【作者】 黄东风；

【导师】 王果；

【作者基本信息】 福建农林大学 ， 生态学， 2009， 博士

【摘要】 针对蔬菜不合理施肥导致菜地土壤氮磷过量累积及理化性状恶化、蔬菜的硝酸盐含量超标、菜地地下水的硝酸盐污染和地表水的富营养化等一系列农业面源污染问题,以福州市郊菜地为研究对象,采用实地调查、室内分析、土培盆栽、温室模拟土柱及田间径流小区试验等方法,调查了福州市郊蔬菜的施肥现状、菜地土壤养分累积特征、蔬菜硝酸盐污染现状、菜地田面水及地下水的氮磷面源污染现状;研究了7种不同硝、铵态氮用量配比（即,NO₃^--N / NH₄⁺-N比为:3/1,2/1,3/2,1/1,2/3,1/2和1/3）及与3种硝化抑制剂（即,双氰胺、咪唑、吡啶）配施对蔬菜产量、硝酸盐含量及蔬菜内源硝酸盐有效利用性的影响;探讨了7种不同施肥模式（即,不施肥、化肥基施、化肥基追肥各半、化肥和双氰胺基施、化肥和双氰胺基追肥各半、化肥和有机肥基追肥各半、有机肥基施）与蔬菜生长、硝酸盐含量、营养累积、肥料利用率、菜地氮（磷）随渗漏水淋失及地表径流流失的关系规律;建立了以蔬菜丰产、优质、高效且环境友好为目标的优化施肥模式,为解决蔬菜生产上的高氮磷面源污染风险问题提供理论依据。主要研究结果如下:1、福州市郊蔬菜地以施用化肥为主、有机肥为辅,不同类型蔬菜的平均施肥水平（N、P₂O₅和K₂O总养分）在493.6¹ 212.2 kg·hm^-2·茬^-1,N:P₂O₅:K₂O比例为1:0.58⁰.98:0.55⁰.92,平均为1:0.77:0.75,氮磷钾比例不协调,磷肥施用量明显偏高;不同轮作制度下蔬菜的平均施肥量（N、P₂O₅和K₂O总养分）在2 002.3³ 455.2 kg·hm^-2·a^-1。与林坡地自然土壤相比,菜地土壤的全磷(2.04 g·kg^-1)、速效磷(182.9 mg·kg^-1)、CaCl₂-P(1.02 mg·kg^-1)明显累积,分别高出3.16、6.87和12.3倍;有机质(37.4 g·kg^-1)和全氮(2.18 g·kg^-1)平均含量分别提高33.43%和17.16%;全钾含量变化不明显;而碱解氮(200 mg·kg^-1)、速效钾(243.8 mg·kg^-1)、CEC(14.7 cmol·kg^-1)和pH（5.97）则分别降低15.01%、38.2%、3.14 %和9.7%。2、福州市郊菜地氮磷面源污染现状:（1）处于严重污染(NO₃^-≥3 100 mg·kg^-1)的蔬菜样品占检测总数的13.33%,处于重度污染(NO₃^-≥1 440 mg·kg^-1)以上的蔬菜样品占检测总数的32.5%,处于中度污染以上(NO3-≥785 mg·kg^-1)的蔬菜样品占检测总数的50.83%。（2）氨氮含量超过地表水Ⅲ类(1 mg·L^-1)和Ⅴ类(2 mg·L^-1)水质标准的菜地田面水样数量分别占调查总量的62.5%和56.25%;硝态氮含量超过国家集中式生活饮用水地表水标准(10 mg·L^-1)的菜地田面水样数量占调查总量的12.5%;总氮平均含量和最高含量分别为10.99和33.80 mg·L^-1,分别是地表水Ⅴ类水质氮标准(2 mg·L^-1)的5.5和16.9倍;总磷平均含量和最高含量分别为4.75和12.75 mg·L^-1,分别是地表水Ⅴ类水质磷标准(0.4 mg·L^-1)的11.9和31.9倍。（3）氨氮含量超过Ⅴ类水质标准(0.5 mg·L^-1)的地下水样数量占调查总量的18.18%;硝态氮含量处于超标级别(≥10 mg·L^-1)以上的地下水样数量占调查总数的54.55%,处于严重超标级别(≥20 mg·L^-1)以上的地下水样数量占调查总量的27.27%;总氮含量全部超过Ⅴ类水质标准(2 mg·L^-1,GB3838^-2002),超标率为100%;总磷含量超过Ⅴ类水质标准(0.4 mg·L^-1,GB3838^-2002)的占调查总量的81.82%。3、优化施肥模式控制蔬菜硝酸盐污染:（1）在试验设计的硝、铵态氮配比水平范围（3/1¹/3）内,随硝/铵态氮施用量比值的降低,小白菜植株株高、株重及产量均大体表现出先升高而后降低的趋势,而小白菜植株硝酸盐含量则大体表现出先升高而后降低再升高的趋势。与硝铵比3/1处理相比,硝铵比2/3处理可分别提高小白菜植株株高、株重及产量15.57%、45.05%和13.67%,同时降低蔬菜的硝酸盐含量37.49%。因此,硝/铵比为2/3处理比较适宜土培小白菜的生长及蔬菜硝酸盐含量的降低。（2）以硝铵比2/3为对照,在此基础上分别添加3种硝化抑制剂（即,双氰胺、咪唑、吡啶）组成的3种优化施肥模式可提高小白菜产量6.06%²8.55%,降低蔬菜硝酸盐含量2.69%¹9.66%,提高植株氮累积量2.38%³8.42%,小白菜叶片硝酸还原酶活性（NRA）、硝态氮还原代谢库大小（MPS）和硝态氮还原贮藏库大小（SPS ）分别提高24.28%⁷7.32%、29.45%²72.17%和2.78%¹7.38%,并增加代谢库/贮藏库（MPS/SPS）比值0.04%⁰.59%,从而提高了小白菜内源硝酸盐的有效利用性。4、优化施肥模式控制菜地氮磷淋溶损失:（1）土壤磷素淋失“阈值”及淋失潜能研究表明,Langmuir等温方程可以很好拟合供试菜地土样对磷的吸持特征（R2=0.991**⁰.998**）。据Langmuir方程求得菜地土壤指导施磷量范围为11.62⁶7.37 （P）kg·hm^-2,平均为27.18 （P）kg·hm^-2;菜地土壤的速效磷和全磷含量均显著高于由回归方程求得的土壤发生磷素淋失的速效磷临界值(56.96 mg·kg^-1)和全磷的临界值(1.146 g·kg^-1);菜地土壤的磷吸持饱度（DPS）平均为23.12%,已经接近容易淋失的阈值（25%）,其中4片菜地土样的DPS已经超过容易淋失的阈值。因此,福州市郊菜地土壤磷素具有很高的淋失潜能。（2）温室模拟土柱试验结果表明,“化肥和双氰胺基施”和“有机肥基施”2种施肥模式,不仅可比“不施肥”处理改善蔬菜植株的农艺性状,分别提高蔬菜产量113%³01%和238%²50%,提高蔬菜植株氮累积量194%³36%和208%²27%,磷累积量93.5%¹33%和144%²29%,提高氮磷肥料利用率,还可比“化肥基施”处理分别降低蔬菜硝酸盐含量10.9%³9.6%和6.8%³4.3%,减少蔬菜种植期间模拟土柱中硝态氮和铵态氮的淋溶损失53.4%和46.6%、水溶性总磷的淋溶损失17.0%和11.3%,从而有效地减少了菜地土壤的氮、磷对地下水水体造成的农业面源污染。5、优化施肥模式控制菜地氮磷随地表径流流失:“化肥和双氰胺基施”和“化肥和有机肥基追肥各半”2种施肥模式,不仅可比“不施肥”处理改善蔬菜植株的农艺性状,分别提高蔬菜产量93%²26%和143%¹54%,提高蔬菜植株氮累积量231%³20%和153%²16%,磷累积量131%⁴17%和169%¹167%,肥料利用率较高,蔬菜硝酸盐含量较低,还可比“化肥基施”处理分别减少蔬菜种植期间菜地土壤随地表径流流失的硝铵态氮总量46.46%和48.10%、水溶性总磷量21.02%和10.73%,从而有效地减少了菜地土壤的氮、磷对地表水水体造成的农业面源污染。更多还原

