• ISSN 1008-505X
  • CN 11-3996/S
Volume 27 Issue 9
Oct.  2021
Article Contents

Citation:

Combining N-inhibitor and chicken manure with reduced N fertilizer to improve the conversion and utilization of fertilizer N in a paddy soil

  • Corresponding author: ZHANG Li-li, llzhang@iae.ac.cn
  • Received Date: 2021-01-05
  •   【Objectives】  The nitrogen supply and utilization of soil and fertilizer-derived N were studied under the condition of reduced urea N input and combined with N-inhibitors and chicken manure, to provide a theoretical basis for rice cultivation in Northeast of China, in terms of improving the nitrogen use and fertilizer efficiencies.   【Methods】  15N isotope tracer technology was adopted in a rice pot experiment. The five treatments included: no nitrogen fertilizer control (CK), conventional rate of urea (urea-15N), 80% urea N + 20% chicken manure N (NM), 80% urea N+ inhibitor (NI), 80% urea N + inhibitor + 20% chicken manure N (NIM). The contents of ammonia nitrogen and microbial biomass N in soil and urea-derived nitrogen, and nitrogen content of rice plant at different growth stages were analyzed, investigated the rice yield was investigated.  【Results】  1) NI treatments had considerable soil ammonium N and fertilizer derived N supply ability compared with N treatment, inhibitors had a compensatory effect on nitrogen reduction. NM treatment had markedly higher N supply ability at the tillering and filling stages, compared to N treatment. Compared with N treatment, soil NH4+-N in NIM treatment increased by 19.2%, 66.3%, and 36.5%; NO3-N content increased by 13.9%, 12.7%, and 17.3% at returning green, tillering and filling stage, respectively, 15NH4+-N content increased by 14.59 mg/kg at tillering stage. 2) N and NI treatments had no significant effect on soil microbial biomass carbon (MBC) content, however, NM and NIM treatments significantly improved soil microbial biomass N (MBN) content at the returning green and filling stage (P < 0.05). Compared with N treatment, the MBC content in NIM treatment increased by 32.61%, 29.23%, 53.46% and 2.85%, and the MBN content increased by 147.98%, 22.97%, 133.33% and 24.63% at the returning green, tillering, filling and mature stages, respectively, while 15N-MBN increased by 22.56 mg/kg at the tillering stage. 3) N-inhibitor with chicken manure addition increased the rice yield and biomass. Compared with N treatment, NIM increased the biomass, yield and nitrogen uptake of rice by 83.59%, 124.18% and 46.66%. It also significantly increased fertilizer N residue in the soil by 56.48% and reduced the fertilizer N loss by 78.7%. Compared with N treatment, NIM treatment had a significant effect on N absorption and utilization of fertilizer, and its N absorption, N utilization rate and N agronomic efficiency were significantly higher than other treatments.  【Conclusions】  For brown paddy soil of northern China, the addition of inhibitor (1% PPD+1% NBPT+2% DMPP) and chicken manure could replenish soil N supply. Based on 20% reduction in urea, augments with the application of inhibitors and chicken manure increased the fertilizer utilization rate and increased the rice yield. From the perspectives of fertilizer N release and utilization in rice, NI and NIM treatments shows superior agronomic performances.
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Combining N-inhibitor and chicken manure with reduced N fertilizer to improve the conversion and utilization of fertilizer N in a paddy soil

    Corresponding author: ZHANG Li-li, llzhang@iae.ac.cn
  • 1. Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, China
  • 2. Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, Shandong 264003, China
  • 3. Shenyang Chemical Research Institute Co., LTD., Shenyang, Liaoning 110021, China

