Effect of Nitrogen Regimes on Grain Yield,Nitrogen Utilization,Radiation Use Efficiency,and Sheath Blight Disease Intensity in Super Hybrid Rice

Poor nitrogen use efficiency in rice production is a critical issue in China. Site-specific N managements (SSNM) such as real-time N management (RTNM) and fixed-time adjustable-dose N management (FTNM) improve fertilizer-N use efficiency of irrigated rice. This study was aimed to compare the different nitrogen (N) rates and application methods (FFP, SSNM, and RTNM methods) under with- and without-fungicide application conditions on grain yield, yield components, solar radiation use efficiency (RUE), agronomic-nitrogen use efficiency (AE_N), and sheath blight disease intensity. Field experiments were carried out at Liuyang County, Hunan Province, China, during 2006 and 2007. A super hybrid rice Liangyou 293 (LY293) was used as experimental material. The results showed that RTNM and SSNM have great potential for improving agronomic-nitrogen use efficiency without sacrificing the grain yield. There were significant differences in light interception rate, sheath blight disease incidence (DI) and the disease index (ShBI), and total dry matter among the different nitrogen management methods. The radiation use efficiency was increased in a certain level of applied N. But, the harvest index (HI) decreased with the increase in applied N. There is a quadratic curve relationship between grain yield and applied N rates. With the same N fertilizer rate, different fertilizer-N application methods affected the RUE and grain yield. The fungicide application not only improved the canopy light interception rate, RUE, grain filling, and harvest index, but also reduced the degree of sheath blight disease. The treatment of RTNM under the SPAD threshold value 40 obtained the highest yield. While the treatment of SSNM led to the highest nitrogen agronomic efficiency and higher rice yield, and decreased the infestation of sheath blight disease dramatically as well. Nitrogen application regimes and diseases control in rice caused obvious effects on light interception rate, RUE, and HI. Optimal N rate is helpful to get higher light interception rate, RUE, and HI. Disease control with fungicide application decreased and delayed the negative effects of the high N on rice yield formation. SSNM and RTNM under the proper SPAD threshold value obtained highyield with high efficiency and could alleviate environmental pollution in rice production.     

秸秆还田与实地氮肥管理对直播水稻产量、品质及氮肥利用的影响

 【目的】探讨麦秸秆还田与施氮技术对直播水稻产量、品质的影响及氮肥利用效率的表现。【方法】以直播粳稻扬粳9538为材料进行大田对比试验,设置麦秸还田与不还田、实地氮肥管理（SSNM）和农民习惯施肥法（FFP）等处理,测定水稻产量、品质及氮肥利用效率。【结果】无论是SSNM还是FFP,与秸秆未还田相比,秸秆还田降低了单位面积穗数,提高了每穗粒数、结实率与千粒重,增加了产量,改善了稻米的外观品质与蒸煮品质。与FFP相比,SSNM显著提高水稻产量,降低了稻米蛋白质含量,改善了稻米的食味性。秸秆还田结合SSNM增大了籽粒最大灌浆速率与平均灌浆速率,缩短了活跃灌浆期,增加了粒重,并提高了氮收获指数、氮肥吸收利用率、氮肥农学利用率、氮肥生理利用率和氮肥偏生产力。【结论】秸秆还田结合SSNM可增加产量,改善稻米品质,提高氮肥利用效率。     

寒地水稻实地氮肥管理的研究与应用

 为解决东北寒地水稻施肥中存在的问题，引进了国际水稻研究所的实地养分管理技术。田间小区试验结果表明，寒地水稻叶片的叶绿素值（SPAD值）在穗分化期、抽穗期与叶片含氮量及叶色卡值（LCC值）之间都呈极显著的正相关（P﹤0.01）。 初步确定寒地水稻的SPAD阈值为38～40，LCC阈值为3.5。与农民习惯施肥（FFP）相比，实地氮肥管理（SSNM）氮肥用量减少25%，千粒重增加0.75 g，氮肥利用率显著提高。研究表明，在产量不降低甚至有所增加的前提下，SSNM可以降低氮肥用量，具有在广大寒地稻区推广的前景。     

