基于EM38长江河口地区土壤盐渍化特征研究

运用电磁感应仪EM38,结合GIS技术和地统计方法对长江河口地区土壤含盐量的空间变异性进行研究,结果表明:EM38所测土壤表观电导率与土壤电导率(EG_(1:5))的相关系数均达到1%显著水平,其中以EM_h+EM_v为自变量的多元回归方程的拟合效果最好.盐分含量统计特征表明,土壤盐分含量变幅较大,且随着深度的增加变化幅度逐渐减小,各层土壤盐分含量均值介于0.713 6～0.813 7 g/kg之间,且随着深度的增加盐分含量均值逐渐增大,总体上盐分分布具有一定的底聚性;各土层含盐量均呈现中等变异强度.变异系数相差较大,在水平方向上含盐量的变异随深度的增加而逐步趋弱.盐分含量空间分布表明,各层土壤盐分含量由南向北、自东向西有逐渐降低的趋势,随着深度的增加土壤含盐量不断升高.盐化土面积百分比表明,该地区大部分为非盐化土,轻度盐化土和中度盐化土所占比例较小,但由于含盐母质和地下水矿化度两个主要因素的影响,土壤盐渍化的发生存在巨大的潜在性威胁,运用EM38测值解译所得土壤盐分含量真实地反映了研究区的土壤盐渍化状况,为该地区土壤盐渍化的改良及防范提供依据.     

太仓市郊大棚菜地土壤盐分累积与分布特征研究

以太仓市郊大棚菜地土壤为研究对象,研究了太仓市典型大棚菜地土壤盐分累积现状及变化规律。结果表明:太仓市郊大棚菜地土壤全盐含量平均值为3.38 g/kg,已达轻度盐化水平;大棚菜地土壤盐分累积区域分布差异较大,最小值为0.42 g/kg,最大值达12.6 g/kg,变异系数达65.7%;大棚菜地土壤盐分累积量有69.84%超过安全水平,其中51.59%为轻度盐土,10.32%为中度盐土,5.56%为重度盐土;大棚菜地土壤盐分累积分布具有明显的地域性,以浏河镇、沙溪镇和新区发生盐化现象最为严重,盐化土所占比例分别达91.4%、91.0%和83.0%;八大离子组成中,阳离子以Ca~(2+)为主,其次为Na~+和K~+,阴离子以NO_3~–为主,其次为Cl~–和SO_4~(2–);相关性分析表明,影响太仓市郊菜地土壤发生盐化的主要因素是全盐含量、NO_3~–、Cl~–、Ca~(2+)等指标,造成土壤发生次生盐渍化的主要原因是不合理施肥、种植及管理模式等人为外在因素;太仓市郊菜地土壤盐分含量随着大棚种植年限的增加而显著提高,在种植年限为4~5 a时达到峰值,平均值为3.64 g/kg,是种植年限为1 a的大棚土壤含盐量的1.29倍。     

气候变暖对宁夏引黄灌区土壤盐分及其灌水量的影响

气候变暖加剧了土壤水分蒸发,带动土壤盐分向上移动,引起土壤盐分增加,导致土壤盐碱危害加剧。采用近35 a来的土壤盐分定位观测资料和气象资料,研究气候变暖对宁夏引黄灌区土壤盐分变化的影响。研究结果表明：近 35 a随着全球变暖,宁夏引黄灌区土壤全盐含量呈明显的增加趋势,轻盐化土壤、中盐化土壤和重盐化土壤全盐质量分数分别增加0.08、0.13和0.19 g/kg;当温度增加0.5～3.0℃时,宁夏引黄灌区轻盐化土壤、中盐化土壤和重盐化土壤淋洗土壤增加盐分所需的灌水量分别增加8.2%～9.1%、8.2%～8.7%和8.3%～8.8%,总灌水量增加1.29～1.40亿m3。     

风化煤对苏打盐化土盐分运移的影响

针对山西省大同盆地中度苏打盐化土,利用山西灵石风化煤作为改良材料,进行室内培养试验和原状土柱模拟试验,研究风化煤不同施用量对苏打盐化土的pH、电导率(EC)、水溶性全盐量、水溶性Na~+的影响,以及风化煤对水溶性全盐量、水溶性Na~+在土壤中运移规律的影响。研究表明:通过培养试验发现15g/kg的风化煤处理的效果最佳,pH和碱化度(ESP)分别降低4.1%和34.6%。通过风化煤和纯水淋洗的共同作用下,试验中5个处理土壤0—10cm的pH值分别降低3.0%,7.2%,9.6%,10.6%和9.1%。风化煤15g/kg的处理,使0—10cm土壤中盐分占总盐分的比例从39.0%下降到11.8%。15g/kg的处理,能降低土壤中28.4%水溶性Na~+。结果表明,在大同盆地苏打盐化土改良,风化煤能有效降低土壤表层pH、水溶性盐分和水溶性Na~+,最佳用量是15g/kg。     