【Abstract】 Excessive fertilizers are often applied on vegetable fields in order to pursue higher yields. In some areas, the amounts of chemical fertilizers and manures so applied are several times of that needed by vegetables. Nitrogen （N） and phosphorus （P） have been obviously accumulated in the vegetable soils, resulting in excessive nitrate and poor quality of vegetables. Furthermore, a series of environmental problems are produced, i.e., the deterioration of physical and chemical properties of vegetable soils, the nitrate’s pollution of vegetables, groundwater and the eutrophication of surface water. A series of field investigations over the vegetable fields in the suburb of Fuzhou City, Fujian Province and studies in laboratory were carried out to deal with the above environmental problems caused by the exessive fertilization for vegetables. The fertilization status quo of vegetable fields, accumulative characteristics of nutrients in vegetable-field soils, the concentration of nitrate in vegetable, non-point source pollution of surface-field water and groundwater in vegetable fields were analyzed. Pot experiments with 7 different ratios of nitrate-N and ammonium-N and 3 kinds of nitration inhibitors （dicyandiamide, imidazole and pyridine, respectively） were conducted to test the effects on the yield, nitrate’s concentration of vegetable and the available metabolism of endogenous nitrate of vegetable. An experiment with 7 different fertilization models （none fertilization, basal application of chemical fertilizer, half-basal application and half-top-dressing of chemical fertilizer, basal application of chemical fertilizer and dicyandiamide, half-basal application and half-top-dressing of chemical fertilizer and dicyandiamide, half-basal application and half-top-dressing of chemical fertilizer and organic manure, basal application of organic manure） was carried out to verify the effects of different fertilization modes on the growth of vegetables, nitrate’s content, N and P-accumulation of vegetables, the utilization ratio of fertilizer, and the loss of N and P from the field. The aim of this dissertation was to establish an optimized fertilization model which is suitable for the production of higher yield & quality of vegetable, and friend with the environment. The main results were as follows:1. Fertilizers applied on the vegetable fields in the suburb of Fuzhou were mainly chemical fertilizers with a small part of organic manure. The average fertilization rate （N、P₂O₅ and K₂O） of different kinds of vegetables was between 493.6¹ 212.2 kg·hm^-2·stubble ^-1. The proportion of N:P₂O₅:K₂O was 1:0.58⁰.98:0.55⁰.92 with an average of 1:0.77:0.75, indicating the inbalanced fertilization of N:P₂O₅:K₂O and apparent over-fertilization of phosphorus. The range of average fertilization rate （N、P₂O₅ and K₂O） for vegetable was 2 002.3³ 455.2 kg·hm^-2·a^-1 under various kinds of rotation systems. The average contents of total phosphorus (2.04 g·kg^-1), Oslen-P(182.9 mg·kg^-1) and CaCl2-P (1.018 mg·kg^-1) of the vegetable soils were 3.16、6.87 and 12.3 times higher than those in the natural soils sampled from the neighbouring hills, respectively. The average organic matter content (37.4 g·kg^-1) and total nitrogen (2.178 g·kg^-1) were increased by 33.43% and 17.16%, respectively; The content of total potassium changed a little. However, the average contents of alkaline hydrolyzable nitrogen (200.2 mg·kg^-1), available