长期不同施肥模式对日光温室土壤硝态氮时空分布及累积的影响

通过连续7 年的定位试验, 研究了日光温室生产中不同施肥模式(常规模式、无公害模式和有机模式)对土壤NO₃^--N 时空分布及累积的影响。结果表明, 随着种植年限的增加, 3 种施肥模式土壤剖面各层次NO₃^--N含量均呈上升趋势, 年增加量顺序为常规施肥模式＞无公害施肥模式＞有机施肥模式。受氮素输入量(施肥)的影响, NO₃^--N 主要分布在0~40 cm 土层, 0~60 cm 土层NO₃^--N 含量总体呈作物生长前期低、中期高、后期低的趋势; 与上层土壤相比, 100 cm 以下土层NO₃^--N 含量有不同程度的增加。0～200 cm 土体NO₃^--N 平均累积量有机施肥模式比无公害施肥模式低33.8%, 比常规施肥模式低45.9%; 无公害施肥模式比常规施肥模式低18.3%。3 种施肥模式下, NO₃^--N 都有向2 m 以下土体淋洗的趋势。与施用化学肥料相比, 施用有机肥能明显降低土壤剖面NO₃^--N 含量, 控制其累积峰的下移, 但不合理施用有机肥也会产生NO₃^--N 淋洗而污染环境。     

总氮量的测定

众所周知,对于富含NO₃^--N、NO₂^--N的土壤、肥料、污水以及其他样品,用K氏法测得的全氮值不能反映出NO₃^--N、NO₂^--N的含量,因此不能代表总氮量。     

尿素肥斑中氮素形态转化初探

采用特制模拟容器,通过尿素扩散形成营养斑,观察斑内NH₄⁺、NO₂^-和NO₃^-浓度变化及它们之间的相互转化。结果表明,NH₄⁺、NO₂^-和NO₃^-浓度在距离肥斑7～8cm处的微域达到最大,尤以NO₂^-浓度增加较为显著,是一般土壤NO₂^-水平的数千倍。随培养时间增加,NO₂^-和NO₃^-最大浓度峰向施肥点移动,但两者浓度变化趋势不同,NO₂^-浓度在21d前随培养时间增加而增加,之后随培养时间增加而下降,而NO₃^-浓度随培养时间增加一直增加。结果还表明,NO₂^-是尿素营养斑内主要离子形态,从NH₄⁺到NO₂^-的转化比较迅速,而NO₂^-转化为NO₃^-不是短暂的过程,这可能与施肥引起的土壤pH值变化有很大关系。     

滇池流域大棚土壤硝酸盐累积特征及其对环境的影响

对滇池流域主要大棚土壤的分析结果表明：随着大棚年限的增长,土壤剖面(0～60 cm)土层中硝态氮在不断累积,加重了土壤次生盐渍化;大棚内0～20 cm、20～40 cm土壤硝态氮含量与全盐的相关性均达极显著水平。同时对大棚区的地下水、地表水的分析结果表明：地下水中NO^-₃含量与土壤NO^-₃含量呈正相关,相关系数为0.945^**,大棚种植区土壤的NO^-₃累积严重威胁地下水环境;地表水中的总氮含量与大棚土壤NO^-₃含量的相关性很好(r=0.994^**),大棚种植区土壤的NO^-₃累积将加重滇池面源污染的负荷。     

影响土壤镉吸持和解吸的因子

研究了土壤的pH、离子浓度(0.01mol/L、0.05mol/L、0.1mol/L)、阴(阳)离子种类(NO₃^-、Cl^-、OAc^-、SO₄^2-、HPO₄^-及Zn和Pb)及石灰和葡萄糖对土壤镉吸持及其解吸的影响。     