Abstract:   【Objectives】  The nitrogen supply and utilization of soil and fertilizer-derived N were studied under the condition of reduced urea N input and combined with N-inhibitors and chicken manure, to provide a theoretical basis for rice cultivation in Northeast of China, in terms of improving the nitrogen use and fertilizer efficiencies.   【Methods】  15N isotope tracer technology was adopted in a rice pot experiment. The five treatments included: no nitrogen fertilizer control (CK), conventional rate of urea (urea-15N), 80% urea N + 20% chicken manure N (NM), 80% urea N+ inhibitor (NI), 80% urea N + inhibitor + 20% chicken manure N (NIM). The contents of ammonia nitrogen and microbial biomass N in soil and urea-derived nitrogen, and nitrogen content of rice plant at different growth stages were analyzed, investigated the rice yield was investigated.  【Results】  1) NI treatments had considerable soil ammonium N and fertilizer derived N supply ability compared with N treatment, inhibitors had a compensatory effect on nitrogen reduction. NM treatment had markedly higher N supply ability at the tillering and filling stages, compared to N treatment. Compared with N treatment, soil NH4+-N in NIM treatment increased by 19.2%, 66.3%, and 36.5%; NO3-N content increased by 13.9%, 12.7%, and 17.3% at returning green, tillering and filling stage, respectively, 15NH4+-N content increased by 14.59 mg/kg at tillering stage. 2) N and NI treatments had no significant effect on soil microbial biomass carbon (MBC) content, however, NM and NIM treatments significantly improved soil microbial biomass N (MBN) content at the returning green and filling stage (P < 0.05). Compared with N treatment, the MBC content in NIM treatment increased by 32.61%, 29.23%, 53.46% and 2.85%, and the MBN content increased by 147.98%, 22.97%, 133.33% and 24.63% at the returning green, tillering, filling and mature stages, respectively, while 15N-MBN increased by 22.56 mg/kg at the tillering stage. 3) N-inhibitor with chicken manure addition increased the rice yield and biomass. Compared with N treatment, NIM increased the biomass, yield and nitrogen uptake of rice by 83.59%, 124.18% and 46.66%. It also significantly increased fertilizer N residue in the soil by 56.48% and reduced the fertilizer N loss by 78.7%. Compared with N treatment, NIM treatment had a significant effect on N absorption and utilization of fertilizer, and its N absorption, N utilization rate and N agronomic efficiency were significantly higher than other treatments.  【Conclusions】  For brown paddy soil of northern China, the addition of inhibitor (1% PPD+1% NBPT+2% DMPP) and chicken manure could replenish soil N supply. Based on 20% reduction in urea, augments with the application of inhibitors and chicken manure increased the fertilizer utilization rate and increased the rice yield. From the perspectives of fertilizer N release and utilization in rice, NI and NIM treatments shows superior agronomic performances.

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  • 肥料在我国农业生产中占有非常重要的地位。目前,由于存在化肥不合理使用、盲目施肥等现象,导致作物肥料利用率低,土壤肥力下降,进而对粮食持续增产、农业提质增效产生严重影响[1]。2017年我国氮素施用量已达到2978.19万t[2]。氮肥用量大和吸收利用率相对较低,不仅导致资源浪费,还给生态环境带来负面影响。农业农村部提出到2020年我国农业要实现“一控两减三基本”,即控制农业用水总量,减少化肥农药使用量,化肥、农药用量实现零增长,基本实现畜禽养殖排泄物资源化利用等[3]。截止到2016年,我国化肥用量实现了负增长[1]。因此,科学合理的施肥方式,提高肥料资源利用率,是我国可持续发展的关键举措之一,抑制剂及有机肥能从减少损失和增加固持两方面提高土壤氮素供应能力,是目前较为有效的提高肥料利用率的举措。

    抑制剂的施用是提高肥料利用率,减少化肥施用量的有效途径。研究表明,在稻田中施用脲酶抑制剂能增产8.5%~16.1%,节肥3.8%~8.4%,施用硝化抑制剂能增产3.9%~12.4%,增效11.1%~25.0%,节肥25.0%[4]。且脲酶硝化抑制剂组合能有效减少稻田土壤中氨挥发和温室气体的排放[5-6],还能提高尿素氮的利用效率,促进水稻增产[7],脲酶硝化抑制剂 (NBPT+DMPP) 配合施用效果最为理想[8-9]。不同抑制剂类型及组合对氮素转化及氮的利用效率影响不同,对于两种脲酶抑制剂与硝化抑制剂组合 (NBPT+PPD+DMPP) 在稻田中的应用是否能进一步提高肥料利用率和增加水稻产量?尤其是在氮肥减量施用条件下,抑制剂在外源肥料氮素的提质增效方面有待于进一步研究。

    我国有机肥料实物量约57亿t,折合氮量约3000万t,有机肥资源量大,养分含量丰富,有机肥还田在补充土壤养分方面作用巨大[10-13]。有机无机肥配施在提高肥料利用率、改善土壤性状等方面产生良好的效果[14]。朱菜红等[15]利用15N示踪技术研究化肥配施鸡粪后15N的利用状况,其利用率大于60%,而单施化肥处理15N利用率仅为39%[16]。李燕青等[17]研究表明,氮肥减量配施有机肥能够实现与化肥相当的氮素利用效率,同时提升土壤肥力。实施化肥减量配施有机肥,是推进农业可持续发展的重大措施,也是促进节本增效、农业资源再利用的现实需求。减施无机肥增施有机肥能有效改善土壤理化性状,提升土壤质量[18],还能显著降低稻田氨挥发累积排放量,减少径流损失氮量,可有效抑制N2O排放[10]。故化肥减量并不会对水稻和秸秆产量产生不利影响,还能显著提升耕地质量,增加土壤碳氮储量[19],减量施肥+有机肥处理的综合效果最好[20]。合理的有机肥化肥配施能确保养分在水稻各个时期的持续供应,增加水稻总吸氮量,协调水稻产量各构成因素,促进茎叶和籽粒产量全面提高。在我国稻田生态系统中,化肥配施鸡粪的研究已有部分报道。研究表明,施用鸡粪能节肥约20%[21]。但氮肥减量配施抑制剂或鸡粪及两者配施,在提高土壤氮素供应及提高肥料氮素利用效率方面是否有协同增效作用?还有待于进一步研究。

