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1.
浮萍对稻田田面水中氮素转化与可溶性氮的影响 总被引：1，自引：0，他引：1
浮萍是稻田田面水中大量存在的典型水生植物，本试验采用室内培养的方法，以采自浙江省嘉兴市双桥农场的青紫泥水稻土为例，探讨了不同初始密度的浮萍对稻田施尿素后田面水尿素水解及可溶性氮浓度的影响。结果表明，浮萍可明显加快田面水尿素态氮的水解过程，对照、低浓度浮萍（D1）和高浓度浮萍（D2）处理中尿素水解速率常数k分别为0．02，0．03，0、04／h；试验前期，浮萍将大量的铵态氮（NH4^＋-N）吸收同化后储存于体内．而从第12天（D2处理）和15天（D1处理）开始，由于浮萍的释氮作用导致田面水中NH4^＋-N浓度逐步回升，同时硝态氮（NO3^--N）浓度也明显增加，说明浮萍在田面水氮索浓度较高时可大量积累氮索而浓度较低时可以向田面水中释放氮素，这有利于降低施肥初期田面水氮素流失潜能和保证施肥后期作物的氮营养供应。 相似文献
2.
养分流失和重金属积累是沼液还田资源化利用过程中的主要问题。为探讨利用浮萍吸收氮磷、富集重金属的能力调控沼液施用中环境污染问题的可行性,在上海市金山区开展了水稻田间试验,研究沼液施用条件下添加浮萍对稻田氮素流失和Cu、Pb的影响。试验设置4个处理:常规化肥、常规化肥+浮萍、沼液全量替代化肥和沼液全量替代化肥+浮萍,测定并比较了不同处理下稻田田面水氮素浓度变化、径流水氮素流失负荷,土壤、水稻籽粒及秸秆中Cu和Pb含量差异。结果表明:不同处理田面水总氮、铵态氮(NH_4~+-N)浓度变化趋势基本一致,均在每次施肥后第1d达到峰值,此后逐日递减,在施肥后第5d降至峰值的30%以下;硝态氮(NO_3~–-N)浓度峰值滞后3～7 d。稻田中添加浮萍能够显著降低田面水TN含量,沼液全量替代化肥+浮萍处理的TN总径流流失负荷为3.67 kg·hm~(-2),比常规化肥处理显著降低37.2%。沼液全量替代化肥+浮萍处理土壤Cu和Pb含量为22.65mg·kg~(-1)和49.05mg·kg~(-1),与其他处理间无显著差异;但土壤有效态Cu和Pb含量较常规化肥处理显著提高18.6%和17.5%。不同处理水稻秸秆Cu和Pb、籽粒Pb含量无显著差异,但沼液全量替代化肥+浮萍处理水稻籽粒Cu含量较沼液全量替代化肥处理显著减少41.1%。综上,沼液施用条件下添加浮萍可以降低稻田氮素流失,在控制土壤、籽粒和秸秆中重金属Cu和Pb含量增加方面具有一定效果,在短期内可以作为沼液还田模式下水体和土壤污染有效的调控手段。 相似文献
3.
为明确氮素形态及其配比对三七根腐病发生的影响,采用盆栽试验,研究了5种不同氮素形态配比(铵硝配比分别为0∶100、25∶75、50∶50、75∶25和100∶0)及尖孢镰刀菌(Fusarium oxysporum)侵染对三七[Panax notoginseng (Burk.) F. H. Chen]生长、有效成分以及抗性指标的影响。结果表明,不同氮素形态配比对三七生物量和皂苷含量无明显影响,铵态氮(${NH_{4}}^{+}-N$)可促进可溶性糖的累积;病原菌侵染使三七叶绿素、可溶性糖和黄酮含量降低,随着${NH_{4}}^{+}-N$比例的增加,病情指数增加,过氧化物酶(POD)、多酚氧化酶(PPO)和苯丙氨酸解氨酶(PAL)活性升高,同时伴随酚类和木质素的累积。综上所述,低铵硝配比(特别是25∶75)有利于三七的生长,可降低三七病情指数,减轻三七根腐病的发生。本研究从氮肥施用层面为三七根腐病的防控提供了理论依据。 相似文献
4.