基于稳定同位素和贝叶斯模型的引黄灌区地下水硝酸盐污染源解析

地下水硝酸盐（NO₃^-）污染已经成为全球严重的水环境问题之一,由于饮用水中高含量NO₃^-会转化成亚硝酸盐而增加各种疾病和癌症风险,其来源的确定对于NO₃^-污染的预防和控制非常重要。本文以黄河下游第二大灌区——潘庄灌区为例,首次采用NO₃^-的氮氧稳定同位素结合贝叶斯模型追溯地下水NO₃^-的来源并量化各种来源的贡献比例。结果表明,地下水NO₃^-含量分布在0.1~197.0 mg·L^-1,平均值为34.2 mg·L^-1。与《生活饮用水卫生标准》中规定的地下水NO₃^-最大含量[20 mg（N）·L^-1,相当于NO₃^-含量90 mg·L^-1]相比,有10%的样品NO₃^-含量超标。井深<30 m、30~60 m和>60 m的地下水NO₃^-平均含量分别为25.9 mg·L^-1、39.7 mg·L^-1和20.1 mg·L^-1。空间上,宁津县、武城县、平原县和禹城市有大片区域地下水NO₃^-含量较高。地下水NO₃^-的δ¹⁵N组成范围为0.72‰~23.93‰,平均值为11.62‰;δ¹⁸O组成范围为0.49‰~22.50‰,平均值为8.46‰。同位素结果表明粪便和污水、农业化肥是地下水中NO₃^-的主要污染来源。这反映了人类活动是引起地下水NO₃^-污染的主要原因。贝叶斯模型结果显示,粪便和污水对潘庄灌区地下水中NO₃^-平均贡献率高达56.2%,化肥的平均贡献率为19.3%,大气降水和土壤的平均贡献率分别为6.2%和12.3%。由于污水、粪便和化肥是地下水中NO₃^-的主要来源,为保护和改善研究区地下水水质,建议加强污水管道建设,强化畜禽粪便的管理以及提高化肥利用效率。     

太湖地区水稻土优势反硝化细菌的数量、组成与酶活性

本研究结果表明太湖地区主要水稻土中反硝化细菌常在百万/克干土以上,占细菌总数的50—80%。同一类型土壤中,肥力高者含菌数多于肥力低者。各类土壤中反硝化细菌数与细菌总数呈显著正相关。其优势种中,以巨大芽孢杆菌、荧光假单胞菌和施氏假单胞菌等出现的机率最高,占反硝化细菌的10—50%;地衣芽孢杆菌及坚强芽孢杆菌等出现的机率较少。具有使NO₃^-还原为N₂O的菌株和使N₂O还原为N₂的菌株,分别占供试菌株的67%和56%;使¹⁵NO₃^-异化还原为¹⁵NH₄⁺的菌株占供试菌株的92%,其中以蜡质芽孢杆菌和地衣芽孢杆菌的这种能力特别强。     

水培条件下CO2与NH+4/NO-3配比对番茄幼苗生育的影响

升高CO₂浓度能够促进作物的光合作用，提高作物的生物量和产量，但关于CO₂与NH⁺₄/NO^-₃比及其交互作用对作物影响的研究较少，为探索番茄幼苗生长发育对CO₂浓度升高的响应是否对NH⁺₄/NO^-₃配比有较强的依赖关系，本试验在营养液栽培条件下，以番茄(Lycopersicun esculentum Mill)为试材，研究正常大气CO₂浓度(360 μL/L)和倍增CO₂浓度(720 μL/L)与不同NH⁺₄/NO^-₃配比的交互作用对番茄幼苗生长的影响。结果表明：CO₂浓度升高提高了低NH⁺₄/NO^-₃比例处理中番茄叶片的光合速率和水分利用率，提高幅度随NH⁺₄/NO^-₃比例的降低而增强，光合速率增强最大达55%。在同一CO₂浓度处理下净光合速率与水分利用率均随NH⁺₄/NO^-₃比例的增加而显著降低。这说明CO₂浓度升高对番茄幼苗生长发育的促进作用随NH⁺₄/NO^-₃比例的降低而提高，但并没有减弱全NH⁺₄-N处理中番茄幼苗的受毒害作用。综上所述，CO₂浓度升高能提高植物生产的节水能力和水分生产力；水培条件下，NO^-₃-N是最适合番茄幼苗生长发育的氮源，其它NH⁺₄/NO^-₃比例对番茄幼苗的生长发育有一定的抑制作用，仅以NH⁺₄-N作氮源则番茄幼苗很难生长。     