    为探究抑制剂组配有机物料鸡粪在氮肥减施条件下对肥料氮的补偿及增效作用,本研究借助于15N同位素示踪技术,采用盆栽试验,以我国北方棕壤发育的水稻土为供试土壤,探究在氮肥减量配施鸡粪或抑制剂及与两者配施的情况下,土壤氮素及肥料氮素供应状况及与水稻需氮关系,结合水稻产量及氮肥利用率,探究复配的可行性及最佳的施肥方式。

  • 1.   材料与方法

      1.1.   试验地概况

    • 供试土壤为棕壤水稻土,土壤质地为砂壤土,采自沈阳农业大学水稻研究所试验地 (41°8′N、123°38′E)。盆栽试验在中科院沈阳应用生态研究所野外实验站 (43°31′N、123°22′E) 网室进行,该站位于辽河平原南部,气候类型为温带大陆性季风气候,年均气温在7℃~8℃,大于10℃的活动积温为3100℃~3400℃,年降水量为650~700 mm,无霜期为147~164天。供试土壤基本理化性质如下:容重为1.3 g/cm3,pH为6.7,全氮1.2 g/kg,碱解氮84.5 mg/kg,速效钾158 mg/kg,速效磷15.9 mg/kg。

    • 1.2.   试验材料

    • 供试鸡粪基本理化性质为:全氮29.5 g/kg,有机碳314 g/kg,碳氮比10.63,20%化肥氮所需鸡粪添加量为5.05 g/kg,相当于每kg土添加纯氮30 mg。

    • 1.3.   试验设计

    • 2019年5—10月进行盆栽试验。选用直径18 cm、高20 cm的塑料盆,每盆称相当于3 kg干土重量的鲜土,与有机无机肥混合均匀后装盆,淹水一夜,第二天进行水稻移栽,每盆移栽水稻3穴,每穴2株,共6株,水稻品种为‘美锋 9’。氯化钾和过磷酸钙作为底肥一次性施入,添加量分别为120和150 mg/kg,相当于田间施磷量212 kg/hm2、施钾量 318 kg/hm2。氮肥为15N标记尿素 (丰度为10.02%),常规施氮量为N 150 mg/kg土,相当于田间施氮量318 kg/hm2,按基肥、返青肥和分蘖肥40%、30%和30%的比例施用。抑制剂为苯基磷酰二胺 (PPD) +N-丁基硫代磷酰三胺 (NBPT) +3,4-二甲基吡唑磷酸盐 (DMPP)组合,抑制剂添加量均按尿素纯氮量的1%、1%和2%添加。试验设5个处理:不施氮对照 (CK)、常量尿素 (N)、80%常量尿素+20%鸡粪氮 (NM)、80%常量尿素+抑制剂 (NI)、80%常量尿素+抑制剂+20%鸡粪氮 (NIM)。

    • 1.4.   样品采集

    • 水稻秧苗于3月下旬在大棚温室中采用育苗盘进行育苗,秧苗长至5个叶片时进行移栽。水稻于2019年5月29日定植,水稻管理同大田水分管理。分别于返青期 (2019年6月4日)、分蘖期 (2019年6月25日)、灌浆期 (2019年8月12日) 和成熟期 (2019年9月21日) 进行破坏性取样,每个处理各取3盆。返青期和分蘖期分别在施肥后7 天进行取样。每盆水稻收获所有6株样品 (茎和穗)。土壤选用五点取样法采集,除去水稻根系后充分混匀待测。测定土壤铵态氮、硝态氮、微生物生物量碳氮、肥料来源的铵态氮 (15NH4+-N) 及微生物量氮 (15N-MBN),以及水稻地上部分生物量和吸氮量、水稻对肥料氮的吸收利用等指标。

