0 引言
【研究意义】因温室气体浓度升高而引起的全球气候变化问题备受人们关注。N2O和CH4作为重要的农田非CO2温室气体占温室气体总量的比例相对较小,分别为22.9%和7.1%[1],但其全球增温潜力相对较大,据IPCC最新研究报告表明在100 年尺度上其增温潜势分别是 CO2的265倍和28倍[2]。据估计,全球农业源排放的非CO2温室气体占人为源的13.5%,与交通源（13.1%）排放的温室气体量相当[2]。根据《中华人民共和国气候变化第二次国家信息通报》,中国农业源产生的N2O和CH4分别占全国总排放量的56.62%和73.79%,农业源温室气体占全国温室气体排放总量的10.97%[3],我国政府在气候变化外交谈判中正面临着来自各方的巨大压力。前人对农田的温室气体排放做了大量的研究工作,农田N2O产生主要通过土壤的硝化和反硝化过程,CH4可在长期淹水的稻田中经发酵产生,除气候条件和土壤特性外,农业管理措施如耕作制度、水稻品种和田间管理措施都能影响N2O和CH4的排放,而通过控制氮肥施用是温室气体减排最直接有效的方法[4,5,6,7,8,9]。因此,在稳产的前提下研究低排放的稻田施肥技术,对于减少农业源温室气体排放意义重大。【前人研究进展】在当前农村劳动力不足且成本大幅提升的背景下,作物整个生长季一次性施肥技术得到了越来越广泛的推广。其核心是根据作物不同生长发育阶段对养分的不同需求,通过在肥料的表面包上一层膜来控制其释放速度和释放量,一次性施肥就能满足作物整个生长发育期对养分的需求,具有减少施肥量、施肥次数、提高肥料利用率和减少劳动力等优点[10,11,12]。褚清河等[16]研究表明,北方稻田插秧前一次性施氮可以在减少氮肥用量的同时稳产。张木等[17]研究表明,与分次施肥相比一次性施用缓控释肥提高了水稻的产量12.5%。控释肥类型对温室气体的影响研究也较多,王斌等[12]研究表明,不同的控释肥和添加剂在保产或者增产前提下,均可不同程度的减少江汉平原地区早稻和晚稻CH4和N2O的排放,纪洋等[13]研究表明,与单施尿素处理相比,控释肥对水稻生长期N2O排放量减少59.6%,水稻产量增加7.8%。谢勇等[14]研究也表明,相比普通尿素,控释氮肥减氮20%时,既能降低的N2O排放量,又能增加春玉米的产量。而将控释肥与一次性施肥方式相结合对温室气体影响的研究较少,张婧等[15]对华北平原冬小麦/夏玉米轮作中研究表明,一次性施肥技术能够在保证产量的前提下有效减少土壤N2O排放。【本研究切入点】有关一次性施肥技术的研究大多侧重于对作物产量和氮肥利用率的影响,但是一次性施肥技术在减少劳动力成本提高氮肥利用效率等的同时,是否具有良好的环境效益的研究仍不足,比如对温室气体排放影响,尤其是针对土壤水热条件经常改变的水旱复种轮作系统。【拟解决的关键问题】水稻-油菜复种轮作作为我国南方的主要耕作制度之一[18],其种植面积仅次于稻麦轮作系统,水旱交替轮换导致的土壤季节间的干湿交替变化,这种干湿交替会引起土壤水热条件的变化,进而影响到土壤的物理、化学及生物学性状,从而对作物的生长及土壤N2O和CH4的排放产生影响。本文从长江中下游地区典型的油菜-水稻复种系统出发,探究一次性施肥技术对水旱复种轮作系统N2O和CH4的排放量的特征及其影响因素,以期了解一次性施肥技术对净温室气体排放的贡献,从而为一次性施肥技术的推广应用提供科学依据。1 材料与方法
1.1 试验设计
田间试验于2015年10月到2016年9月在荆州太湖港农场（30.36N,112.08E）油菜-水稻复种试验田进行。试验地处江汉平原腹地,属亚热带季风气候,年平均气温15.9—16.6 ℃,无霜期242—263 d,年降雨量1 100—1 300 mm,太阳年辐射总量为4.4×105—4.6×105 J·cm-2,年日照时数1 800—2 000 h。土壤质地为砂质壤土,供试土壤（0—20 cm土层）基本理化性质：pH 7.62,有机质15.91 g·kg-1,全氮1.27 g·kg-1,速效磷7.07 mg·kg-1,有效钾79.85 mg·kg-1,硝态氮12.58 mg·kg-1,铵态氮9.97 mg·kg-1,其中油菜于2015年10月28日移栽,2016年5月1日收割,品种为华油杂8号（Brassica napus L.）,移栽密度为10万株/hm2,油菜季氮肥追肥方式为降雨后撒施;水稻于2016年5月28日插秧,2016年9月10日收获,品种为广两优476号（Oryza sativa L.）,移栽密度为20万穴/hm2,前期浅水灌溉,分蘖末期（7月26日）排水晒田,一周后复水,之后进行干湿交替灌溉,收获前一周停止灌溉使其自然落干,田间其他管理措施与当地生产保持一致。2016年作物收获之后测得土壤的硝态氮含量1.21 mg·kg-1,铵态氮含量0.74 mg·kg-1,全氮1.21 g·kg-1,速效磷13.08 mg·kg-1,速效钾138.16 mg·kg-1。田间试验采用随机区组设计,5个处理,分别是：对照处理（CK）、农民习惯施肥处理（FP）、优化施肥处理（OPT）、一次性尿素基施处理（UA）和一次性控释肥基施处理（CRF）。优化施肥处理施肥量是根据当地测土配方施肥结果确定的施氮量,控释肥是美国嘉洋控释尿素,具体肥料包膜材料为聚氨酯。每个处理重复3次,每个小区面积是32 m2（长8 m,宽4 m）,施肥方式和施肥量见表1。基肥施用采用沟施肥,施肥深度为10 cm,追肥采用表施,优化施肥（OPT）处理、一次性尿素基施（UA）和一次性控释肥基施 （CRF）处理均施用相同量的氮肥,各处理的磷肥和钾肥用量均为75 kg·hm-2,均在播前撒施。本研究中其他管理措施与当地高产栽培措施一致。
Table 1
表1
表1油菜-水稻复种期内氮肥施肥种类和施肥量
Table 1The different types and amounts of nitrogen fertilizers during the whole periods
| 处理 Treatment | 氮肥种类 Types of fertilizers | 施肥方式 Nitrogen supply methods | 氮肥用量Level of N fertilizers (kg N·hm-2) | |
|---|---|---|---|---|
| 油菜Rape | 水稻Paddy | |||
| CK | - | - | - | - |
| FP | 尿素Urea | 60%基肥+20%越冬+20%抽薹前期(油菜) 60% Base fertilizer + 20% Overwintering + 20% Prophase of bolting (Rape) 70%基肥+30%分蘖肥(水稻) 70% Base fertilizer + 30% Tillering stage dressing (Rice) | 210 | 210 |
| OPT | 尿素Urea | 60%基肥+20%越冬+20%抽薹前期(油菜) 60% Base fertilizer + 20% Overwintering + 20% Prophase of bolting(Rape) 50%基肥+25%分蘖肥+25%穗肥(水稻) 50% Base fertilizer + 25% Tillering stage dressing + 25% Panicle fertilizer (Rice) | 165 | 165 |
| UA | 尿素Urea | 全部基施All basal fertilization | 165 | 165 |
| CRF | CRF | 全部基施All basal fertilization | 165 | 165 |
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1.2 数据获取与计算
1.2.1 N2O和CH4通量的测定 土壤N2O和CH4排放通量的监测采用静态暗箱-气相色谱法[15,19-20]。采样箱体与底座均由不锈钢制成,箱体底部边缘有密封条保证采样时的密封性。箱体（长50 cm,宽50 cm,高50 cm）为正方体,最大限度保证气体取样的代表性。每次采样于上午8：00—10：00进行,采样间隔6 min,取样5次,在记录采样时间的同时,利用同时测定箱内气温和5 cm土壤温度,每个小区取样重复3次。取样频率为每月观测两次,有灌溉或降雨量超过10 mm,逐日观测2—3 d。气体样品存放于铝膜气袋中（大连普莱特公司生产）,之后用改进的气相色谱仪（Agilent 7890A）分析N2O和CH4浓度。气体通量按下式计算：
F=x$\text{ }\!\!\rho\!\!\text{ H}\frac{\text{dc}}{\text{dt}}\frac{\text{273}}{\text{273+T}}\frac{\text{P}}{{{\text{P}}_{\text{0}}}}$
式中,F为N2O（μg·m-2·h-1）或CH4（mg·m-2·h-1）的排放通量,正值为排放,负值为吸收,$\rho$为标准大气压下N2O或CH4的密度（g·L-1）,H为采样箱气室高度（cm）,T为采样箱内气温（℃）,P为采样时气压（kPa）,P0 为标准大气压（kPa）,P/P0≈1,dc/dt为采样箱内N2O或CH4浓度的变化速率（μL·L-1·min-1）。
1.2.2 N2O和CH4排放总量 采用平均值内插法,用相近两个观测日的日通量平均值作为期间非观测日的日通量,然后将每天的日通量累加即可估计年度气体排放总量。
1.2.3 N2O排放系数 IPCC将同期内由化肥氮施用引起的N2O排放量占总施氮量的百分比定义为N2O排放系数（EFd）,计算公式：
EFd=100×(EF - EC)/N
式中,EF和EC分别为施氮肥和对照组下作物生长季N2O排放总量（kg N·hm-2）;N为当季施氮量（kg N·hm-2）。
1.2.4 全球增温潜势的计算 净温室气体排放以全球增温潜势来计算。全球增温潜势（GWP）是基于温室气体辐射特征的一个指数,用于衡量相对于CO2而言,在所选定时间内进行积分得出的当前大气中某个脉冲排放后给定单位质量温室气体的辐射强迫。GWP代表不同时间长度内温室气体在大气中的综合影响及其造成辐射强迫的相对效果[1,2]。N2O和CH4 100年的增温潜势分别为CO2的265倍和28倍[2],其计算式为：
GWP（kgCO2-eq·hm-2）=28×CH4+265×N2O-44/12×SOCSR
式中,GWP为2种温室气体引发的增温潜势,CH4、N2O为累积排放量,采用线性内插法计算。由于SOC的年际变化不大,所以本研究中只讨论N2O和CH4的净温室气体排放效果。
1.2.5 温室气体排放强度 单位产量的GWP,即
GWP与相应处理作物产量的比值。计算公式：
GHGI = GWP/Y
式中,GHGI为温室气体排放强度（kgCO2-eq·kg-1, 以CO2计）;GWP为全球增温潜势（kgCO2-eq·hm-2）;Y为作物产量（kg·hm-2）。
1.3 其他数据的测定
整个油菜-水稻复种一年的降雨量和气温数据来源为当地气象站。土壤样品的采集和测定：作物种植前和收获后,取深度为1 m的土层（每20 cm为一个层次）,测定土壤的基本理化性质,包括pH、碱解氮、速效氮、速效钾、有机质、全氮、全磷、全钾、硝态氮和铵态氮。
1.4 数据处理分析
用Excel 2010进行数据处理及作图,SPSS 19.0进行不同处理间的差异显著性检验（ANOVA程序单因素方差分析,显著水平为0.05）,处理间采用LSD多重比较方法,采用Duncan进行显著性检验。2 结果
2.1 油菜-水稻季中土壤N2O和CH4的周年排放特征
对于N2O排放特征,各处理N2O排放通量变现为明显的季节动态变化特征,具有油菜季低、水稻季高的季节特点,在油菜季的变化范围为-4.08—35.51 μg N·m-2·h-1,而水稻季则在-16.52—193.30 μg N·m-2·h-1。随着环境温度的下降逐渐降低,结合日均气温、降雨量（图1）和N2O的排放通量特征（图2）进行分析,可以看出N2O的排放峰集中在6—9月份的水稻生长季,降雨和温度是影响N2O排放的主要因素,降雨和气温共同影响微生物的活性和O2含量,从而影响土壤N2O的形成和排放。对于CH4排放,与N2O排放特征相似,各处理的CH4排放通量也具有油菜季低、水稻季高的季节变化特征（图3）,油菜季CH4 排放微弱,在-0.08—0.05 mg C·m-2·h-2之间,而在温度降雨相对高的6—9月份水稻生长季,CH4排放量为-0.54—4.81 mg C·m-2·h-2,主要是因为CH4排放主要通过淹水条件（厌氧还原环境）下产生,在旱季很难有淹水的条件,而在水稻季由于淹水从而排放大量CH4,从图3中可以看出,CH4排放峰值出现在水稻生长分蘖到抽穗阶段,这一时期水稻生长旺盛,植株生物量大量增加,并充当了土壤和大气的通道,将淹水环境下产生的CH4排放到大气中。
显示原图|下载原图ZIP|生成PPT图1观测期降雨量和日平均气温的变化
-->Fig. 1The precipitation and average daily air temperature during the whole observed period
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显示原图|下载原图ZIP|生成PPT图2不同处理下油菜-水稻复种系统土壤N2O排放通量
-->Fig. 2The N2O emission flux in rape-paddy multiple cropping system under different treatments
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显示原图|下载原图ZIP|生成PPT图3不同处理下油菜-水稻复种系统土壤CH4排放通量
-->Fig. 3The CH4 emission flux in rape-paddy multiple cropping system under different treatments
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2.2 油菜-水稻季中土壤N2O和CH4的排放总量
从整个复种周期来看,各处理的N2O年排放总量从高到低依次是FP、CRF、OPT、UA、CK,分别为1.31、1.19、1.04、0.82、0.37 kg N·hm-2,排放系数依次为0.22%、0.25%、0.20%、0.14%,均低于IPCC的推荐值1%。OPT处理比FP处理在减少氮肥用量21.4%的条件下减少了N2O排放20.5%,可见,施肥量直接影响了N2O的排放;而在同等施氮水平下,一次性施肥的UA和比OPT处理减少了21.2%,一次性施肥的CRF处理却增加了14.8%,但是差异均不显著。从不同作物生长季来看,油菜季的各处理的N2O的排放量在0.17—0.41 kg N·hm-2,由于各处理之间N2O的排放量不高,一次性施肥对油菜季N2O排放影响不明显（图4）。水稻季的各处理的N2O排放总量在0.20—0.99 kg N·hm-2,一次性施肥条件下水稻季的UA比OPT处理减少25.1%,而CRF处理比OPT增加45.0%（图4）。说明在水稻季UA的减排作用大于CRF,可能的原因是温度和水分对N2O排放影响很大,一次性施肥均是基施肥,由于控释肥的肥效持续时间长于普通尿素,参与N2O产生过程的基质浓度较高,因此在相对较高的温度和水分的月份,会比普通尿素产生更多的N2O。
显示原图|下载原图ZIP|生成PPT图4不同施肥方式下油菜-水稻季N2O排放总量
-->Fig. 4The seasonal cumulative N2O emissions in each treatment
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从整个复种周期看CH4年排放总量,其中FP最高,达到了24.58 kg C·hm-2,OPT为21.25 kg C·hm-2,CK为19.26 kg C·hm-2,CRF和UA最低,分别是14.89和15.08 kg C·hm-2,一次性施肥的CRF和UA分别比OPT减少CH4排放量29.9%和29.0%,而减氮OPT处理比FP减少了13.5%的,说明一次性施肥可减少CH4的排放量,施用氮肥虽然没有直接对CH4的排放产生作用,但是可以通过促进作物的生长发育来提供CH4的排向大气的通道。从不同作物生长季来看,油菜季的各处理CH4排放量在-0.77—0.38 kg C·hm-2,其中CK、UA和CRF的排放均是负值（吸收）,而水稻季的各处理的CH4排放量达到了15.15—24.26 kg C·hm-2,一次性施肥处理的UA和CRF分别比OPT减少27.4%和25.0%,但是差异不显著,原因可能是增施氮会促进水稻的生长发育从而间接增加CH4的排放量（图5）。
显示原图|下载原图ZIP|生成PPT图5不同施肥方式下油菜-水稻季CH4排放总量
-->Fig. 5The seasonal cumulative CH4 emissions in each treatment
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2.3 不同处理下油菜-水稻周年的GWP
本研究利用GWP综合研究了N2O和CH4的净温室气体排放。各处理的GWP从大到小排列为FP>OPT>CRF>CK>UA,FP最高,达到了1 062.36 kgCO2-eq·hm-2,显著（P<0.05）高于两个一次性施肥处理UA和CRF,其次为OPT处理,GWP值达到了8 90.61 kgCO2-eq·hm-2,显著（P<0.05）高于UA处理。与OPT处理相比,UA和CRF处理分别减少了28.0%和18.2%的GWP。综合考虑N2O和CH4两种气体的温室效应,说明两种一次性施肥处理可以降低温室效应,其中UA的效果较好（表2）。值得一提的是,通过分析N2O和CH4两种温室气体对 GWP的贡献率表明,各处理CH4对GWP的净贡献率处于58.7%—85.7%之间,说明在油菜-水稻的水旱复种中CH4对GWP的贡献更高,应该更加关注水稻生长季CH4的减排。Table 2
表2
表2不同施肥方式下油菜-水稻的GWP（100 a）
Table 2The GWP of rape/paddy in each treatment (100 a) (kgCO2-eq·hm-2)
| 处理 Treatment | CH4 | N2O | GWP | ||
|---|---|---|---|---|---|
