土柱栽培法研究了不同盐分和氮肥水平对菠菜水分与氮素利用效率的影响。结果表明,300 kg ha-1氮水平下,菠菜增产16.6%,水分利用效率(Water Use Efficiency,WUE)提高9.6%;其中以0.87 dS m-1处理的WUE最大,为25.8 kg m-3,盐分和氮肥的交互影响使WUE提高1.55 kg m-3。同时3,00 kg ha-1氮水平比100 kg ha-1氮水平的氮素利用效率(Nitrogen UseEfficiency,NUE)平均降低40%。盐分增加,NUE降低。高盐高氮处理的氮肥回收率(Nitrogen Fertilizer Recovery Efficiency,NRE)和农业氮利用效率(Agronomic Nitrogen Use Efficiency,NAE)最低,土壤残留氮量最高,对环境造成的潜在危害最大。     

Interactive Effect of Sulfur and Nitrogen on Nitrogen Accumulation and Harvest in Oilseed Crops Differing in Nitrogen Assimilation Potential

ABSTRACT

Field experiments were conducted to determine the interactive effect of sulfur (S) and nitrogen (N) on nitrogen accumulation, its distribution in various plant parts, and nitrogen harvest of oilseed crops viz. rapeseed (Brassica campestris L. cv. ‘Pusa Gold’) and taramira (Eruca sativa Mill.) differing in their N-assimilation potential. Two combinations of S and N (in Kg/ha): 0S + 100N (?S+N) and 40S + 100N (+S+N) were used. The results showed that combined application of S and N (+S+N) significantly (P < 0.05) increased the nitrogen accumulation in both the genotypes at all the growth stages compared with N applied alone (?S+N). This increase in nitrogen accumulation was due to the improvement in the reduction of nitrate into reduced nitrogen as evident from higher nitrate reductase (NR) activity in the leaves of plants grown with both S and N, compared with N alone. Nitrate-N content in the leaves of plants grown with only N (?S+N) was higher compared to those grown with both S and N (+S+N), showing that combined application of S along with N (+S+N) appreciably reduced the nitrate content in the leaves due to higher NR activity. This decline in nitrate (NO₃ ^?) was followed by an overall increase in N-accumulation in the plants. Consequently, the nitrogen content in the plant was increased by 29–148% in rapeseed and 38-166% in taramira with +S+N treatment. Combined application of S along with N (+S+N) also increased seed protein content and nitrogen harvest index of both the genotypes. It is concluded that combined application of S along with N (+S+N) not only increased the N-accumulation, but also its mobilization towards economic sinks.     

Effect of Sodium Chloride Salinity on Growth and Ion Accumulation in Some Halophytes

Abstract

Effects of salinity on biomass production, water content, and ion accumulation pattern in Atriplex amnicola P. G. Wilson, Atriplex calotheca L., Atriplex hortensis L., Chenopodium album L., Salsola kali L., and Suaeda nudiflora Moq. (all Chenopodiaceae) have been studied. The plants survived and exhibited no toxicity symptoms up to 6000 mg L^?1 NaCl treatment. Ion composition was variable in plants grown under different salinity treatments. Salinity, except in Suaeda nudiflora where the least biomass was produced in control, affected all other species negatively, and they produced the least biomass at high salinity treatment. Shoot water content of Suaeda nudiflora and Chenopodium album increased significantly in response to salinity. Among all the species examined here, maximum sodium (Na⁺) accumulation was recorded for Suaeda nudiflora, and it increased with the increasing salinity. This study concluded that among all the species tested, Suaeda nudiflora was most suitable plant for bioremediation of salt‐contaminated soils.     