    • 1.5.   测定指标与方法

    • 土壤基本理化指标参照鲁如坤[22]的方法测定。土壤铵态氮和硝态氮含量测定:取10 g采集的新鲜土壤样品,用100 mL 2 mol/L氯化钾溶液浸提 (土∶液=1∶10),在160 r/min的震荡器中震荡1 h,过滤浸提液,使用AA3型连续流动分析仪分别在波长660和540 nm处测定土壤铵态氮和硝态氮含量。土壤微生物量碳、氮含量采用氯仿熏蒸法测定:称取20 g新鲜土壤2份,一份在黑暗处熏蒸24 h,一份不做熏蒸,两份样品均加入80 mL 0.5 mol/L K2SO4浸提液进行往复震荡浸提,采用TOC分析仪 (Vario TOC Cube, Elementar, Germany) 测定熏蒸和未熏蒸样品,微生物量碳、氮计算分别采用熏蒸系数0.45和0.54[23-24]。在水稻成熟期,分别收获每盆水稻秸秆和穗,于烘箱中65℃下烘干至恒重,测定水稻籽粒产量、生物产量、穗数、千粒重等生物学指标。将烘干后的水稻植株样品 (秸秆、籽粒),用球磨仪 (RETSCH MM 400,Germany) 粉碎过0.074 mm筛。采用Vario Macro元素分析仪测定土壤和植株的有机碳和全氮含量。土壤及植株中的15N丰度采用过筛后的样品,用锡舟包样,植物样称样量为2.5 mg,土壤样品称样量为18 mg,用同位素比例质谱仪 (253 MAT, Thermo Finnigan, Germany) 进行检测,测定顺序按照丰度从低到高测定,减少污染。15NH4+-N采用扩散包法进行提取[25]15N-MBN采用过硫酸钾碱液消煮法和扩散包法进行提取[26],提取结束后的扩散包在−60℃冰箱中冷冻0.5 h,然后采用冷冻干燥仪 (ALPHA 1-2 LDplus, Germany) 冷冻干燥,将扩散包中玻璃纤维包在锡舟中,采用同位素比例质谱仪 (253 MAT, Thermo Finnigan, Germany) 检测扩散包中15N丰度。

    • 1.6.   计算公式

    • 水稻氮素累积吸收量 (g/pot) = 植株氮素含量 × 植株干物质质量;

      氮素籽粒生产效率 (g/g) = 籽粒产量/植株氮素累积吸收量;

      氮收获指数= 籽粒氮素累积量/地上部干物质氮素累积吸收量;

      肥料氮贡献率 (%) = (施氮产量-不施氮产量)/施氮产量 × 100;

      收获指数= 籽粒产量/地上部干物质量;

      氮素吸收率 (%) = (施氮吸氮量-不施氮吸氮量)/施氮量 × 100;

      氮肥农学效率 (g/g) = (施氮处理籽粒产量-不施氮处理籽粒产量)/施氮量 ;

      氮肥偏生产力 (g/g) = 施氮处理籽粒产量/氮肥施用量;

      土壤或植株中15N丰度=检测15N丰度值 × 土壤或植株中全氮含量/尿素中15N丰度;

      土壤肥料来源的氮含量 (mg/kg) = 氮库中15N丰度 × 该形态氮的含量/尿素中15N 丰度;

      15N残留 (%) = 收获后土壤残留15N量/加入的15N 量 × 100。

    • 1.7.   数据处理

    • 用Microsoft office 2010软件进行数据处理和计算,用SPSS 18.0进行差异显著性方差分析 (Duncan, P < 0.05),并运用Pearson相关性分析,用Origin 2020进行图表制作。

    2.   结果与分析

      2.1.   不同施肥方式对土壤无机氮库转化的影响

    • 图1可知,减量尿素配施抑制剂和鸡粪处理 (NIM) 显著影响了土壤中铵态氮含量,但是对硝态氮含量影响不显著。在返青期、分蘖期乃至灌浆期,80%尿素配施抑制剂 (NI) 与常规氮肥 (N) 处理铵态氮供应无显著差异 (P > 0.05),与鸡粪配施 (NIM) 后提高了土壤铵态氮的含量。在返青期,NIM处理铵态氮含量显著高于NM和CK处理;在分蘖期,NIM处理显著高于N、NI处理 (P < 0.05),但与NM处理之间差异不显著 (P > 0.05)。与N处理相比,NM、NI处理铵态氮含量分别提高了43.6%、4.9%;在灌浆期和成熟期,各处理差异不显著 (P > 0.05)。与N处理相比,NIM处理在水稻返青期、分蘖期和灌浆期土壤中铵态氮含量分别提高了 19.2%、66.3% 和36.5%,15NH4+-N含量在分蘖期增加了14.59 mg/kg。表明在施肥初期,抑制剂添加在延缓氮素释放方面作用显著,其抑制效果高于鸡粪的供氮能力,但在分蘖期,鸡粪的铵态氮补偿能力要显著高于抑制剂,在水稻生长后期,抑制剂添加和鸡粪替代对铵态氮的影响较小。稻田土壤硝态氮含量较低,NM处理在返青期和成熟期硝态氮含量最高,显著高出N处理57.65%。NIM处理在生育时期内均有较低的硝态氮含量,但与N处理差异不显著 (P > 0.05),与N处理相比,NIM处理在水稻返青期、分蘖期和灌浆期土壤中硝态氮含量分别提高 13.87%、12.70% 和17.30%,这表明硝化抑制剂在抑制硝化作用方面效果显著。综合无机氮含量,NIM处理在生育前期增加铵态氮含量、减少硝态氮含量方面的作用显著 (P < 0.05)。

