【作者】 王淳；

【导师】 刘光荣； 周卫；

【作者基本信息】 中国农业科学院 ， 植物营养学， 2012， 硕士

【摘要】 双季稻连作体系是华南和长江中下游地区的主要种植模式，在我国粮食生产中的地位举足轻重。氮素是生命元素，也是粮食增产的重要因素，目前该体系普遍存在着氮肥盲目施用，利用率低、环境风险高等问题，通过对农田化肥氮去向的定量化研究能够更科学全面地评价氮肥农学效应和环境效应，将为科学施用氮肥提供理论依据。为此本研究于2010年在双季稻主产区江西省开展氮肥用量田间试验及¹⁵N微区试验，监测不同施氮水平下土壤氨挥发、N₂O排放、无机氮动态分布以及肥料¹⁵N的去向。田间试验和¹⁵N微区试验均设置6个处理，（1）N0（不施氮），（2）N60(施氮60kgN/hm²)，（3）N₁₂0(施氮120kgN/hm²)，（4）N180(施氮180kgN/hm²)，（5）N240(施氮240kgN/hm²),（6）N300(施氮300kgN/hm²)，早晚稻施肥量一致，按5：2：3的比例于基肥期、分蘖期及孕穗期三次施用。采用田间原位密闭室间歇抽气法测定稻田土壤氨挥发、密闭箱-气相色谱法原位监测稻田N₂O排放，以及使用流动注射分析仪测定土壤无机氮含量，同时监测大气氮素干湿沉降及灌溉水输入的氮素。研究的主要进展如下：1.双季稻连作体系肥料氮的主要损失途径是氨挥发。早稻氨挥发损失主要发生在施肥后的15d内，第3-5d出现峰值，施氮处理肥料氮氨挥发损失总量为17.57-156.97kgN/hm²，损失率为29.29%-52.32%；晚稻氨挥发主要发生在施肥后的11d内，第3d出现峰值，肥料氮氨挥发损失总量为21.45-142.79kgN/hm²，损失率为35.75%-46.82%。早、晚稻及连作周期的氨挥发量均与施氮量呈显著线性正相关。2.双季稻连作体系土壤N₂O排放具有明显的季节性变化规律。早、晚稻季土壤N₂O排放峰值主要出现在施肥后3-7d以及生长期后期干湿交替之际。早稻季各处理N₂O平均排放通量为3.76-81.31μg/(m²·h)；晚稻季为3.46-81.74μg/(m²·h)。早稻季各处理N₂O排放量为0.14-1.37kgN/hm²；晚稻季为0.04-1.57kgN/hm²。早、晚稻季氮肥损失率分别为0.34%-1.02%、0.42%-0.86%。整个双季稻连作周期N₂O排放量为0.18-2.94kgN/hm²，氮肥损失率为0.46%-0.94%。早、晚稻土壤N₂O平均排放通量及排放量均与施氮量呈显著线性正相关。3.双季稻连作体系稻田土壤中氮素主要以铵态氮形式存在，硝态氮含量很少，随着施氮量的增加，0-40cm土壤中硝态氮和铵态氮的浓度及累积量明显提高。0-40cm土壤的表观平衡，早稻的表观回收率为35.38%-48.64%，晚稻为42.66%-58.57%，表观损失率分别为39.44%-48.72%、32.27%-49.15%。4.¹⁵N微区试验结果表明，早、晚稻季及两季平均的作物回收率分别为34.27%-42.00%、36.93%-47.61%、35.60%-44.81%；早、晚稻肥料氮在土壤中残留量的70%以上主要分布于0-20cm，残留率分别为9.08%-16.69%、17.40%-35.54%，两季平均土壤残留率为13.97%-26.11%；早、晚及两季平均肥料¹⁵N氨挥发损失率分别为20.33%-43.10%、20.30%-35.86%和20.31%-39.48%。作物回收率随着施氮量的增加而显著下降，呈显著的线性负相关；土壤残留量、氨挥发损失量均随施氮量的增加而升高，呈显著的线性正相关。更多还原