Effect of Nitrogen Fertilizers on Zinc Accumulation in Fescue

Abstract

This research evaluated effects of nitrogen fertilizers on availability of zinc (Zn) in soils. Two slit loams of the Hadley series (Typic Udifluvents) were used. Zinc sulfate was mixed with the soils to give Zn at 125, 250, 500, or 1,000 mg/kg and incubated for 14 days. Fertilizers (compost, cow manure, urea) were mixed with the soils to supply N at 200 mg/kg. Fourteen days after the fertilizers were mixed with the Zn‐treated soils, soil samples were taken for analysis of plant‐available Zn by extraction with Morgan's solution or water. After the soil samples were taken, fescue (Festuca arundinacea Schreb.) seeds were placed into pots to assess germination, growth, and Zn accumulation. Higher concentrations of Morgan's extractable Zn were detected in soils treated with compost (201 mg/kg) than with calcium nitrate (179 mg/kg), manure (153 mg/kg), or urea (152 mg/kg). However, with water extraction, higher Zn concentrations were detected in soils treated with calcium nitrate (36 mg/kg) with the lowest concentrations being extracted from soils treated with urea (8 mg/kg). Extraction of Zn by Morgan's solution or water increased as the soil‐Zn levels increased. Fescue germinated and grew at all of the soil‐Zn levels. The highest concentration of Zn occurred in plants grown in soils amended with calcium nitrate or urea, and the lowest concentration was in plants grown in soils amended with compost or manure. Fescue grown in soils amended with urea had the largest dry mass, and plants grown with compost or manure had the smallest. Zinc concentration and accumulation for fescue shoots increased as the soil‐Zn levels increased. These results suggest that accumulation of Zn in fescue can be enhanced by selection of nitrogen‐containing fertilizers that affect the solubility of Zn in soils.     

氮水平对桤木属幼苗根系形态及氮累积利用影响

采用温室沙培试验,通过不同浓度氮处理,研究红桤木、喜马拉雅灰桤木、欧洲桤木和灰桤木4种国外引种的桤木属幼苗对不同氮水平的响应差异,分析了氮胁迫对桤木属幼苗根系形态和氮累积利用的影响.结果表明:随着氮水平(N0、N1/2、N1(标准E.G.Bollard营养液)、N2)的增加,各桤木属植物的生物量、氮累积量和根长、根体积、根表面积、须根数等生长参数均呈先增后降的趋势,且在N1/2水平中各参数值最大;细根比例及氮利用效率、氮利用率均呈持续下降趋势.参试的4种桤木中欧洲桤木、红桤木的生物量、氮累积量、根系形态参数均较高,且在N1/2时氮利用率较高,分别为44.57％、40.14％,具有在我国长江中下游地区作为生态防护和短周期工业用材树种推广应用潜力;灰桤木和喜马拉雅灰桤木各生长参数均较低,不宜推广.试验结果也表明尽管桤木属植物具有一定的固氮能力,但在低地力河滩沙地、丘陵等地区集约化经营中仍需采取一定施肥措施.     

Salinity effects on growth,proline and ion accumulation in strawberry plants

Abstract

Freeze tolerance of red raspberry cultivars and selections, including one specimen each from eight indigenous Norwegian Rubus idaeus L. populations, showed that there were significant differences in bud survival and tissue browning in a two-year test at Stj?rdal, Norway. Selections from the Norwegian breeding program and the Norwegian cultivar Balder had the most freeze-tolerant buds at the May screening in both years, while the Norwegian cultivar Vene was tolerant in one year. The cultivars Malling Admiral, Nootka, Chilcotin, Glen Isla and Gradina were tolerant in one of the years but not in the other. Meeker, Glen Moy, Skeena, Glen Prosen, Malling Joy, Malling Leo and Malling Orion were not tolerant in either year. The selections from indigenous Norwegian Rubus idaeus were all freeze-tolerant in one year, but less tolerant than the best the other year. Tissue browning was preferred as a screening test for freeze injury in midwinter, while bud growth is preferable in spring.     

膜下滴灌条件下不同土壤盐度和施氮量对棉花生长的影响

通过盆栽试验研究了膜下滴灌条件下不同土壤盐度水平和施氮量对棉花生长的影响。研究结果表明低盐度处理,随着施氮量的增加棉花株高显著增加;而在土壤盐度较高的条件下棉花株高则随着施氮量的增加显著降低。棉花籽棉和总干物质重随土壤盐度的增加显著降低,合理的施用氮肥可显著提高籽棉重和总干物质积累量。棉花的氮素吸收量受盐分、施氮量和盐氮交互作用影响显著。随着土壤盐度的增加,棉花氮素吸收量显著降低。在低盐度条件下,增加氮肥施用量可显著提高棉花的氮素吸收量;中量盐度下,适量的氮肥施用可显著提高棉花的氮素吸收量,但施用量过大并不能增加棉花的氮素吸收量;高盐度条件下,盐分是限制棉花生长和氮素吸收的主要因素,施用氮肥对棉花的氮素吸收量无显著影响。     