potassium (243.8 mg·kg^-1), CEC (14.7 cmol·kg^-1) and pH （5.97） were decreased by 15.01%, 38.2%, 3.14 % and 9.7%, respectively.2. N and P non-point source pollution status quo of the vegetable fields in the suburb of Fuzhou city: （1） The proportions of the vegetable samples of which the nitrate contents were above the very severely polluted level (NO₃^-≥3 100 mg·kg^-1), severely polluted level (NO₃^-≥1 440 mg·kg^-1) and moderately polluted level (NO₃^-≥785 mg·kg^-1) were 13.33%, 32.5% and 50.83%, respectively. （2） The proportions of the surface-field water samples of which the ammonia-N contents were above theⅢclass surface water limitation (1 mg·L^-1) andⅤclass (2 mg·L^-1) were 62.5% and 56.25%, respectively. 12.5% of the surface-field water samples of which the nitrate-N contents was above the limitation of Chinese surface water of collective living-drinking water (10 mg·L^-1). The average and maximal N concentrations of the vegetable surface-field water samples were 10.99 and 33.80 mg·L^-1, respectively, and 5.5 and 16.9 times of the theⅤclass limitation of the surface water quality standard (N 2 mg·L^-1), respectively. The average and maximal total P contents of the vegetable surface-field water samples were 4.75 and 12.75 mg·L^-1, respectively, and 11.9和31.9 times of theⅤclass limitation of the surface water quality standard (P 0.4 mg·L^-1), respectively. （3） The proportion of the vegetable field groundwater samples of which the ammonia-N content was beyond the V class water quality limitation (0.5 mg·L^-1) was 18.18%. The Proportions of groundwater samples of which the nitrate content was super-scale (≥10 mg·L^-1) and seriously super-scale (≥20 mg·L^-1) were 54.55% and 27.27%, respectively. The total N of all the groundwater samples were beyond the V class water quality limitation (N 2 mg·L^-1,GB3838^-2002). The proportion of the vegetable field groundwater samples of which the total P was beyond the V class water quality limitation (P 0.4 mg·L^-1, GB3838^-2002) was 81.82%.3. The optimized fertilization models for controlling nitrate pollution of vegetable: （1） Within the ranges of ratios of NO₃^--N / NH₄⁺-N （3/1¹/3）, with the decreasing ratios of NO₃^--N / NH₄⁺-N, the plant’s tallness, weight and yield of vegetable were increased firstly and decreased afterwards while the content of nitrate in the vegetable was increased firstly, decreased after and increased again. As compared with the ratio of NO₃^--N / NH₄⁺-N of 1/3, the ratio of NO₃^--N / NH₄⁺-N of 2/3 resulted in the increase in the tallness, weight and yield of Pakchoi by 15.57%、45.05% and 13.67%, respectively, and in the reduce in the nitrate of Pakchoi by 37.49%. Therefore, the ratio of NO₃^--N / NH₄⁺-N of 2/3 was better for the growth and the decrease of nitrate of Pakchoi. （2） When three kinds of nitration inhibitors, dicyandiamide, imidazole and pyridine, were applied with the fertilization model （NO₃^--N / NH₄⁺-N = 2/3）, the yields of Pakchoi were increased by 6.06%²8.55%, the nitrate concentration was decreased by 2.69%¹9.66%, the N amount of Pakchoi was increased by 2.38%³8.42%, the leaf’s NRA （Nitrate Reductase Activity） was increased by 24.28%⁷7.32%, MPS （Metabolic Pool Size） was increased by 29.45%²72.17%,, SPS （Storage Pool Size） and