秸秆还田配施氮肥对稻田增产及田面水氮动态变化的影响 总被引：6，自引：1，他引：5
针对我国南方稻田氮素流失污染严重问题,为明确高产稻田秸秆还田下氮肥施用效应,采用田间试验,研究秸秆全量还田下不同氮肥用量对水稻产量及稻田田面水氮素动态变化的影响,以期为长江下游径流易发地区探寻兼顾产量与环境效益的秸秆还田配施氮肥措施。结果表明:(1)秸秆还田下配施氮肥可显著提高水稻产量,但当氮肥用量过高则增产效应降低,连续秸秆还田4年以上可以发挥秸秆部分替代氮肥的增产效应;(2)稻田田面水总氮TN、NH_4~+-N在每次施肥后1～2 d达到峰值,之后迅速下降至相对低浓度水平,施肥后一周内是氮素径流损失的风险期,秸秆还田可有效降低水稻生育前期稻田田面水TN浓度,但同时一定程度增大了可溶性有机氮(DON)的流失潜力;(3)秸秆还田下搭配减氮施肥(SN1)较推荐氮肥(SN2)与常规施肥(SN3)可分别减少25%、40%氮肥用量,同时可分别降低田面水中9.6%、20.8%TN含量(P 0.05),是兼顾产量与环境效益的最佳措施。因此,推荐长江中下游径流易发的水稻种植区,对秸秆长期全量还田,配施氮肥用量180～225 kg·hm~(–2)。 相似文献
5.
为了明确掺混控释肥侧深施对稻田氮素损失的控制效果,采用大田试验,以武运粳23号为试验材料,通过设置无机化肥常规用量分次施用(CN)、掺混控释肥梯度减量一次性基施(常规用量、减量10%、减量20%和减量30%)共5个处理,研究了掺混控释肥(RBB)减量对太湖地区稻田田面水不同形态氮素浓度的影响及产量效益。结果表明,与无机化肥常规用量分次施用CN处理(270 kg/hm~2)相比,RBB减量10%～30%不会造成水稻减产。田面水氮素以铵态氮为主,无机化肥施用后田面水氮素浓度在施肥后1～2 d即达到峰值浓度,此后逐渐下降;掺混控释肥处理的3个肥期田面水氮素峰值浓度较低,均显著低于CN处理。由于田面水氮素以铵态氮为主,因此总氮均值浓度降低幅度与铵态氮较一致。其中,基肥期、蘖肥期、穗肥期田面水总氮均值浓度两年降低幅度分别为87.19%～93.87%(2015年)和76.93%～83.48%(2016年),69.74%～79.73%(2015年)和74.46%～87.52%(2016年),94.43%～96.69%(2015年)和95.52%～96.57%(2016年)。RBB减量能够降低前期(基肥期和蘖肥期)田面水氮浓度,总体呈随用量减少而降低的趋势。但减量幅度相近处理的田面水氮素浓度未呈现一致性规律变化。结果说明,RBB施用减少了太湖地区稻田肥期氮素流失风险,RBB肥料用量为189～216 kg/hm~2能够在保证水稻产量的前提下降低前期田面水氮素浓度,减少氮素流失风险。 相似文献
6.
为探究全球气候变暖对东北农田黑土氮、磷有效性的影响,该研究以东北农田黑土为研究对象,采用红外辐射增温技术模拟气候变暖（增温5 ℃）,将样地分为增温组（W）和对照组（C）来进行野外原位试验,通过测定土壤温度、土壤湿度、冻融循环次数、积雪厚度、冻结深度、铵态氮（ammonium N,${\rm{NH}}_4^+-{\rm{N}}$）、硝态氮（nitrate N,${\rm{NO}}_{3}^{-}-{\rm{N}}$）、全氮（total N,TN）、微生物量氮（microbial biomass N,MBN）、速效磷（available P,AP）、全磷（total P,TP）浓度,分析不同指标在冬季增温下的动态变化过程及其响应。结果表明：冬季增温显著提升土壤温度和含水率,进而增加土壤的冻融循环次数,并且减少了土壤积雪深度和冻结深度,使冻结时间点延后和融化时间点提前。增温组土壤相较于对照组,经过整个冬季后,土壤${\rm{NH}}_4^+ -{\rm{N}}$、${\rm{NO}}_{3}^{-}-{\rm{N}}$、TN、MBN和TP浓度分别降低126.38%、146.98%、51.23%、21.48%和12.61%, AP浓度提升了25.54%（P<0.05）。在冬季增温过程中,各时期土壤温度的提升会对土壤有效养分产生显著影响,导致在融化期氮素大量的流失。研究结果可为后续春季合理高效施肥,改善东北农田土壤质量提供理论基础。 相似文献
7.