模拟盐度变化对人工湿地脱氮除磷效果的影响

为探究人工湿地处理含盐生活废水的可行性,本研究构建了小尺度的人工湿地模拟系统,比较了不同盐度(0.0%、0.5%、1.0%、1.5%、2.0%)下人工湿地芦苇的生长情况以及几种典型污染物的去除效果。结果表明:①盐度对人工湿地中芦苇生长的影响表现出"低盐促进"、"高盐抑制"的特点,在0.5%进水盐度下,芦苇有最高株高1.22 m和最大基径0.48cm;②人工湿地对COD的去除率总体表现为随盐度的升高先升高后降低,在盐度为0.5%时,COD去除率达到最高84.86%;③当进水盐度为0.5%时,人工湿地对氮磷的去除几乎没有受到盐度的抑制;当进水盐度高于1.0%,随着盐度的升高,TN(总氮)、NH_4~+-N、NO_3~–-N、TP(总磷)的去除率均显著降低(P0.05),在2.0%盐度下分别下降到了44.40%、58.89%、49.23%、49.49%,相较0.0%盐度时分别降低了38.5%、23.4%、23.8%、19.2%。④不同污染物受盐分抑制程度不同,氮比磷更容易受到盐分的抑制,NH_4~+-N比NO_3~–-N更容易受到盐分的抑制。     

不同水分条件下葡萄临界氮稀释曲线模型的建立及氮素营养诊断

以1a生葡萄植株“红提”为试材,在Venlo型试验温室内进行土壤水分和施氮量双因素区组试验。试验设置4个灌水水平,分别为正常灌溉量W1（田间最大持水量的70%～80%）、轻度水分胁迫W2（60%～70%）、中度水分胁迫W3（50%～60%）和重度水分胁迫W4（30%～40%）;设置4个施氮水平,分别为1.5倍推荐施氮量（N1,25.5g plant-1）、正常推荐施氮量（N2,17g plant-1）、0.5倍推荐施氮量（N3,8.5g plant-1）和不施用氮肥（N4,0g plant-1）。每10d观测一次植株体内氮浓度和植株地上部生物量,利用不同水分条件下葡萄植株在一定生长时期内所获最大生物量时对应的最小氮浓度值即临界氮浓度（Nc）构建葡萄临界氮浓度稀释曲线模型,并在此基础上建立氮素吸收模型（Nupt）和氮素营养指数模型（NNI）,对不同水分条件下葡萄氮营养状况进行定量诊断。结果表明：设施葡萄植株临界氮浓度与地上部生物量存在幂函数关系,随着灌水量的增加,葡萄植株临界氮浓度值增大,氮素吸收量及地上部生物量也呈增加趋势;在W1、W2水分条件下,葡萄植株生物量随施氮量增加而增加,而W3和W4处理葡萄生物量随施氮量增加呈先增后降的趋势;在相同水分条件下,氮浓度随施氮量增加而增加,随葡萄生长进程而降低;利用Nupt和NNI模型可对植株体内氮营养元素亏缺与否进行有效诊断。     

腐植酸与氮肥互作对烤烟生长和氮素吸收的影响

采用盆栽试验,研究了腐植酸的三个水平(H1:0 mg kg~(-1)、H2:300 mg kg~(-1)、H3:900 mg kg~(-1))与氮肥三个水平(N1:0mg kg~(-1)、N2:40 mg kg~(-1)、N3:120 mg kg~(-1))互作对烤烟品种中烟100生长和氮素吸收的影响。结果表明,腐植酸与氮肥互作对烤烟干物质和氮素积累的影响达到极显著水平(P0.01)。其中腐植酸用量H2、H3与氮肥N2、N3互作时,与H1N1(CK,不施肥)相比,H2N2、H2N3、H3N2、H3N3处理的烤烟干物质积累量分别提高了97.6%、89.7%、77.7%和114.4%,氮素积累量提高了1.7、1.2、1.1和2.0倍;H3(900 mg kg~(-1))与N3(120 mg kg~(-1))二者互作效果较好。     