| 油菜 Rape | 水稻 Paddy | 油菜 Rape | 水稻 Paddy | ||
| CK | -12.93a | 552.24ab | 47.74a | 73.65c | 660.71c |
| FP | 5.84a | 709.76a | 85.32a | 261.44a | 1062.36a |
| OPT | 10.76a | 584.26ab | 117.52a | 178.06ab | 890.61ab |
| UA | -5.16a | 389.17b | 93.91a | 125.54bc | 603.46c |
| CRF | -21.52a | 438.41b | 73.27a | 243.09ab | 733.25bc |
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2.4 油菜-水稻季的作物产量和GHGI
作物产量是评价一种施肥技术最重要的指标。研究中表明（图6）,除CK处理之外,各施肥处理间的油菜产量在2 150—2 441 kg·hm-2和水稻产量在9 207—9 806 kg·hm-2。在油菜季,OPT处理比FP处理减少了油菜产量11.9%,可见,在减少氮肥用量21.42%的条件下降低了油菜的产量;但是UA处理与OPT产量无差异,而CRF处理比OPT增产9.6%,说明UA可以稳产,而CRF会增加油菜的产量。而在水稻季CRF、UA和OPT之间无差异,说明一次性施肥不会造成作物减产,对产量的影响在可接受范围之内。对于GHGI则呈现油菜季低,而水稻季高的特征（图7）,在油菜季中CRF和UA的排放强度最低,为0.038 kgCO2-eq·kg-1,OPT最高为0.057 kgCO2-eq·kg-1,各处理的温室气体排放强度差异不显著,说明一次性施肥没有降低油菜季的GHGI,而在水稻季UA最小为0.07 kgCO2-eq·kg-1,FP最高达到了0.13 kgCO2-eq·kg-1,各处理间差异不显著,但是一次性施肥处理的排放强度低于传统施肥方式,需进一步研究。
显示原图|下载原图ZIP|生成PPT图6不同施肥方式下油菜、水稻产量
-->Fig. 6The seasonal yield of rape, paddy in each treatment
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显示原图|下载原图ZIP|生成PPT图7不同施肥方式下油菜-水稻季温室气体排放强度
-->Fig. 7The GHGI of rape-paddy in each treatment
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3 讨论
3.1 油菜-水稻复种系统的N2O和CH4排放特征
本研究中,油菜-水稻复种系统各处理的土壤N2O通量有明显的季节变化规律,油菜季N2O通量在-4.08—35.51 μg N·m-2·h-1,而水稻季则在-16.52—193.30 μg N·m-2·h-1,呈现水稻季高,油菜季低的特点,该现象与荆光军等[21]、石将来等[22]对水稻/油菜复种系统的N2O排放规律的研究一致,原因是N2O的主要排放机制是硝化/反硝化过程,两个过程的相对重要性取决于环境条件[23],最适合硝化和反硝化作用的温度分别为25—35℃[24],在未达到最适温度前,随着土壤温度的升高,硝化和反硝化作用加强[21]。同时水分也是关键因素,土壤产生N2O的主要来源在土壤含水量未处于饱和含水量时是硝化作用,而当水分饱和时则是反硝化过程[25],而本研究中在6—9月的均温在27.45℃,降雨量584.1 mm,温度和水分都较高,综合加强了土壤硝化/反硝化的过程,因而会出现较强的N2O排放峰。本研究中还观察到了稻田土壤吸收N2O的现象,在三江平原典型沼泽湿地[26]和太湖地区稻麦菜复种地N2O排放也有类似的现象[27],原因可能是水稻季持续淹水导致土壤处于强还原状态,使得微生物吸收N2O并将其反硝化还原成N2[28]。同样,本研究中各处理的土壤CH4通量有明显的季节变化规律,各个处理之间尤其是一次性施肥处理对CH4和N2O周期排放特征影响不显著,均呈现出水稻季高,油菜季低的特点,这在水旱轮作CH4排放的研究中均可见[22,29],原因是相比于油菜季,水稻季常处于淹水状态,土壤达到饱和含水量,易形成厌氧的还原性环境,利于产CH4菌等的厌氧菌的繁殖,从而分解土壤中的有机物产生CH4[25]。本研究还观察到了水稻生长季呈“中间高两头低”的变化趋势,这与卢维盛等[30]、韩广轩等[31]的研究中水稻CH4排放特征一致。原因是随着水稻的生长,根系逐渐发达,水稻地上部和地下部良好的生长为土壤中产生的CH4气体向大气的排放提供了通道,排放CH4的能力慢慢增强,在抽穗中期达到最大,之后随着水稻成熟而减小[31]。
3.2 一次性施肥对土壤N2O和CH4排放总量的影响
从不同作物生长季来看,油菜季的各处理的N2O的排放量不高,为0.17—0.41 kg N·hm-2,可以看出一次性施肥对油菜季N2O排放影响不明显,大多研究表明,旱作农田N2O排放远高于灌溉稻田,《2006年IPCC国家温室气体清单指南》中,旱作农田和灌溉稻田N2O排放因子的缺省值分别为1%和0.3%,即旱作农田N2O排放远高于灌溉稻田,但本文中得到的结果是油菜季的N2O排放低于灌溉稻田。主要是本研究中油菜季处于温度和降水都较少的冬春两季,气温和土壤水分含量高低能明显影响微生物的活性大小和土壤中的O2含量,从而成为土壤排放N2O的主要影响因素[26],而冬春季低活性的微生物导致了N2O的排放量不高,而水稻季由于频繁的干湿交替灌溉促进了N2O的排放,从而水稻季比旱作油菜季高。另一个原因是油菜季取样频率偏低。实际上,油菜季的测定频率为每月至少2次,那么整个油菜季应该有8—10次数据。造成最终只有5次有效数据的原因是,由于田间测量误差比如产生了漏气现象等,影响了数据浓度的计算,N2O排放浓度和测量时间没有形成显著的相关关系（线性或非线性关系）,即依据文中气体通量计算公式dc/dt是负值或为零,因此为了保证数据的有效性合理性,在原始通量数据处理过程中舍掉了一部分数据。由于田间试验困难且复杂,影响因素多,基于静态箱的观测方法本身条件的限制,因此,在以后的试验中增加取样频率或改善研究方法必不可少。水稻季的各处理的N2O排放总量在0.20—0.99 kg N·hm-2,一次性施肥条件下水稻季的UA比OPT处理减少25.1%,而CRF处理比OPT增加45.0%。可能的原因是一次性施肥都是基施,控释肥的肥效持续时间长于普通尿素,导致基施控释肥参与N2O产生过程的基质浓度较高,同时水稻季6月开始逐渐升高的环境温度和增多的水分也会影响N2O的排放[21,25],从而会比普通尿素产生更多的N2O,这与其他的研究结果[36,37]不相符,同时刘晓伟等[36]的研究表明深施肥可以延长肥料养分在土壤中的贮存时间,降低了氮肥当季损失量。本研究中的施肥深度在10 cm,因此深施也可能是本研究中基施处理的N2O排放量不高的原因。未来应进一步关注一次性控释肥对N2O排放的影响。CH4的排放量主要发生在水稻季,施用氮肥虽然没有直接对CH4的排放产生作用,但是可以通过促进作物的生长发育来提供CH4的排向大气的通道[32],各处理的CH4排放量为15.15—24.26 kg C·hm-2,一次性施肥处理的UA和CRF分别比OPT减少27.4%和25.0%,但是差异不显著,可能原因是在OPT处理在水稻关键生长期的追肥会促进水稻的生长发育从而间接增加CH4的排放量[32]。3.3 一次性施肥对土壤GHGI和作物产量的影响
单位产量的GHGI呈现油菜季低,水稻季高的特征,说明在相同的产量下,水稻季排放的温室气体多于油菜季,原因可能是油菜季主要的温室气体来源是N2O,本研究中油菜季的降雨少且持续短,同时整个油菜生长季节的温度并不高,所以油菜季N2O排放较弱;而在水稻季中有主要排放两种温室气体,虽然水稻产量明显高于油菜,但稻田的干湿交替促进了N2O排放[34,35],同时稻田大量排放的CH4综合作用使得最终计算水稻季的GHGI较高,所以我们应重点关注水稻季的温室气体排放。与CK、FP和CRF处理相比,一次性施肥的CRF与UA处理的GHGI在油菜和水稻季均较低,但是两季中各处理间差异不显著。原因可能是本研究中一次性施肥的肥料采用基肥深施,刘晓伟等[38]的研究表明深施可以延长肥料养分在土壤中的贮存时间,降低了氮肥当季损失量,在保证产量的前提下,一次性深施肥通过减少了温室气体排放从而降低温室气体排放强度。因此,一次性施肥作为一种温室气体减排的技术是值得推荐的。各施氮肥处理间的油菜产量2 150—2 441 kg·hm-2和水稻产量9 207— 9 806 kg·hm-2。减氮施肥的3个处理均没有显著降低作物的产量。一次性施肥CRF处理比OPT处理可以增加油菜产量9.6%,但对水稻产量增加不明显,可能是控释氮肥的养分释放周期长于普通氮肥,为油菜提供氮素的时间较长[39],土壤成分含量的不同可能会影响控释尿素控制养分释放的速率以及作物产量和肥料利用效率[40,41]。本研究试验区的土壤质地是砂壤土,具有较弱的氧化还原电位缓冲能力及较差的有机质保持能力。控释肥可能由于前期土壤环境导致释放过快,作物生长期长,等到后期需要肥旺季和普通尿素一样,难以提供大量尿素,同时比较了作物种植前后土壤的养分变化,发现硝态氮和铵态氮含量大幅度下降,这也可能是基施尿素没有造成减产的原因。同时施肥方也可能是另一影响因素,刘晓伟等[38]的研究表明深10 cm的根区施肥可以延长肥料养分在土壤中的贮存时间,显著提高水稻的氮肥利用效率,这也有利于保持产量。本研究中施肥方式采用的沟施肥,施肥深度在10 cm,在节省肥料,提高氮肥利用效率的同时保证了作物产量。油菜季可能是深施肥和降雨少、温度低的环境共同减缓了养分的释放[39],而水稻季降雨多、温度高的环境使得控释肥前期释放过快,但深施肥技术提高了氮肥利用效率,使得一次性基施控释肥和普通尿素的肥效接近,在保证产量的同时降低了温室气体排放。但也有罗宏东等[42]的研究表明先期施用基肥分开施肥的效果优于一次性施肥,一次性全量基施普通氮肥会造成水稻减产[43]。因此,未来也要关注一次性施肥技术对产量的影响。3.4 一次性施肥技术对GWP的影响
由于CH4和N2O存在着此消彼长的关系[44],如果只是单独考虑对N2O和CH4各自的影响,可能会造成减排技术效应的不准确评估,甚至会产生相反的结果。本文为了分析净温室气体排放,采用了GWP。石将来等[22]在西南紫土研究中,油菜-水稻轮作系统GWP（100 a）为3 454.17 kgCO2-eq·hm-2,张岳芳等[7]在阳澄湖平原研究中,水旱轮作稻田的GWP（100 a）为3 127 kgCO2-eq·hm-2,本研究中计算出FP处理的GWP最高,为1 062.36 kgCO2-eq·hm-2,相比之下,GWP更低。各处理CH4排放对GWP的贡献更大,达到了58.7%以上,张岳芳等[7]的研究也表明,CH4排放在稻季温室效应中起着决定性作用。可能的原因一是由于油菜-水稻复种系统温室气体主要产生在水稻季;二是由于稻田的CH4的排放量大于N2O的排放量,且与水稻地上生物量之间有显著的正相关关系[45],而且相比N2O更易排放到大气中。此外,分析不同处理之间的GWP表明,减氮21.4%的OPT比FP减少了16.4%,这说明氮肥的减量施用降低了净温室气体排放 [32,46]。在同样施氮水平下,与OPT处理相比,UA和CRF处理分别减少了28.0%和18.2%的GWP。说明两种一次性施肥处理可以降低GWP,但UA的效果较好。这主要由于控释肥对稻田N2O排放的影响更取决于田间水分状况和温度条件[47],控释肥的肥效持续时间长于普通尿素,在稻田干湿交替的过程中,其缓慢释放养分增加了形成硝化反硝化的底物[15],从而加大了N2O排放量,因而对水稻季N2O排放减排效果不明显。降雨是影响旱地N2O排放的重要因素[34,35],在休闲期降雨较多且温度20℃以上,但本研究中在休闲期温室气体测定频率偏低,必然会造成对周年温室效应估算的偏差。虽然相关研究表明[22,48]在作物轮作季休闲期测定的温室气体排放量不高,但是对于研究周年温室气体排放效应,在未来的试验设计中应当完善取样测定的频率。可见,控释肥对水稻季N2O的减排效果仍需长期观测。但综合考虑两种气体的GWP,UA或者CRF处理仍是值得推荐的温室气体减排技术。4 结论
4.1 在油菜-水稻复种系统各处理的土壤N2O和CH4排放通量具有明显的油菜季低、水稻季高的季节特点;排放强度（GHGI）呈现油菜季低,而水稻季高的特征。4.2 在减少21.4%（45 kg）的农民习惯氮肥施用量下,可以同时减少N2O排放量20.5%,CH4排放量13.5%。与氮肥施用量（165 kg）相同的分次施肥相比,一次性基施普通尿素可以同时减少21.2%的N2O排放量和29.0%的CH4排放量,而一次性基施控释肥减少了29.9%的CH4排放量却增加了14.8%的N2O排放量。
4.3 在相同的氮肥施肥量（165 kg）下,一次性施肥基施尿素和控释肥分别比分次施肥减少了28.0%（641.69 kgCO2-eq·hm-2）和18.2%（733.25 kgCO2-eq·hm-2）的GWP,但是油菜产量（2 150—2 379 kg·hm-2）和水稻产量（9 147—9 246 kg·hm-2）并未减少。
可见,一次性施肥包括基施尿素或者基施控释肥不会造成作物减产,同时可以降低净温室气体的排放,但仍需长期试验的验证。
The authors have declared that no competing interests exist.
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| [4] | . 以位于西南大学农业部重庆紫色土生态环境重点野外科学观测试验站 内1990年设立的长期免耕试验田为研究对象,采用静态暗箱/气相色谱法,对传统的冬水田平作（CT）及由其改良而成的水旱轮作（CTR）、厢作免耕 （NTP）和垄作免耕（NTR）等农田生态系统CH4和N2O的排放进行了连续1 a的田间原位观测研究.结果表明,传统的CT处理中,CH4和N2O主要排放时期为水稻种植季,该时期的持续时间仅占全年的27.1%,但2种温室气体的 总排放量分别占全年的77.6%和55.0%;耕作制度改良后,CH4排放降低而N2O排放增加.不同耕作方式下CH4的年平均排放通量[以CH4 计,mg.（m2.h）-1]为CT（2.96±0.04）〉NTR（1.83±0.21）〉NTP（1.42±0.01）〉 CTR（0.96±0.09）,CT处理的CH4排放极显著高于CTR和NTP处理（P〈0.01）,显著高于NTR处理（P〈0.05）;N2O的年平 均排放通量[以N2O计,μg.（m2.h）-1]依次为CTR（123.6±47.1）〉NTR（115.2±22.1）〉 NTP（100.5±25.8）〉CT（81.3±13.5）,CTR处理N2O的排放显著高于CT（P〈0.05）.通过对不同时间尺度（20、100 及500 a）2种温室气体综合全球增温潜势（global warming potential,GWP）的计算,可以发现,改良后的3种耕作方式对CH4和N2O的综合GWP有一定的减排作用,无论时间尺度长短,4种耕作处理全 年所排放的CH4和N2O所产生的综合GWP均为CT〉NTR〉NTP〉CTR.因此,耕作方式的改良对紫色水稻土农田生态系统中CH4和N2O综合 GWP减排有着明显的效果. . 以位于西南大学农业部重庆紫色土生态环境重点野外科学观测试验站 内1990年设立的长期免耕试验田为研究对象,采用静态暗箱/气相色谱法,对传统的冬水田平作（CT）及由其改良而成的水旱轮作（CTR）、厢作免耕 （NTP）和垄作免耕（NTR）等农田生态系统CH4和N2O的排放进行了连续1 a的田间原位观测研究.结果表明,传统的CT处理中,CH4和N2O主要排放时期为水稻种植季,该时期的持续时间仅占全年的27.1%,但2种温室气体的 总排放量分别占全年的77.6%和55.0%;耕作制度改良后,CH4排放降低而N2O排放增加.不同耕作方式下CH4的年平均排放通量[以CH4 计,mg.（m2.h）-1]为CT（2.96±0.04）〉NTR（1.83±0.21）〉NTP（1.42±0.01）〉 CTR（0.96±0.09）,CT处理的CH4排放极显著高于CTR和NTP处理（P〈0.01）,显著高于NTR处理（P〈0.05）;N2O的年平 均排放通量[以N2O计,μg.（m2.h）-1]依次为CTR（123.6±47.1）〉NTR（115.2±22.1）〉 NTP（100.5±25.8）〉CT（81.3±13.5）,CTR处理N2O的排放显著高于CT（P〈0.05）.通过对不同时间尺度（20、100 及500 a）2种温室气体综合全球增温潜势（global warming potential,GWP）的计算,可以发现,改良后的3种耕作方式对CH4和N2O的综合GWP有一定的减排作用,无论时间尺度长短,4种耕作处理全 年所排放的CH4和N2O所产生的综合GWP均为CT〉NTR〉NTP〉CTR.因此,耕作方式的改良对紫色水稻土农田生态系统中CH4和N2O综合 GWP减排有着明显的效果. |
| [5] | [D]. [D]. |
| [6] | [D]. [D]. |