河北滨海平原土壤盐分空间异质性与淋排均质化作用研究

本文运用经典统计学和地统计学方法,结合GIS技术,研究了滨海盐土土壤盐分的空间异质性和采用降雨淋盐与暗管排盐措施后土壤盐分变化及淋排均质化作用的分析,主要结果如下:1雨淋管排可促进土壤盐分均质化。淋排后,变异系数CV由48.13%降至28.14%,空间相关程度(C0/(C0+C))由72.86%变化至59.42%;2雨淋管排后土壤盐分存在"高盐异质性–低盐均质性"转化趋势。7 g/kg的土壤含盐量经雨季淋排可降至1.5~2 g/kg,且在7 g/kg土壤含盐量范围内,脱盐率与初始土壤含盐量呈正相关,反之,为负相关;3对"高盐异质性–低盐均质性"转化过程的定量分析结果显示,淋排后,实验区土壤类型由中重度盐渍化土降为轻度盐渍化土,雨季土壤脱盐量为67.78 t,其中重度盐渍化土对脱盐量的贡献最大,可达91%,轻度盐渍化土反而因淋排作用有所增加,其脱盐量的贡献为负值(–35%)。     

改良剂对盐化潮土饱和导水率的影响

土壤导水性是影响土壤水分入渗、淋溶等过程的重要性质,而饱和导水率是在土壤为水饱和后影响土壤渗透能力、地表径流发生程度、盐分淋洗状况的重要参数。以室内土柱试验为主要手段,以盐化潮土为研究对象,探究聚丙烯酰胺(PAM)、竹炭型土壤调理剂(BC)、菌型有机复合肥(BO)对盐化潮土饱和导水率的影响。(1)盐化潮土饱和导水率随着BC用量增加而增大,BC用量为20 g/kg时盐化潮土饱和导水率为0.041 cm/min,较CK增加32.3%;盐化潮土的饱和导水率随PAM用量的增加而减小,PAM施用量为1 g/kg土壤饱和导水率为0.0127 cm/min,较CK降低59.0%;文中选取的BO各处理对土壤饱和导水率的影响效果较小,各用量间无显著差异。(2)与CK相比,BC和BO各处理所需的渗透时间均较短,7 h的累计出流量较大;PAM各处理所需的渗透时间较长,7 h的累计出流量较小。不同改良剂对盐化潮土导水性能的作用效果不同,本研究可为改良剂的选择与用量提供数据支持。     

湖南植烟土壤盐分及其表聚特征研究

对湖南主要植烟区表层土壤总盐及主要盐分离子的组成进行了分析.结果表明:烟叶收获后,植烟土壤盐分表聚现象严重,表层土壤总盐量达4.17 g/kg,与强度盐化土相当.烟-稻轮作土壤盐分表聚明显强于早地烟土壤,同时,在烟-稻轮作区又以衡阳土壤盐分含量最高,永州和郴州其次:烟-稻轮作区植烟土壤表层盐分离子以N03-、SO42-、Ca2 和K 为主,占总盐量的95.21%.     

渭北地区农田土壤物理性质对土壤剖面盐分的影响

通过网格布点法对渭北地区农田土壤进行采样分析,研究了土壤团聚体、土壤容重、土壤质地对土壤剖面盐分的影响。结果表明:(1)研究区轻度盐渍化面积占46.56%,中度盐渍化占23.01%,渭北地区农田土壤盐渍化程度总体不严重但存在较大潜在风险。(2)各层土壤水稳性团聚体与含盐量呈负相关,容重与含盐量的关系因盐渍化程度不同而在各土层表现出不同的正负效应,土壤质地与含盐量仅在0—20cm土层存在显著相关性。(3)土壤物理性质对含盐量的异位影响与含盐量水平有关。当土壤含盐量1g/kg时,40—60cm容重与20—40cm含盐量为幂函数关系,且呈递增趋势;土壤含盐量在2~4g/kg时,20—40cm容重与0—20cm含盐量为一次函数关系,且呈递增趋势;当含盐量2g/kg时,0—20cm容重与20—40cm含盐量为一次函数关系,且呈递减趋势;含盐量2g/kg时,水稳性团聚体与含盐量呈显著线性负相关。     