Soil Plus Foliar Nitrogen Application increases Cotton Growth and Salinity Tolerance

Soil or foliar application of nitrogen (N) can increase plant growth and salinity tolerance in cotton, but a combination of both methods is seldom studied under salinity stress. A pot experiment was conducted to study the effects of soil application (S), foliar application (F), and a combination of both (S+F) with labeled nitrogen (¹⁵N) on cotton growth, N uptake and translocation under salinity stress (ECe = 12.5 dS m^?1). Plant biomass, leaf area, leaf chlorophyll (Chl) content, leaf net photosynthetic (Pn) rate, levels of ¹⁵N and [Na⁺] and K⁺/ Na⁺ ratio in plant tissues were determined at 3, 7, 14 and 28 days after N application (DAN). Results showed that soil or foliar nitrogen fertilization improved plant biomass, leaf area per plant and leaf photosynthesis, and a combination of soil- plus foliar-applied N was superior to either S or F alone under salinity stress. Although foliar application favored a rapid accumulation of leaf N and soil application a rapid accumulation of root N, S+F enhanced N accumulation in both leaf and root under salinity stress. The combined N application also maintained significantly greater [K⁺] and K⁺/Na⁺ than either soil or foliar application alone. Therefore, the improved plant growth and salinity tolerance under S+F relative to soil or foliar N application alone was attributed to the increased total uptake of N, balanced N concentrations in different tissues through enhanced uptake and accumulation in both leaves and roots, and higher ratio of K⁺/Na⁺.     

不同氮素供应对烟草品质指标的影响

用盆栽试验研究了不同氮形态和不同氮浓度对烟草钾、氯、总糖和烟碱等品质指标的影响。两种氮形态均有助于叶片钾和氯的积累,铵态氮有助于增加氯的积累,硝态氮更有利于钾的积累。铵态氮有利于总糖提高,其比例超过硝态氮时不利于烟碱含量的提高。任何铵/硝比下,氮浓度增加均会降低糖/烟碱比。下部叶对氮的反应不同于上部和中部叶,也是其烟叶品质不同于上部和中部叶的内在原因。     

氮磷钾对桔梗干物质积累及桔梗皂苷D含量的影响

采用3因素3水平的盆栽正交试验研究了不同浓度N(7.5、15、30 mmol L-1)、P(0.5、2、4 mmol L-1)和K(3、6、18 mmol L-1)营养液配比对桔梗干物质积累、养分吸收利用及桔梗皂苷D含量的影响。结果表明:在N_3、P_2、K_2水平处理下桔梗叶片光和色素含量及净光合速率各自达到最大值。随着栽培时间的延长,桔梗根部干物质及N、P、K积累量逐步增加,桔梗皂苷D含量则先下降后上升,但均在10月份显著升高。N、P、K肥对桔梗干物质积累及桔梗皂苷D含量的影响顺序为氮肥钾肥磷肥。10月收获时,分别在N_2、P_2、K_2水平处理下,桔梗根部干物质积累量及桔梗皂苷D含量最大。全生育期内桔梗植株对N、P、K的吸收量为101.93、86.24、158.10 mg plant-1。且春夏季N、P、K营养在桔梗地上部分高于地下部分,而秋季营养物质向根部集中。结论:桔梗植株全生育期内对氮、钾肥需求较多,且氮肥对桔梗的生长影响最大,每生产100 kg桔梗干物质需N、P_2O_5、K_2O的比例为1∶0.90∶1.27。     