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| [10] | . Abstract: It has illustrated that application of controlled-release fertilizers obviously saved labor power and fertilizers, and significantly increased yield as well for rice production. Pot trials and cylinder trials were carried out in 2002-2005 to study the mechanism of single basal application of controlled-release fertilizers for increasing yield of rice (Oryza Sative L.). The trials involved in the following 6 treatments, splitting Nongke rice-specific fertilizer (SNRSF, ck), single basal of Nongke rice-specific fertilizer (BNRSF), single basal of Nongke controlled-release fertilizer (BNCRF), single basal of controlled-release fertilizer with NH4MgPO4 coated (BLCRF), single basal of bulk blend fertilizer with resin coated urea (BCUF), no fertilization (NF). It was observed, that treatments of BLCRF and BNCRF resulted in apparently higher concentrations of soil available N than BCUF, while soil available N of SNRSF fluctuated greatly within 30 days after fertilization. After 30 days of fertilization, there were no significantly differences in soil available N concentrations among the fertilization treatments under rice planting, however, available N concentrations for the 3 treatments of controlled-release fertilizers (CRFs) were greater than SNRSF without rice planting. In comparison to SNRSF, better nutrition from the CRFs resulted in the following advanced characteristics. (1) CRFs developed larger rice root weights, volumes, total absorption areas and deeper distribution, higher root bleeding intensity, with greater output intensity of amino acids in root bleeding through out all the growth stages. (2) There were higher chlorophyll concent and activity of CAT, but lower POD for the CRFs in the flag leaves after 12 days of flowering, in which dissoluble protein decomposed slower during all filling stages. (3) Application of the CRFs enlarged the base of rice stems, declined the proportion of shoot and root, increased root depth index. These indicated that single basal application of the CRFs should be able significantly to promote development of root system, enhance nutrient uptake, slower senescence speed and strengthen the capacity of lodging resistance. . Abstract: It has illustrated that application of controlled-release fertilizers obviously saved labor power and fertilizers, and significantly increased yield as well for rice production. Pot trials and cylinder trials were carried out in 2002-2005 to study the mechanism of single basal application of controlled-release fertilizers for increasing yield of rice (Oryza Sative L.). The trials involved in the following 6 treatments, splitting Nongke rice-specific fertilizer (SNRSF, ck), single basal of Nongke rice-specific fertilizer (BNRSF), single basal of Nongke controlled-release fertilizer (BNCRF), single basal of controlled-release fertilizer with NH4MgPO4 coated (BLCRF), single basal of bulk blend fertilizer with resin coated urea (BCUF), no fertilization (NF). It was observed, that treatments of BLCRF and BNCRF resulted in apparently higher concentrations of soil available N than BCUF, while soil available N of SNRSF fluctuated greatly within 30 days after fertilization. After 30 days of fertilization, there were no significantly differences in soil available N concentrations among the fertilization treatments under rice planting, however, available N concentrations for the 3 treatments of controlled-release fertilizers (CRFs) were greater than SNRSF without rice planting. In comparison to SNRSF, better nutrition from the CRFs resulted in the following advanced characteristics. (1) CRFs developed larger rice root weights, volumes, total absorption areas and deeper distribution, higher root bleeding intensity, with greater output intensity of amino acids in root bleeding through out all the growth stages. (2) There were higher chlorophyll concent and activity of CAT, but lower POD for the CRFs in the flag leaves after 12 days of flowering, in which dissoluble protein decomposed slower during all filling stages. (3) Application of the CRFs enlarged the base of rice stems, declined the proportion of shoot and root, increased root depth index. These indicated that single basal application of the CRFs should be able significantly to promote development of root system, enhance nutrient uptake, slower senescence speed and strengthen the capacity of lodging resistance. |
| [11] | . 【目的】研究不同缓控释肥及施肥方式对机插常规粳稻群体光合物质生产和产量的影响。【方法】2013—2014年在江苏省丹阳市延陵镇南京农业大学水稻试验基地进行,以当地常规粳稻武运粳24号进行机插种植,试验设置3种缓控释肥(掺混肥、4个月树脂尿素、硫包衣尿素)以及一次性施肥和一基一蘖两种施肥方式,共7个处理,分别为掺混肥的一次性基肥施用(B-BSRB)、4个月树脂尿素的一次性基肥施用(B-PCU)、硫包衣尿素的一次性基肥施用(B-SCU)、掺混肥的一基一蘖施用(BT-BSRB)、4个月树脂尿素的一基一蘖施用(BT-PCU)、硫包衣尿素的一基一蘖施用(BT-SCU)和当地高产施肥方式(CK)为对照,各处理的施氮量一致,磷钾肥用量均相同。【结果】水稻产量表现为掺混肥4个月树脂尿素硫包衣尿素,2年结果一致;一基一蘖施肥方式一次性施肥,掺混肥一基一蘖处理产量最高,2年产量分别为11.6 t·hm~(-2)和10.1 t·hm~(-2),较常规高产施肥(CK)处理2年产量分别提高9.4%、12.2%。群体干物质重、叶面积指数、光合势均表现为掺混肥硫包衣尿素4个月树脂尿素;群体干物质重、叶面积指数和光合势均表现为一基一蘖施肥方式一次性施肥,2年结果一致。干物质积累量、群体生长率在拔节期表现为掺混肥硫包衣尿素4个月树脂尿素,但是在成熟期表现为掺混肥4个月树脂尿素硫包衣尿素,一基一蘖施肥方式一次性施肥。【结论】掺混肥在提高水稻群体干物质、叶面积指数、光合势及产量上优于4个月树脂包衣尿素和硫包衣尿素,一基一蘖施肥方式优于一次性施肥处理。与当地常规高产施肥相比,组配的掺混肥配合分蘖期速效氮肥的施用可以显著提高水稻群体的光合物质生产和产量。 . 【目的】研究不同缓控释肥及施肥方式对机插常规粳稻群体光合物质生产和产量的影响。【方法】2013—2014年在江苏省丹阳市延陵镇南京农业大学水稻试验基地进行,以当地常规粳稻武运粳24号进行机插种植,试验设置3种缓控释肥(掺混肥、4个月树脂尿素、硫包衣尿素)以及一次性施肥和一基一蘖两种施肥方式,共7个处理,分别为掺混肥的一次性基肥施用(B-BSRB)、4个月树脂尿素的一次性基肥施用(B-PCU)、硫包衣尿素的一次性基肥施用(B-SCU)、掺混肥的一基一蘖施用(BT-BSRB)、4个月树脂尿素的一基一蘖施用(BT-PCU)、硫包衣尿素的一基一蘖施用(BT-SCU)和当地高产施肥方式(CK)为对照,各处理的施氮量一致,磷钾肥用量均相同。【结果】水稻产量表现为掺混肥4个月树脂尿素硫包衣尿素,2年结果一致;一基一蘖施肥方式一次性施肥,掺混肥一基一蘖处理产量最高,2年产量分别为11.6 t·hm~(-2)和10.1 t·hm~(-2),较常规高产施肥(CK)处理2年产量分别提高9.4%、12.2%。群体干物质重、叶面积指数、光合势均表现为掺混肥硫包衣尿素4个月树脂尿素;群体干物质重、叶面积指数和光合势均表现为一基一蘖施肥方式一次性施肥,2年结果一致。干物质积累量、群体生长率在拔节期表现为掺混肥硫包衣尿素4个月树脂尿素,但是在成熟期表现为掺混肥4个月树脂尿素硫包衣尿素,一基一蘖施肥方式一次性施肥。【结论】掺混肥在提高水稻群体干物质、叶面积指数、光合势及产量上优于4个月树脂包衣尿素和硫包衣尿素,一基一蘖施肥方式优于一次性施肥处理。与当地常规高产施肥相比,组配的掺混肥配合分蘖期速效氮肥的施用可以显著提高水稻群体的光合物质生产和产量。 |
| [12] | . 【Objective】It is well known that the issue of greenhouse gases (GHGs) emission from rice ecosystem has been concerned within the scope of climate change research over years. The effect of controlled release fertilizer and additive treatments on GHGs emission and rice yield in a double rice (Oryza sative L) field was investigated to evaluate their potential of GHGs reduction and yield promotion, this study is also very important for the development of low-carbon agriculture and the mitigation research of global warming.【Method】Taking the double rice in Jianghan Plain, Hubei province, Central China as the object, a continuous observation of greenhouse gas emission from six different controlled release fertilizer or additive treatments (CK: conventional urea, CRU1: sulfur-coated urea, CRU2: polymer-coated urea, CU: nitrapyrin crystal urea, DMPP: nitrification inhibitor, EM: effective microorganisms) was conducted by using the automatic static chamber-GC (gas chromatography) method, the rice yield and soil properties were also monitored simultaneously. Variation and characterization of GHGs (CH4 and N2O) emission, greenhouse effect (CO2-e) and greenhouse gas intensity of each treatment were analyzed comprehensively.【Result】The results indicated that CH4 and N2O emission in different fertilizer treatments had an obvious daily and seasonal variation law in double rice ecosystem. Controlled release urea (polymer-coated) caused the lowest CH4 emission during the early rice, while the nitrapyrin crystal urea had the lowest CH4 emission during the late rice growing season. In consideration of N2O, the DMPP had the lowest emission during the two rice growing season compared to the other field applications. Pronounced differences were discovered among 6 treatments on global greenhouse effect (CO2-e，on 100 a horizon) during the whole rice growing season (P<0.05). Among the field applications, CRU1 had the lowest global greenhouse effect, followed by CU, EM, DMPP, CRU2, and CK, respectively. Furthermore, significant greenhouse effect reduction potential was also employed; the polymer-coated urea dominated the fashion with the highest reduction potential of 56.2% compared to traditional fertilization, followed by nitrapyrin crystal urea (45.6%). In the view of rice yield, five other treatments were significantly higher than CK during late rice (stimulated rice yield by 13.5%-16.2%) while no statistical differences were found during early rice. Additionally, GHGI of polymer-coated urea was statistically lower than the other applications including the conventional fertilization (P＜0.01). 