通过田间小区试验,在施氮量180 kg/hm~2水平下,设置4个氮肥运筹比例,基肥∶分蘖肥∶穗肥的比例分别为10∶0∶0(T1),4∶3∶3(T2),2∶3∶5(T3),0∶3∶7(T4),研究氮肥后移对水稻产量形成和稻田田面水氮素动态变化的影响。结果表明:与氮肥全部作为基肥施用的处理相比,将前期氮肥的30%甚至50%后移到穗肥施用,对水稻产量没有明显影响,而氮肥后移70%至穗肥会使水稻产量显著下降。田面水中总氮(TN)和可溶性总氮(DTN)浓度在每次施肥后1天达到峰值,铵态氮(NH_4~+-N)浓度在基肥和分蘖肥后1天达到峰值,穗肥后3天达到峰值,随后逐渐降低至与不施氮肥处理相当。整个基肥期、分蘖肥后20天内和穗肥后9天内是防止稻田氮素流失的关键期。施尿素后,DTN是田面水氮素的主要部分,DTN以无机氮(IN)为主,而NH_4~+-N在IN中所占比例达64.0%以上。比较水稻生育过程中氮素流失风险期内的TN、DTN和NH_4~+-N三氮浓度,相比T1,T2的三氮浓度分别降低了2.9%,1.6%,3.1%,T3的三氮浓度分别降低了15.5%,14.7%,22.3%,T4的三氮浓度分别降低了16.1%,22.9%,34.1%,结合产量,确定基肥∶分蘖肥∶穗肥比例为2∶3∶5的氮肥后移措施能够在保证水稻产量不下降的同时,有效降低稻田氮素的流失风险。 相似文献
8.
聚天门冬氨酸钙盐对水稻田面水中三氮动态变化的影响 总被引：4，自引：3，他引：1
利用桶栽试验探究不同浓度水平的聚天门冬氨酸钙盐(PASP-Ca)对水稻田面水中铵态氮(NH_4~+)、硝态氮(NO_3~-)和总氮(TN)浓度动态变化的影响。结果表明,施氮后,田面水中TN、NH_4~+和NO_3~-分别于第1,3,9天达到最大值,随后逐渐降低。NO_3~-/TN多在0.1以下,(NH_4~++NO_3~-)/TN多在0.5以上。因此,可以将NH_4~+和TN作为农田水污染防治的主要监测指标,NO_3~-作为辅助指标。添加一定浓度的PASP—Ca能对田面水中氮素浓度的变化起到缓释作用,其中0.3%浓度水平的PASP—Ca效果相对较好,田面水中NH_4~+和TN的下降速率分别为3.452,4.806mg/(L·d),与单施氮肥(CK)相比,分别降低了11.68%和16.25%;同时,NH_4~+的平均浓度为6.999mg/L,较CK低了3.88%;NO_3~-的平均浓度为0.396mg/L,较CK低了24.83%;TN的平均浓度为20.077mg/L,较CK提升了3.10%。施氮后田面水中TN浓度随时间呈对数递减,而NH_4~+浓度在施氮后3天内随时间呈对数增加,之后随时间呈对数递减趋势。施氮后的9天内是防止稻田田面水中氮素流失的关键时期。 相似文献
9.
