黄河三角洲海水灌溉对土壤性质的影响研究

通过2年在黄河三角洲进行海水灌溉对土壤性质的影响研究．结果表明：海水灌溉后土壤剖面中盐分含量有所上升,并在0～100cm土层中有盐分积累现象;土壤中存在的盐分主要以NaCI为主,Na^ 和Cl^-与土壤全盐含量呈直线线性相关,且达到极显著水平;海水灌溉后土壤的钠吸附比(SAR)在0～60crn土层内有所升高;土壤的pH值在海水灌溉前后基本没有什么变化;残余碳酸钠(RSC)都为负值。因此,在黄河三角洲地区运用海水灌溉不会引起土壤的碱化,并使土壤性质变差,但在海水灌溉过程中必须防治次生盐渍化的发生。     

应用土壤质地预测干旱区葡萄园土壤饱和导水率空间分布

田间表层土壤饱和导水率的空间变异性是影响灌溉水分入渗和土壤水分再分布的主要因素之一,研究土壤饱和导水率的空间变化规律,有助于定量估计土壤水分的空间分布和设计农田的精准灌溉管理制度。为了探究应用其他土壤性质如质地、容重、有机质预测土壤饱和导水率空间分布的可行性,试验在7.6 hm2的葡萄园内,采用均匀网格25 m×25 m与随机取样相结合的方式,测定了表层(0～10 cm)土壤饱和导水率、粘粒、粉粒、砂粒、容重和有机质含量,借助经典统计学和地统计学,分析了表层土壤饱和导水率的空间分布规律、与土壤属性的空间相关性,并对普通克里格法、回归法和回归克里格法预测土壤饱和导水率空间分布的结果进行了对比。结果表明:1)土壤饱和导水率具有较强的变异性,平均值为1.64 cm/d,变异系数为1.17;2)表层土壤饱和导水率60%的空间变化是由随机性或小于取样尺度的空间变异造成;3)土壤饱和导水率与粘粒、粉粒、砂粒和有机质含量具有一定空间相关性,而与土壤容重几乎没有空间相关性;4)在中值区以土壤属性辅助的回归克里格法对土壤饱和导水率的预测精度较好,在低值和高值区其与普通克里格法表现类似。研究结果将为更好地描述土壤饱和导水率空间变异结构及更准确地预测其空间分布提供参考。     

苏打碱土盐分淋洗与饱和导水率的关系

土壤饱和导水率是土壤重要的物理性质之一,反映了土壤入渗和渗漏性质,是计算土壤剖面水通量和排水工程设计的一个重要土壤水力参数[1]。准确地估测农田饱和导水率,对于制定正确的水分和盐分、水分和养分的管理措施及有效地防止污染物对环境的影响,都有十分重要的意义。已有研究表明,饱和导水率受土壤质地、结构、盐分含量与组成、容重或孔隙度、土壤水分特征等诸多因素影响[2-7]。就碱土而言,饱和导水率低是其标志性特征之一[8-10],提高饱和导水率是有效淋洗碱土盐分的基本前提[11]。松嫩平原是国内仅次于黄淮海平原的第二大平原,其西部是中国五大盐渍土分布区域之一[12]。土壤盐分以NaHCO3和NaCO3为主[     

滩涂围垦农田土壤饱和导水率的影响因素及转换函数研究

确定苏北沿海滩涂围垦农田耕层土壤饱和导水率的影响因素,构建适合该区的土壤转换函数,是研究该区田间土壤水盐运动和盐渍化防控的重要前提。本文在该区典型地块实测土壤饱和导水率和相关土壤基本理化性质,探讨了该区土壤饱和导水率的剖面分布特点,对影响饱和导水率的土壤基本性质进行了主成分分析,并建立了用于该区饱和导水率间接估算的土壤转换函数。结果表明:滩涂围垦农田土壤饱和导水率随剖面深度增加呈表土层高、亚表层低、底土层又升高的趋势,20~40 cm土层饱和导水率最小,介于2.75~6.73 cm·d-1,属低透水强度;土壤容重随剖面深度增加表现出与饱和导水率相反的变化特点。除了容重、孔隙度、质地等物理因素外,土壤肥力、盐分等化学性质也是影响饱和导水率的重要因素;影响滩涂围垦农田土壤饱和导水率的因素可由持水特性、盐碱状况、养分特征和土壤质地4个主成分反映,其累计贡献率达78.17%。在Vereecken转换函数中引入土壤盐分后可提高预测精度,修正函数Vereecken_1是最适合滩涂围垦农区土壤、具有最佳预测精度的转换函数。本文构建的土壤转换函数,可通过较易获得的砂粒、黏粒、容重、盐分和有机质对耕层土壤饱和导水率进行较高精度的预测,其结果可为滩涂盐渍化农区田间尺度土壤饱和导水率间接估算以及水盐运动数值模拟提供支持。     