【Conclusion】Various reduction potential and yield promotion effects existed among different field applications from the double rice cropping system, this influence was significant during the late rice growing season but not remarkable in the early rice，while synthetically consideration of their economic earnings and environmental effects, the application of controlled release urea benefitted the most to the rice production, followed by nitrification inhibitor and biopreparate under the current field management conditions. . 【Objective】It is well known that the issue of greenhouse gases (GHGs) emission from rice ecosystem has been concerned within the scope of climate change research over years. The effect of controlled release fertilizer and additive treatments on GHGs emission and rice yield in a double rice (Oryza sative L) field was investigated to evaluate their potential of GHGs reduction and yield promotion, this study is also very important for the development of low-carbon agriculture and the mitigation research of global warming.【Method】Taking the double rice in Jianghan Plain, Hubei province, Central China as the object, a continuous observation of greenhouse gas emission from six different controlled release fertilizer or additive treatments (CK: conventional urea, CRU1: sulfur-coated urea, CRU2: polymer-coated urea, CU: nitrapyrin crystal urea, DMPP: nitrification inhibitor, EM: effective microorganisms) was conducted by using the automatic static chamber-GC (gas chromatography) method, the rice yield and soil properties were also monitored simultaneously. Variation and characterization of GHGs (CH4 and N2O) emission, greenhouse effect (CO2-e) and greenhouse gas intensity of each treatment were analyzed comprehensively.【Result】The results indicated that CH4 and N2O emission in different fertilizer treatments had an obvious daily and seasonal variation law in double rice ecosystem. Controlled release urea (polymer-coated) caused the lowest CH4 emission during the early rice, while the nitrapyrin crystal urea had the lowest CH4 emission during the late rice growing season. In consideration of N2O, the DMPP had the lowest emission during the two rice growing season compared to the other field applications. Pronounced differences were discovered among 6 treatments on global greenhouse effect (CO2-e，on 100 a horizon) during the whole rice growing season (P<0.05). Among the field applications, CRU1 had the lowest global greenhouse effect, followed by CU, EM, DMPP, CRU2, and CK, respectively. Furthermore, significant greenhouse effect reduction potential was also employed; the polymer-coated urea dominated the fashion with the highest reduction potential of 56.2% compared to traditional fertilization, followed by nitrapyrin crystal urea (45.6%). In the view of rice yield, five other treatments were significantly higher than CK during late rice (stimulated rice yield by 13.5%-16.2%) while no statistical differences were found during early rice. Additionally, GHGI of polymer-coated urea was statistically lower than the other applications including the conventional fertilization (P＜0.01). 【Conclusion】Various reduction potential and yield promotion effects existed among different field applications from the double rice cropping system, this influence was significant during the late rice growing season but not remarkable in the early rice，while synthetically consideration of their economic earnings and environmental effects, the application of controlled release urea benefitted the most to the rice production, followed by nitrification inhibitor and biopreparate under the current field management conditions. |
| [13] | . By the method of static chamber, a field experiment was conducted to study the effects of applying controlled-release fertilizer (CRF) and its combination with urea on the NO emission during rice growth period. Four treatments, O emission during rice growth season by 40.4% and 59.6%, and decreased the emission at midseason aeration stage by 65.1% and 83.9%, respectively (O emission in treatment U+C had a slight decrease, and decreased by 53.9% at midseason aeration stage. Applying CRF increased rice yield, and the increment in treatments C and U+C was 7.8% and 9.8%, respectively, as compared to treatment U. Applying CRF delayed the peak time of soil inorganic nitrogen concentration, resulting in the reduction of NO emission at midseason aeration stage. During rice growth season, no significant correlation was observed between NO flux and soil Eh or soil temperature. . By the method of static chamber, a field experiment was conducted to study the effects of applying controlled-release fertilizer (CRF) and its combination with urea on the NO emission during rice growth period. Four treatments, O emission during rice growth season by 40.4% and 59.6%, and decreased the emission at midseason aeration stage by 65.1% and 83.9%, respectively (O emission in treatment U+C had a slight decrease, and decreased by 53.9% at midseason aeration stage. Applying CRF increased rice yield, and the increment in treatments C and U+C was 7.8% and 9.8%, respectively, as compared to treatment U. Applying CRF delayed the peak time of soil inorganic nitrogen concentration, resulting in the reduction of NO emission at midseason aeration stage. During rice growth season, no significant correlation was observed between NO flux and soil Eh or soil temperature. |
| [14] | . . |
| [15] | . . |
| [16] | . 设计了适量和过量总施氮量下的一次和分次施氮的田间试验，研究了不同施肥方式对山西半干旱地 区肥力水平较低的盐渍型水稻土水稻产量的影响。结果表明，适宜氮量（N 198kg hm^-2下，水稻插秧前基肥一次性施氮较分三次在不同生育期施氮稻谷平均增产达10％；但过量施氮下，一次性基肥施氮较分三次施用平均减产6．6％。总 施氮量小于适宜施氮量时，基肥一次性施氮较分三次施用平均增产则达到30％。插秧前基肥一次性施氮与基肥和分蘖初期分两次施氮相比，稻谷产量无明显差异。 这说明插秧前和分蘖初期是该地水稻的有效施肥期。在不施磷肥或磷肥做基肥一次施用而氮肥分次施用的情况下，基肥氮磷施用比例也影响所施用氮肥的肥效；因 此，就所试验的肥力较低的盐渍型水稻土来说，可以实行在减量施氮下的插秧前基肥一次性施氮，而不需要追施氮肥，并且在施P2O5130kg hm^-2的条件下，总施氮190kg hm^-2即可满足高产，因而可以减少习惯施氮量的1／3。 . 设计了适量和过量总施氮量下的一次和分次施氮的田间试验，研究了不同施肥方式对山西半干旱地 区肥力水平较低的盐渍型水稻土水稻产量的影响。结果表明，适宜氮量（N 198kg hm^-2下，水稻插秧前基肥一次性施氮较分三次在不同生育期施氮稻谷平均增产达10％；但过量施氮下，一次性基肥施氮较分三次施用平均减产6．6％。总 施氮量小于适宜施氮量时，基肥一次性施氮较分三次施用平均增产则达到30％。插秧前基肥一次性施氮与基肥和分蘖初期分两次施氮相比，稻谷产量无明显差异。 这说明插秧前和分蘖初期是该地水稻的有效施肥期。在不施磷肥或磷肥做基肥一次施用而氮肥分次施用的情况下，基肥氮磷施用比例也影响所施用氮肥的肥效；因 此，就所试验的肥力较低的盐渍型水稻土来说，可以实行在减量施氮下的插秧前基肥一次性施氮，而不需要追施氮肥，并且在施P2O5130kg hm^-2的条件下，总施氮190kg hm^-2即可满足高产，因而可以减少习惯施氮量的1／3。 |
| [17] | . . |
| [18] | . 【Objective】A split field experiment was carried out to study the effects of different P fertilizer application rates on crop yield, P uptake, P recovery efficiency and residual efficiency under annual rice-rapeseed rotation. The effects of residual P in rice season on rapeseed yields and crop P uptakes were evaluated to explore the distribution of P fertilizer in annual rice-rapeseed rotation for the purpose of optimization of P fertilization strategy in rice-rapeseed rotation.【Method】An annual rice-rapeseed field experiment was conducted in Honghu County, Hubei province from May, 2010 to May, 2011. In rice season, there were four different P application rates treatment (P0, 0 P2O5, P30, 30 kg P2O561hm-2, P60, 60 kg P2O561hm-2 and P90, 90 kg P2O561hm-2), while in later rapeseed season, the original P application rate treatments were split into two sub-treatments (with P fertilization treatment, 60 kg P2O561hm-2, and without P fertilization treatment, 0 kg P2O561hm-2). Besides crop yield, crop P uptake, P recovery efficiency and residual P utilization efficiency under different P treatments were analyzed, the concept of “the substitute rate of P fertilizer” was adopted to estimate the residual effects of P fertilizer applied in rice season on the rapeseed yield. 