江汉平原稻田田面水氮磷变化特征研究 总被引：9，自引：1，他引：8
在江汉平原地区,因水肥管理粗放,特别是人为排放刚施肥泡田水,水稻种植引发的氮磷面源污染问题比较严重,迫切需要掌握稻田氮、磷动态特征,并据此进行科学的肥水管理。采用大田试验的方法,设置不同氮磷梯度,研究了江汉平原稻田田面水氮磷形态与浓度动态变化特征及施肥的影响。结果表明:施尿素后,田面水可溶性总氮(DTN)、可溶性有机氮(DON)和铵态氮(NH_4~+-N)占总氮(TN)的比例分别在88.0%、44.7%和31.6%以上,且随施氮量增加而增大;施磷肥后,田面水中颗粒态磷(PP)占总磷(TP)的比例为76%～93%,且随施磷量的增加而降低。田面水中氮素浓度与施氮量之间呈分段线性相关关系,当施氮量分别超过287.8、289.9、231.5和336.7kg·hm-2后,TN、DTN、NH_4~+-N和DON的浓度会跃增;田面水中各形态磷素浓度均随施磷量的增加而线性增加。施氮肥后,田面水中TN和DTN浓度均在施肥后1 d达到峰值,在基肥和分蘖肥后5 d、穗肥后2 d降低至与不施氮肥基本接近;NH_4~+-N浓度在基肥和分蘖肥后2d、穗肥后1d达到峰值,基肥和分蘖肥后5 d、穗肥后2 d后降低至与不施氮肥趋同。施磷肥后TP、PP和可溶性总磷(DTP)的浓度均在施肥后1 d达到峰值,3 d后急剧降低,降幅均在79.0%以上。可见,在江汉平原地区,施尿素后田面水中氮素以DTN为主,尤其是DON和NH_4~+-N,施磷肥后以PP为主。减少氮、磷肥用量可降低稻田氮、磷损失,且氮肥施用量应尽可能控制在231.5 kg·hm-2以内。施基肥和分蘖肥后5 d内、施穗肥后2 d内是江汉平原稻田氮素损失的关键控制期,施磷肥后3 d内是磷素流失的关键控制期。 相似文献
10.
生物炭施用对稻田氮磷肥流失的影响 总被引：3，自引：0，他引：3
针对宁夏引黄灌区稻田过量施肥导致土壤养分利用效率低的问题,通过田间小区试验,在优化施氮条件下(240kg·hm~(-2)),设4个生物炭水平(0、4500、9000、13500kg·hm~(-2)),研究施用外源生物炭对稻田氮磷流失和土壤养分含量的影响。结果表明:生物炭对稻田田面水氮素动态产生影响,表现为田面水中全氮、硝态氮含量随生物炭用量的增加而降低,铵态氮表现则相反;全氮和铵态氮的最大峰值出现在第1次追施氮肥后的第2天,最大值为34.86、8.28mg·L~(-1);硝态氮最大峰值3.31mg·L~(-1)出现在第2次追施氮肥后的第2天。随后均迅速下降,全氮含量在施氮肥后10d回到第1次追氮前的含量水平,并趋于稳定,铵态氮和硝态氮则在7d后。生物炭对田面水全磷未产生显著影响,全磷含量在第1次施氮肥后3d达到峰值,为3.69mg·L~(-1),之后迅速下降,6~7d后降至追氮前的含量水平,并趋于稳定。生物炭处理显著降低了稻田全氮流失量8.03%~13.36%,高量炭处理(13500kg·hm~(-2))显著提高了土壤全氮和有机质含量,提高幅度分别为41.2%和27.5%(P0.05)。说明生物炭对稻田磷流失、土壤全磷和速效磷含量无显著影响,对降低稻田氮素淋失表现出积极效果。 相似文献
11.
生物炭和其他有机土壤改良剂对Ustoxic Quartzipsamment土壤上植物养分有效性的影响 总被引：1，自引：0，他引：1
A sandy soil, Nampong soil(classified as Ustoxic Quartzipsamment), was incubated under controlled condition i) to compare the mineralization of major plant nutrients derived from different types of biochars and other organic soil amendments; ii) to examine their effects on soil properties and plant nutrient availability; and iii) to evaluate the plant nutrient losses in leachate from the rooting zone of soil incorporated with the different amendments. The experiment was arranged in a completely randomized design with 3 replications.Five treatments of soil amendments used were cassava stem base biochar(CSB), rice husk biochar(RHB), chicken manure(CM),compost(CP), and no amendment application(control). The RHB treatment released the highest amounts of mineralized NO-3-N,available P and K(2.30–17.26, 5.50–42.90 and 43.00–187.63 mg kg-1, respectively) while the CM treatment releasing the highest NH+4-N in the range of 1.86–53.67 mg kg-1. The CSB and RHB treatments showed better continuity of mineralization of nutrients than the treatments of CM and CP, particularly in the case of the CSB treatment. In the soil column incubation experiment, the amounts of NH+4-N and NO-3-N in all treatments barely changed on Day 1 to Day 30 of incubation and then the amounts increased markedly on Day 60. On Day 60, the RHB treatment contained a very high amount of NO-3-N( 250 mg kg-1). This suggests that N would become more available 30 d after the incorporation. The CM treatment gave the highest amounts of organic matter and available P in the ranges of 4.64–8.94 g kg-1and 14.41–36.33 mg kg-1, respectively, during the 60-d column incubation. The CSB treatment tended to have higher available K throughout the measuring period. The NO-3-N was leached from the soil column quite quickly on Day 1 of incubation while the loss of NH+4-N decreased slightly from Day 1 until the end of the measurement. The amounts of P and K losses varied with the type of soil amendments, and the pattern of the loss was irregular. 相似文献
12.
