Inorganic transformation of applied phosphorus in brackishwater fish pond soil under different water salinity levels

Transformation of applied phosphorus in a brackishwater fish pond soil was studied under different water salinity levels, as occurring in such ponds, in presence and in absence of added organic matter. Added phosphorus was found to disappear rapidly from the water phase with some variations under different water salinities. The amount of added phosphorus in saloid-bound form increased with increase in water salinity but the same in Bray's (No. 2) extractable form showed a reverse trend. Applied phosphorus was transformed mostly into insoluble calcium phosphate form which increased with increase in water salinity. Transformation was intermediate into iron phosphate and the least into aluminium phosphate form. Application of organic matter reduced the fixation of added phosphorus into the iron phosphate form during the initial period of study and thus increased availability of phosphorus both in water as well as soil phases.This work formed a part of a thesis submitted for the Degree of Doctor of Philosophy to Bidhan Chandra Agricultural University, West Bengal in 1978This work formed a part of a thesis submitted for the Degree of Doctor of Philosophy to Bidhan Chandra Agricultural University, West Bengal in 1978     

Effect of different levels of water salinity on the decomposition of organic manures in a brackish water fish pond soil

Effects of different water salinity levels on the decomposition of the two organic manures cowdung and poultry manure were studied under laboratory condition. Application of the manures increased the free CO₂ content and decreased D.O. levels of water. pH values of soil and water declined slightly on addition of the manures. The amount of nitrogen, released from the organic manures to water and soil phases, increased gradually with the period of incubation but decreased with increase in water salinity levels. NH₄ ⁺ was found to occur in comparatively higher amount than NO₃ ^–, due to prevailing anaerobic environmental conditions. The amount of added organic carbon remaining in the soil decreased gradually as the decomposition proceeded, but recorded slightly higher values with increase in water salinity levels.The results showed that the rates of decomposition of added organic manures were comparatively lower under higher water salinity levels and hence indicated that use of well decomposed manures might be more suitable for use under such water salinities in brackish water fish ponds.This work formed a part of a thesis submitted for the Degree of Doctor of Philosophy to Bidhan Chandra Agricultural University, West Bengal in 1978This work formed a part of a thesis submitted for the Degree of Doctor of Philosophy to Bidhan Chandra Agricultural University, West Bengal in 1978     

Effects of deforestation and cultivation on soil CEC and contents of exchangeable bases: A case study in Simlipal National Park,India

Deforestation in the tropics seems to be a serious problem probably because of the reduction in soil CEC and the consequent losses of nutrients from the soils. Here, changes in these parameters as influenced by deforestation as well as vegetative cover were studied; statistical methods were applied to interpret the results. Cultivation causes a significant reduction in CEC, total content of the exchangeable bases and exchangeable Ca2+ and Mg2+ levels compared to the adjoining unmanaged forest land. Levels of exchangeable K⁺ and Na⁺, however, do not change significantly. Evergreen forest soils have the highest levels of CEC, total exchangeable bases, exchangeable Ca²⁺ and K⁺. Deciduous forest, grassland and cultivated soils have statistically similar contents of exchangeable Ca²⁺, Mg²⁺, K⁺ and Na⁺. Exchangeable Mg²⁺, however, is not affected by vegetative cover. Soil CEC shows fairly good correlation with the organic carbon content only in evergreen forest soils. In others, organic carbon apparently does not influence CEC significantly. All soils show excellent correlation between their CEC and total exchangeable bases. It is concluded that for regeneration of weathered tropical soils, an evergreen cover provides the most effective means; deciduous vegetation or grass cover do not seem promising.     

