IMHE OpenIR  > 山地表生过程与生态调控重点实验室
施肥方式对紫色土坡耕地氮氧化物排放与氮流失的影响
Alternative TitleEffects of Fertilization Regimes on Nitrous Oxide Emissions and Diffuse Nitrogen Loss from Hillslope Cropland of Purple Soil
Language中文
柳文丽
Thesis Advisor朱波
2014
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name硕士
Degree Discipline工程硕士专业学位
Keyword“氮氧化物排放” “氮流失” “n2o间接排放” “施肥方式” “紫色土” “坡耕地”
Abstract氮是作物生长最重要的养分限制因子,氮肥施用是保障粮食增产的基础。但过量施用氮肥已导致严重的环境问题,活性氮污染已成为仅次于气候变化和生物多样性衰减的全球性环境威胁。农田土壤氮氧化物排放和氮素径流损失是农田生态系统氮素循环研究的两个重要过程,前者影响大气温室气体浓度,后者是农田面源污染的核心问题。本研究以紫色土坡地农田为研究对象,依托中国科学院盐亭紫色土农业生态试验站,利用可同步观测氮氧化物排放和氮素径流迁移的大型自由排水采集器(Free-drain-lysimeter)群,进行连续野外定位观测,研究了紫色土坡耕地氮氧化物排放与氮流失过程与通量,分析了单施氮肥(N)、猪厩肥(OM)、常规氮磷钾肥(NPK)、猪厩肥配施氮磷钾肥(OMNPK)、秸秆还田配施氮磷钾肥(CRNPK)及对照不施肥(NF)等施肥方式对紫色土坡耕地氮氧化物排放与氮流失的影响,并结合作物产量,筛选出实现紫色土坡耕地氮氧化物排放和氮流失协同减排的优化施肥措施。主要研究结果和结论如下: (1) 紫色土N2O和NO排放速率波动幅度大,分别为-2.18~214.52和0.17~71.46 ug (N)·m-2 ·h-1。施肥初期排放速率不断增加,小麦季N2O在施肥后第5天出现排放峰值,玉米季N2O在第6天达到峰值,而NO则在第7天出现峰值。之后排放通量迅速下降,施肥是紫色土氮氧化物排放出现高峰的主要驱动因子。土壤无机氮(NO3--N和NH4+-N)含量是紫色土N2O排放的主要限制因子,降雨可激发土壤N2O排放。 (2)地表径流和壤中流是紫色土坡耕地氮素径流损失的两种途径。其中,壤中流中总氮浓度变化范围较大,为2.63~90.72 mg·L-1,呈现明显的先增加后迅速下降的单峰变化特征,硝态氮是壤中流氮素流失的主要形态。同时,地表径流总氮浓度波动范围为1.36~8.91 mg·L-1,变化相对较小。颗粒态氮是地表径流氮素迁移的主要形态。壤中流氮素迁移损失量占径流损失总氮量的95%,氮素随壤中流的淋溶损失是氮素径流损失的主要方式。氮淋溶引发的N2O间接排放量达到0.44 kg(N)·ha-1, 占N2O总排放量的28%。 (3)施肥方式对紫色土N2O和NO累积排放量具有显著影响(P<0.05)。施肥方式是紫色土N2O排放的主要调控措施,而调控土壤C/N,控制土壤无机氮水平是主要调控机制。秸秆还田配施氮磷钾(CRNPK)处理的土壤N2O和NO全年累积排放量分别为0.79±0.06和0.15±0.05 kg (N)· ha-1,显著低于NPK、OM 和OMNPK,能有效减少因施肥引发的氮氧化物排放,而有机肥可能促进土壤氮氧化物的排放。施肥方式对紫色土坡耕地氮素流失量具有显著影响(P<0.05),与常规NPK施肥方式相比,OM、OMNPK和CRNPK的氮素流失总量显著减少44.4%、25.4%和15.4%。有机肥或秸秆的施用,能有效抑制紫色土坡耕地氮素流失。此外,施肥方式对紫色土坡耕地氮氧化物排放和氮流失协同损失总氮量具有显著影响(P<0.05)。OM 、OMNPK和CRNPK氮素协同损失量分别为40.99±4.71、53.71±5.00 和 59.78±4.57 kg(N)· ha-1,均显著低于常规施肥NPK。有机肥或秸秆的施用,能有效抑制紫色土坡耕地氮氧化物排放和氮流失的协同损失。 (4)N、NPK、OM、OMNPK、CRNPK的全年作物产量分别为4.35±0.33、8.39±0.92、11.95±0.77、9.77±0.45和10.93±0.70 t·ha-1,秸秆还田配施氮磷钾(CRNPK)处理的产量与OM、OMNPK无显著差异,但显著高于其他处理。OM单位产量的氮氧化物排放与氮流失协同损失总氮量最小,为3.42±0.22 kg(N)·t-1,CRNPK与之无显著差异,但均显著低于其他处理。同时,CRNPK处理的基于单位产量的直接和间接N2O排放的GWP值仅为49.19±3.08 kg (CO2 eq)·t-1,比常规施肥方式(NPK)显著减少44.32%,并显著低于其他施肥方式。综合考虑作物产量和氮氧化物排放、氮素流失,秸秆还田配施氮磷钾肥能保证作物的高产,同时能有效实现氮氧化物排放和氮素径流流失的协同减排,达到生产效益和环境效益的协同一致,可作为紫色土地区推荐的最佳施肥措施。
Other AbstractNitrogen is the most important nutrient element which can control the crop growth and ensure the crop yields improved. However, external N inputs caused by overuse synthetic N fertilizer have resulted in serious environmental challenges. Reactive nitrogen pollution is regarded as the third major global environmental threaten to earth next to climate change and biodiversity loss. Research on nitrogen oxides (N2O and NO) emissions and nitrogen loss via runoff from agro-ecosystem is becoming hot topics worldwide for both green house gases emissions and non-point-source pollutions. In this study, in situ field monitoring for both gas emissions of nitrogen oxides and diffuse nitrogen loss via overland flow and interflow have been conducted for a round-year of wheat-maize rotation system by free-drain lysimeters at Yanting Agro-ecological Experimental Station of Purple Soil, Chinese Academy of Sciences. Meanwhile, different fertilization regimes involved in pure synthetic N fertilizer (N), pig manure (OM), synthetic N, P, K fertilizer (NPK), pig manure with synthetic NPK fertilizer (OMNPK) , crop residues returned with synthetic NPK fertilizer (CRNPK) and no fertilizer (NF) were compared to understand the effects of N fertilization regimes on gas emissions of nitrogen oxides and diffuse nitrogen loss. Based on the comparisons of nitrogen loss and crop yield, optimal N fertilizer management practices for simultaneous mitigation of both nitrogen gas emissions and diffuse N loss from slope cropland of purple soil will be recommended. The results and conclusions were listed as follows: (1) Soil N2O and NO emission fluxes from cropland of purple soil was -2.18~214.52 and 0.17~71.46 ug(N)·m-2· h-1. N2O and NO emission increased rapidly at the early stage of fertilization with peak emission rates soon after fertilizers applied. In the wheat season, the highest N2O flux occurred on the fifth day after fertilization. The highest N2O and NO flux occurred on the sixth and seventh day after fertilization in