      Figure 1.  Effects of urea reduction combined with inhibitor and chicken manure on ammonium and nitrate nitrogen contents in paddy soil during rice growth

    • 2.2.   不同施肥方式对土壤微生物量碳氮含量的影响

    • 图2可知,施用无机氮肥 (N、NI) 处理对土壤微生物量碳含量无显著影响 (P > 0.05),与N处理相比,NIM处理显著提高了返青期、分蘖期和灌浆期土壤微生物量碳的含量 (P < 0.05),施用鸡粪 (NM、NIM) 显著提高了返青期至灌浆期微生物量氮含量 (P < 0.05),抑制剂配施鸡粪在促进微生物活性,增加生物固持方面发挥重要作用。与单施氮肥处理相比,NI、NIM处理中抑制剂的添加显著增加了返青期微生物量氮 (P < 0.05),NIM显著提高了生育期内微生物量碳、氮含量 (P < 0.05),在返青期、分蘖期、灌浆期和成熟期微生物量碳含量分别比N处理提高了32.61%、29.23%、53.46%和2.85%,微生物量氮含量分别提高了147.98%、22.97%、133.33%和24.63%。

      Figure 2.  Effects of urea reduction combined with inhibitor and chicken manure on the transformation of soil microbial biomass carbon and nitrogen during rice growth

    • 2.3.   肥料氮在土壤铵态氮及微生物量氮库中的转化

    • 图3可知,减氮配施抑制剂及鸡粪影响了肥料氮在铵态氮及微生物量氮中的转化。水稻返青期NIM处理土壤15NH4+-N含量显著高于NM处理 (P < 0.05);在水稻灌浆期NI处理土壤15N-微生物量氮含量显著高于其他处理 (P < 0.05),表明抑制剂的添加抑制了尿素的水解,增加了肥料来源氮素的供给,为微生物固持肥料氮素提供来源。而鸡粪添加对肥料氮转化的影响要高于抑制剂,且主要体现在分蘖期。与N处理相比,鸡粪添加显著提高了分蘖期肥料来源的15NH4+-N含量及15N-微生物量氮的含量 (P < 0.05)。相比于N处理,分蘖期NM、NIM处理土壤15NH4+-N分别增加了13.60和14.59 mg/kg,分别增加了93.63%和98.99%;15N-微生物量氮分别增加了33.48和22.56 mg/kg,分别增加了70.07%和51.39%。

      Figure 3.  Effects of inhibitor and chicken manure addition on the conversion of urea-derived nitrogen in ammonium nitrogen and microbial biomass nitrogen during rice growth

    • 2.4.   不同施肥方式对水稻产量及农学指标的影响

    • 表1可知,在等氮量添加及鸡粪替代20%氮肥条件下,各处理生物量在返青期和分蘖期差异均不显著 (P > 0.05),在灌浆期和成熟期,NM、NI、NIM处理生物量显著高于CK和N处理 (P < 0.05)。在成熟期,相比于N处理,NM、NI和NIM处理生物量分别提高了69.49%、74.75%和83.59%,表明抑制剂和鸡粪添加后显著提高灌浆期水稻生物量,在水稻生殖生长的关键阶段起着重要作用;鸡粪配施氮肥后氮素供应能力较强,利于水稻生长。NIM处理穗数、产量均最高,其次为NM、NI处理,其穗数和产量均显著高于CK和N处理 (P < 0.05)。NIM处理水稻产量是CK的2.64倍,是N处理的2.24倍。与N处理相比,NM、NI和NIM处理产量分别提高了105.99%、89.47%和124.18%,且均达到显著水平。各施氮处理千粒重均显著高于CK处理 (P < 0.05),各施氮处理之间差异不显著 (P > 0.05)。综上所述,鸡粪和抑制剂在氮肥减施及提高水稻生物量和产量方面作用显著。

      处理
      Treatment
      生物量 Biomass (g/plant)穗数
      Panicle No.
      per plant
      产量
      Yield
      (g/plant)
      千粒重
      1000-grain weight
      (g)
      返青期 Returning green分蘖期 Tillering灌浆期 Filling成熟期 Maturing
      CK 0.17 ± 0.08 a2.28 ± 0.07 a18.44 ± 0.43 d30.52 ± 9.46 b4.00 ± 0.00 d10.65 ± 0.23 c15.7 ± 6.4 b
      N 0.18 ± 0.02 a2.77 ± 1.04 a35.10 ± 0.77 c30.65 ± 10.25 b6.33 ± 0.58 c12.53 ± 5.34 c22.6 ± 1.5 a
      NM 0.16 ± 0.04 a2.67 ± 1.28 a51.24 ± 0.73 a51.95 ± 7.20 a8.33 ± 1.53 ab25.81 ± 4.03 a22.7 ± 1.8 a
      NI 0.16 ± 0.04 a3.61 ± 0.62 a44.50 ± 3.74 b53.56 ± 13.95 a8.67 ± 0.58 ab23.74 ± 1.28 ab21.1 ± 3.0 a
      NIM0.18 ± 0.04 a3.60 ± 0.44 a44.13 ± 4.19 b56.27 ± 3.49 a9.33 ± 0.58 a28.09 ± 3.68 a21.1 ± 2.0 a
      注(Note):表中数值为平均值 ± 标准差 Values in the table are mean ± standard deviation (n = 3); CK—不施氮对照 No nitrogen control; N—常量尿素 Applying urea N 318 kg/hm2; NM—80% 常量尿素+20% 鸡粪氮 Applying 80% of urea and replace the left 20% with chicken manure; NI—80% 尿素+抑制剂 Applying 80% of urea and adding nitrogen inhibitor; NIM—80% 常量尿素+抑制剂+20% 鸡粪氮 NM plus nitrogen inhibitor in urea. 同列数据后不同小写字母代表处理间差异显著 (Duncan, P < 0.05) Different lowercase letters in the same column represent significant difference among treatments of the same index (Duncan, P < 0.05).