旱地施有机肥对土壤有机质和水稳性团聚体的影响

通过渭北旱塬2007-2010年田间定位试验,研究了有机肥不同施用量(低量7500 kg·hm^-2、中量15000 kg·hm^-2、高量22500 kg·hm^-2)对连作玉米地土壤有机质、团聚体各层粒径分布和稳定性的影响.结果表明：0～20 cm土层,高量有机肥处理土壤有机质含量较低量有机肥处理提高4.1%～4.6%,高、中量有机肥处理较对照提高4.6%～11.2%,低量有机肥处理在施肥第4年（2010年）较CK提高4.7%～6.3%.0～30 cm土层,所有有机肥处理>5 mm水稳性团聚体的增幅最大,其含量随有机肥用量的增加而显著升高;有机肥处理显著提高了土壤>0.25 mm水稳性团聚体含量、团聚体平均质量直径和团聚体稳定率,且随有机肥用量的增加而显著增加;中、高量有机肥处理比单施化肥处理增加效果显著.     

Effect of soil salinity and soil water availability on growth and chemical composition ofSorghum halepense L.

Summary Effects of soil salinity and soil water regime on growth and chemical composition ofSorghum halepense L. was studied with a view to evaluating its potential as a forage crop in saline soils. The experiment was conducted under controlled conditions using pot-culture with three levels of soil salinity (EC_e 0.5, 5.0, 10.0 ds/m) and three soil water regimes (60%, 40% and 20% of water holding capacity of the soil). High soil salinity and low soil water combiningly had an adverse effect on plant growth but the biomass production was appreciably high (57 to 75% of control) even under high soil salinity (EC_e 10 ds/m) when sufficient water was available. Belowground plant parts were relatively more salt-tolerant than shoots. There occurred an increase in the concentration of certain nutrients (N, Ca, Mg, TNC) in the plants in response to salinity, which along with increased root: shoot ratios was inferred as an adaptive feature of the plant for persistence under saline conditions.     

雪被覆盖对高山森林凋落物分解过程中水溶性和有机溶性组分含量的影响

季节性雪被可能通过冻结、淋溶以及冻融循环等对高山森林凋落物水溶性和有机溶性组分含量产生影响.本文采用凋落物分解袋法,以川西高山森林典型乔木（四川红杉、岷江冷杉、红桦、方枝柏）和灌木（高山杜鹃、康定柳）凋落物为研究对象,研究了雪被覆盖不同时期（雪被形成期、雪被覆盖期和雪被融化期）和雪被厚度（厚型雪被、中型雪被、薄型雪被和无雪被）下凋落物水溶性和有机溶性组分含量的动态变化特征.结果表明： 在一个冬季的分解过程中,6种凋落物水溶性组分含量在雪被形成期和融化期降低而雪被覆盖期增加,但除高山杜鹃凋落物有机溶性组分含量在雪被覆盖期增加外,其他5种凋落物有机溶性组分含量在整个冬季呈降低趋势.相对于凋落物有机溶性组分含量,不同厚度雪被斑块对凋落物水溶性组分含量变化的影响更大,且主要表现在雪被形成期和雪被覆盖期.相对于其他雪被斑块,薄型雪被斑块更加显著地促进了高山柳和高山杜鹃凋落物水溶性组分含量降低,但显著抑制了方枝柏凋落物水溶性组分含量降低,而其他凋落物水溶性组分含量变化在不同斑块间无显著差异.冬季高山森林雪被对凋落物水溶性和有机溶性组分含量的影响主要受控于凋落物质量.     