【Abstract】 Double cropping rice system is the main planting patterns of China, it plays an important role ingrain production. Nitrogen is essential for life and is the most important plant nutrient for cropproduction. However, overuse of fertilizer N, low N recorery and high environmental risk werecommonly found in farmer’s practices in this area, so quantitative study on the fate of nitrogen will benecessary to evaluate the agronomic and environmental effect scientifically and comprehensively and toprovide scientific base for N management strategies. In this study, field experiments and¹⁵N labeledmiro-plot experiments were set up in the double cropping rice field in Jiangxi province in2010toinvestigate ammonia volatilization, N₂O emission, distribution of inorganic nitrogen and the fate of¹⁵Nlabeled under different fertilizer N application rates. The treatments of field experiments and¹⁵N labeledexperiments included:（1）N0（no fertilizer N）;（2） N60(60kg N/hm²);（3） N120(120kg N/hm²);（4）N180(180kg N/hm²);（5） N240(240kg N/hm²);（6） N300(300kg N/hm²). The fertilizer applicationfor early rice and late rice were the same, with the ratio of5:2:3at basic, tillering stage and bootingstage. The enclosure intermittent vent method was adopted to measure the ammonia volatilization, staticchamber-GC method was used to measure N₂O emission and flow injection analyzer was used toanalyze ammonium and nitrate nitrogen, nitrogen deposition and N from irrigation water weremonitored and calculated in rice growing season. The main findings obtained are summed up asfollows:1. Field plot trials showed that the NH3-N volatilization （NV） mainly occured within15days offertilizer applied, and the peak appeared during3-5days after fertilization in the early rice season.However, in the late rice season, the NV loss occured within11days and the peak appeared in thethird days after the fertilization. The total NV losses varied from17.57-156.97kgN/hm²and21.45-140.45kgN/hm²in the early rice and late rice, accounted for29.29%-52.32%and35.75%-46.82%of the applied N amounts, respectively. The total NV losses and their percentagesin early rice and late rice were linearly increased with the urea application rates.2. There were significant seansonal variations of N₂O emission flux during the double cropping ricegrowing season. The peak occured mainly within3-7d after urea application and when the soil waschanged from wetting to drying in the late period of growing stage.The average N₂O fluxes was3.76-81.31μg/(m²·h) and3.46-81.74μg/(m²·h) in the early and late rice seasons, respectively. Thecumulative seasonal N₂O emission varied from0.14to1.37kgN/hm²in the early rice season whichaccounted for0.34%to1.02%of applied N, and from0.04to1.57kgN/hm²during the late riceseason which ranged from0.46%-0.94%of applied N. The average N₂O fluxes and cumulativeseasonal N₂O emission in the early and late rice seasons were linearly increased with the increaseof the urea application rates as well.3. The main inorganic nitrogen form in paddy soil was NH+4-N. The NH+4-N, NO-3-N content and thecumulative amounts increased with the urea application rates.The results of the nitrogen balancesheet within0-40cm soil layes indicated that the apparent nitrogen recovery were35.38%-48.64% and42.66%-58.57%in the early and late rice season, respectively; and the apparent of N loss were39.44%-48.72%、32.27%-49.15%,respectively.4. Micro-plot experiment with¹⁵N tracing showed that N recovery for early,late rice and in the wholerotation season were34.27%-42.00%、36.93%-47.61%and35.60%-44.81%, respectively. Above70%of N residual existed in0-20cm soil layer, and the N residual rate were9.08-16.69%、17.40-35.54%in the early and late rice, respectively, and it was13.97%-26.11%in the wholerotation seaason; NV loss rate from fertilizer¹⁵N under different N application ranged from20.33%-43.10%、20.30%-33.86%and20.31%-39.48%in the early, late rice and in whole rotationseason, respectively; the N recovery linearly decrased with the increase of N application. On thecontrary, the cumulative NV amounts and N residual from fertilizer¹⁵N inceased with the increaseof the urea application rates.更多还原