Few studies are conducted to quantify the effects of enhanced N deposition on soil nitrous oxide (N2O) emission and methane (CH4) uptake in the meadow steppe of Inner Mongolia,China.A two-year field experiment was conducted to assess the effects of nitrogen (N) deposition rates (0,10,and 20 kg N ha-1 year-1 as (NH4)2SO4) on soil N2O and CH4 fluxes.The seasonal and diurnal variations of soil N2O and CH4 fluxes were determined using the static chamber-gas chromatography method during the two growing seasons of 2008 and 2009.Soil temperature,moisture and mineral N (NH4+-N and NO3--N) concentration were simultaneously measured.Results showed that low level of (NH4)2SO4 (10 kg N ha-1 year-1) did not significantly affect soil CH4 and N2O fluxes and other variables.High level of (NH4)2SO4 (20 kg N ha-1 year-1) significantly increased soil NO3--N concentration by 24.1％ to 35.6％,decreased soil CH4 uptake by an average of 20.1％,and significantly promoted soil N2O emission by an average of 98.2％.Soil N2O emission responded more strongly to the added N compared to CH4 uptake.However,soil CH4 fluxes were mainly driven by soil moisture,followed by soil NO3--N concentration.Soil N2O fluxes were mainly driven by soil temperature,followed by soil moisture.Soil inorganic N availability was a key integrator of soil CH4 uptake and N2O emission.These results suggest that the changes of availability of inorganic N induced by the increased N deposition in soil may affect the CH4 and N2O fluxes in the cold semi-arid meadow steppe over the short term. 相似文献
13.
铁锰镁离子改性生物炭对溶液硝态氮的吸附性能研究 总被引：1，自引：0，他引：1
为突破生物炭对硝态氮吸附的局限性,以花生壳为原料,在600℃条件下热解制备生物炭(BC),分别用FeCl3、MnCl2、MgCl2对其进行金属负载改性(BC-Fe、BC-Mn和BC-Mg),设计批量吸附试验,结合扫描电镜(SEM)、傅里叶变换红外光谱(FTIR)和X射线衍射(XRD)等进行表征分析。结果表明,铁、锰、镁离子改性使生物炭的比表面积增大6.67~12.16倍,孔容增加3.30~6.00倍,并显著增强了对硝态氮($\text{NO}_{3}^{-}$-N)的吸附性能(P<0.05),吸附量较BC增加11.5%~17.1%,BC-Fe、BC-Mn和BC-Mg对$\text{NO}_{3}^{-}$-N的最大吸附量分别为41.58、39.04、39.58 mg·g-1,铁、锰、镁离子与炭的最佳质量比分别为0.80、0.20、0.20,铁离子改性效果最好;酸性条件有利于改性生物炭对$\text{NO}_{3}^{-}$-N的吸附,吸附动态符合Langmuir方程(R2=0.935~0.961),吸附过程符合准一级动力学方程(R2=0.971~0.980)。综上,通过金属离子改性,增大了生物炭的比表面积和孔容,优化了表面结构。此外,改性生物炭表面的含氧官能团和金属离子能通过形成氢键或静电作用吸附$\text{NO}_{3}^{-}$-N,进而增强对$\text{NO}_{3}^{-}$-N的吸附能力。本研究结果为生物炭吸附材料的制备及吸附性能优化提供了理论依据。 相似文献
14.