灌水对不同品种小麦茎和叶鞘糖含量及产量的影响

以冬小麦品种济麦20和泰山22为材料,设置全生育期不灌水(W0)、灌冬水+拔节水(W1)、灌冬水+拔节水+开花水(W2)、灌冬水+拔节水+开花水+灌浆水(W3)4个处理,研究不同灌水处理对小麦倒二茎节间和叶鞘中水溶性碳水化合物含量和籽粒产量的影响.结果表明:两品种W0处理灌浆初期倒二茎节间和叶鞘的可溶性总糖、聚合度(DP) ≥4和DP=3的果聚糖含量最高,灌浆后期的果糖含量最高,这有利于倒二茎节间和叶鞘水溶性碳水化合物的积累与降解,从而提高千粒重,灌水处理间比较,济麦20的W1处理在灌浆初期倒二茎节间和叶鞘的DP≥4、DP=3果聚糖含量和灌浆中后期的可溶性总糖、果糖含量最高,其籽粒产量也最高;泰山22的W2处理在灌浆初期倒二茎节间和叶鞘的DP≥4、DP=3果聚糖含量最高,灌浆后期的果糖含量高于W1处理,其籽粒产量也最高,品种间比较,泰山22灌浆阶段的倒二茎节间和叶鞘的可溶性总糖、DP≥4果聚糖含量和灌浆后期的果糖含量高于济麦20.两品种的籽粒产量对水分处理的响应不同,济麦20的籽粒产量在W0和W1条件下高于泰山22,在W2和W3条件下低于泰山22.本试验中,济麦20的W1处理和泰山22的W2处理有利于倒二茎节间和叶鞘中水溶性碳水化合物的积累与降解,其籽粒产量显著高于其他处理,分别是两品种的最优水分处理.     

稻鸭、稻鱼共作生态系统土壤可溶性有机N的动态和损失

通过田间试验研究了稻鸭、稻鱼共作生态系统土壤可溶性有机N(SON)的动态和损失,及其与土壤微生物量N和水稻吸N量的相关性.结果表明,(1)土壤SON是稻田土壤主要的可溶性N,其中处理CK,RD和RF土壤SON库分别为121.16, 109 30 和113.71 kg/hm2,高于土壤无机N库.(2)土壤SON与土壤可溶性无机N显著正相关(p<0.01);在水稻生育期间,土壤SON含量随水稻的生长而逐渐降低;同时由于鸭和鱼的存在,处理RD和RF土壤SON含量显著低于处理CK;土壤SON与水稻累积吸N量呈显著负相关(p<0.01),表明水稻生长强烈影响着土壤SON.(3)在水稻生长前期,渗漏水各形态N含量最大;溶解性有机N(DON)是稻田渗漏水N素的主要形态;同时,统计分析显示,相对于处理CK,RF土壤SON的下渗淋失量显著降低,RD土壤SON的下渗淋失量则略为降低.(4)水稻生育期间,土壤微生物量N不断地变化着,此外,由于鸭和鱼的存在,相对与处理CK,处理RD和RF土壤显著的提高了土壤MBN.同时,由于水稻吸收和N的淋失,土壤微生物量N与土壤SON不相关.总之,在水稻生长期间,土壤可溶性有机N受水稻吸N、微生物吸N与分解和N淋失的共同作用.     

Effect of heterotrophic nanoflagellates on the loss of virus-like particles in pond water

A decrease in the abundance of virus-like particles (VLP) by heterotrophic nanoflagellates (HNF) was examined using size-fractionated water samples taken from a hypereutrophic pond in December 1999, and in March and July 2000. We recorded a considerable decrease in the abundance of VLP in the 5.0µm filtrate relative to the 0.2–0.8µm filtrates. Decrease rates of VLP were reduced in a parallel 5.0µm filtrate treated with cycloheximide. The loss rates of VLP in 5.0µm filtrate varied in each experiment, and a high rate of loss was found when the growth rate of HNF was high. These results suggested that HNF consumed the VLP and that HNF is an important factor for decreasing viral abundance in freshwater environments.     