天津滨海开发区绿地土壤盐分时空变异特征

该文依据天津滨海经济技术开发区多年土壤盐分数据,采用传统统计学和地统计学的方法,对区域内表层土壤(0~20 cm)及底层土壤(60~80 cm)含盐量和p H值的时空变异特征进行分析。结果表明,在2006、2008、2011年,表层土壤都属于非盐化土,底层土壤盐化程度从中度转变为轻度,平均值从2.82 g/kg降低到1.65 g/kg;p H值随深度略有增大,但表层和底层的值均逐年降低。区域内表层土壤含盐量在这3a中都表现出空间分布独立性,底层土壤具有强空间相关性,受结构因素影响很大,而p H值在所有层次中都表现强空间相关性。区域内绿地土壤质量基本稳定在当地绿化用客土标准值范围内,即土壤全盐含量≤3 g/kg、p H值≤8.5。该研究对于评价当地土壤改良效果,提高绿地管理水平,积累滨海盐渍地改良经验,实现当地土地资源的可持续发展具有现实意义。     

不同水盐处理对苜蓿耗水、品质及产量的影响

为探索河套灌区不同盐分土壤苜蓿生长的适宜水分展开盆栽试验,设置3个水分水平、3个盐分水平和1个对照处理CK,监测不同水盐处理苜蓿现蕾期至初花期土壤贮水变化量、品质及产量。结果表明:(1)相同盐分条件下,植株株高、地上生物量、地下生物量、耗水量及干草产量随灌水量的增加而增大,但苜蓿的增产效应明显降低;相同水分条件下,随盐分增加,苜蓿耗水量及地下生物量整体呈现先增大后减小的变化趋势。土壤含盐量超过3 g/kg,土壤中剩余水分显著增加,且随灌水量增加逐渐增加。(2)土壤含盐量1～3 g/kg,水分胁迫有利于提高苜蓿粗蛋白含量;其中低水处理粗蛋白含量均显著高于中水及高水处理(p0.05);含盐量3～4 g/kg,盐分改变水分胁迫阈值,中水处理粗蛋白含量显著高于低水与高水处理(p0.05)。盐分与水分胁迫下,植株体内氨基酸含量增加,其中F_3W_1处理氨基酸含量最大,为20.90%。对各游离氨基酸及粗蛋白含量进行相关性分析,其中甘氨酸、蛋氨酸与粗蛋白相关性不显著;其他氨基酸与粗蛋白均呈显著正相关(p0.05)。(3)土壤盐分1～2 g/kg,苜蓿的水分利用效率随灌水量增加而降低,土壤盐分超过2 g/kg,苜蓿水分利用效率随灌水量呈现先增大后减小趋势。土壤含盐量1～2 g/kg,水分70%～75%θ_f,干草产量增加,水分利用效率提高;土壤含盐量2～3 g/kg,水分70%～85%θ_f,水分利用效率提高干草产量减小,但差异不显著;土壤含盐量3～4 g/kg,水分85%θ_f以上,苜蓿干草产量增加。该研究结果初步可为盐渍化农田苜蓿种植及合理灌溉提供理论依据。     

Verification of freezing point depression method for measuring matric potential of soil water

The matric potential of soil water was determined using the freezing point depression method for a range of soil types. Soil water characteristic curves of these soils were obtained and compared with those obtained by the pressure plate, psychrometer, and vapor pressure methods resulting in excellent agreement between the freezing point depression method and the other methods over the range of -10.0 to -0.1 MPa in matric potential (i.e., temperature range of -8.00 to -0.08°C for freezing point) in all soil types. Over those ranges of matric potentials and temperatures, the effect of temperature-dependence on the freezing point of soils both in terms of specific volume of water and latent heat of water freezing was negligibly small. Freezing point of soils was independent of the bulk density of soils due to the fact that soil water in the range of matric potentials less than -0.1 MPa was affected predominantly by adsorptive forces between water and the soil matrix. The results from this study indicate that the freezing point depression method is a simple and practical technique to determine the soil water content in the vicinity of the wilting point     