在尿素减量施用条件下,探究添加酸化沸石(SF)对氮素淋失及籽粒氮肥利用率的影响。通过等温吸附试验,结合土柱淋溶和玉米盆栽试验,研究酸化沸石对NH_4+—N和NO_3-—N的吸附性能,以及不同施氮梯度下,酸化沸石对氮素淋失和氮肥利用率的影响,试验分别设置农民习惯施肥(CN)、氮肥减量15%(CN1)、氮肥减量30%(CN2)3个施氮梯度并分别添加土重0.2%的酸化沸石(CN+SF、CN1+SF、CN2+SF)。结果表明,酸化沸石对NH_4+—N和NO_3-—N的最大吸附量分别为25.44,31.59 mg/g,吸附过程可用Langmuir模型较好拟合。在减氮15%和30%时,添加酸化沸石,使NH_4+—N累计淋失量较CN1、CN2分别降低7.10%,8.76%。在减氮30%时,酸化沸石可有效降低NO_3-—N累计淋失量,较CN2处理减少15.90%。酸化沸石可有效提高土壤氮素含量和玉米籽粒氮肥利用率,添加酸化沸石(CN+SF、CN1+SF、CN2+SF)较单施尿素(CN、CN1、CN2)籽粒氮肥利用率分别提高10.37%,20.79%,47.14%。综上,酸化沸石在减施尿素条件下可有效降低土壤氮素淋失,提高玉米籽粒氮肥利用率,具有一定的农艺价值。 相似文献
15.
Masato Kamisako Hiroyuki Sase Taeko Matsui Hiroko Suzuki Akiomi Takahashi Takuji Oida Makoto Nakata Tsumugu Totsuka Hiromasa Ueda 《Water, air, and soil pollution》2008,195(1-4):51-61
Fluxes of major ions in rainfall (RF), throughfall plus stemflow (TF + SF), and stream water (SW) were measured for five water years in a small catchment of a Japanese cedar forest near the Sea of Japan. The fluxes of most ions in RF and in TF + SF, including the non-sea-salt constituents, increased from late autumn to midwinter owing to the seasonal westerly wind. The concentrations of most ions in SW showed no obvious seasonal trend during the study period, whereas ${\text{NO}}_3 ^ - $ concentrations were lowest in summer, with a small seasonality. The Ca2+ and Mg2+ outputs in SW were approximately 3.7 and 1.8 times the TF + SF inputs of these cations, respectively. The large net outputs of base cations in the catchment may indicate a decrease in the soil's acid-neutralizing capacity. Annual dissolved inorganic nitrogen inputs in RF and in TF + SF were 17.7 and 17.9 kg N ha?1 year?1, respectively, which exceeded previously published thresholds in Europe and the U.S. (i.e., the values at which these inputs increased ${\text{NO}}_3 ^ - $ levels in SW) and equaled the highest level of nitrogen deposition previously reported in Japan. The ${\text{NO}}_{\text{3}} ^{\text{ - }} $ concentrations in SW were relatively high even in summer. During high-precipitation events, ${\text{NO}}_{\text{3}} ^{\text{ - }} $ concentrations in SW increased with increasing water discharge, and the pH decreased simultaneously during several events. Nitrogen deposition may contribute to the high ${\text{NO}}_{\text{3}} ^{\text{ - }} $ concentrations in SW and the temporary acidification that occurred during the rain events. 相似文献
16.
Junhong Bai Haifeng Gao Wei Deng Zhifeng Yang Baoshan Cui Rong Xiao 《Biology and Fertility of Soils》2010,46(5):525-529
Few studies have been carried out on nitrification potential of marsh soils in natural saline wetlands with high alkalinity.
The nitrification potentials of a closed wetland and an open wetland were monitored by an aerobic incubation at 25°C for 28 days.
The relative nitrification index
( RNI,\frac\textNO3- \text - NNO3- - N + NH4+ - N ) \left( {{\hbox{RNI,}}\frac{{{\text{NO}}_3^{-} {\text{ - N}}}}{{{\hbox{NO}}_3^{-} {\hbox{ - N}} + {\hbox{NH}}_4^{+} {\hbox{ - N}}}}} \right) rapidly increased with time in both wetlands and decreased with depth in soil profiles in both wetlands within the first
21 days. Nitrification proceeded much faster in the closed wetland than in the open wetland. The higher rate of nitrogen removal
in closed wetlands than open wetland was probably due to the fast nitrification followed by denitrification or leaching loss. 相似文献
17.