耕作扰动对喀斯特土壤可溶性有机质及其组分迁移淋失的影响

土壤可溶性有机质(DOM)及其组分淋失特征研究对深入理解干扰作用下土壤碳氮养分损失机制具有重要意义,本研究基于翻耕模拟试验,分析喀斯特石灰土可溶性有机碳(DOC)、可溶性有机氮(DON)、及DOM官能团组分的淋失动态特征及其对不同耕作频率的响应,并探讨其影响因子。结果表明:(1)土壤DOC与DON的淋失量均随翻耕频率的增加而增加,但4个官能团特征参数对翻耕频率响应均不显著;DOC/DON淋失比随翻耕频率的增大而减少,DON占淋溶水可溶性总氮(TDN)比例随翻耕频率增加而增加。(2)DOC和DON月淋失量同时受翻耕处理与季节变化及其交互作用的影响,4个官能团特征参数仅受季节变化的影响;翻耕处理实施后,DOC月淋失量表现为初期大、后期小,各处理间差异性逐渐降低;但DON月淋失量初期小、后期大,各处理间差异性逐渐增大。(3)DOC淋失量与4个官能团特征参数呈显著负相关(P0.05),与Ca~(2+)、NH_4~+-N的淋失量呈显著正相关;DON淋失量与4个官能团参数无显著相关关系,与Mg~(2+)淋失量呈显著正相关关系。以上结果表明耕作扰动会加剧土壤DOM淋失,但淋失组分中稳定性组分没有变化,意味着耕作干扰将导致土壤有机质的持续损失,且由于其淋失组分碳氮比(DOC/DON)随扰动频率增加而降低,DON/TDN比随扰动频率增加而增加,持续的耕作干扰将大大增加水体氮素污染风险。     

不同有机物覆盖对冷凉地区苹果园土壤水温环境及速效养分的影响

为了探究不同有机物覆盖对冷凉地区果园土壤理化性质的影响,在‘寒富’苹果园设置了杂草、稻草、玉米秸秆、粉碎枝条4个覆盖处理,对比分析了各处理果园土壤水分、养分等指标的变化.结果表明: 有机物覆盖增加了土壤含水量,以干旱季节最为明显;减缓了春季土壤温度上升速度,不利于果树前期生长,但降低了夏季土壤的最高温,提高了秋冬季土壤的最低温;提高了土壤的pH值,以玉米秸秆覆盖处理最为明显,减轻了土壤酸化,使土壤pH接近中性;不同程度提高了土壤有机质含量,以杂草覆盖处理最为明显.覆盖还增加了土壤碱解氮、速效磷、速效钾含量,但稻草覆盖处理碱解氮含量低于对照.     

不同水分条件下源库调节对小麦营养器官可溶性碳水化合物和籽粒千粒重的影响

以抗旱性有显著差异的两个冬小麦品种为材料,在干旱胁迫(DS)和正常灌溉(WW)条件下,研究了源库调节对小麦营养器官中可溶性碳水化合物(WSC)和籽粒千粒重(TGM)的影响.结果表明:缩库处理显著增加了小麦各营养器官WSC含量,且正向促进WSC的相对转运;减源处理反之.源库调节WSC含量及其相对转运量/率的效应为:干旱胁迫显著高于正常灌溉,抗旱品种(陇鉴19)显著高于水分敏感品种(Q9086),缩库处理对WSC含量的影响强度显著高于减源处理,穗下节和倒二节普遍高于倒三节、叶鞘和叶.减源处理下,陇鉴19的总WSC相对转运率的强势器官主要为叶鞘、穗下节和倒二节,而Q9086主要表现在倒二节和倒三节;两小麦品种果聚糖相对转运率的强势器官均为叶鞘、穗下节和倒二节.减源处理使陇鉴19和Q9086的TGM在干旱胁迫下分别下降27.3%和31.7%,在正常灌溉下分别下降25.3%和12.1%.缩库处理的WSC含量及其相对转运与TGM的相关系数显著大于减源处理;干旱胁迫处理显著高于正常灌溉处理,不同器官中WSC总含量和果聚糖含量与TGM普遍表现出较高的相关系数(r2>0.900);小麦WSC含量及其相对转运与TGM关联度较为密切的器官主要集中在叶鞘和穗下节.在干旱胁迫条件下,WSC总含量有关性状与TGM表现出较高关联度,而在正常灌溉条件下,蔗糖和葡聚糖有关性状与TGM普遍表现出较高关联度.源库关系对小麦不同营养器官WSC及籽粒千粒重的调节易受水分环境、基因型和营养器官位置的显著影响.     