      Table 1.  Effects of fertilization treatments on agronomic indexes of rice

    • 2.5.   不同施肥方式对水稻氮肥利用率的影响

    • 表2可知,与CK相比,氮肥、抑制剂及鸡粪的添加降低了水稻的氮素籽粒生产效率,却显著提高了肥料氮贡献率及收获指数等。与N处理相比,NM、NI和NIM处理均显著提高了氮素吸收率、氮肥农学效率及氮肥偏生产力等,其中,NM、NI和NIM处理氮素吸收率分别提高了41.96%、48.80%和89.80%,氮肥农学效率分别提高了139.48%、150.92%和234.45%,氮肥偏生产力分别提高了45.88%、49.64%和77.11%。NIM处理具有最高的氮素吸收率、氮肥农学效率和氮肥偏生产力,显著高于其他处理,其氮肥偏生产力高达62.43 g/g,抑制剂及鸡粪在提高氮素利用方面发挥着显著的交互作用 (P < 0.05)。

      处理
      Treatment
      氮素籽粒生产效率
      NGPE
      (g/g)
      氮收获指数
      NHI
      肥料氮贡献率
      FCR
      (%)
      收获指数
      HI
      氮素吸收率
      NUE
      (%)
      氮肥农学效率
      NAE
      (g/g)
      氮肥偏生产力
      NPFP
      (g/g)
      CK 56.28 ± 2.44 a0.56 ± 0.02 a33.27 ± 2.02 b0.33 ± 0.02 b
      N 40.15 ± 7.71 b0.54 ± 0.06 a42.73 ± 5.22 a0.43 ± 0.05 a45.57 ± 5.28 c11.59 ± 5.62 c35.25 ± 5.62 b
      NM 48.54 ±5.46 ab0.59 ± 0.02 a43.18 ± 2.82 a0.43 ± 0.03 a64.69 ± 13.43 b27.76 ± 3.48 b51.42 ± 3.48 a
      NI 48.17 ± 4.76 ab0.59 ±0.05 a41.88 ± 3.13 a0.42 ± 0.03 a67.81 ± 7.81 b29.08 ± 2.84 b52.75 ± 2.84 a
      NIM48.44 ± 1.65 ab0.60 ± 0.03 a44.30 ± 1.26 a0.44 ± 0.01 a86.49 ± 13.21 a38.76 ± 8.19 a62.43 ±8.19 a
      注(Note):CK—不施氮对照 No nitrogen control; N—常量尿素 Applying urea N 318 kg/hm2; NM—80% 常量尿素+20% 鸡粪氮 Applying 80% of urea and replace the left 20% with chicken manure; NI—80% 尿素+抑制剂 Applying 80% of urea and adding nitrogen inhibitor; NIM—80% 常量尿素+抑制剂+20% 鸡粪氮 NM plus nitrogen inhibitor in urea. NGPE—Grain production efficiency of nitrogen; NHI—Nitrogen harvest index; FCR—Fertilizer N contribution rate; HI—Harvest index; NUE—N uptake efficiency; NAE—Agronomic efficiency of N fertilizer; NPFP—Nitrogen partial factor productivity. 表中数值为平均值 ± 标准差 Values in the table are mean ± standard deviation (n = 3). 同列数据后不同小写字母代表处理间差异显著 (Duncan, P < 0.05) Values followed by different lowercase letters in the same column represent significant difference among treatments (Duncan, P < 0.05).