Salinity effects on carbon mineralization in soils of varying texture

In salt-affected soils, soil organic carbon (SOC) levels are usually low as a result of poor plant growth; additionally, decomposition of soil organic matter (SOM) may be negatively affected. Soil organic carbon models, such as the Rothamsted Carbon Model (RothC), that are used to estimate carbon dioxide (CO₂) emission and SOC stocks at various spatial scales, do not consider the effect of salinity on CO₂ emissions and may therefore over-estimate CO₂ release from saline soils. Two laboratory incubation experiments were conducted to assess the effect of soil texture on the response of CO₂ release to salinity, and to calculate a rate modifier for salinity to be introduced into the RothC model. The soils used were a sandy loam (18.7% clay) and a sandy clay loam (22.5% clay) in one experiment and a loamy sand (6.3% clay) and a clay (42% clay) in another experiment. The water content was adjusted to 75%, 55%, 50% and 45% water holding capacity (WHC) for the loamy sand, sandy loam, sandy clay loam and the clay, respectively to ensure optimal soil moisture for decomposition. Sodium chloride (NaCl) was used to develop a range of salinities: electrical conductivity of the 1:5 soil: water extract (EC_1:5) 1, 2, 3, 4 and 5 dS m⁻¹. The soils were amended with 2% (w/w) wheat residues and CO₂ emission was measured over 4 months. Carbon dioxide release was also measured from five salt-affected soils from the field for model evaluation. In all soils, cumulative CO₂-C g⁻¹ soil significantly decreased with increasing EC_1:5 developed by addition of NaCl, but the relative decrease differed among the soils. In the salt-amended soils, the reduction in normalised cumulative respiration (in percentage for the control) at EC_1:5 > 1.0 dS m⁻¹ was most pronounced in the loamy sand. This is due to the differential water content of the soils, at the same EC_1:5; the salt concentration in the soil solution is higher in the coarser textured soils than in fine textured soils because in the former soils, the water content for optimal decomposition is lower. When salinity was expressed as osmotic potential, the decrease in normalised cumulative respiration with increasing salinity was less than with EC_1:5. The osmotic potential of the soil solution is a more appropriate parameter for estimating the salinity effect on microbial activity than the electrical conductivity (EC) because osmotic potential, unlike EC, takes account into salt concentration in the soil solution as a function of the water content. The decrease in particulate organic carbon (POC) was smaller in soils with low osmotic potential whereas total organic carbon, humus-C and charcoal-C did not change over time, and were not significantly affected by salinity. The modelling of cumulative respiration data using a two compartment model showed that the decomposition of labile carbon (C) pool is more sensitive to salinity than that of the slow C pool. The evaluation of RothC, modified to include the decomposition rate modifier for salinity developed from the salt-amended soils, against saline soils from the field, suggested that salinity had a greater effect on cumulative respiration in the salt-amended soils. The results of this study show (i) salinity needs to be taken into account when modelling CO₂ release and SOC turnover in salt-affected soils, and (ii) a decomposition rate modifier developed from salt-amended soils may overestimate the effect of salinity on CO₂ release.     

中国盐渍土研究：历程、现状与展望

盐渍土研究是以盐渍土和盐渍生境作为主要研究对象，以盐渍土和盐渍化的发生与演变过程、环境要素和人类活动对盐渍化的影响与作用机制、盐渍土的治理、改良和利用的理论与技术为主体的研究领域。我国盐渍土面积巨大、种类繁多，盐渍化问题突出，对农业生产和生态环境造成不同程度的影响。我国科学家提出的盐渍土“水盐调控”“水盐平衡”，“淡化肥沃层”和“障碍消减”等理论与技术方法，为发展农业生产、提高土地产能、保障粮食安全、拓展耕地资源等发挥了积极作用。近期我国在土壤盐渍化演变过程的监测与多源数据融合、土壤水盐运移过程模拟与尺度转换、盐渍农田养分循环与减损增效、盐渍障碍的生态消减、盐渍障碍微生物修复、盐渍农田灌排优化管理与边际水安全利用等方面取得了积极的进展和成果。建议今后深入开展盐渍土精准控盐的高效和安全用水、土壤盐渍障碍的绿色消减与健康保育、盐渍农田养分库容扩增与增碳减排、土壤盐渍化与区域生态的耦合响应和协同适应等方面的理论与技术研究。应面向农业、资源、生态、环境等领域和行业，致力于拓展理论和新技术的研究，为国家农业升级、粮食安全、耕地保护、生态安全、高质量发展发挥重要作用。本文回顾了我国盐渍土研究工作的...     