长期种植苜蓿对土壤氮素营养的作用

13年长期施肥和轮作试验结果表明，连续种植苜蓿时N肥、P肥、有机肥的配合施用(NPM)较单施P肥对提高土壤硝态氮(NO^-₃-N)含量水平有较好效果；而无论施肥与否，种植苜蓿对土壤深层NO^-₃-N均造成不同程度的亏缺。苜蓿(NPM)连作较小麦(NPM)连作土壤NO^-₃-N利用率高；种植苜蓿对土壤铵态氮(NH⁺₄-N)分布影响与NO^-₃-N不同，深层土壤CK、NPM配施处理NH⁺₄-N含量明显高于施P和裸地处理，不同作物种植系统中以苜蓿连作土壤剖面中NH⁺₄-N含量最高。与其他轮作相比，苜蓿连作在提高土壤剖面供N能力方面有较好作用。     

肥液浓度对单膜孔入渗NO-3-N运移特性影响的室内试验研究

该文通过室内入渗试验，研究了不同浓度的单膜孔肥液入渗NO^-₃-N的分布特性。研究表明：不同浓度的膜孔肥液入渗土壤NO^-₃-N浓度的湿润锋运移距离与土壤水分运动的湿润锋一致；肥液浓度越大，相同入渗时间的NO^-₃-N浓度锋运移距离越大，土壤剖面NO^-₃-N浓度最大值越大，相同深度处土壤NO^-₃-N浓度也越大。肥液入渗土壤NO^-₃-N浓度分布特征与湿润体深度符合分段函数模型。供水入渗过程中，NO^-₃-N浓度锋运移距离和浓度最大值均随时间的延长而增大；再分布过程中，NO^-₃-N浓度锋运移距离继续增大，而NO^-₃-N浓度最大值逐渐减小。     

水培和土培条件下氮素供应对燕麦生长和磷素吸收的影响

Plants show different growth responses to N sources supplied with either NH₄⁺ or NO₃^-. The uptake of different N sources also affects the rhizosphere pH and therefore the bioavailability of soil phosphorus, particularly in alkaline soils. The plant growth, P uptake, and P availability in the rhizosphere of oat (Avena nuda L.) grown in hydroponics and in soil culture were investigated under supply with sole NH₄⁺-N, sole NO₃^--N, or a combination. Sole NO₃^--fed oat plants accumulated more biomass than sole NH₄⁺-fed ones. The highest biomass accumulation was observed when N was suppliedw ith both NH₄⁺-N and NO₃^--N. Growth of the plant root increased with the proportion of NO₃^- in the cultural medium. Better root growth and higher root/shoot ratio were consistently observed in NO₃^--fed plants. However, root vigor was the highest when N was supplied with NO₃^-+NH₄⁺. NH₄⁺ supply reduced the rhizosphere pH but did not affect P uptake by plants grown in soils with CaHPO₄ added as P source. No P deficiency was observed, and plant P concentrations were generally above 2 g kg^-1. P uptake was increased when N was supplied partly or solely as NO₃^--N, similarly as biomass accumulation. The results suggested that oat was an NO₃^--preferring plant, and NO₃^--N was essential for plant growth and the maintenance of root absorption capacity. N supply with NH₄⁺-N did not improve P nutrition, which was most likely due to the absence of P deficiency.     

不同施肥条件下农田硝态氮迁移的试验研究

NO^-₃-N的淋失是旱地农田氮素损失的重要途径之一，也是引起地下水污染的一个主要原因。在黄土高原地区，夏玉米生长正逢雨季，是NO^-₃-N淋失的主要时期。该研究基于阻水层理论和黄土高原地区传统的垄作习惯，在手工模拟机具成垄压实施肥的基础上研究了该施肥法与传统的平地施肥、垄沟施肥(成垄不压实)条件下土壤NO^-₃-N的迁移动态，结果表明，在供水量相同条件下，由于平地和垄沟条件下水分分布的差异，导致平地土壤中的NO^-₃-N较垄沟耕作易于迁移。在生育前期，由于作物根系对NO^-₃-N的吸收和拦截，成垄压实与成垄不压实施肥对阻止NO^-₃-N随水下移差异不大；生育后期，当作物需肥量减小时，成垄压实施肥能够阻止NO^-₃-N向深层土壤迁移累积。玉米收获后，3种施肥方式下土壤NO^-₃-N迁移深度为平地(>60 cm)>垄沟施肥(>45 cm)>成垄压实施肥(＜35 cm)。     