实时实地氮肥管理对不同杂交水稻氮肥利用率的影响

 【目的】探讨两系和三系杂交水稻在实时实地氮肥管理模式下对氮素的吸收和氮肥利用率的差异。【方法】试验于2004和2005年在大田条件下,以两优培九、汕优63为材料比较研究了实时实地氮肥管理模式下不同叶绿素仪（SPAD）预设阈值对其吸氮特性与氮肥利用率的影响。【结果】水稻叶片叶色存在基因型差异,汕优63顶叶的SPAD值比两优培九平均低1.7～2.0个数值单位。在实时氮肥管理模式下,施氮量与SPAD预设阈值呈指数相关关系。对于汕优63而言,Nrate=0.9956 e0.132 SPAD （r2=0.8338**）,对于两优培九则为Nrate=0.1565 e0.173 SPAD（r2=0.9508**）。在SPAD预设阈值介于36～40的范围内,若要保持两个品种同一时期顶叶的SPAD值相同,汕优63比两优培九需要多施用氮肥37.3 kg N•ha-1。【结论】在实时实地氮肥管理模式下,当氮肥平均用量接近160 kg N•ha-1时,两优培九的吸氮能力、氮肥吸收利用率和氮素籽粒生产效率与汕优63相当;其氮素干物质生产效率、氮肥农学利用率高于汕优63;其氮素收获指数低于汕优63。此外,两优培九比汕优63表现出较高的耐肥抗倒伏能力。     

实时实地氮肥管理对水稻产量和稻米品质的影响

【目的】探讨实时实地氮肥管理对水稻产量和品质的影响。【方法】试验于2004和2005年在大田条件下，以两优培九、汕优63为材料研究了不同叶绿素仪（SPAD）预设阈值指导下的实时实地氮肥管理方式的产量与产量形成以及相应的稻米品质特性。【结果】在实时氮肥管理（RTNM）模式下，两优培九和汕优63各施氮处理比不施氮处理增产幅度分别达21.12%～57.65%和15.00%～31.18%。在实地氮肥管理（SSNM）模式下，两优培九和汕优63 SSNM处理比不施氮小区增产幅度分别达45.44%～50.71%和28.53%～32.40%。两优培九SPAD阈值分别由34～45的RTNM模式下，当SPAD阈值介于38～41之间时（氮肥用量120～165 kgN•ha-1）可以改善稻米的外观品质和加工品质；汕优63则以SPAD阈值36～39（氮肥用量：120～165 kgN•ha-1）范围内有利于改善米质。SSNM模式下以SPAD施肥阈值为37-39（氮肥用量130 kgN•ha-1）进行氮肥运筹能显著改善两优培九的加工品质、外观品质和营养品质；SSNM模式下汕优63以SPAD阈值为35～37时稻米品质相对较好，同时产量也比较高。【结论】实时实地氮肥管理能较好地协调水稻产量和品质的关系，关键措施是依据品种特性确定适宜的预设SPAD阈值。在本试验条件下，实时实地氮肥管理模式两优培九以SPAD 38～39、汕优63以SPAD 35～37左右时能获得较高的产量和部分地改善米质，可以作为生产上应用实时实地氮肥管理时的推荐阈值。     

实地氮肥管理对寒地水稻干物质积累和产量的影响

【目的】以寒地5个粳稻品种为试验材料，研究实地氮肥管理的增产机理。【方法】2004和2005年，通过农民习惯施肥和实地氮肥管理的大田对比试验和不同SPAD阈值的小区试验，探讨实地氮肥管理对水稻群体质量、干物质积累规律和氮积累的影响。【结果】与农民习惯施肥相比，实地氮肥管理使氮肥总量平均减少了33.8%，水稻成穗率平均提高了12.3%（P＜0.05），灌浆期水稻叶面积指数提高了14.1%～27.6% （P＜0.05），抽穗期以后水稻干物质增加了4.3%～29.1%，抽穗后干物重与产量呈极显著正相关关系(P＜0.01)，产量平均增加了9.8%；抽穗后氮积累量增加了11.8%～55.1% (P＜0.05)，氮肥吸收利用率和农学利用率分别提高了38.5%～133.4%（P＜0.05）和 39.78%～194.26%（P＜0.05）。【结论】该技术通过改善水稻群体质量，增加抽穗后LAI，促进干物质和氮积累，增加水稻产量和氮肥利用率。     

Effects of Site-Specific Nitrogen Management on Yield and Dry Matter Accumulation of Rice from Cold Areas of Northeastern China

