石灰性砂质土上锰肥对小麦的增产作用

锰是植物正常生长不可缺少的微量营养元素。土壤中锰的供给情况决定于土壤条件,其中土壤PH值、氧化还原电位和通气性的影响最大。     

变动氧化还原状况下酸性土壤中活性锰的变化

锰是一种常见的变价元素,其在土壤中的有效性主要依赖于土壤总锰量、pH、有机质含量、通气状况及微生物活性等,其中,最直接的是土壤通气状况和pH。自20世纪50年代以来,渍水土壤中锰的化学行为及移动性就引起了人们的关注[1~7]。在自然状态下,锰以多种氧化物形式存在,Mn(Ⅲ)和Mn(Ⅳ)发生在氧化环境中,Mn2+主要存在于还原条件下,土壤体系中的氧化还原状况显著地影响着土壤锰的溶出和生物有效性。到目前为止,有关土壤pH、Eh和Mn2+的关系研究的较少。1970年,Bohn[8]通过测定土壤pH、Eh和全锰含量预测了土壤悬浮液中Mn2+的含量。刘鑫等[9]运用能斯特方程式研究了盆栽土壤pH、Eh和     

水稻土中氧化还原过程的研究(Ⅱ)土壤与植物的相互影响

1.水稻根部的氧化还原电位较根外部者为高。根愈密集,电位也愈高。小麦根部的电位则较根外者为低。水稻根系对土壤氧化还原电位的影响,随其生理情况而不同。2.在氧化性较强的土壤中生长的萵苣体内的电位较高,在还原性较强的土壤中生长者,电位也较低。3.在土壤的氧化还原电位低时,萵苣的生长受到抑制,而在本试验的条件下,水稻仍能生长良好。4.叙述了一种甘汞电极的制作方法,用这种电极,可以很方便地作为直接用白金电极测定植物体中氧化还原电位时的对照电极。     

水稻土中氧化还原过程的研究 (Ⅲ)氧化还原条件对水稻生长的影响

1.土壤处于强烈的还原条件下时,对水稻生长有不良的影响,如果将土壤中的氧化还原条件改善,则对水稻的生长有益。2.土壤中的氧化还原情况,直接影响水稻体中的氧化还原电位,土壤电位低者,水稻中的电位也低。3.土壤中还原性物质的数量与水稻生长情况表现了明显的一致性,可见水稻在强烈还原条件下的生长不良,与还原性物质的过多有关。在还原性物质中,亚铁离子约占一半左右。4.试验结果指明,土壤中过多的亚铁离子,对水稻有毒害作用。     

酸性土壤活性锰与pH、Eh关系及其生物反应

以灰潮土为对照研究了湖北省 3种有代表性的酸性土壤在盆栽条件下 ,不同酸化处理土壤pH、Eh与活性锰的动态变化关系。结果表明 ,供试的棕红壤和黄棕壤酸化后 ,在盆栽油菜生长的前 70d内 ,土壤交换性锰含量增加 ,土壤交换性锰与碳酸盐结合态锰呈一定负相关 ,且交换性锰含量增加明显滞后于碳酸盐结合态锰的增加 ;30～90d内 ,碳酸盐结合态锰与易还原性锰呈一定正相关。虽然土壤pH和Eh在作物生长季节不断变化 ,但其 pe +pH仍维持不变。土壤 pH、Eh与交换性锰的关系能较好地反映土壤锰的转化机制 ,在进一步酸化时 ,供试的棕红壤MnO2/Mn2+电对是该土壤锰化合物变化的主要形式 ,MnO2是变化过程的电子受体。供试的黄棕壤则以MnOOH MnO电对为其锰化合物氧化还原的主要形式 ,土壤酸化对其锰电对电位的影响没有直接引起Mn2+ 的变化 ;Mn2+的增加可能是MnO在该过程中进一步溶解所致。试验结果还表明 ,油菜体内的锰铁比随锰中毒程度的加强而急剧增加 ,这一趋势远高于土壤锰铁比的增加。     