【Result】 Reasonable P fertilization substantially increased the yield of the rice and rapeseed. Crop yield and P recovery efficiency in rice season were the highest in P60 treatment, with the average of 9 694 kg61hm-2 and 19.2%, respectively. Insufficient or excessive P fertilization decreased rice yield and P recovery efficiency. Compared with without P fertilization treatment in rapeseed season, rapeseed dry matter increased significantly, ranging from 756 to 1 195 kg61hm-2 in P fertilization treatment; while seed yields were also improved, ranging from 427 to 503 kg61hm-2. P fertilizer applied in rice season significantly affected the seed yield and crop nutrient uptake of the following rapeseed. In contrast to the plots without P fertilization in rice season, rapeseed dry matter of the plots with P fertilization in rice season dramatically increased, varying from 212 to 816 kg61hm-2, and the yield of rapeseed varying from 136 to 409 kg61hm-2, and the P uptake by rapeseed increased from 0.4 to 4.9 kg61hm-2. The P fertilizer applied in rice season could be utilized by rapeseed which consequently increased the agronomic efficiencies and the contribution rate of P fertilizer applied in rapeseed season. The recovery efficiency of P applied in rice season ranged from 16.3% to 19.2%, the residual utilization efficiency ranged from 5.4% to 7.3% and the annual P fertilizer accumulate efficiency was 21.8% - 25.6%. P fertilizer applied in rice season had a significant residual effect, which showed a positive correlation with P fertilizer application rate. The residual effects of P fertilizer applied in rice season were equivalent to 2-9 kg P2O561hm-2 used in the rapeseed season. Furthermore, the residual effects of P fertilizer applied in rice season were also positively affected by the P fertilizer application rate in rapeseed season. The residual effects of P fertilizer in rapeseed season with P fertilization were higher than those without P fertilization. 【Conclusion】 Reasonable P fertilization could substantially increase crop yield, P uptake and P use efficiency under rice-rapeseed rotation system. The P fertilizer application in rice season had a significant residual effect on increase rapeseed yield and P, which showed a positive correlation with P fertilizer application rate. Considering “more P fertilization used in upland season and less P fertilization used in paddy season” in P fertilization management strategy under paddy-upland rotation, P fertilization management in rapeseed season thus should be optimized taking the residual effect of P application in rice season into consideration. . 【Objective】A split field experiment was carried out to study the effects of different P fertilizer application rates on crop yield, P uptake, P recovery efficiency and residual efficiency under annual rice-rapeseed rotation. The effects of residual P in rice season on rapeseed yields and crop P uptakes were evaluated to explore the distribution of P fertilizer in annual rice-rapeseed rotation for the purpose of optimization of P fertilization strategy in rice-rapeseed rotation.【Method】An annual rice-rapeseed field experiment was conducted in Honghu County, Hubei province from May, 2010 to May, 2011. In rice season, there were four different P application rates treatment (P0, 0 P2O5, P30, 30 kg P2O561hm-2, P60, 60 kg P2O561hm-2 and P90, 90 kg P2O561hm-2), while in later rapeseed season, the original P application rate treatments were split into two sub-treatments (with P fertilization treatment, 60 kg P2O561hm-2, and without P fertilization treatment, 0 kg P2O561hm-2). Besides crop yield, crop P uptake, P recovery efficiency and residual P utilization efficiency under different P treatments were analyzed, the concept of “the substitute rate of P fertilizer” was adopted to estimate the residual effects of P fertilizer applied in rice season on the rapeseed yield. 【Result】 Reasonable P fertilization substantially increased the yield of the rice and rapeseed. Crop yield and P recovery efficiency in rice season were the highest in P60 treatment, with the average of 9 694 kg61hm-2 and 19.2%, respectively. Insufficient or excessive P fertilization decreased rice yield and P recovery efficiency. Compared with without P fertilization treatment in rapeseed season, rapeseed dry matter increased significantly, ranging from 756 to 1 195 kg61hm-2 in P fertilization treatment; while seed yields were also improved, ranging from 427 to 503 kg61hm-2. P fertilizer applied in rice season significantly affected the seed yield and crop nutrient uptake of the following rapeseed. In contrast to the plots without P fertilization in rice season, rapeseed dry matter of the plots with P fertilization in rice season dramatically increased, varying from 212 to 816 kg61hm-2, and the yield of rapeseed varying from 136 to 409 kg61hm-2, and the P uptake by rapeseed increased from 0.4 to 4.9 kg61hm-2. The P fertilizer applied in rice season could be utilized by rapeseed which consequently increased the agronomic efficiencies and the contribution rate of P fertilizer applied in rapeseed season. The recovery efficiency of P applied in rice season ranged from 16.3% to 19.2%, the residual utilization efficiency ranged from 5.4% to 7.3% and the annual P fertilizer accumulate efficiency was 21.8% - 25.6%. P fertilizer applied in rice season had a significant residual effect, which showed a positive correlation with P fertilizer application rate. The residual effects of P fertilizer applied in rice season were equivalent to 2-9 kg P2O561hm-2 used in the rapeseed season. Furthermore, the residual effects of P fertilizer applied in rice season were also positively affected by the P fertilizer application rate in rapeseed season. The residual effects of P fertilizer in rapeseed season with P fertilization were higher than those without P fertilization. 【Conclusion】 Reasonable P fertilization could substantially increase crop yield, P uptake and P use efficiency under rice-rapeseed rotation system. The P fertilizer application in rice season had a significant residual effect on increase rapeseed yield and P, which showed a positive correlation with P fertilizer application rate. Considering “more P fertilization used in upland season and less P fertilization used in paddy season” in P fertilization management strategy under paddy-upland rotation, P fertilization management in rapeseed season thus should be optimized taking the residual effect of P application in rice season into consideration. |
| [19] | . . |
| [20] | . 控释肥作为一种能够提高肥料利用率、保障作物产量和节约劳动力的新型肥料已经在作物生产中得到广泛应用,而控释肥对土壤N2O排放影响结果的差异使其成为当前科学评估控释肥施用环境效应的焦点问题之一。因此,旨在探讨不同种类控释肥及氮素水平施用对华北平原冬小麦/夏玉米轮作系统土壤N2O排放的影响,为科学评价控释肥施用的环境效应及其推广应用提供科学依据。本研究监测采用静态暗箱—气相色谱法对不同控释肥施用下土壤N2O排放、环境因素以及产量进行了周年监测,探讨了不同处理（对照处理（CK）、控释肥处理1（CRF1）、优化控释肥处理1（80%CRF1）、优化控释肥处理2（80%CRF2）和控释肥处理3（CRF3＋尿素））下土壤N2O排放特征及土壤温湿度对其的影响。结果表明：控释肥施用下冬小麦/夏玉米轮作系统中土壤N2O排放峰高值主要出现在基肥施用并伴随灌溉（或降雨）后,一般持续时间约为7—10 d,小麦返青期灌溉以及玉米后期降雨会引起微弱的N2O排放峰。不同处理土壤N2O排放通量变化范围为-235.61—2625.01μg N2O m-2h-1,平均排放通量为23.88—51.39μg N2O m-2h-1,与CRFI相比,80%CRF1和80%CRF2处理能够减小施肥期的N2O排放峰值,但不改变轮作周期土壤N2O排放季节变化规律。CK处理和CRF3＋尿素处理土壤N2O排放通量与5cm深度土壤温度之间表现出显著的正相关性（r2=0.38,P〈0.01;r2=0.30,P〈0.05）;CRF1处理和80%CRF1处理在冬小麦生长季及整个轮作周期内与土壤孔隙含水率（WFPS）表现为显著的正相关关系（冬小麦生长季分别为r2=0.50,P〈0.01;r2=0.39,P〈0.05;整个轮作周期分别为r2=0.39,P〈0.05;r2=0.43,P〈0.05）。80%CRF2处理N2O年排放总量最高,为（2.89±0.24）kg N/hm2。相同控释肥种类条件下,80%CRF1处理比CRF1处理减少了14.23%,但并未达到显著水平;相同施氮量水平下,CRF1处理与（CRF317 . 控释肥作为一种能够提高肥料利用率、保障作物产量和节约劳动力的新型肥料已经在作物生产中得到广泛应用,而控释肥对土壤N2O排放影响结果的差异使其成为当前科学评估控释肥施用环境效应的焦点问题之一。因此,旨在探讨不同种类控释肥及氮素水平施用对华北平原冬小麦/夏玉米轮作系统土壤N2O排放的影响,为科学评价控释肥施用的环境效应及其推广应用提供科学依据。本研究监测采用静态暗箱—气相色谱法对不同控释肥施用下土壤N2O排放、环境因素以及产量进行了周年监测,探讨了不同处理（对照处理（CK）、控释肥处理1（CRF1）、优化控释肥处理1（80%CRF1）、优化控释肥处理2（80%CRF2）和控释肥处理3（CRF3＋尿素））下土壤N2O排放特征及土壤温湿度对其的影响。结果表明：控释肥施用下冬小麦/夏玉米轮作系统中土壤N2O排放峰高值主要出现在基肥施用并伴随灌溉（或降雨）后,一般持续时间约为7—10 d,小麦返青期灌溉以及玉米后期降雨会引起微弱的N2O排放峰。不同处理土壤N2O排放通量变化范围为-235.61—2625.01μg N2O m-2h-1,平均排放通量为23.88—51.39μg N2O m-2h-1,与CRFI相比,80%CRF1和80%CRF2处理能够减小施肥期的N2O排放峰值,但不改变轮作周期土壤N2O排放季节变化规律。CK处理和CRF3＋尿素处理土壤N2O排放通量与5cm深度土壤温度之间表现出显著的正相关性（r2=0.38,P〈0.01;r2=0.30,P〈0.05）;CRF1处理和80%CRF1处理在冬小麦生长季及整个轮作周期内与土壤孔隙含水率（WFPS）表现为显著的正相关关系（冬小麦生长季分别为r2=0.50,P〈0.01;r2=0.39,P〈0.05;整个轮作周期分别为r2=0.39,P〈0.05;r2=0.43,P〈0.05）。80%CRF2处理N2O年排放总量最高,为（2.89±0.24）kg N/hm2。相同控释肥种类条件下,80%CRF1处理比CRF1处理减少了14.23%,但并未达到显著水平;相同施氮量水平下,CRF1处理与（CRF317 |