The effects of yield increase and mechanism of site-specific nitrogen management （SSNM） in five rice varieties from cold areas of northeastern China were studied. Plot experiment for critical SPAD value and experiments of two fertilization methods, SSNM and farmer＇s fertilization practice （FFP） were conducted to study their effects on the quality and dry matter accumulation of rice population, as well as N uptake. Compared with FFP, SSNM significantly decreased the average N rate by 33.8%, significantly increased average ear-bearing tiller rate and LAI for grain-filling stage by 12.3% and 14.1-27.6%, correspondingly, improved dry matter weight and N uptake after heading period by 4.3-29.1% and 11.8-55.1% （P 〈 0.05）, and heightened recovery efficiency and agronomic efficiency by 38.5-133.4% （P 〈 0.05） and 39.8-194.3% （P 〈 0.05）, respectively, as well as increased the average yield by 9.8% in 2004 and 2005. The results indicated that the accumulation rate of dry matter and N increased the rice yield and N use efficiency, because of improving rice population quality and increasing LAI after heading period.     

氮肥模式对稻田温室气体排放和产量的影响

为探明不同施肥模式对稻田温室气体排放和水稻产量的影响,本研究以江汉平原一季中稻为研究对象,通过大田试验设置5个氮肥处理:不施氮肥(CK)、农民习惯施肥(FFP)、实时氮肥管理(RTNM)、精确定量施氮(PQNA)和一次性施肥(OOF),采用静态箱-气相色谱法研究了稻田CH_4和N_2O排放特征。结果表明:与CK相比,FFP、PQNA、RTNM和OOF显著增加了CH_4和N_2O排放。FFP、PQNA和RTNM处理CH_4排放并没有显著差异,但是OOF处理比FFP处理CH_4减排27.5%;RTNM和OOF处理比FFP处理N_2O排放分别减少了23.1%和25.0%。与FFP相比,OOF并没有降低水稻产量,而RTNM和PQNA显著增加了水稻产量。OOF较FFP、RTNM和PQNA处理增温潜势(GWP)分别减少了27.4%、12.5%和18.5%。PQNA、RTNM和OOF处理的温室气体排放强度(GHGI)较FFP分别降低了22.2%、24.4%和26.7%。研究表明,采用合理的施肥模式,在保障水稻产量的同时,能够减缓稻田温室气体排放,实现丰产增效和环境友好。在所有施肥模式中,OOF具有最低的GWP,同时能够维持水稻产量并减少追肥次数,是一种低碳丰产的施肥技术,值得在江汉平原大面积推广。     

实地氮肥管理对寒地水稻品质的影响

田间试验表明,实地氮肥管理(SSNM)与农民习惯施肥(FFP)相比,稻米的糙米率、精米率、整精米率和脂肪含量有所增加,蛋白质和直链淀粉含量有所降低。SSNM不但可以降低氮肥用量,保证产量不降低甚至有所增加,而且能够改善稻米品质,在广大寒地稻区具有推广前景。     

寒地稻田施氮状况与氮素调控对水稻投入和产出的影响

文章通过对黑龙江省1～3积温带240个农户的施肥情况调查,以及对试验区水稻氮素收支状况分析,研究了黑龙江省稻田土壤氮循环规律。结果表明,寒地稻田化肥投入氮量平均为150 kg.hm-2,占投入总量的72.4%,而且90%以上作基蘖肥施用,近60%的稻田氮素用量过高,稻田氮有17.2%的盈余,氮肥利用率较低。针对寒地水稻施氮问题,提出进行实地氮肥管理的策略,经过3年9个点次田间对比试验,证明该技术能降低氮肥用量30%以上,水稻产量增加10%以上,每公顷增收1 450元。     

实地氮肥管理对水稻产量和氮肥利用率的影响

以汕优63和淮稻9号为试材,设置不同氮肥管理模式,研究其对水稻产量和氮素利用率的影响。结果表明,与农民习惯法(FFP)相比,实地氮肥管理模式(SSNM)增产6.32%(汕优63)和3.3%(淮稻9号),SS-NM的氮肥产谷效益和农学利用率分别较FFP提高了35.68%(汕优63)、40.48%(淮稻9号)和172.61%(汕优63)、154.50%(淮稻9号),SSNM的氮素转运率显著高于FFP。说明在产量不降低甚至有所增加的前提下,实地氮肥管理可减少氮肥施用量,并较大幅度地提高水稻氮肥利用率。     