稻田晒田期土壤Eh、rH与土壤空气容量的相关分析

稻田的土壤氧化还原电位的高低,主要受土壤中氧体系的支配,土壤中氧的含量又直接与土壤空气中氧分压的高低有关。土壤的氧化还原电位高,则表明氧的含量高,通气性好。     

日光温室番茄缺镁与土壤盐分组成及离子活度的关系

研究了石灰性土壤日光温室不同栽培年限及番茄不同程度缺镁的土壤水溶盐分中离子组成、比例及Mg2+、Ca2+、K+离子活度等的变化及关系.结果表明:随着栽培年限的增加,温室土壤水溶盐分中Ca2+、K+、NO3-含量显著增加;水溶性盐分中阳离子以Ca2+为主,栽培5 a后NO3-成为阴离子主要成分;土壤中NO3-含量的增加是导致土壤盐分累积的主要因素.随番茄缺镁程度的加剧,土壤水溶性盐中Ca2+、K+、NO3-、全盐量及Ca2+/Mg2+、K+/Mg2+摩尔比均呈增加趋势,番茄出现缺镁的土壤含盐量达到盐渍化水平.随着土壤盐分含量增加,Ca2+、Mg2+活度均呈指数下降趋势,番茄缺镁的土壤溶液中Mg2+和Ca2+活度显著低于不缺镁土壤,(K+)/(Mg2+)、(Ca2+)/(Mg2+)活度比显著高于不缺镁土壤,(K+)/(Mg2+)活度比随缺镁程度加剧达显著差异,番茄缺镁的土壤溶液(K+)/(Mg2+)活度比大于1.盐分累积使Mg2+活度大幅降低以及K+富集对植物吸收Mg2+的拮抗作用是石灰性土壤上番茄缺镁的主要诱因.     

土壤中锰的化学行为及其生物有效性

锰是土壤中化学性质十分活跃的营养元素。锰的氧化还原和淋溶特征是土壤中锰容易缺乏或过量的重要原因。本文综述了土壤中锰的化学行为及其影响因素，重点是土壤中锰的形态转化和影响锰形态转化的各种土环境因素，并概述了近年来土壤锰化学研究方面的一些新进展。     

厌氧还原土壤灭菌对设施蔬菜地连作障碍土壤性质的影响

设施蔬菜地连作土壤,往往由于大量施用化肥、蒸发量大、受雨水淋滤少等原因,导致土壤退化,引发土传植物病害频发等连作障碍问题。厌氧还原土壤灭菌处理设施蔬菜地连作障碍土壤,降低土壤的氧化-还原电位,创造强还原环境,快速调节退化土壤理化性质和微生态结构,改良设施蔬菜地连作障碍土壤,提高设施蔬菜产量和品质,增加农民收入。对采集蚌埠市蔬菜基地设施蔬菜地连作障碍土壤,分设对照(不添加物料、不淹水)、处理1(少量稻草+淹水)、处理2(高量稻草+淹水)、处理3(少量稻草+少量猪粪+淹水)、处理4(高量稻草+高量猪粪+淹水)、处理5(高量稻草+饱和水)、处理6(高量稻草+高量猪粪+饱和水)共7组样品,每组样品分设3个平行样,实验室内30℃恒温箱密封培养15天,期间取样3次分析土壤理化性质及可培养微生物数量变化。结果表明,厌氧还原土壤灭菌处理可以降低土壤p H值和Ec值,去除SO42-和NO3-等水溶性盐分离子,调节土壤理化性质,尖孢镰刀菌由处理前104cfu g-1降低至103cfu g-1的致病临界浓度,起到抑制土传植物病原菌作用,防治设施农业连作障碍。不同有机物料的处理效果均较好,但处理间差异不显著,虽处理10天与处理15天相比,各处理样品的理化性质和微生物含量变化不显著,但与处理5天相比较,差异显著(P<0.05)。     