Chemical Behavior of Chromium in Soils: Ⅲ. Mechanism of Cr(Ⅵ) Adsorption by Soils

An analysis of Cr (Ⅵ)-sorbed surface of the soils by using a scanning electron microscope and an electron probe microscope has proved that aluminium is the chief element affecting Cr (Ⅵ) adsoption. As the ionic strength of the solution increased, the amounts of Cr (Ⅵ) adsorbed by goethite and soils decreased. Cr (Ⅵ) adsorption was greatly depressed in the presence of SO₄^2-, WO₄^2-, MoO₄^2-, HPO₄^2- and H₂PO^4- which competed for anion adsorption sites. The depressing extent of these anions was found to follow the sequence: HPO₄^2-, H₂PO^4->MoO₄^2->WO₄^2->SO₄^2->>Cl^-, NO^3-. The amounts of Cr (Ⅵ) desorption varied with different extractants.     

间作及伴随阴离子肥料对油菜吸收积累镉的影响

为提高Cd污染土壤植物修复效率, 采用盆栽方法研究了Cd含量为10.0 mg·kg^-1的土壤中, 伴随阴离子肥料和间作鹰嘴豆对油菜生长与吸收积累Cd的影响。结果表明: 单作下, 不同肥料处理土壤DTPA提取态Cd含量为Cl^->NO₃^->SO₄^2- >无伴随阴离子; 间作鹰嘴豆提高土壤DTPA提取态Cd含量, 且伴随C₁^-、SO₄^2- 或NO₃^- 条件下达显著水平。单作下, 油菜主根长为NO₃^- >C₁^- >SO₄^2- >无伴随阴离子, 根系体积为SO₄^2->NO₃^- >C₁^- >无伴随阴离子, 根系活力NO3 >SO42 >Cl >无伴随阴离子; 间作鹰嘴豆在无肥处理下可显著提高油菜的主根长与根系体积, 在无肥处理、SO₄^2- 、NO₃^- 处理下显著提高根系活力。单作下, 油菜地上部Cd含量表现为C₁^- >SO₄^2- >NO₃^- >无伴随阴离子, 间作鹰嘴豆可显著降低无肥处理地上部Cd含量, 但显著提高施肥处理地上部的Cd含量。单作下, 施肥可显著增加油菜的Cd积累总量, 以伴随C₁^-处理最大, 达470.4 μg·plant^-1; 间作鹰嘴豆也可提高油菜的Cd积累总量, 且伴随C₁^- 处理最大, 达783.7 μg·plant^-1。除伴随C₁^- 处理外, 施肥处理均可显著提高油菜的Cd转移系数, 施肥处理的Cd转移系数均大于1; 间作鹰嘴豆也可提高油菜的Cd转移系数, 且施肥条件下达显著水平。因此, 如果把油菜用作Cd污染土壤植物修复作物, 可选择施用含Cl 肥料和间作鹰嘴豆, 以提高修复效率。     

盐胁迫下硝态氮对囊果碱蓬根系发育和氮吸收的影响

The effiects of NaCl salinity and NO₃^- on growth, root morphology, and nitrogen uptake of a halophyte Suaeda physophora were evaluated in a factorial experiment with four concentrations of NaCl (1, 150, 300, and 450 mmol L^-1) and three NO₃^- levels (0.05, 5, and 10 mmol L^-1) in solution culture for 30 d. Addition of NO₃^- at 10 mmol L^-1 significantly improved the shoot (P < 0.001) and root (P < 0.001) growth and the promotive effect of NO₃^- was more pronounced on root dry weight despite the high NaCl concentration in the culture solution, leading to a significant increase in the root:shoot ratio (P < 0.01). Lateral root length, but not primary root length, considerably increased with increasing NaCl salinity and NO₃^- levels (P < 0.001), implying that Na⁺ and NO₃^- in the culture solution simultaneously stimulated lateral root growth. Concentrations of Na⁺ in plant tissues were also significantly increased by higher NaCl treatments (P < 0.001). At 10 mmol L^-1 NO₃^- , the concentrations of NO₃^- and total nitrogen and nitrate reductase activities in the roots were remarkably reduced by increasing salinity (P < 0.001), but were unaffected in the shoots. The results indicated that the fine lateral root development and effective nitrogen uptake of the shoots might contribute to high salt tolerance of S. physophora under adequate NO₃^- supply.     