高肥力稻田分次施氮对氮素淋失的影响 总被引：8，自引：5，他引：8
通过自行设计的渗漏计研究在控水灌溉条件下稻田不同氮肥处理氮素淋失的动态规律,结果表明:在水稻整个生育期间,渗漏水中铵态氮、硝态氮保持较低的浓度,均小于1mg/L,但对硝态氮而言,仍是氮素淋失的主要类型。从总的趋势来看,渗漏水中氮素浓度随施肥量增加而增加。每次施肥后,不同处理渗漏水中的NO3--N浓度均表现为短期内迅速上升、后期逐渐下降的趋势,其中NH4 -N浓度与NO3--N消长规律相似,但表现出峰值超前的特征。各小区渗漏计中NH4 -N、NO3--N及TN累积渗漏量与施肥量之间存在显著相关性,R2分别达到0.933*,0.984**和0.982**。另外从环境和经济角度考虑,建议在土壤质地粘重、基础肥力较高的水稻土施肥量控制在75～150kg/hm2为宜,控制氮素淋失主要时期为施肥后一周内,特别在基肥施后尤为关键。 相似文献
18.
炭基肥和竹炭对土壤氮素淋失和微生物的影响 总被引：1，自引：0，他引：1
为了研究竹炭和炭基缓释肥添加对毛竹林土壤氮素流失和细菌群落结构的影响,采用室内土柱淋溶试验,测定了淋溶水中NH_4+—N和NO_3-—N浓度,分析了细菌群落多样性和组成。结果表明,与对照相比,炭基缓释肥的添加可以使土柱NH_4+—N和NO_3-—N累积淋溶量分别降低12.5%和13.6%。此外,竹炭的添加可以显著降低NH_4+—N累积淋溶量(P<0.05),但是对NO_3-—N的影响不显著。炭基缓释肥的添加可以增加土壤Nitrospira(硝化螺菌属)、Nitrosospria(亚硝化螺菌属)和Nitrobacter(硝化杆菌属)细菌的相对丰度,提高下层淋溶土壤反硝化优势菌群(丰度>0.1%)Burkholderia(伯克霍尔德菌属)、Cupriavidus(贪铜菌属)和Bradyrhizobium(慢生根瘤菌属)的相对丰度。炭基缓释肥添加对土壤NH_4+—N和NO_3-—N的淋溶影响可能与土壤氮素循环微生物密切相关。 相似文献
19.
The chemical composition of precipitation in the city of Mersin on the Mediterranean coast of Turkey has been studied. Spatial and temporal variability of rainwater constituents have been determined from samples collected at two central and two suburban stations for the December 2003–May 2005 period. A total of 246 samples covering all precipitation events were analyzed to determine pH, conductivity, as well as major anion (Cl?, ${\text{NO}}_3^ - $ , ${\text{SO}}_4^{2 - } $ ); major cation (H+, Na+, K+, Ca2+, Mg2+, ${\text{NH}}_4^ + $ ) and formaldehyde (HCHO) concentrations. The pH varied within a range of 4.8–8.5, with only 8 out of 246 samples being acidic (pH?<?5.6), and the remaining highly alkaline samples being neutralized by either ${\text{NH}}_4^ + $ in rainwater, or by CaCO3 resulting from wet deposition of atmospheric dust. The volume weighted mean ΣAnion/ΣCation ratio was 0.49. The equivalent concentration of major ionic species followed the order: ${\text{Ca}}^{2 + } > {\text{HCO}}_3^ - > {\text{SO}}_4^{2 - } > {\text{Cl}}^ - > {\text{NH}}_4^ + > {\text{Na}}^ + > {\text{Mg}}^{2 + } > {\text{NO}}_3^ - > {\text{K}}^ + > {\text{H}}^ + $ . Formaldehyde concentrations varied in the range of 0.01–17.9 μM, and was found to be dependent on precipitation volume. Relatively higher ${\text{NH}}_4^ + $ , ${\text{SO}}_4^{2 - } $ , ${\text{NO}}_3^ - $ and HCHO concentrations, mainly of anthropogenic origin, measured near the city center suggest increased pollution from local anthropogenic sources, e.g., residential heating, industrial and/or traffic emissions. In general, the results of this study suggest local precipitation chemistry is more strongly influenced by natural (mineral dust and marine) sources compared to anthropogenic ones. 相似文献