土壤改良剂对鄱阳湖区潜育性稻田的改良作用研究

潜育化水稻土存在渍、冷、烂、闭(气)、毒及缺素等障碍因素,土壤改良剂是其改良的有效办法之一。本文研究了有机与无机材料相结合对鄱阳湖区潜育化稻田的改良效果,旨在为湖区此类土壤改良提供技术参考。田间定位试验设有机、无机改良剂10个互作处理,分别为(1)对照,T1;(2)牛粪+粉煤灰,T2;(3)牛粪+石灰,T3;(4)枯饼+粉煤灰,T4;(5)枯饼+石灰,T5;(6)牛粪+粉煤灰+石灰,T6;(7)枯饼+粉煤灰+石灰,T7;(8)牛粪+枯饼+粉煤灰,T8;(9)牛粪+枯饼+石灰,T9;(10)牛粪+枯饼+粉煤灰+石灰,T10,研究了土壤改良剂对土壤氧化还原电位、还原物质总量及土壤肥力的影响,并结合水稻产量分析了有机无机改良剂相结合的改良作用。结果表明:在提高土壤氧化还原电位方面,T5处理最明显,在抽穗期比T1显著提升了69.2%(P0.05)。在消减土壤还原性物质方面,各施用改良剂处理均能显著降低土壤还原性物质,其中T5、T8、T10三个施用石灰的处理效果最为显著,比T1分别降低了84.5%、79.3%和72.2%(P0.05)。施用土壤改良剂对土壤有机质、碱解氮、水溶性碳无显著影响,但对土壤速效磷、速效钾、pH值、电导率和水溶性氮有显著的提升作用。在提高水稻SPAD值方面,所有施枯饼的处理T4、T5,T7~T10均能显著提高水稻SPAD值,在抽穗期比T1提高了13.5~28.6%(P0.05)。3年平均产量表明,T10能显著提高潜育性稻田产量,比T1显著提高10.3%(P0.05)。因此,枯饼与石灰配合是降低鄱阳湖区潜育化稻田土壤还原性物质、提升氧化还原电位、电导率的最有效措施;牛粪、枯饼、粉煤灰、石灰相配合则是综合提升水稻产量的最有效措施。     

Ion content and ion excretion of Spartina anglica in relation to salinity and redox potential of salt marsh soil

Concentrations of Na, K, Ca, Mg, Fe, Mn, and Zn were determined in polluted estuarine (Western Scheldt) and non-polluted (Eastern Scheldt) salt marsh soil, in the shoot tissue of plants of Spartina anglica and in the excretion of the salt glands of Spartina anglica. Excretion of ions by the salt glands of Spartina anglica was analysed with increasing salinity (0, 300, and 500 mM NaCl) and with increasing values of the redox potential of the salt marsh soil (from ?300 mV to +600 mV). Salt glands of Spartina anglica, growing in containers filled with salt marsh soil in the greenhouse excreted Na-ions at a rate of 1.0–1.8 mmol Na⁺ g^?1 dry wt of the shoot tissue over a period of 18 days implying that about every 6–18 days the amount of Na⁺ present in the shoot tissue is being removed by the salt glands. The excretion rate of K-ions was 0.02–0.14 mmol g^?1 dry wt/18 days. Zinc ions are excreted by the salt glands to such a rate (0.03–0.11 μmol g^?1 dry wt/18 days) that every 36–900 days the amount of zinc present in the leaves is removed. There was no relation between excretion of Zn ions by the plants and the concentration of zinc in the soil. The excretion of Fe and Mn is reported and was found to be related to increasing values of the redox potential.     

The Influence of Heavy Metals on Carbon Dioxide Evolution from a Typic Xerochrept Soil

In a laboratory study the effects on soil respiration of trace metals (Ni, Cd, Cu, Mn, Pb, Zn)added at loading rates ranging from 0 to 1000 µg g-1 were determined. Differences intoxicity with respect to the type of metal salt added were also evaluated. The inhibitory effect onsoil respiration differed considerably among the heavy metals and increased with the increasingloading rate. No linear relationships were found between the degree of inhibition and the levels oftotal and available metals. Toxicity evaluation at 20 and 50% inhibition of soil respiration showedCu as the most toxic and Mn as the most tolerable metal. A ‘metal equivalent’ was calculated asthe sum of the amounts of the available metals weighted to their relative toxicity with respect tothe least toxic one: Mn equivalent = Mn + 1.9Pb + 2.1Ni + 2.5Zn + 6.7Cd + 6.7Cu. The ionicpotential of the heavy metals was found to be positively related to the percent inhibition of soilrespiration. Chlorides and sulphates appeared to depress soil respiration more than nitrates, thelatter counter-balancing the toxic effect of the heavy metals.     

Salt bridge for field redox potential measurements

Abstract

Conventional redox potential measurements in the field frequently become erratic during the summer season due to low moisture contents in the surface soil. A KCl‐salt bridge which circumvents this problem was designed for in situ, long‐term, nondestructive redox determinations in the subsoil. Measurements are rapid, and redox values are not affected by the use of the salt bridge, irrespective of depth of measurement.     