| [21] | . . |
| [22] | . . |
| [23] | |
| [24] | [D]. [D]. |
| [25] | . . |
| [26] | . 2002~2004年利用静态箱-气相色谱法对三江平原3种具有代表性的湿地类型(常年积水的毛果苔草沼泽、季节性积水的小叶章湿草甸和常年土壤过湿的灌丛湿地)进行了为期两年半的N2O现场观测研究.结果表明,三江平原3种类型湿地N2O通量均有明显的季节变化和年际变化,一般在非冰冻期表现为排放,冰雪覆盖期表现为微弱的吸收.生长季的N2O通量以灌丛湿地N2O排放通量最大,毛果苔草沼泽最小.全年平均N2O交换通量:毛果苔草沼泽为53.928 mg.m-2.yr-1,小叶章湿地为21.408 mg.m-2.yr-1,灌丛湿地为657.120 mg.m-2.yr-1,证明沼泽湿地是大气N2O的源.3种类型湿地生长季N2O通量无明显的日变化,与温度的相关性不大. . 2002~2004年利用静态箱-气相色谱法对三江平原3种具有代表性的湿地类型(常年积水的毛果苔草沼泽、季节性积水的小叶章湿草甸和常年土壤过湿的灌丛湿地)进行了为期两年半的N2O现场观测研究.结果表明,三江平原3种类型湿地N2O通量均有明显的季节变化和年际变化,一般在非冰冻期表现为排放,冰雪覆盖期表现为微弱的吸收.生长季的N2O通量以灌丛湿地N2O排放通量最大,毛果苔草沼泽最小.全年平均N2O交换通量:毛果苔草沼泽为53.928 mg.m-2.yr-1,小叶章湿地为21.408 mg.m-2.yr-1,灌丛湿地为657.120 mg.m-2.yr-1,证明沼泽湿地是大气N2O的源.3种类型湿地生长季N2O通量无明显的日变化,与温度的相关性不大. |
| [27] | . 2003年11月8日至 2004年6月5日对太湖地区相邻的蔬菜地和稻麦轮作生态系统的冬小麦田,在当季不施肥情况下的N2O排放进行了田间同步对比观测,分析了N2O排放时间 变化以及土壤湿度、土壤温度、土壤速效氮含量和农业管理措施对N2O排放的影响。研究结果表明,小麦播种前的耕翻(表层大约7cm土壤旋耕)处理不会明显 改变稻麦轮作农田整个旱地阶段的N2O排放总量,但却使小麦生长季初期的N2O排放明显减弱69%(p0.01,p为相关概率),使小麦生长季后期的 N2O排放明显偏高2.6倍(p0.05),而对其余时间段的N2O排放作用不明显。与长期实行稻麦轮作的旱地阶段农田相比,由稻田改种蔬菜20多年的蔬 菜地,其整个观测期的N2O排放总量比免耕处理小麦田同期的排放高85%(p0.05),比耕翻处理小麦田同期的排放高99%(p0.01)。蔬菜地 N2O排放偏高的原因是土壤速效氮,特别是铵态氮含量明显偏高(p0.01)。 . 2003年11月8日至 2004年6月5日对太湖地区相邻的蔬菜地和稻麦轮作生态系统的冬小麦田,在当季不施肥情况下的N2O排放进行了田间同步对比观测,分析了N2O排放时间 变化以及土壤湿度、土壤温度、土壤速效氮含量和农业管理措施对N2O排放的影响。研究结果表明,小麦播种前的耕翻(表层大约7cm土壤旋耕)处理不会明显 改变稻麦轮作农田整个旱地阶段的N2O排放总量,但却使小麦生长季初期的N2O排放明显减弱69%(p0.01,p为相关概率),使小麦生长季后期的 N2O排放明显偏高2.6倍(p0.05),而对其余时间段的N2O排放作用不明显。与长期实行稻麦轮作的旱地阶段农田相比,由稻田改种蔬菜20多年的蔬 菜地,其整个观测期的N2O排放总量比免耕处理小麦田同期的排放高85%(p0.05),比耕翻处理小麦田同期的排放高99%(p0.01)。蔬菜地 N2O排放偏高的原因是土壤速效氮,特别是铵态氮含量明显偏高(p0.01)。 |
| [28] | . Regulation of trace N-gas production via nitrification and denitrification occurs at two levels: (a) control of the rates of these processes and (b) control of the relative proportions of end products. At the cellular level nitrification rates are controlled primarily by O2 and NH4+ availability. Similarly, denitrification is affected primarily by O2, NO3-, and organic-C availability. The availability of each of these cellular controllers is affected by numerous physical, chemical, and biological properties of the ecosystem, many of which have been characterized for a number of ecosystems. In contrast, the relationship between ecosystem properties and factors affecting relative proportions of end products is less well understood. Production of N2O by nitrifying bacteria results from reduction of NO2- when O2 is limiting, but the mechanism and factors affecting NO production during nitrification are not clear. Production of N2O via denitrification is affected by relative availabilities of electron donors (organic-C) and electron acceptors (N-oxides). Any factor that slows the overall rate of denitrification may also cause N2O to accumulate as a major end product. Production of NO via denitrification is more difficult to assess because control of cellular production and consumption is poorly understood. When NO diffusion is restricted by soil moisture, consumption by biological or abiological processes may be a dominant fate of this N-gas. Interaction of biological NO2- production and chemical NO2- decomposition (particularly in soil microsites) may also be an important source of NO. |
| [29] | . Permanently flooded rice fields, widely distributed in south and south-west China, emit more CH 4 than those drained in the winter crop season. For understanding CH 4 emissions from permanently flooded rice fields and developing mitigation options, CH 4 emission was measured year-round for 6 years from 1995 to 2000, in a permanently flooded rice field in Chongqing, China, where two cultivations with four treatments were prepared as follows: plain-cultivation, summer rice crop and winter fallow with floodwater layer annually (convention, Ch-FF), and winter upland crop under drained conditions (Ch-Wheat); ridge-cultivation without tillage, summer rice and winter fallow with floodwater layer annually (Ch-FFR), and winter upland crop under drained conditions (Ch-RW), respectively. On a 6-year average, compared to the treatments with floodwater in the winter crop season, the CH 4 flux during rice-growing period from the treatments draining floodwater and planting winter crop was reduced by 42% in plain-cultivation and by 13% in ridge-cultivation ( P < 0.05), respectively. The reduction of annual CH 4 emission reached 68 and 48%, respectively. Compared to plain-cultivation (Ch-FF), ridge-cultivation (Ch-FFR) reduced annual CH 4 emission by 33%, and which was mainly occurred in the winter crop season. These results indicate that draining floodwater layer for winter upland crop growth was not only able to prevent CH 4 emission from permanently flooded paddy soils directly in the winter crop season, but also to reduce CH 4 emission substantially during the following rice-growing period. As an alternative to the completely drainage of floodwater layer in the winter crop season, ridge-cultivation could also significantly mitigate CH 4 emissions from permanently flooded rice fields. |
| [30] | . CH and NO fluxes from late-rice fileds in Guangzhou region were measured simultaneously by closed chamber method.The results show that the mean CH fluxes are respectively 17.63,2.84 and 0.36mg·m·h from the treatments of continuous flooding ,routine succession cropping and rice-vegetabele rotation,and the mean NO fluxes are 6.74,11.69 and 55.07 μg NO-N·m·h correspondingly,which indicates that continuous floodin can greatly increase CH emission,while sinnificantly reduce NO emission.Rice vegetable rotation is the reverse.There exists a trade off between CH and NO emission.The factors affectin CH and NO emssion are discussed,and the contribution of CH and NO to global warming is preliminarily alalysed. . CH and NO fluxes from late-rice fileds in Guangzhou region were measured simultaneously by closed chamber method.The results show that the mean CH fluxes are respectively 17.63,2.84 and 0.36mg·m·h from the treatments of continuous flooding ,routine succession cropping and rice-vegetabele rotation,and the mean NO fluxes are 6.74,11.69 and 55.07 μg NO-N·m·h correspondingly,which indicates that continuous floodin can greatly increase CH emission,while sinnificantly reduce NO emission.Rice vegetable rotation is the reverse.There exists a trade off between CH and NO emission.The factors affectin CH and NO emssion are discussed,and the contribution of CH and NO to global warming is preliminarily alalysed. |
| [31] | . Methane emission fluxes from rice-rape rotation paddy fields were measured by the static chamber-gas chromatographic techniques in hilly area of the central Sichuan Basin. The results show that CH emission from paddy fields varies remarkably and seasonally during the rice-growing season, and the peak value of methane emission is presented in the metaphase of rice bearing stage. The average flux of CH emission from paddy fields is 6.20 mg/m銉籬. The influencing factors on CH emission from paddy fields are discussed in this paper. The rice plants play a key role in the methane emission during the early growing stage of rice; while the temperature plays a key role in the methane emission during the tassel and mature stage of rice. The total amount of CH emission during the rice growing season is about 173.96kg/hm. . Methane emission fluxes from rice-rape rotation paddy fields were measured by the static chamber-gas chromatographic techniques in hilly area of the central Sichuan Basin. The results show that CH emission from paddy fields varies remarkably and seasonally during the rice-growing season, and the peak value of methane emission is presented in the metaphase of rice bearing stage. The average flux of CH emission from paddy fields is 6.20 mg/m銉籬. The influencing factors on CH emission from paddy fields are discussed in this paper. The rice plants play a key role in the methane emission during the early growing stage of rice; while the temperature plays a key role in the methane emission during the tassel and mature stage of rice. The total amount of CH emission during the rice growing season is about 173.96kg/hm. |