      Table 2.  Effects of different fertilization treatments on N-use efficiencies of rice

    • 2.6.   不同施肥方式对肥料及土壤氮在水稻–土壤系统中分配的影响

    • 氮肥减量配施抑制剂及鸡粪,虽未显著影响土壤全氮含量,但显著影响了肥料氮在土壤中的残留状况 (表3)。相比于N,NM、NI和NIM处理肥料氮在土壤中的残留量显著提高,分别增加了30.49%、56.94%和56.48%。同时,NI和NM处理均显著提高水稻总吸氮量及水稻利用肥料氮比例 (P < 0.05),但对水稻吸收肥料氮量影响不显著 (P > 0.05)。与N处理相比,NM、NI和NIM处理提高水稻吸氮量约21.81%、25.36%和46.66%,促进水稻吸收肥料氮约4.92%、18.30%和21.61%。综合肥料氮在土壤中保存及水稻吸收利用状况,NI及NIM处理效果较好,不仅促进肥料氮在土壤中的保存,还提高了水稻对肥料氮的吸收利用,将肥料氮的利用率提高到70%及以上,损失降到约10%左右。NM处理效果亦显著高于N处理,故在棕壤水稻土上,氮肥减量20%配施鸡粪,不仅不会减产,还会提高肥料利用率及促进水稻生长。

      处理
      Treatment
      土壤全氮
      Soil total N
      (g/kg)
      水稻吸收氮
      N uptake by rice
      (g/pot)
      土壤中肥料氮
      Fertilizer N in soil
      (mg/kg)
      水稻吸收肥料氮
      Urea N uptake by rice
      (mg/pot)
      土壤中肥料氮比例
      Urea N ratio in soil
      (%)
      水稻利用肥料氮比例
      Urea N uptake ratio by rice
      (%)
      肥料损失率
      Urea N loss ratio
      (%)
      CK 1.26 ± 0.07 a189.61 ± 11.73 d
      N 1.30 ± 0.02 a394.66 ± 23.78 c30.63 ± 1.14 c182.22 ± 14.97 b6.81 ± 0.25 c40.49 ± 3.33 c50.51 ± 4.06 a
      NM 1.27 ± 0.03 a480.72 ± 60.42 b39.97 ± 4.64 b191.20 ± 15.56 b8.88 ± 1.03 b63.73 ± 5.19 b22.10 ± 6.34 b
      NI 1.28 ± 0.05 a494.75 ± 35.15 b48.07 ± 5.50 a215.57 ± 4.84 ab10.68 ± 1.22 ab71.86 ± 1.61 ab12.17 ± 1.97 c
      NIM1.32 ± 0.04 a578.82 ± 59.43 a47.93 ± 3.62 a221.67 ± 17.61 a10.65 ± 0.80 a77.76 ± 8.65 a10.76 ± 5.75 c
      注(Note):表中数值为平均值 ± 标准差 Values in the table are mean ± standard deviation (n = 3); CK—不施氮对照 No nitrogen control; N—常量尿素 Applying urea N 318 kg/hm2; NM—80% 常量尿素+20% 鸡粪氮 Applying 80% of urea and replace the left 20% with chicken manure; NI—80% 尿素+抑制剂 Applying 80% of urea and adding nitrogen inhibitor; NIM—80% 常量尿素+抑制剂+20% 鸡粪氮 NM plus nitrogen inhibitor in urea. 同列数值后不同小写字母表示处理间差异显著 (Duncan, P < 0.05) Values followed by different lowercase letters in the same column represent significant difference among treatments (Duncan, P < 0.05).

      Table 3.  Distribution of fertilizer and soil source nitrogen in rice-soil system under different fertilization management

    • 2.7.   减氮配施抑制剂及鸡粪下水稻生长及土壤氮转化指标间的相关关系

    • 图4相关分析表明,肥料氮的残留量 (FN) 与取样时间、氮总吸收量、水稻生物量之间呈极显著正相关关系,肥料氮添加对水稻生长及氮素吸收的促进效果显著。肥料氮残留量与铵态氮含量呈极显著负相关关系,而铵态氮含量又与土壤微生物量氮含量和土壤全氮呈显著正相关关系,表明抑制剂及鸡粪添加促进了微生物同化铵态氮,增加了肥料氮的微生物固持,对土壤培肥有良好的效果。土壤全碳与全氮之间具有极显著的正相关关系,表明本试验中的处理在一定程度上具有良好的碳氮耦合关系。