硝态氮促进水稻生长和氮素吸收的生理机制

Rice is being increasingly cultivated in intermittently irrigated regious and also in aerobic soil in which Nitrate (NO₃^-) plays important role in nutrition of plant. However, there is no information regarding the influence of nitrate on the overall growth and uptake of nitrogen (N) in rice plant. Solution culture experiments were carried out to study the effects of NO₃^- on the plant growth, uptake of N, and uptake kinetics of NH₄⁺ in four typical rice (Oryza sativa L.) cultivars (conveutioual indica, conventional japonica, hybrid indica, and hybrid japonica), and on plasma membrane potential in roots of two conventional rice cultivars (indica and japonica) at the seedling stage. The results obtained indicated that a ratio of 50/50 NH₄⁺-N/NO₃^--N increased the average biomass of rice shoots and roots by 20% when compared with that of 100/0 NH₄⁺-N/NO₃^--N. In case of the 50/50 ratio, as compared with the 100/0 ratio, total N accumulated in shoots and roots of rice increased on an average by 42% and 57%, respectively. Conventional indica responds to NO₃^- more than any other cultivars that were tested. The NO₃^- supply increased the maximum uptake rate (V_max) of NH₄⁺ by rice but did not show any effect on the apparent Michaelis-Menten constant (K_m) value, with the average value of V_max for NH₄⁺ among the four cultivars being increased by 31.5% in comparison with those in the absence of NO₃^-. This suggested that NO₃^- significantly increased the numbers of the ammonium transporters. However, the lack of effect on the K_m value also suggested that the presence of NO₃^- had no effect on the affinity of the transporters for NH₄⁺. The plasma membrane potential in the roots of conventional indica and japonica were greatly increased by the addition of NO₃^-, suggesting that NO₃^- could improve the uptake of N by roots of the rice plant. In conclusion, the mechanisms by which NO₃^- enhances the growth and N uptake of rice plant was found by the increased value of V_max of NH₄⁺ and increased plasma membrane potential. Thus promotion of nitrification in paddy soil is of great significance for improving the production of rice.     

尕海湿地区沼泽草甸生长季土壤碳氮组分对增温施氮的响应

[目的] 为探究高寒湿地土壤碳氮组分对气候变暖和氮沉降的响应特征。[方法] 以尕海湿地沼泽草甸为研究对象,采用开顶箱增温(OTC)和外源氮素(NH₄NO₃)添加模拟未来气候变暖及氮沉降试验,分别设置对照(CK)、增温(W)、施氮(N)和增温施氮(WN)4种处理。在试验进行1.5年后对土壤碳氮组分含量进行测定。[结果] (1)开顶箱增温装置提高0—20 cm土层平均温度1.126℃,显著降低0—10 cm土层土壤含水量(SMC)、pH、全氮(TN)、微生物量氮(MBN)、铵态氮(NH₄⁺—N)、有机碳(SOC)和可溶性有机碳(DOC)含量,提高硝态氮(NO₃^-—N)含量。(2)施氮显著降低NH₄⁺—N、SOC和10—20 cm土层微生物生物量碳(MBC)及DOC含量,增加土壤TN、MBN和NO₃^-—N含量。(3)增温施氮显著增加土壤SMC、TN、NO₃^-—N和MBC含量,降低MBN、NH₄⁺—N和DOC含量。(4)相关分析显示,土壤水分与各理化因子均存在正相关性,土壤碳氮组分间均呈正相关性。[结论] 模拟增温施氮缓解尕海湿地植物生长的温度和氮的限制,促进TN的积累,对土壤微生物量碳氮影响较大,导致土壤微生物量碳氮及分布特征发生转换。     