the maize season, respectively. Then, the emission rates were decreasing. Fertilization was obviously the main driving force of peak emission of soil nitrogen oxides. Soil inorganic N (ammonium and nitrate) content was the main controlling factor for soil N2O emission. Rainfall significantly stimulated soil N2O emission. (2) Interflow and overland flow were the major nitrogen loss pathways through runoff. Total nitrogen (TN) contents of interflow water were very high in range of 2.63 to 90.72 mg·L-1. Besides, there was one TN content peak during interflow process, and nitrate nitrogen (NN) was the dominant N forms. There were small changes on TN contents of overland flow water with particulate nitrogen (PN) was the dominant nitrogen forms. The nitrogen loss through interflow accounted for about 95% of amount of diffuse nitrogen loss, suggesting that nitrate leaching loss via interflow is the major route of nitrogen discharged from the sloping cropland of purple soil. Indirect N2O emissions induced by nitrate leaching losses was 0.44 kg(N)·ha-1, which accounted for about 28% of total N2O emissions. (3) The cumulative soil N2O and NO fluxes from different fertilization regimes had significant differences (P<0.05), even if they were applied at the same rate of total N. Fertilization regime was the main control measures on soil N2O and NO emission. Soil inorganic nitrogen (NH4+-N and NO3-) contents were the main controlling factors which could be regulated by soil C/N influenced by fertilization regimes. The cumulative soil N2O and NO fluxes in CRNPK treatment was 0.79±0.06 and 0.15±0.05 kg (N)· ha-1, which was much lower than those in NPK, OM and OMNPK treatments. Crop residues returned with synthetic NPK fertilizer could reduce nitrogen oxide emission due to application of N fertilizer effectively. On the contrary, organic manure increased gas emissions of nitrogen oxides. Diffuse nitrogen loss fluxes from different fertilization regimes had significant differences (P<0.05). In contrast with conventional N, P and K fertilization regime (NPK), diffuse nitrogen loss fluxes from OM、OMNPK and CRNPK treatment were decreased by 44.4%, 25.4% and 15.4%, respectively. Organic manure or crop straw returned could restrain nitrogen loss via runoff from sloping cropland of purple soil. Besides, total nitrogen loadings induced by nitrous/nitric oxide emissions and diffuse nitrogen loss from different fertilization regimes had significant differences (P<0.05). Total nitrogen loadings from OM、OMNPK and CRNPK treatment was 40.99±4.71, 53.71±5.00 and 59.78±4.57 kg N· ha-1, respectively, which was much lower than those in NPK (P<0.05). Crop straw returned or organic manure and with synthetic N, P, K fertilizers could restrain nitrogen loss via gas emissions and diffuse losses. (4) The annual crop yields of N, OM, NPK, OMNPK and CRNPK treatment was 4.35±0.33,8.39±0.92, 11.95±0.77, 9.77±0.45 and 10.93±0.70 t·ha-1, respectively. Crop yield of CRNPK was much higher than other treatments (P<0.05), whereas, had no significant differences with that of OM and OMNPK treatment. The yield-scaled nitrogen loss fluxes via nitrogen oxide emissions and diffuse nitrogen loss in OM treatment was the lowest in all treatments. Those in CRNPK treatment was much lower than other treatments (P<0.05), whereas, had no significant differences with those in OM treatment. Meanwhile, the yield-scaled direct and indirect N2O emissions on CRNPK treatment was 49.19±3.08 kg (CO2 eq)·t-1. It was decreased by 44.3% of that in conventional N, P and K fertilization regime (NPK) and was much lower than in other treatments. This implies that crop residues returned with synthetic NPK fertilizer could not only increase grain yields, but also decrease soil nitrogen oxide emissions and diffuse nitrogen loss. The fertilizer application regimes of crop residues returned with synthetic fertilizer could be recommended as the optimal fertilization measure in slope cropland of purple soil.
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/7827
Collection山地表生过程与生态调控重点实验室
Recommended Citation
GB/T 7714
柳文丽. 施肥方式对紫色土坡耕地氮氧化物排放与氮流失的影响[D]. 北京. 中国科学院研究生院,2014.
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