A soil surface psychrometer for measuring humidity and studying evaporation

The gradient of water vapor pressure between soil and air controls the rate of evaporation from soil, but it has not been possible to determine the humidity at the soil surface. We have devised an instrument to measure the surface humidity in the field. Thermocouple psychrometry is used to monitor air equilibrated with the soil surface in a chamber placed briefly on the soil. A programmable data logger scans the thermocouples and stores the data. We calibrated the instrument over saturated salt solutions, and over soils whose relative humidity was calculated from measured water potentials. The instrument worked well, but underestimated slightly at relative humidities above 90%. It can be used to distinguish between stage 1 and stage 2 evaporation for soils. In field trials, the surface psychrometer was used to monitor diurnal and day-to-day changes in soil surface humidity during the drying cycle after irrigation. The cumulative vapor pressure difference between the soil surface and the air at 1.5 m was highly correlated with soil evaporation from microlysimeters set between crop rows. Changes in the cumulative difference in vapor pressure were also closely related to the changes in the evaporation component of measured evapotranspiration, as estimated with a simulation model.     

Salt-affected soils of the Barguzin Depression

Factual materials on salt-affected soils in the Barguzin Depression (Buryat Republic) are generalized. A geomorphic map of the depression has been developed. The distribution of salt-affected soils and the specificity of salinization in different geomorphic regions are characterized. These soils tend to be developed within the low lacustrine–alluvial plain of the depression, on the floodplain of the Barguzin River and its tributaries. Smaller areas of salt-affected soils are found on the river terraces. They are virtually absent on ancient sandy ridged terraces (kuituns). The genesis and chemistry of soil salinization are mainly related to the discharge of slightly saline deep water along tectonic faults and fissures. An additional source of soil salinity is represented by surface water flows. The presence of permafrost preventing the leaching of salts and the cryoarid climate favoring the migration of salts toward the soil surface during the dry spring and early summer periods and during the soil freezing in the winter contribute to the soil salinization. Slightly saline hydromorphic solonchakous soils predominate among salt-affected soils of the depression; the portion of semihydromorphic saline soils is smaller. Automorphic saline soils rarely occur in the depression. Strongly saline soils— solonchaks—are widespread within lacustrine depressions around salt lakes. Soils of the soda and sulfate salinization predominate. The content of chlorides is small; their increased amounts, as well as the presence of sulfates, are indicative of the discharge of dee ground water onto the surface. The soda type of salinization is also related to the discharge of deep stratal water with further transformation of salt solutions during freeze–thaw cycles. Under anaerobic conditions, the formation of soda is favored the processes of sulfate reduction.     

Desiccation tolerance of four strains of Rhizobium japonicum

The survival of different strains of Rhizobium japonicum was evaluated in three soils with two matric- and three osmotic-induced moisture potentials. Both drying and added NaCl significantly decreased populations. Strains CC 709 and USDA 110 were less affected by the matric- or osmotic-induced desiccation than strains CB 1809 and USDA 123. The survival of CC 709 and USDA 110 at 2 weeks with 0.7% added NaCI was 33 and 46% of initial counts in soils undergoing drying, and 70 and 69% in soils maintained at the 30kPa (0.3 bar) potential. Comparable survivals of CB 1809 and USDA 123 were 15 and 18% and 56 and 59%, respectively. The soil with the greatest clay and organic C contents maintained the highest populations during desiccation. Turbidity measurements indicated similar rates of growth of the four strains at a water activity (A_w) of 0.999 in yeast mannitol broth (YMB). When the YMB was adjusted with glycerol to lower water activities, strains CC 709 and USDA 110 consistently showed greater growth than did strains CB 1809 and USDA 123. No growth of CB 1809 and USDA 123 was observed at an (A_w) of 0.975. Water adsorption isotherms of freeze-dried cells showed that the more desiccation-susceptible strains (CC 709 and USDA 110) retained greater amounts of water at a given relative vapor pressure than did the two more tolerant strains.     