MPS/SPS were increased by 2.78%¹7.38% and 0.04%⁰.59%, respectively. Consequently, the availability of endogenous nitrate in Pakchoi was improved.4. The optimized fertilization models for controlling the leaching of N and P: （1） The phosphrous adsorption characteristics of the vegetable field soils can be well fitted by Langmuir isotherm equation （R2=0.991**⁰.998**）. The range of the instructive phosphorus application rates estimated from the Langmuir equation were between 11.62⁶7.37 （P）kg·hm^-2 with an average of 27.18 （P）kg·hm^-2. The contents of the available and total phosphorus of the vegetable soils were much higher than the leaching thresholds (56.96 mg·kg^-1 and 1.146 g·kg^-1) estimated by regression equation. The average DPS of the vegetable soils was 23.12%, close to the easily leaching threshold （25%） of the soil. The DPS of 4 pieces of the vegetable fields investigated had already been beyond the threshold. It is obvious that the phosphorus lost potential of the vegetable soils in the suburb of Fuzhou City is rather high. （2） The soil colum experiment in greenhouse showed that“Basal application of chemical fertilizer and dicyandiamide”and“Basal application of organic fertilizer”were better than the other models because they not only improved the vegetable’s agronomic properties, increased the yields （by 113%³01% and 238%²50% compared with none fertilization） and the N accumulation （by 194%³36% and 208%²27% compared with none fertilization treatment）, P accumulation （by 93.5%¹33% and 144%²29% compared with none fertilization treatment） by the vegetable and therefore the utilization ratio of the fertilizer, but also reduced the nitrate concentration of the vegetable （by 10.9%³9.6% and 6.8%³4.3% compared with the basal application of chemical fertilizer treatment） and the leaching loss of NO₃^--N and NH4₊^-N （by 53.4% and 46.6%% compared with the basal application of chemical fertilizer treatment） and water-soluble P （by 17%% and 11.3% compared with the basal application of chemical fertilizer treatment ） during the vegetable growth period and hence reduced the risk of agricultural non-point source pollution.5. The optimized fertilization models for controlling the loss of N and P along with the surface runoff:“Basal application of chemical fertilizer and dicyandiamide”and“half-basal application and half-top-dressing of chemical fertilizer and organic manure”were better than the other models because they not only improved the vegetable’s agronomic properties, increased the yields （by 93%²26% and143%¹54% compared with none fertilization teatment） and the N accumulation （by 231%³20% and 153%²16% compared with none fertilization treatment） and P accumulation （by 131%⁴17% and 169%¹167% compared with none fertilization treatment） by the vegetable and the utilization ratios of fertilizer by the vegetables, but also reduced the loss of the NO₃^--N and NH₄⁺-N （by 46.46% and 48.10% compared with basal application of chemical fertilizer treatment） and water-soluble P （by 21.02% and 10.73% compared with basal application of chemical fertilizer treatment） from the field along with the surface runoff during the vegetable growth period and hence reduced the risk of agricultural non-point source pollution.更多还原