秸秆还田与实地氮肥管理对水稻产量及品质的影响

以扬粳9538为材料,通过秸秆还田与氮素管理与秸秆不还田(对照)比较试验,研究了水稻产量及品质的表现。结果表明:秸秆还田与实地氮肥管理(SSNM)可以在减少氮肥施用量,秸秆全量还田的同时,增加水稻的产量,降低单位面积穗数,提高每穗粒数、结实率。秸秆还田与实地氮肥管理降低稻米的垩白米率、垩白度和直链淀粉含量,改善稻米的外观品质和营养品质,淀粉谱的最高粘度和崩解值增加,消减值减低,稻米食味品质得到改善,该技术同时减少穗分化前干物质积累,增加抽穗期光合速率、根系活力与ATP酶活性,促进同化物向籽粒的运转,减少茎杆中非结构性碳水化合物的残留。对秸秆还田与不同氮素管理在产量、品质上的差异进行了讨论。     

氮肥施用措施对湖北中稻产量、品质和氮肥利用率的影响

 【目的】以湖北省大面积推广的4个中稻品种(珞优8号、国豪杂优1号、丰优22和巨风优72)为试验材料,研究氮肥不同施用对湖北省中稻产量、品质和氮肥利用率的影响。【方法】田间试验设计了5个处理,,分别为不施氮处理(CK)、农民习惯施肥法(FFP)、FFP优化、增氮处理(SHY)和SHY优化,4次重复于2008和2009年分别在湖北赤壁和荆门进行。【结果】湖北赤壁CK处理两年试验的水稻产量均低于湖北荆门,表明荆门的基础地力好于赤壁。两年试验中,与农民习惯施肥法(FFP)相比,赤壁FFP优化、增氮处理(SHY)和SHY优化3个处理都有增产作用,其中2008年增产率分别为10.0%、2.3%和23.2%,2009年增产率分别为16.6%、11.8%和22.6%;荆门FFP优化、SHY、SHY优化3个处理,在2008年略有减产,在2009年增产作用也不显著,仅为2.0%、6.7%和1.7%。与农民习惯施肥法(FFP)相比,赤壁FFP优化和SHY优化,氮肥农学利用率和偏生产力都有显著提高;荆门FFP优化和SHY优化氮肥偏生产力显著提高,而氮肥农学利用率仅略有提高;两年两地SHY处理的氮素利用率各个指标的值均较小。【结论】两个优化处理(FFP优化和SHY优化)的产量和氮肥利用率都达到较高水平,即在当前农民习惯施肥条件下,将氮肥减少20%左右,不仅不会减产反而还会增产增效;在高氮的投入下,高产田水稻增产不明显甚至减产。此外,氮肥优化施用还可以改善稻米的营养品质。     

不同基础地力土壤优化施肥对水稻产量和氮肥利用率的影响

【目的】研究江汉平原地区不同基础地力土壤和优化施肥对水稻产量和氮肥利用率的影响。【方法】以江汉平原水稻主推品种丰两优香一号为试验材料,通过3年田间小区试验,考察分析土壤基础地力不同的稻田优化施肥、农民习惯施肥和不施肥处理的产量、氮肥贡献率、土壤氮素依存率和氮肥利用率等的差异。【结果】土壤基础地力不同的稻田均是优化施肥处理的产量最高,与农民习惯施肥处理比较,高地力和低地力稻田优化施肥处理的产量分别平均提高6.9%和5.0%;与不施肥处理比较,产量分别平均提高17.3%和30.3%。与农民习惯施肥处理比较,优化施肥处理的氮肥吸收利用率、农学利用率和偏生产力均大幅度提高。高地力稻田土壤氮素依存率高、氮肥贡献率小、施肥增产的潜力小;低地力稻田土壤氮素依存率低、氮肥贡献率大、施肥增产的潜力大。【结论】优化施肥可以降低水稻产量对土壤基础地力的依赖,提高氮肥利用率。     

Comparisons of Yield and Growth Behaviors of Hybrid Rice Under Different Nitrogen Management Methods in Tropical and Subtropical Environments

To compare the grain yield and growth behaviors of hybrid rice, field experiments were conducted in a subtropical environment in Changsha, Hunan Province, China, and in two tropical environments in Gazipur and Habiganj in Bangladesh during 2009 to 2011. Three hybrid rice cultivars were grown under three nitrogen (N) management treatments in each experiment. The results showed that grain yield was significantly affected by locations, N treatments and their interaction but not by cultivars. Changsha produced 8–58% higher grain yields than Bangladesh locations. Sink size (spikelet number per unit land area) was responsible for these yield differences. Larger panicle size (spikelet number per panicle) contributed to greater sink size in Changsha. Aboveground total biomass was greater in Changsha than in Bangladesh locations, whereas harvest index was higher in Bangladesh locations than in Changsha. Crop growth rate (CGR) was greater at Changsha than Bangladesh locations during vegetative phase, while the difference was relatively small and not consistent during the later growth phases. Higher leaf area index and leaf area duration were partly responsible for the greater CGR in Changsha. Real-time N management (RTNM) produced lower grain yields than fixed-time N management in more than half of the experiments. Our study suggested that further improvement in rice yield in the tropical environments similar to those of Bangladesh will depend mainly on the ability to increase panicle size as well as CGR during vegetative phase, and the chlorophyll meter threshold value used in RTNM needs to be modified according to environmental conditions and cultivar characteristics to achieve a desirable grain yield.     