滨海盐渍土的碱化问题

滨海盐渍土是否有碱化问题,特别是在开垦利用以后,土壤是否会向碱化方向演化,这是很多生产单位所关心的问题。对此,过去已做了不少工作。有人认为滨海盐渍土由于长期受海水浸渍,土壤胶体表面吸附着大量的钠离子,因此有比较高的碱化度,盐渍程度愈重则碱化度愈高,随着土壤脱盐同时脱碱,当不致进一步碱化^[3]。也有人认为滨海盐债土耕垦后不会发生碱化,其碱化度随改良利用年限而降低^[1]。还有人在滨海盐溃土耕垦种稻后,观测到在土壤脱盐过程中,土壤pH值和总碱度有所增高,认为土壤发生了碱化^[2,5]1)。我们就这一间题曾先后对浙江上虞、乐清,江苏东台、大丰、滨海、灌云以及辽宁兴城、锦县、大洼等县的滨海地区进行了调查研究和室内试验。     

Relationships between carbon dioxide emission and soil properties in salt-affected landscapes

Net carbon dioxide (CO₂) emission from soils is controlled by the input rate of organic material and the rate of decomposition which in turn are affected by temperature, moisture and soil factors. While the relationships between CO₂ emission and soil factors are well-studied in non-salt-affected soils, little is known about soil properties controlling CO₂ emission from salt-affected soils. To close this knowledge gap, non-salt-affected and salt-affected soils (0-0.30 m) were collected from two agricultural regions: in India (irrigation induced salinity) and in Australia (salinity associated with ground water or non-ground water associated salinity). A subset (50 Indian and 70 Australian soils) covering the range of electrical conductivity (EC) and sodium adsorption ratio (SAR) in each region was used in a laboratory incubation experiment. The soils were left unamended or amended with mature wheat residues (2% w/w) and CO₂ release was measured over 120 days at constant temperature and soil water content. Residues were added to overcome carbon limitation for soil respiration. For the unamended soils, separation in multidimensional scaling plots was a function of differences in soil texture (clay, sand), SOC pools (particulate organic carbon (POC) and humus-C) and also EC. Cumulative CO₂-C emission from unamended and amended soils was related to soil properties by stepwise regression models. Cumulative CO₂-C emission was negatively correlated with EC in saline soils (R² = 0.50, p < 0.05) from both regions. In the unamended non-salt-affected soils, cumulative CO₂-C emission was significantly positively related to the content of POC for the Indian soils and negatively related to clay content for the Australian soils. In the wheat residue amended soils, cumulative CO₂-C emission had positive relationship with POC and humus-C but a negative correlation with EC for both Indian and Australian soils. SAR was negatively related (β = −0.66, p < 0.05) with cumulative CO₂-C emission only for the unamended saline-sodic soils of Australia. Cumulative CO₂-C emission was significantly negatively correlated with bulk density in amended soils from both regions. The study showed that in salt-affected soils, EC was the main factor influencing for soil respiration but the content of POC, humus-C and clay were also influential with the magnitude of influence depending on whether the soils were salt affected or not.     

咸淡水间歇组合灌溉对盐碱耕地土壤水盐运移特性的影响

为探明土壤水盐在咸淡水间歇组合灌溉条件下的运移情况,采用室内一维垂直积水入渗试验,以全淡水和微咸水直接灌溉作为对照,设置了四种间歇时间,分别为0、30、60、120 min,三种咸淡水组合比例,分别为2∶1、1∶1、1∶2,进行咸淡水间歇组合灌溉。结果表明:在同一入渗时间,间歇组合灌溉的累积入渗量大于淡水灌溉,与微咸水直接灌溉差异较小;累积入渗量(I)与湿润锋运移深度(Zf)的决定系数R2均大于0.99,I和Zf呈良好的线性关系;间歇组合灌溉的土壤含水率、灌水均匀度均远远大于淡水灌溉,但间歇组合灌溉的灌水均匀度随着淡水所占灌水定额比例的增加而减小;在5~45 cm作物根系密集区,土壤整体脱盐,但间歇组合灌溉土壤脱盐率显著高于微咸水直接灌溉,与淡水灌溉差异较小;不同间歇时间、组合比例对土壤脱盐率的影响均达到显著性水平。     

不同含盐土壤圆盘入渗特征试验

不同含盐土壤水分入渗特征是获得准确的土壤水力参数的基础。该文通过圆盘入渗试验,分析了4种土壤在5个（-1、-3、-6、-9和-12 cm）负水头下的入渗特征。结果表明,随着水头的减小,4种土壤的吸湿率线性减小,稳定入渗率和非饱和导水率呈不同程度减小。随土壤含盐量增加稳定入渗率和导水率呈增大规律。根据实测资料确定了不同负水头下非饱和导水率的Gardner指数模型参数,为盐渍化土壤水力参数的确定提供理论参考。