不同铵硝配比对弱光下白菜氮素吸收及相关酶的影响

以黑色遮阳网覆盖模仿弱光环境, 使光照强度为自然光的20%左右, 以自然光照为对照, 采用精确控制水培溶液氮素营养, 研究NH₄⁺-N/NO₃^--N 比例分别为0/100、25/75、50/50、75/25、100/0 对弱光下白菜氮代谢及硝酸还原酶和谷氨酰胺合成酶活性的影响。结果表明, 弱光下, 白菜的鲜重及叶片总氮量以NH₄⁺-N/NO₃^--N 比为25/75 时最大, NH₄⁺-N/NO₃^--N 比为100/0 时最低。随弱光处理的进行, 白菜叶片中硝酸还原酶活性及谷氨酰胺合成酶活性均呈下降趋势, 但NH₄⁺-N/NO₃^--N 比为25/75 时, 可维持叶片内较高的硝酸还原酶活性及谷氨酰胺合成酶活性。试验表明, NH₄⁺-N/NO₃^--N 比25/75 是白菜在弱光下生长的较适宜氮素形态配比。     

第四纪红色粘土发育的红壤中营养元素的淋失

A red soil derived from Quaternary red clay was employed to study nutrient leaching with soil columns repacked in laboratory. The objective was to identify the effects of fertilization practices on leaching patterns and magnitudes of Ca²⁺, Mg²⁺, K⁺, NH₄⁺, and NO₃^-. The treatments were CK (as a control), CaCO₃, CaSO₄, MgCO₃, Ca(H₂PO₄)₂, urea, KCl, and multiple (a mixture of the above-mentioned fertilizers). The fertilizers were added to the bare surface of the soil columns, and then the columns were leached with 120 mL deionized water daily through peristaltic pumps over a period of 92 days. Leaching processes of NH₄⁺, and NO₃^- were only measured in CK, urea, and multiple treatments which were directly related to N leaching. Results showed that sole application of CaSO₄, and Ca(H₂PO₄)₂ scarcely had any effect on the leaching losses of Ca²⁺, Mg²⁺, and K⁺; the application of MgCO₃ stimulated the leaching of Mg²⁺; the application of CaCO₃ promoted the leaching of Ca²⁺, Mg²⁺ and K⁺; urea treatment also promoted the leaching of K⁺ and NH₄⁺, and NO₃^- leaching mainly occurred at late stage of leaching process in particular; under KCl treatment, leaching of Ca²⁺, Mg²⁺, and K⁺ was promoted to a large extent; under multiple treatment, leaching of Ca²⁺, Mg²⁺, K⁺, NH₄⁺, and NO₃^- was all increased and NO₃^- was mainly leached at the end of leaching process and still had a trend of increase.     

3 种挺水植物吸收水体NH4+、NO3-、H2PO4- 的动力学特征比较

本文用动力学试验研究了具有景观价值的3 种挺水植物—— 水生美人蕉(Canna generalis)、细叶莎草(Cyperus papyrus)、紫芋(Colocasia tonoimo)对H₂PO₄^-、NH₄⁺、NO₃^- 的吸收特征及差异。试验结果表明: 3 种挺水植物吸收H₂PO₄^- 时, 美人蕉的吸收速率最快, 且在较低离子浓度条件下也可以吸收该离子, 说明其具有嗜磷特性, 能够适应广范围浓度H₂PO₄^- 环境; 吸收NO₃^- 时, 细叶莎草的速率最快, 但对低浓度NO₃^- 环境的适应能力较差, 美人蕉吸收NO₃^- 的特性与细叶莎草刚好相反; 吸收NH₄⁺ 时, 细叶莎草的吸收速率最快, 且在低浓度NH₄⁺ 环境下仍能吸收该离子, 而美人蕉的吸收速率最慢, 但能在低浓度NH₄⁺ 环境下吸收该离子。说明不同植物对养分的吸收特性存在较大差异, 各自的污染水体修复适用范围也不同。美人蕉可用于各种浓度H₂PO₄^- 污染的水体修复; 而NO₃^- 污染严重的水体最适宜用细叶莎草作先锋植物, 修复到一定程度后再种植美人蕉来维持水质; 细叶莎草在各种浓度NH₄⁺ 污染的水体中均适用, NH₄⁺ 污染较轻的水体也可用美人蕉修复。