Effects of Nitrogen Management on the Yield of WinterWheat in Cold Area of Northeastern China

A plot experiment including four treatments, CK (N 105 kg ha-1 as urea, including a basal N application of 35 kg ha-1 and a topdressing N 70 kg ha-1 at turned green stage) and optimized N management (OPT1, OPT2 and OPT3, applied two-thirds, one-third and two-fifths N at jointing stage, respectively, total N 60 kg ha-1), was conducted to evaluate the effects of nitrogen management on growth and N uptake of winter wheat (Triticum aestivum), Dongnong 1, which is the first highly cold tolerant winter wheat in China. Index of population quality, N uptake and yield were determined. The ear-bearing tiller rate was increased by above 12%, and the leaf area index, biomass and N uptake were significantly decreased (P<0.05) at jointing stage. OPT treatments increased the grain to leaf area ratio at heading stage, the dry matter weight and N uptake after heading by 14.3-27.9%, 11.6-28.7% and 118.1-161.8 %, respectively. The yield of the OPT treatments was increased by 14.2-37.5% compared with CK, and there was a significant difference (P<0.05) between CK and OPT1 treatments. Harvest index and N partial factor productivity (PFP, kg grain yield per kg N applied) was clearly enhanced from 0.4 and 35.6 kg, respectively for CK to an average of 0.48 (P<0.05) and 77.6 kg (P<0.05) in the OPT treatments. These results indicated that the optimized N management increased the harvest index, yield and N use efficiency by decreasing the N application rate and postponing N application time, improved wheat population quality, controlled excessive growth in the vegetative stages and increased dry matter and N accumulation rates after heading.     

不同施氮下优质稻植株花后碳氮物质流转与籽粒生长的相关性

以桂华占、八桂香为材料,在高氮(NH,High nitrogen)、中氮(NM,Middle nitrogen)、低氮(NL,Low nitrogen)三个施氮水平下,研究了优质稻花后碳氮物质积累、运转与籽粒生长特征及其相互的关系。结果表明:①在不同施氮水平下,干物质转运效率为53.60%～62.23%,氮素转运效率为12.33%～37.95%,茎鞘和叶片干物质转运对籽粒干物质积累的贡献率为12.33%～37.95%,茎鞘和叶片氮素转运对籽粒氮素积累贡献率为47.93%～117.2%。②施氮水平影响桂华占和八桂香花后碳氮流转及籽粒的生长。高氮条件下增加叶片碳氮同化物的转运,不利于茎鞘碳氮同化物向籽粒转运。增施氮肥在一定程度上提高了地上总氮和籽粒氮的积累量,提高了籽粒氮收获指数,蛋白质含量上升。低氮处理虽能促进茎鞘碳氮同化物的转运率,但籽粒收获指数明显变低。③不同施氮水平下,桂华占和八桂香花后碳氮流转与籽粒的生长间存在密切的相关,花后茎叶干物质运转速度和转运率都与籽粒起始灌浆势呈正相关;籽粒最大灌浆速率与叶干物质运转速度和转运率呈正相关;叶片中总氮转运率与籽粒蛋白质产量呈正相关。花后茎叶氮素积累量的减少,伴随着籽粒氮素积累量的增加和籽粒蛋白质含量的升高是同步的;茎鞘花后同化物碳氮比与籽粒蛋白质含量及产量呈正相关,与籽粒直链淀粉含量及淀粉、蛋白质比呈负相关。不同施氮水平下氮素转运效率和贡献率表现出一定差异,这种差异与水稻植株自身对氮生理利用效率密切相关。     