Phytoextraction of Zinc by Indian Mustard and Tall Fescue

Abstract

This experiment evaluated the capacity of two species, Indian mustard (Brassica juncea Czern.) and tall fescue (Festuca arundinacea Schreb.) to extract zinc (Zn) from soils. Also, this experiment focused on using nitrogen (N) fertilizers to increase the phytoextraction of Zn. Two soils of the Hadley series (Typic Udifluvents) were studied. A treatment array of Zn concentrations in soils was supplied as zinc sulfate. Nitrogen was supplied at 200 mg N/kg of soil as calcium nitrate, urea, or compost. Two successive plantings of Indian mustard in the same media were grown until flowering and harvested. Fescue was grown from seeding to a height of 15 cm, harvested, grown again in the same media to a height of 15 cm, and harvested again. After the second harvests of Indian mustard and fescue, soil samples were taken for analysis of extracts with water and with Morgan's solution. Indian mustard was grown with Zn additions ranging from 0 to 100 mg/kg soil. The shoot mass of Indian mustard in both harvests increased to a soil‐Zn level of 25 mg/kg and then decreased. Although growth decreased as the soil‐Zn levels increased beyond 25 mg/kg, Zn concentration and total accumulation increased linearly as the soil‐Zn levels increased. Zinc concentration and accumulation in Indian mustard were highest in soils amended with urea and were lowest in soils with no fertilizer. Fescue was grown with Zn additions ranging from 0 to 1000 mg/kg soil. The shoot mass of fescue increased to a soil‐Zn level of 125 mg/kg (harvest 1) or 250 mg/kg (harvest 2) and then decreased as the soil‐Zn levels increased. Concentration and accumulation of Zn in fescue increased linearly as the soil‐Zn levels increased. Zinc concentration and accumulation were highest in fescue grown in soils amended with urea and lowest in soils with no fertilizer. The highest accumulation of Zn in fescue (3800 mg/pot) occurred at 1000 mg Zn/kg soil. Highest concentrations of soil Zn were extracted with Morgan's solution or water from soils amended with urea, regardless of the species grown in the soils. Lowest concentrations of Zn were extracted from soils with no fertilizer added, regardless of extract or species. In general, if fertilizers (calcium nitrate, urea, or compost) were added to the soils, the pH decreased. Fescue was easy to grow, tolerated much higher soil‐Zn levels than Indian mustard in this research, and could be a species useful for phytoextraction of Zn.     

不同氮形态对两种基因型水稻根系形态及氮吸收效率的影响

为了探索不同铵硝配比对水稻根系形态和地上部N累积量的影响及其与根系吸N量的关系,以苗期N高效品种桂单4号和N低效品种南光为材料,设置1.0mmol/L NO3--N、0.5mmol/L NH4NO3、1.0mmol/L NH4 -N 3个N处理开展了研究.结果表明:含有NO3--N的处理总根长、总根数和总根表面积均明显高于NH4 -N的处理,且桂单4号和南光两种基因型水稻之间存在差异.两品种均在0.5 mmol/L NH4NO3处理中根系吸N量最高,其次是1.0 mmol/L NH4 -N处理,1.0 mmol/L NO3--N的处理根系吸N量最少.     

液培条件下氮素形态和化控技术对蔬菜硝酸盐累积的影响

以生菜和青菜作为供试材料,在液培条件下,研究了不同形态N素对蔬菜硝酸盐累积的影响,同时观测了叶面喷施两种低硝酸化剂的化控技术对降低蔬菜硝酸盐积累的效果.研究结果表明:N素形态对生菜的生长和硝酸盐的积累影响显著,而对青菜的影响不显著;相同形态N素供应时,青菜叶片中硝酸盐含量显著高于生菜中的含量,硝酸盐的积累取决于不同蔬菜品种的遗传特性.青菜和生菜叶面喷施两种低硝酸化剂对降低蔬菜中硝酸盐含量的作用不显著.     