禹城市耕地土壤盐分与有机质的指示克里格分析

针对目前黄淮海平原盐渍土改良区存在的土壤盐碱、瘠薄等障碍问题,以该区域典型县域禹城市为研究对象,综合运用GIS和非参数地质统计学的指示克立格法,对0-20 cm深度的耕地土壤盐分和有机质的空间变异性进行了分析,并给出了土壤盐分和有机质满足一定阀值条件的概率分布图。结果表明,土壤盐分和有机质采用指示克里格方法都可以获得较为稳健的变异函数;受结构性因素与随机性因素共同影响,它们的指示半方差均表现为中等强度的空间自相关性,且单元指示克里格与多元指示克里格插值结果表明,土壤盐分、有机质的概率分布存在空间上的规律性与相似性;在空间分布上,研究区域土壤盐分含量高和有机质含量低的高概率区域主要分布在西北部的张庄镇、西部的房寺镇以及南部的莒镇乡等地区,该区域有一定的次生盐渍化风险;而土壤盐分含量高和有机质含量低的低概率分布区域主要分在徒骇河流经的河滩高地,土壤类型为褐土化潮土,是研究区域的主要高产区,基本无盐渍化。研究获取的综合指示概率分布图和概率风险评价对土壤可持续利用管理具有重要意义,为区域土壤质量的提高和土壤障碍因子消减提供参考。     

Effect of temperature,hydrogen ion concentration and osmotic potential on zoospore production by threePythium species isolated from pond water

Pythium fluminum produced zoospores most abundantly at 15°C, whereas the optima forPythium group F andP. marsipium were 20 and 25°C, respectively. Increasing the incubation temperature above the optimum resulted in the decrease of the duration of zoospore production. InPythium group F the ability to produce zoospores was not lost even after incubation at 40°C for 24 h. On the other hand,P. marsipium andP. fluminum lost the ability under these conditions. Zoospore production was inhibited at pH 4.5 and 10.5 in all the species tested.Pythium fluminum andP. marsipium were found to have two pH optima for zoospore production (7.5 and 9.5 for the former and 5.5 and 8.5 for the latter). The optimum pH for zoospore production byPythium group F was 6.5–7.5. Moderate osmotic potentials (–0.27–0.47 MPa) appeared to favor zoospore production by the pythia tested. The effect of temperature, pH and osmotic potential on zoospore production was discussed in relation to pollution of pond water.     

子午岭植被演替过程中土壤剖面有机质与持水性能变化

研究表明,自然植被正向演替对土壤剖面有机质积累有显著促进作用,表现为：由弃耕地、草地、灌木、乔灌群聚到乔木的植被演替过程中,0-25cm土层有机质含量逐步增加,且演替初期的增加速度较快,而后增加速度相对变缓。植被演替过程中土壤有机质含量变化的主要原因在于植物凋落物归还量的变化。在同一时间测定的土壤剖面水分含量以及0-5cm土层田间持水量、容重、总孔度等与土壤持水性能相关的指标都与有机质含量呈极显著或显著相关,表明随剖面有机质的积累,土壤持水性能得到改善。     

Inferred ionic composition and salinity of a Bolivian Quaternary lake,as estimated from fossil diatoms in the sediments

Multiple Linear Regression (MLR) was used to estimate past salinity and ionic composition in sediments of a paleolake in the southernmost Bolivian Altiplano. Modern diatom assemblages were sampled from the subsurface sediments of 14 saline lagoons, and compared quantitatively with fossil assemblages. Only one application of the method is reported: to a Quaternary outcrop located on the border of one of them (Laguna Ballivian). Multivariate analysis was performed on diatom data to check the range of variation of both the fossil and modern flora. It also allowed a reduced set of explanatory variables for regression analysis. Finally, a number of transformations of the chemical variables was computed prior to the regression process in order to stabilize the residuals variance and obtain a good error estimate. Only ten chemical components were studied, but the method could be applied to other palaoenvironmental parameters.     