| [32] | . The difference of methane transport ability and its reasons were clemonstrated by detecting different rice varieties, which grow in water-nutrient solution cultivation.In the same time, the influence of paddy rice satus on methane transport was demonstrated by controlling the methane transport path. The main results were as follows: with the evolution of Indicia rice varieties, Methane transport rate of plant increased, the root oxidizes increased gradually. In seedling stage, leaves transported 50 percent of methane. Methane transport rate varied with the number of root and the dry weight of root. They were obviously and lineally correlated. The number of stems and tillers of plant affected methane transport rate. In a certain range, the more the stems and tillers, the higher methane transport rate. These results indicate that root oxidizes mostly cause difference of methane transport rate in rice varieties. Healthy plant, more leaves, root system upgrowth, more stem and tiller cause more methane transport rate. . The difference of methane transport ability and its reasons were clemonstrated by detecting different rice varieties, which grow in water-nutrient solution cultivation.In the same time, the influence of paddy rice satus on methane transport was demonstrated by controlling the methane transport path. The main results were as follows: with the evolution of Indicia rice varieties, Methane transport rate of plant increased, the root oxidizes increased gradually. In seedling stage, leaves transported 50 percent of methane. Methane transport rate varied with the number of root and the dry weight of root. They were obviously and lineally correlated. The number of stems and tillers of plant affected methane transport rate. In a certain range, the more the stems and tillers, the higher methane transport rate. These results indicate that root oxidizes mostly cause difference of methane transport rate in rice varieties. Healthy plant, more leaves, root system upgrowth, more stem and tiller cause more methane transport rate. |
| [33] | . 氮肥深施（条施、穴施）有利于提高肥料利用率和作物产量,但其对农田氧化亚氮排放的影响尚不明确。以不施氮肥为对照,研究了氮肥撒施、条施和穴施对水稻-油菜轮作系统油菜生长季氧化亚氮排放、氮肥利用率和产量的影响。结果表明：氮肥的施用改变了油菜生长期间N2O排放通量的季节变化规律,不施氮对照除在油菜移栽后第10dN2O排放通量较大外,其余时间排放均较为微弱。氮肥撒施、氮肥条施和氮肥穴施均在油菜移栽后第10d和第117d出现N2O排放小高峰,排放最大高峰出现在移栽后第100d。氮肥深施显著提高油菜生长季N2O总排放量、氮肥利用率和产量。与氮肥撒施相比,氮肥条施和氮肥穴施分别增加N2O总排放量37.2%和19.3%,提高氮肥利用率72.3%和59.3%,增产28.8%和25.8%,而单位产量N2O排放量与氮肥撒施无显著差异;氮肥条施的单位产量N2O排放量显著低于氮肥穴施。研究表明,在获得相同产量的前提下氮肥撒施并无减排N2O的优势,水稻-油菜轮作系统油菜生长过程中在氮肥深施时采用条施有利于N2O减排。 . 氮肥深施（条施、穴施）有利于提高肥料利用率和作物产量,但其对农田氧化亚氮排放的影响尚不明确。以不施氮肥为对照,研究了氮肥撒施、条施和穴施对水稻-油菜轮作系统油菜生长季氧化亚氮排放、氮肥利用率和产量的影响。结果表明：氮肥的施用改变了油菜生长期间N2O排放通量的季节变化规律,不施氮对照除在油菜移栽后第10dN2O排放通量较大外,其余时间排放均较为微弱。氮肥撒施、氮肥条施和氮肥穴施均在油菜移栽后第10d和第117d出现N2O排放小高峰,排放最大高峰出现在移栽后第100d。氮肥深施显著提高油菜生长季N2O总排放量、氮肥利用率和产量。与氮肥撒施相比,氮肥条施和氮肥穴施分别增加N2O总排放量37.2%和19.3%,提高氮肥利用率72.3%和59.3%,增产28.8%和25.8%,而单位产量N2O排放量与氮肥撒施无显著差异;氮肥条施的单位产量N2O排放量显著低于氮肥穴施。研究表明,在获得相同产量的前提下氮肥撒施并无减排N2O的优势,水稻-油菜轮作系统油菜生长过程中在氮肥深施时采用条施有利于N2O减排。 |
| [34] | . Methane (CH4) and nitrous oxide (N2O) emissions from an irrigated rice field under continuous flooding and intermittent irrigation water management practices in northern China were measured in situ by the static chamber technique during May to October in 2000. The intermittent irrigation reduced total growing‐season CH4 emission by 24.22% but increased N2O emission by 23.72%, when compared with the continuous flooding. Soil Eh and four related bacterial groups were also measured to clarify their effects on gaseous emissions. Three ranges of soil redox potential were related to gas emissions: below 6110002mV with vigorous CH4 emission, above +10002mV with significant N2O emission, and +100 to 6110002mV with little CH4 and N2O emissions. Intermittently draining the field increased soil oxidation, with a decrease in CH4 emission and an increase in N2O emission. In general the mid‐season drainage slightly increased the populations of methanotrophs, nitrifiers, and denitrifiers but decreased that of methanogens. |
| [35] | . [1] A 3-year field experiment was conducted to simultaneously measure methane (CH4) and nitrous oxide (N2O) emissions from rice paddies under various agricultural managements including water regime, crop residue incorporation, and synthetic fertilizer application. In contrast with continuous flooding, midseason drainage incurred a drop in CH4 fluxes while triggering substantial N2O emission. Moreover, N2O emissions after midseason drainage depended strongly on whether or not fields were waterlogged due to intermittent irrigation. Urea application tended to reduce CH4 emissions but significantly increased N2O emissions. Under a water regime of flooding-midseason drainage-reflooding-moist intermittent irrigation but without water logging (F-D-F-M), both wheat straw and rapeseed cake incorporation increased CH4 emissions by 252%, and rapeseed cake increased N2O by 17% while wheat straw reduced N2O by 19% compared to controls. Seasonal average fluxes of CH4 ranged from 25.4 mg m0908082 d0908081 when no additional residue was applied under the water regime of flooding-midseason drainage-reflooding to 116.9 mg m0908082 d0908081 when wheat straw was applied at 2.25 t ha0908081 under continuous irrigation flooding. Seasonal average fluxes of N2O varied between 0.03 mg N2O-N m0908082 d0908081 under continuous flooding and 5.23 mg N2O-N m0908082 d0908081 under the water regime of F-D-F-M. Both crop residue-induced CH4, ranging from 9 to 15% of the incorporated residue C, and N2O, ranging from 0.01 to 1.78% of the applied N, were dependent on water regime in rice paddies. Estimations of net global warming potentials (GWPs) indicate that water management by flooding with midseason drainage and frequent water logging without the use of organic amendments is an effective option for mitigating the combined climatic impacts from CH4 and N2O in paddy rice production. |
| [36] | . 在实验室培养条件下,研究了3种控释肥对土壤氮素硝化反硝化损失和N2O排放的影响。结果表明,控释肥具有明显控制氮素释放的作用。在培养的前23d,控释肥处理的土壤NH4＋-N含量低于尿素处理,而后则高于尿素处理。各肥料处理土壤NO3--N含量均随培养时间逐渐增加,但不同肥料处理间差异不显著。28d培养期间,施入控释肥的土壤反硝化氮损失量为30.33～30.91mg N·kg-1土,比施加尿素处理土壤低13.83～14.41mgN·kg-1土,差异达到显著水平（P〈0.05）,控释肥降低氮肥的反硝化损失达3.45～3.60个百分点。控释肥处理土壤N2O累积释放量约为15.71～20.45mgN·kg-1土,比尿素处理高0.86～5.60mgN·kg-1土,但差异未达到显著水平。 . 在实验室培养条件下,研究了3种控释肥对土壤氮素硝化反硝化损失和N2O排放的影响。结果表明,控释肥具有明显控制氮素释放的作用。在培养的前23d,控释肥处理的土壤NH4＋-N含量低于尿素处理,而后则高于尿素处理。各肥料处理土壤NO3--N含量均随培养时间逐渐增加,但不同肥料处理间差异不显著。28d培养期间,施入控释肥的土壤反硝化氮损失量为30.33～30.91mg N·kg-1土,比施加尿素处理土壤低13.83～14.41mgN·kg-1土,差异达到显著水平（P〈0.05）,控释肥降低氮肥的反硝化损失达3.45～3.60个百分点。控释肥处理土壤N2O累积释放量约为15.71～20.45mgN·kg-1土,比尿素处理高0.86～5.60mgN·kg-1土,但差异未达到显著水平。 |
| [37] | . Static closed chamber technique and contrast method were adopted to study the effects of three coated compound fertilizers (N:PO:KO=19:8.6:10.5, high N; 14.4:14.4:14.4, balanced NPK; and 12.5:9.6:20.2, high K) on the NO emission from a lateritic red soil under the condition of no crop planting, taking uncoated compound fertilizers (N:PO:KO=20:9:11, high N; 15:15:15, balanced NPK; and 13:10:21, high K) as the contrasts. Different formula of fertilizer NPK induced significant difference in the NO emission. Under the application of uncoated compound fertilizers, the cumulative NO emission was in the order of balanced NPK 鈮 high N > high K. Applying coated compound fertilizers decreased the NOemission significantly, and the emission amount under the application of high N, balanced NPK, and high K was 34.4%, 30.5%, and 89.3% of the corresponding uncoated compound fertilizers, respectively. Comparing with the application of uncoated compound fertilizers, applying coated compound fertilizers also decreased the daily NO flux significantly, and delayed and shortened the NO peak, suggesting that coated fertilizers could reduce soil nitrogen loss and the global warming potential induced by NO emission顎. . Static