      Figure 4.  Correlation analysis among various indexes

    3.   讨论

      3.1.   不同施肥方式对有机无机氮素转化的影响

    • 80%尿素+抑制剂与常规氮肥相比,提高了土壤中及肥料来源的铵态氮含量 (图1图3P > 0.05),聂彦霞等[27]和唐贤等[28]研究表明,NBPT、DMPP组合抑制尿素水解更为有效,并使得大量氮以NH4+-N的形式存在,确保氮素供应,故抑制剂添加后对抑制尿素水解及硝化作用显著,对氮素的补偿作用较好。而80%尿素+鸡粪或80%尿素+抑制剂+鸡粪效果则相反,其显著提高了土壤及分蘖期肥料来源的铵态氮及微生物量碳氮含量 (P < 0.05),鸡粪添加对土壤有机无机态氮的供应能力的提升作用显著 (图1图2图3),这可能与鸡粪中碳氮比有关 (C/N = 10.63)。研究表明,鸡粪的碳氮矿化累积量及矿化速率较大,矿化过程短[29],故鸡粪的矿化和释放为微生物的固持及粘土矿物的固定提供氮素来源,微生物量氮库和固定态铵库发挥氮临时贮存库的作用,待后期氮素供应不足及水稻养分需求量较大时矿化释放,土壤的碳氮供给与水稻的需肥特点得到有效地调节,充分发挥了有机氮替代部分无机氮的氮素供应时间差,这与Liu等[30]的结果相一致。Pan等[31]研究亦表明,在稻田土壤中,有机无机肥配施会通过增加土壤有机碳的积累,增加氮的有效性,也有可能是提高土壤物理、化学、生物化学保护态有机氮的含量,从而提高土壤肥力[32]

    • 3.2.   不同施肥方式对水稻的增产作用

    • 本研究结果显示,80%尿素与抑制剂及鸡粪配施后,水稻产量增加最多,约是CK的2.64倍和N的2.24倍 (表1),将氮肥速效性与有机肥持久性的特点进行了融合。减氮配施抑制剂与常规施氮肥相比,虽然铵态氮及微生物量氮含量差异不显著,但会促进水稻增产,可能原因是抑制剂添加后会促进稻田土壤中黏土矿物对NH4+的固定,增加固定态铵库的库容,在水稻生长过程中缓慢持续释放,发挥“中转库”的作用,供水稻吸收利用[33]。有研究表明,与单施化肥相比,有机肥料氮替代无机肥料氮的最适替代率为10%~25%,能协调土壤肥料的供应与作物需氮的同步性,在水稻全生育期内实现养分的持续稳定供给,水稻产量、氮肥利用率和经济效益都达到最佳水平,这是提高氮肥利用率的关键[34-36]。本研究20%的有机肥替代氮肥,使得氮素吸收率高达64%(表2)。这可能是因为采用15N标记的尿素,能准确地定量肥料氮的含量和去向,较常规计算更为精准。另有研究表明,鸡粪配施氮肥的增产机理,可能是因为有机无机肥配施增加了土壤中的盐基离子,提高土壤的阳离子交换量,另一方面,土壤有机质和鸡粪携带的其他营养元素的补充,正好与氮肥形成缓急相济的养分供应[37]

    • 3.3.   不同施肥方式对水稻氮肥利用率及吸氮量的影响

    • 肥料利用率、肥料农学利用率和肥料偏生产力常被用来表征农田中肥料的利用效率。相比于N处理,配施抑制剂处理 (NI、NIM),具有最高的氮肥利用率,占施入肥料的70%以上,肥料氮的损失率显著减少,仅为10%左右 (表3),氮肥偏生产力亦显著提高,达到61.62 kg/kg,而东北稻区近30年土壤的偏生产力为54 kg/kg[38],与此相比约高出14.11%(表2)。孙祥鑫等[5]研究表明,脲酶和硝化抑制剂配合尿素是减少水田氮素损失和气体排放的首选肥料。氮肥减量配施抑制剂或鸡粪,有很好的铵态氮供应能力及较低的硝态氮含量,增加铵态氮向微生物量氮库中的转化,增加肥料氮的生物固持。同时,图4的相关分析也验证了施肥处理土壤铵态氮、微生物量氮及肥料氮的含量呈显著的相关关系。有研究表明,抑制剂添加后,抑制了尿素水解和硝化作用,尿素氮的吸收利用与硝化作用呈负相关关系[39],这与本研究结果相一致 (图4),抑制剂组合增加了水稻吸收利用的尿素氮的含量,引起氮肥利用及收获指数提高。且水稻籽粒中的养分,除来自根系直接吸收,主要来自营养器官的养分转移。本研究中在水稻分蘖期,肥料来源的NH4+-N及微生物量氮含量的增加促进了水稻分蘖,从而增加了水稻穗数及生物量,为养分的转移奠定了良好的基础。

    4.   结论
    • 氮肥减量配施抑制剂及鸡粪替代20%尿素氮均能促进水稻生长和改善土壤氮素供应。80%尿素配施抑制剂未对土壤铵态氮、硝态氮、微生物量氮的供给产生显著影响,抑制剂组合 (NBPT+PPD+DMPP) 在稻田土壤氮素补偿方面效果显著,约节肥20%。施用鸡粪显著提高了土壤微生物量碳氮含量,增加微生物活性。氮肥减量配施抑制剂及鸡粪在提高土壤铵态氮、土壤微生物量氮、氮素吸收利用率、氮肥农学效率和氮肥偏生产力方面作用显著,且能增加肥料氮的微生物固持,减少肥料氮素损失,抑制剂和鸡粪对氮肥增效具有协同作用。

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