实地养分管理对水稻钙镁吸收的影响

为探求水稻钙和镁吸收规律,进一步提高产量,通过2 a10个点次的田间对比试验,比较了农民习惯施肥（FFP）和实地养分管理（SSNM）下水稻茎叶、植株及籽粒的钙镁吸收和产量的差异。结果表明：与FFP相比,SSNM产量提高了6.66%-20.37%,平均增产13.7%,8个试验点增产显著。FFP水稻茎叶和籽粒的含钙量分别为2.24-3.10 g.kg-1和0.10-0.27 g.kg-1,含镁量分别为0.80-1.38 g.kg-1和0.62-0.97 g.kg-1。水稻植株中氮镁积累量分别是1.55-20.08 kg.hm-2和7.69-14.86 kg.hm-2,1 000 kg籽粒吸收钙1.66-2.56 kg,吸收镁1.16-1.86 kg;SSNM水稻茎叶和籽粒含钙量分别为2.45-3.40 g.kg-1和0.12-0.29 g.kg-1,含镁量分别为0.85-1.37 g.kg-1和0.62-0.94 g.kg-1,水稻植株中氮镁积累量分别是16.71-22.91 kg.hm-2和9.33-16.35 kg.hm-2,1 000 kg籽粒吸收钙1.66-2.67 kg,吸收镁1.19-1.71kg。两种施肥方式下钙镁的含量和1 000 kg籽粒吸收钙镁量无明显差别;SSNM钙镁的积累量均高于农民习惯施肥。表明,寒地水稻钙镁需要量较高,每1 000 kg水稻需要钙镁含量平均为2.04 kg和1.51 kg,SSNM对水稻茎叶和稻穗钙镁含量影响不大,由于其提高了水稻产量,因此促进了钙镁吸收。     

Effects of Nitrogen on N Uptake, Grain Yield and Quality of Medium-Gluten Wheat Yangmai 10

The effects of the basal and top-dressing nitrogen (N) on'N uptake and translocation, N utilization efficiency, grain yield and quality of medium-gluten winter wheat Yangmai 10 were studied from 2000 to 2002. The main results were as follows.Nitrogen content and nitrogen accumulation in plant at maturity increased with the amount of N application. Grain protein content and wet gluten content were significantly correlated with applied N. There was a significantly positive correlation between nitrogen accumulation before anthesis (NBA) and basal N fertilizer, and between nitrogen accumulation after anthesis (NAA) and top-dressing N. N accumulated in grains was significantly correlated to NBA, NAA and N translocation from vegetative organs after anthesis (NTVA). NBA was significantly correlated with N application, but NAA and NTVA had a quadratic curve correlation with applied N. N fertilizer use efficiency (NUE) had a quadratic curve correlation with applied N, and the NUE was high when basal and top-dressing N was equally applied. For the medium-gluten wheat Yangmai 10 under the same N application ratio, there was a N-regulating effect when the N application was less than 266.55 kg ha-1, a stagnation of yield and quality when N application ranged from 266.55 to 309.08 kg ha-1, and an excessive N application when the N application rate was greater than 309.08 kg ha-1. Under the conditions of this experiment, the precise N application is 220-270 kg ha-1 with basal and top-dressing N equally used when a grain yield of more than 6750kg ha-1, protein content higher than 12%, wet gluten content more than 30% and NUE greater than 40% could be obtained.     

Denitrification Losses and N2O Emissions from Different Nitrogen Fertilizers Applied to the Maize-Fluvo-Aquic Soil System

A field experiment was conducted to investigate the variations in denitrification losses and N2O emissions from 4 different types of nitrogen fertilizers (urea, ammonium nitrate, ammonium bicarbonate, and calcium nitrate) applied to the maizefluvo-aquic soil system in the North China Plain by the method of intact soil core incubation and acetylene inhibition, and the responses of nitrogen fertilizers to maize grain yields. Results show that the denitrification loss from different nitrogen fertilizers ranged from 0.38-1.20 kg N ha-1, with no significant differences among different fertilizer treatments, and the N2O emission from 0.05-0.95 kg N ha-1, with a significant difference (P＜0.05) among the treatments. The highest emission was from the treatment of ammonium nitrate, while the lowest from calcium nitrate. The nitrogen fertilizers increased the maize grain yield by 9.7-19.8% compared to control. But there were no significant differences in yield increase among the 4 types of nitrogen fertilizers. In comparison, urea had the best effect, whereas calcium nitrate had the least effect on increasing maize yield. The maize yield was 5.7% higher when urea was separately applied at 2 times than when it was applied at a time. In this case, however, the denitrification loss and the N2O emission were also increased by 4.05 and 1.84 kg N ha-1,respectively.