closed chamber technique and contrast method were adopted to study the effects of three coated compound fertilizers (N:PO:KO=19:8.6:10.5, high N; 14.4:14.4:14.4, balanced NPK; and 12.5:9.6:20.2, high K) on the NO emission from a lateritic red soil under the condition of no crop planting, taking uncoated compound fertilizers (N:PO:KO=20:9:11, high N; 15:15:15, balanced NPK; and 13:10:21, high K) as the contrasts. Different formula of fertilizer NPK induced significant difference in the NO emission. Under the application of uncoated compound fertilizers, the cumulative NO emission was in the order of balanced NPK 鈮 high N > high K. Applying coated compound fertilizers decreased the NOemission significantly, and the emission amount under the application of high N, balanced NPK, and high K was 34.4%, 30.5%, and 89.3% of the corresponding uncoated compound fertilizers, respectively. Comparing with the application of uncoated compound fertilizers, applying coated compound fertilizers also decreased the daily NO flux significantly, and delayed and shortened the NO peak, suggesting that coated fertilizers could reduce soil nitrogen loss and the global warming potential induced by NO emission顎. |
| [38] | . 我国水稻氮肥施用量大,农民习惯氮肥表面撒施,氮肥通过氨挥发以及径流等途径损失严重,造成经济损失和环境污染。农村劳动力缺乏,土地流转迅速,省时省力、节肥高效的施肥方式亟待探索和推广。大田条件下,在环太湖水稻高施氮区,比较常规氮肥用量下（225 kg/hm2）的农民习惯分次施用（40%︰30%︰30%分次施用）与根区一次施用（偏根系5 cm,土表下10 cm穴施）两种施肥方式对水稻产量及氮肥利用率的影响。结果表明不种植水稻的前提下,习惯施氮处理表层土壤NH4~＋-N最高,自表层向下逐渐降低,各层养分均随时间推移而下降。根区一次施氮可显著提高施肥点周围土壤中的NH4~＋-N含量及其贮存时间,施肥后30,60和90 d,根区施氮处理NH4~＋-N最高值分别达到542.6、412.1和39.8 mg/kg。且根区一次施氮处理施肥点周围土壤高NH4~＋-N含量至少可保持60 d。种植水稻后,相对习惯分次施氮而言,根区一次施氮显著提高水稻分蘖数、各器官的氮含量、氮积累量及氮肥利用效率。根区一次施氮处理水稻氮积累量高达196.7 kg/hm2,相对习惯施氮增加34.9%。氮肥表观利用率分别达到59.8%（差值法）和42.5%（15N标记法）,相对习惯施肥分别增加22.6和30.6个百分点。肥料氮损失由分次施用的73.0%下降到29.7%。根区一次施氮显著增加肥料养分在土壤中的贮存时间,降低肥料养分损失的风险,提高水稻氮肥利用效率,是一种节肥高效的施肥方式,值得进一步研发施肥机械和推广应用。 . 我国水稻氮肥施用量大,农民习惯氮肥表面撒施,氮肥通过氨挥发以及径流等途径损失严重,造成经济损失和环境污染。农村劳动力缺乏,土地流转迅速,省时省力、节肥高效的施肥方式亟待探索和推广。大田条件下,在环太湖水稻高施氮区,比较常规氮肥用量下（225 kg/hm2）的农民习惯分次施用（40%︰30%︰30%分次施用）与根区一次施用（偏根系5 cm,土表下10 cm穴施）两种施肥方式对水稻产量及氮肥利用率的影响。结果表明不种植水稻的前提下,习惯施氮处理表层土壤NH4~＋-N最高,自表层向下逐渐降低,各层养分均随时间推移而下降。根区一次施氮可显著提高施肥点周围土壤中的NH4~＋-N含量及其贮存时间,施肥后30,60和90 d,根区施氮处理NH4~＋-N最高值分别达到542.6、412.1和39.8 mg/kg。且根区一次施氮处理施肥点周围土壤高NH4~＋-N含量至少可保持60 d。种植水稻后,相对习惯分次施氮而言,根区一次施氮显著提高水稻分蘖数、各器官的氮含量、氮积累量及氮肥利用效率。根区一次施氮处理水稻氮积累量高达196.7 kg/hm2,相对习惯施氮增加34.9%。氮肥表观利用率分别达到59.8%（差值法）和42.5%（15N标记法）,相对习惯施肥分别增加22.6和30.6个百分点。肥料氮损失由分次施用的73.0%下降到29.7%。根区一次施氮显著增加肥料养分在土壤中的贮存时间,降低肥料养分损失的风险,提高水稻氮肥利用效率,是一种节肥高效的施肥方式,值得进一步研发施肥机械和推广应用。 |
| [39] | . 研究了油菜氮肥的轻简施用技 术,包括适宜的施用方式、用量和缓释比例(即缓释氮肥用量占总氮肥用量的比例),及其在直播和移栽油菜间的差异。结果表明,试验条件下,一次性施用缓释氮 肥产量高于常规氮肥,且移栽油菜产量高于直播油菜;常规氮肥和缓释氮肥的最佳产量的施氮量,直播油菜分别是245.9和242.2kg/hm2,而移栽油 菜分别只需225.0和239.6kg/hm2;高比例缓释氮肥更有利于直播油菜生长和氮肥利用效率提高,直播油菜氮肥最佳缓释比例为 78.8%～80.8%,移栽油菜氮肥最佳缓释比例为25.0%。试验还表明,一次性施氮条件下,条施处理或穴施处理的油菜产量最高,撒施翻盖处理次之, 撒施处理效果最差;在同等施肥水平下,增加氮肥的施用次数可以提高直播油菜的产量,对移栽油菜也表现相似的结果。分析认为,不同油菜产区可以根据劳动力状 况、机械化水平、经济条件和习惯种植模式等选择适宜的氮肥轻简施用技术;一次性施氮条件下,选用普通氮肥可以适度增加用量以获得传统多次施肥的产量,选用 缓释氮肥用量可以适当降低;对直播油菜而言,可以施用更高比例缓释氮肥以达到增加产量和氮肥利用效率的目的。 . 研究了油菜氮肥的轻简施用技 术,包括适宜的施用方式、用量和缓释比例(即缓释氮肥用量占总氮肥用量的比例),及其在直播和移栽油菜间的差异。结果表明,试验条件下,一次性施用缓释氮 肥产量高于常规氮肥,且移栽油菜产量高于直播油菜;常规氮肥和缓释氮肥的最佳产量的施氮量,直播油菜分别是245.9和242.2kg/hm2,而移栽油 菜分别只需225.0和239.6kg/hm2;高比例缓释氮肥更有利于直播油菜生长和氮肥利用效率提高,直播油菜氮肥最佳缓释比例为 78.8%～80.8%,移栽油菜氮肥最佳缓释比例为25.0%。试验还表明,一次性施氮条件下,条施处理或穴施处理的油菜产量最高,撒施翻盖处理次之, 撒施处理效果最差;在同等施肥水平下,增加氮肥的施用次数可以提高直播油菜的产量,对移栽油菜也表现相似的结果。分析认为,不同油菜产区可以根据劳动力状 况、机械化水平、经济条件和习惯种植模式等选择适宜的氮肥轻简施用技术;一次性施氮条件下,选用普通氮肥可以适度增加用量以获得传统多次施肥的产量,选用 缓释氮肥用量可以适当降低;对直播油菜而言,可以施用更高比例缓释氮肥以达到增加产量和氮肥利用效率的目的。 |
| [40] | . The physiological traits of senescence and photosynthetic function of rice leaves were analyzed when two hybrid rice combinations were supplied with controlled release nitrogen fertilizer (CRNF), urea and no nitrogen fertilizer. CRNF showed obvious effects on delaying the senescence and prolonging the photosynthetic function duration of rice leaves. Compared with urea, CRNF could significantly increase the chlorophyll contents of the functional leaves at different stages in both early and late rices, and the difference between the treatments became larger with rice development. Photosynthetic rates of the functional leaves at different stages in CRNF treatment were significantly higher than those in urea treatment. Moreover, compared with urea, CRNF increased the activities of active oxygen scavenging enzymes, such as SOD and POD, and decreased the accumulation amount of MDA in the functional leaves during rice leaf aging. IAA and ABA contents in the functional leaves were also obviously regulated by CRNF. At the every stage, IAA content in CRNF treatment was higher and ABA content was lower than those in urea treatment. Being attributed to the effects of CRNF mentioned above, the rice yield was obviously increased after CRNF application. . The physiological traits of senescence and photosynthetic function of rice leaves were analyzed when two hybrid rice combinations were supplied with controlled release nitrogen fertilizer (CRNF), urea and no nitrogen fertilizer. CRNF showed obvious effects on delaying the senescence and prolonging the photosynthetic function duration of rice leaves. Compared with urea, CRNF could significantly increase the chlorophyll contents of the functional leaves at different stages in both early and late rices, and the difference between the treatments became larger with rice development. Photosynthetic rates of the functional leaves at different stages in CRNF treatment were significantly higher than those in urea treatment. Moreover, compared with urea, CRNF increased the activities of active oxygen scavenging enzymes, such as SOD and POD, and decreased the accumulation amount of MDA in the functional leaves during rice leaf aging. IAA and ABA contents in the functional leaves were also obviously regulated by CRNF. At the every stage, IAA content in CRNF treatment was higher and ABA content was lower than those in urea treatment. Being attributed to the effects of CRNF mentioned above, the rice yield was obviously increased after CRNF application. |
| [41] | . . |
| [42] | . [目的]为了适应"机播机收, 适度管理"的栽培方式,研究缓效控释肥在播种时一次性施用后,其养分分期释放以满足油菜不同时期对营养的需要。[方法]利用根据油菜生长特性,研制出缓效 复合肥,研究其施用效果。[结果]施用控释肥的效果很好。控释肥的养分释放规律和作物需肥规律基本一致,可促进油菜生长发育,培育理想的越冬壮苗,改善植 株经济性状,促进油菜增产。而且施用控释肥一季油菜只需施一次,省工省力。[结论]该研究可以为南方各地区油菜的施肥与油菜的机械化生产提供一定的依据。 . [目的]为了适应"机播机收, 适度管理"的栽培方式,研究缓效控释肥在播种时一次性施用后,其养分分期释放以满足油菜不同时期对营养的需要。[方法]利用根据油菜生长特性,研制出缓效 复合肥,研究其施用效果。[结果]施用控释肥的效果很好。控释肥的养分释放规律和作物需肥规律基本一致,可促进油菜生长发育,培育理想的越冬壮苗,改善植 株经济性状,促进油菜增产。而且施用控释肥一季油菜只需施一次,省工省力。[结论]该研究可以为南方各地区油菜的施肥与油菜的机械化生产提供一定的依据。 |
| [43] | . 以控释氮肥和普通氮肥为试验肥料,通过田间小区试验,研究了不同施肥方法对水稻产量和氮肥利用率的影响。结果表明:一次性全量基施普通氮肥不能满足水稻生长需要,会造成水稻减产;而基施控释氮肥能提高群体的有效穗数,改善单株的产量构成结构,且显著提高氮肥利用率,最终提高水稻产量。在施N量减少30%条件下(CRU70%处理),水稻氮肥利用率最高,且产量显著高于普通氮肥处理(PU100%处理)。本研究条件下,CRU70%+PU30%处理的实粒数和结实率最高,水稻产量最高(8 939 kg/hm2),较CRU70%处理增产显著。 . 以控释氮肥和普通氮肥为试验肥料,通过田间小区试验,研究了不同施肥方法对水稻产量和氮肥利用率的影响。结果表明:一次性全量基施普通氮肥不能满足水稻生长需要,会造成水稻减产;而基施控释氮肥能提高群体的有效穗数,改善单株的产量构成结构,且显著提高氮肥利用率,最终提高水稻产量。在施N量减少30%条件下(CRU70%处理),水稻氮肥利用率最高,且产量显著高于普通氮肥处理(PU100%处理)。本研究条件下,CRU70%+PU30%处理的实粒数和结实率最高,水稻产量最高(8 939 kg/hm2),较CRU70%处理增产显著。 |
| [44] | . 采用静态箱-气相色谱法测定水稻(Oryza sativa)生长期内不同有机无机肥配施条件下双季稻田CH4、N2O的排放量,并根据土壤有机碳库和植株碳素累积量的变化估算稻田CO2净交换通量。结果表明:稻田CH4与N2O的排放之间存在消长关系,CH4是稻田排放的主要温室气体。有机无机肥配施能有效促进稻田CH4的排放和CO2的固定,而对N2O的排放并没有造成显著影响。各处理的综合增温潜势均为负值,表现为减缓温室效应的趋势,其中DF(猪粪堆肥+化肥)和ZYF(沼渣沼液肥+化肥)处理减缓综合温室效应的潜力较CF(纯化肥)处理分别提升了16.43%和5.89%。从全年稻季单位产量的GWP来看,DF、ZYF处理的单位产量全球增温潜势(GWP)分别为-0.37,-0.38kg/kg,与CF(纯化肥)处理大小相当。施用猪粪堆肥和沼渣沼液肥既可以促进作物增产,又可以相对增加稻田生态系统对温室气体的固定量,对减缓温室气体排放潜力巨大,值得推荐。 . 采用静态箱-气相色谱法测定水稻(Oryza sativa)生长期内不同有机无机肥配施条件下双季稻田CH4、N2O的排放量,并根据土壤有机碳库和植株碳素累积量的变化估算稻田CO2净交换通量。结果表明:稻田CH4与N2O的排放之间存在消长关系,CH4是稻田排放的主要温室气体。有机无机肥配施能有效促进稻田CH4的排放和CO2的固定,而对N2O的排放并没有造成显著影响。各处理的综合增温潜势均为负值,表现为减缓温室效应的趋势,其中DF(猪粪堆肥+化肥)和ZYF(沼渣沼液肥+化肥)处理减缓综合温室效应的潜力较CF(纯化肥)处理分别提升了16.43%和5.89%。从全年稻季单位产量的GWP来看,DF、ZYF处理的单位产量全球增温潜势(GWP)分别为-0.37,-0.38kg/kg,与CF(纯化肥)处理大小相当。施用猪粪堆肥和沼渣沼液肥既可以促进作物增产,又可以相对增加稻田生态系统对温室气体的固定量,对减缓温室气体排放潜力巨大,值得推荐。 |
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