Endophyte Effects on Nutrient Acquisition in Tall Fescue Grown in Andisols

ABSTRACT

An experiment was conducted to evaluate the effect of endophyte Neotyphodium coenophialum (Morgan-Jones and Gams) Glenn, Bacon, and Hanlin on the mineral content of tall fescue (Lolium arundinaceum Schreb., SJ Darbyshire) ecotypes (Fukaura, Koiwai, and Showa) grown on two Andisols (Black Andisol and Red Andisol) with different fertilities. Black Andisol, with a naturally low content of phosphorus, was high in other nutrients, while Red Andisol, with a naturally high content of phosphorus, was low in other nutrients. Shoot dry weight was significantly higher in endophyte-infected (E+) than endophyte-free (E?) plants grown in Black Andisol. On the other hand, in Red Andisol, only Fukaura showed higher shoot dry matter production in E+ plants as compared to E- plants. In general, greater concentrations of phosphorus and manganese were found in endophyte-infected (E+) plants than non-infected (E?) plants. Accumulation of all nutrients in E+ plants was remarkably higher than in E? plants. Excluding the plant ecotype effect, the nutrient concentration and accumulation pattern for plants in the two soils was different in E+ and E? plants. Plants growing in Black Andisol had greater concentrations of phosphorus (P), copper (Cu), and zinc (Zn) in E+ plants than those of E? plants whereas for plants in Red Andisol the reverse was true. Significantly higher concentration of manganese (Mn) was found in E+ plants irrespective of soils. Regardless of endophyte and ecotypes, plants grown in Black Andisol showed significantly higher values for both nutrient concentration and accumulation than those in Red Andisol. Apart from the plant ecotype Showa, all other ecotypes had the greatest accumulation and concentration of phosphorus in E+ plants. In two types of soil and among the three plant ecotypes, endophyte infection had different effects on nutrients acquisition. Giving emphasis on nutrient accumulation, endophyte played an overall negative role on plants grown in Red Andisol. There may be a metabolic cost of harboring endophytes offset its benefit in Red Andisol. Since the same species of endophyte infected all three ecotypes, our results show that the host/endophyte interaction depends on plant ecotype as well as the ability of the soil to supply nutrients.     

氮素营养对单作和间套作小麦氮素吸收、同化和籽粒蛋白质含量的影响

本研究通过在栗钙土上设置田间试验。研究结果表明:开花期小麦不同器官中氮的积累量随着施氮量的增加而增加,以叶片中积累的氮素量最高,其次为穗>茎>叶鞘,但当施氮量达到450kg/hm2时,单作小麦叶片和间套作小麦叶鞘、茎、穗氮的积累量减少,而且间套作小麦相同施氮量各器官的氮素积累量大于相应单作小麦各器官的氮素积累量。成熟时小麦各营养体氮积累量随着施氮量的增加而增加,颖壳+穗轴氮积累量最多,其次为茎>叶鞘>叶;成熟时籽粒氮素的吸收积累量随着施氮量的增加而增加,间套作小麦籽粒氮素的吸收积累量大于相同施氮量单作小麦氮素的吸收积累量。在同一施氮水平下,间套作小麦花前氮同化量和总氮同化量都大于相应单作小麦,而间套作小麦花后氮同化量却小于相应单作小麦;单作和间套作小麦总氮同化量与其蛋白质含量之间呈显著正相关(r分别为0.936 ,0.987 )。     

若尔盖高寒沼泽湿地退化过程中土壤有机氮组分的演变特征

为明确湿地退化过程中土壤有机氮组分的变化及其生物有效性,采用实地采样调查、室内分析与数理统计法,研究若尔盖自然湿地保护区内相对原生沼泽(RPM)向轻度退化沼泽(LDM)、中度退化沼泽(MDM)、重度退化沼泽(HDM)退化过程中土壤有机氮组分的演变特征及与有效氮的耦合关系。结果表明,当沼泽发生中度、重度退化时,土壤全氮(TN)含量分别降低33.4%～77.8%、69.4%～93.7%(P0.05),碱解氮(AN)含量分别降低36.8%～80.2%、57.6%～82.2%(P0.05)。4类湿地土壤的酸解氨态氮、氨基酸态氮、未知态氮含量均按RPM、LDM、MDM、HDM的顺序降低。与RPM相比,HDM土壤酸解氨态氮与未知态氮含量分别降低66.3%～70.8%、62.2%～78.4%(P0.05),MDM和HDM土壤氨基酸态氮含量分别降低47.2%～68.6%、85.7%～86.7%(P0.05)。氨基糖态氮含量随着湿地退化先升高后降低。随着湿地退化程度的加剧,氨基糖态氮与酸解氨态氮占全氮的比例上升,而氨基酸态氮的比例下降。酸解氨态氮和未知态氮分别是影响RPM和HDM土壤碱解氮含量的主要有机氮组分,LDM与MDM土壤碱解氮含量却主要受有机氮组分中氨基酸态的控制。若尔盖湿地退化降低了土壤全氮及酸解组分氮含量,减弱了土壤氮"汇"功能,改变了有机氮组分对氮素有效性的贡献。