Nitrous oxide and methane emissions from different soil suspensions: effect of soil redox status

Four soil samples from fields of different land use [US (paddy field), China (paddy field) and Belgium (maize and wheat fields)] were incubated as soil suspension (soil:water ratio 1:4) to study the N₂O and CH₄ emission under different soil redox potential conditions. The results show that the N₂O emission was regulated within a narrow redox potential range of +120 to +250 mV, due to the balance of N₂O production and its further reduction to N₂. Methane emission occurred below a soil specific redox potential point, and the emission rates were inversely related to soil redox potentials. Both linear and exponential relationships between CH₄ emission and the soil redox potential were significant. By extrapolating the linear relationship of CH₄ emission against soil redox potential, the critical redox potentials for CH₄ production were estimated at about -170 (US paddy soil), -150 (Chinese paddy soil), -215 (Belgian maize soil), and -195 mV (Belgian wheat soil), respectively. In addition, the results indicate that a soil with a lower critical redox potential for CH₄ production had a higher CH₄ production potential. In this study, N₂O and CH₄ emissions were found to occur at a distinctly different soil redox potential condition. The range of soil redox potential values where both N₂O and CH₄ emissions were low was different for different soils, but it was situated between +120 and -170 mV. This is a wide redox potential range enabling field management practices to minimize both N₂O and CH₄ emissions from wetland ecosystems.     

钙盐诱导下土壤锰和铁的释放及其对胡椒的生物有效性

Releases of manganese and iron ions from an albic soil (Albic-Udic Luvisol), a yellow-red soil (Hap-Udic Ferrisol) and a yellow-brown soil (Arp-Udic Luvisol) induced by calcium salt addition and their bioavailability to pepper (Capsicum frutescens L.) were studied in a pot experiment. Addition of Ca(NO₃)₂ decreased soil pH and increased both exchangeable and DTPA (diethylenetriamine pentaacetic acid)-extractable Mn and Fe in soils. Meanwhile, total Mn accumulation in the shoots of Capsicum frutescens L. on the salt-treated soils increased significantly (P< 0.01) compared with the control, suggesting that salt addition to soil induced Mn toxicity in Capsicum frutescens L. Although exchangeable and DTPA-extractable Fe increased also in the salt-treated soils, Fe uptake by the shoots of Capsicum frutescens L. decreased. The effect of added salts in soils on dry matter weight of pepper varied with the soil characteristics, showing different buffer capacities of the soils for salt toxicity in an order of yellow-brown soil > albic soil > yellow-red soil. Fe/Mn ratio in shoots of Capsicum frutescens L. decreased with increasing salt addition for all the soils, which was ascribed to the antagonistic effect of Mn on Fe accumulation. The ratio of Fe/Mn in the tissue was a better indicator of the appearance of Mn toxicity symptoms than Mn concentration alone.     

Production of dinitrogen and nitrous oxide in soil suspensions as affected by redox potential

The effect of soil redox potential on N₂O and N₂ emission from soil suspensions was studied under laboratory conditions. Crowley silt loam soil suspensions were equilibrated under controlled (?200, ?100, 0, +100, +200, +300, and +400 mV) redox levels, and the amounts of N₂ and N₂O evolved quantified. At higher redox levels (+300, and +400 mV) nitrification was the dominant soil biological process controlling N chemistry. A small amount of N₂O evolved during nitrification. A redox value between +300 and +200 mV was found critical for denitrification to occur. Both N₂ and N₂O were produced during denitrification. The maximum amount of N₂O evolved at a redox value of 0 mV. Dinitrogen emission increased at lower redox levels. The highest N₂/N₂O evolution ratio was observed at ?200 mV and the ratio decreased with increasing redox. A lack of N-balance during denitrification at redox levels of +100, and +200 mV is also reported.     