不同研究尺度下土壤有机质和全氮的空间变异特征

在北京郊区面积为1075km^2的中尺度（平谷区）以400m&#215;400m网格采样,共采集1076个样点,同时在平谷区内面积为28．8km^2的小尺度（马昌营镇）以100m&#215;100m网格采样,共采集171个样点,测定其耕层土壤有机质和全氮的含量。应用传统统计学和地统计学方法,对两个研究尺度下的数据进行了分析,结果表明：有机质和全氮的变异系数范围为0．31～0．40,均属中等变异强度,随着研究尺度的缩小,土壤全氮的变异系数减少。半方差函数分析结果表明,两个研究尺度下,有机质和全氮均在一定范围内存在空间相关关系,区级尺度有机质和全氮的空间相关距离较大,分别为88．2km和4．9km,镇级尺度有机质和全氮的变程较小,均为0．7km,它们的空间异质性均主要由结构性因素引起。采用Kriging最优内插法对未测点进行了估值,绘制了等值线图,两个研究尺度下的有机质和全氮含量受地形、土壤类型、土地利用方式、施肥等因素的影响,均表现出明显不同的分布规律。     

乡土植物生活型构成对川渝地区边坡植被水土保持效益的影响

乡土植物灌木化建植是高速公路边坡防护的重要生态模式。为了探讨生态恢复过程中乡土植物的生活型构成对边坡植被水土保持效益的影响,揭示乡土植物生活型-物种多样性-生态系统功能间的偶合关系,借助3个物种配置试验,于2009年4月构建了以草本、灌木或乔木为主体的草本型、灌木型、乔木型绿化配置及草-灌-乔混合型试验区。自建植次年(2010年)起,对试验区进行持续5a生态监测。结果表明:1)边坡植被的物种丰富度与乡土植物的生活型有关,呈现乔木型灌木型草-灌-乔混合型草本型趋势;2)植被的物种多样性(Shannon-Wiener指数、Pielou指数)与乡土植物生活型构成及建植年限有关:建植后第1、第2年,多样性水平呈草本型草-灌-乔混合型灌木型乔木型变化趋势;自建植后第三起(2012—2014年),呈草-灌-乔混合型草本型灌木型乔木型波动;3)植被的水土保持性能(径流系数、侵蚀模数)与群落的物种多样性密切相关:多样性水平越高,水土保持性能越强。可见,乡土植物的生活型构成对提高边坡植被的物种多样性、改善生态性能至关重要。     

Effect of NaCl salinity in vivo and in vitro on ribonuclease activity in the halophyte Suaeda maritima

Ribonuclease (EC 2.7.7.17) activity in the obligate halophyte Suaeda maritima (L.) Dum. var. macrocarpa Moq. was studied in relation to salinity (increasing concentrations of NaCl) of incubation and growth media. In vitro, the addition of 50 to 400 m M NaCl did not affect ribonuclease activity. This result, which was also found for Phaseolus vulgaris , indicates that the hydrolase is insensitive to high saline concentrations. The subcellular distribution of RNase activity did not change significantly with the salinity of the medium or with the age of the plant. The microsomal ribonuclease activity expressed on a fresh weight basis represented in every case less than 6% of the total activity. After 23 days of culture, the absence of salt stimulated the activity of soluble ribonuclease in aerial parts of Suaeda ; inversely, the capacity of the enzyme was lower under optimal saline conditions (130 m M NaCl). This was also evidenced by transfer of whole plants from a non-saline to a saline medium. Such a saline shock caused a decrease followed by a stabilization of the capacity of ribonuclease from Suaeda . The influx of NaCl in the tissues lowered the activity of the hydrolase.