长期施用含氯化肥对棕壤硝化作用及氨氧化微生物的影响

【目的】氨氧化微生物是氨氧化过程的主要驱动者，氨氧化过程作为硝化作用的限速步骤对氮循环具有重要作用。本研究以沈阳农业大学棕壤含氯化肥长期定位试验的土壤为研究对象，探讨了连续34年施用高氯和低氯化肥对棕壤硝化作用及氨氧化微生物的影响。【方法】该长期试验在等量氮、磷、钾条件下，设置高氯和低氯处理，共8个处理:T1 (不施肥)；T2 (单施尿素)；T3 (尿素 + 氯化钾)；T4 (尿素 + 过磷酸钙)；T5 (尿素 + 过磷酸钙 + 氯化钾)；T6 (尿素 + 磷酸一铵 + 氯化钾)；T7 (尿素 + 氯磷铵 + 氯化钾)；T8 (硝酸磷肥 + 过磷酸钙 + 氯化钾)，T7为高氯处理。采集0—20 cm土壤样品，利用荧光定量PCR技术测定氨氧化细菌 (AOB) 和古菌 (AOA) 丰度，并结合土壤硝化潜势和基本化学性质，分析长期施用含氯化肥对棕壤硝化作用及氨氧化微生物丰度的影响及影响氨氧化微生物丰度的主要环境因素。【结果】长期施肥降低了土壤pH值，高氯处理降低得最多，显著低于其他处理；高氯处理的土壤硝化潜势也显著低于其他处理，且除高氯处理外，配施磷肥的处理土壤硝化潜势显著高于不施磷处理。各处理土壤中AOA丰度均显著高于AOB，高氯处理土壤中AOA、AOB丰度均显著低于其他处理，土壤硝化潜势与AOA和AOB均呈显著正相关关系。【结论】连续施用高氯化肥34年显著降低了棕壤AOA和AOB丰度，抑制了硝化潜势。该结果可为通过含氯化肥的合理施用来调节土壤AOA和AOB，进而调控土壤氮素循环提供参考。     

土壤盐胁迫降低后甜高粱的补偿生长和盐离子分布特征

逆境补偿效应在作物中普遍存在,对作物生长发育与产量产生重要的影响。为阐明土壤盐度降低后甜高粱的补偿生长效应,本研究采用盆栽方法,将甜高粱拔节期的土壤含盐量设置3个梯度:5 g×kg~(-1)(高盐处理)、由5 g×kg~(-1)降低到2 g×kg~(-1)(盐度降低处理)、2 g×kg~(-1)(低盐对照),测定2个甜高粱品种地上部器官(茎秆、叶片、叶鞘)干物质生长速率与积累,以及盐离子(Na~+、Cl~-、K~+)在不同器官的含量。结果表明:高盐处理甜高粱地上部干物质增长速率一直显著低于对照;土壤盐度降低后,各器官干物质生长速率明显升高,并超过对照,产生了超补偿效应。成熟期高盐处理株高与地上部干物质大幅下降;土壤盐度降低后‘辽甜1号’的株高与地上部干物质较低盐对照分别下降7.69%和33.21%,而‘中科甜3号’的株高和地上部干物质重与对照没有差异。高盐处理后各器官干物质中Na+和Cl-含量较对照大幅度提高,K+含量增加幅度较小。土壤盐分降低后的35 d,甜高粱Na+和Cl-在各器官中含量虽仍高于对照,但比高盐处理已大幅下降;茎秆与叶鞘K+的含量较对照有小幅提高,而叶片K+含量与对照无显著差异。本研究表明:甜高粱盐胁迫降低后离子毒害减轻、生长速率加快直至超过对照,耐盐甜高粱品种补偿效应尤为明显,成熟期干物质产量可与对照相当。本研究结果可为盐碱地甜高粱栽培提供理论依据。     

Effect of manganese-reducing rhizosphere bacteria on the growth of Gaeumannomyces graminis var. tritici and on manganese uptake by wheat (Triticum aestivum L.)

Summary Five bacterial strains capable of Mn reduction were isolated from the rhizosphere of plants growing in different South Australian soils. They differed in their Mn-reducing capacity. The antagonism of these strains compared to the imported strain 2–79 (from the United States) against Gaeumannomyces graminis var. tritici was tested in agar and in a soil sandwich experiment at different Mn²⁺ concentrations in the soil. In addition, wheat seeds were coated with the different strains and with MnSO₄ or with MnSO₄ only in order to investigate their effect on plant growth and Mn uptake. With one exception, all strains inhibited the growth of G. graminis in agar, but to different degrees. In contrast, only two strains significantly inhibited the growth of the fungus in the soil. The hyphal density was decreased more than the hyphal length. The Mn²⁺ concentration in the soil also had a marked effect on fungal growth; low Mn concentrations slightly increased while high Mn concentrations strongly decreased the fungal growth. Seed treatment with MnSO₄ only (+Mn) increased Mn uptake above that of the control (no seed treatment). Only the weakest Mn reducer on agar significantly increased plant growth and Mn uptake from soil in comparison with the Mn treatment. One strain was tested as seed coating without adding MnSO₄; it increased the plant growth to an extent similar to the Mn treatment. Increasing the Mn uptake by plants may be one of the growth-promoting effects exerted by rhizosphere bacteria.