水质和体积质量对碱土饱和导水率和盐分淋洗的影响

以松嫩平原典型碱土为研宄对象,采用承压水、潜水及蒸馏水模拟的雨水3种水源,分别在6种体积质量(容重)下测定了土壤饱和导水率和淋洗液的电导率及pH,分析了水质和体积质量对碱土饱和导水率和盐分淋洗的影响以及饱和导水率与淋洗液电导率和pH值间的关系.结果表明:碱土饱和导水率随测定用水电导率的增加而升高;采用承压水和潜水测定时,碱土饱和导水率随土壤体积质量的增加而降低;采用蒸馏水测定时,饱和导水率在1.08～1.33 g/cm~3体积质量范围内均为0.11mm/d,而当体积质量>1.42g/cm~3时,饱和导水率均为0 mm/d;淋洗液的电导率和pH值随着测定用水电导率的逐渐增加而不断降低;采用潜水和承压水测定时,淋洗液的电导率和pH值随体积质量的增加而升高,用蒸馏水测定时,淋洗液的电导率和pH值不随体积质量的变化而改变;淋洗液电导率和pH均随饱和导水率增加而降低,且二者与饱和导水率均呈指数关系,碱土饱和导水率越高其盐分淋洗效果越好.     

灌溉方式对土壤水分运动参数的影响

通过实测和拟合的方法研究了不同灌溉方式对土壤饱和导水率及非饱和土壤水分运动参数的影响。结果表明:膜下滴灌明显改善了土壤导水性能,0-10 cm各土层土壤饱和导水率明显高于地面漫灌,并且两种灌溉方式下土壤饱和导水率都高于裸盐地;不同灌溉方式下,相同含水率所对应的非饱和导水率及非饱和扩散率均不同,0-100 cm各土层都表现为膜下滴灌>地面漫灌>裸盐地。膜下滴灌对土壤水分运动参数的影响,并不是由土壤质地、容重、温度、盐分等因素作用而引起,可能是由于膜下滴灌改变了土壤的团粒结构或土壤中盐分的离子组成而造成的。     

灌溉水质和方式对土壤水力传导特性的影响

通过对未扰动土芯的模拟灌溉实验,分析了灌溉过程中土壤饱和导水率的变化及不同灌溉处理土壤近饱和导水率的差异;研究了不同水质和灌溉方式对土壤水力传导特性的影响。     

不同改良剂对滨海盐渍土水盐特性的影响

针对滨海盐渍土盐分含量高和土壤导水性能差的问题,采用禾康盐碱土改良剂、康地宝盐碱土改良剂、金满田生物菌剂、腐殖酸和石膏5种土壤改良剂,通过田间小区试验,分析测定了土壤含水量、土壤盐分含量、pH值、容重和饱和导水率等指标,并测定了作物收获产量,筛选适宜于改良研究区滨海盐渍土水盐特性的改良剂.试验结果表明:(1)土壤水分含量变化极大地影响着土壤的含盐量,土壤含水量与土壤含盐量呈极显著线性负相关关系.(2)腐殖酸在抑制滨海盐渍土盐分和降低土壤容重方面效果最佳,经腐殖酸(300 kg/hm2)处理后,0-5,5-20和20-40 cm土层盐分含量较CK分别减少了29.2％,32.6％和25.9％,土壤容重较CK减少了10.2％,土壤孔隙度和饱和导水率较CK也相对提高.(3)5种改良剂不同程度提高了作物的产量,以腐殖酸处理作物增产效果最为明显,玉米和油菜产量较CK分别增加了104.8％和41.6％.     

再生水灌溉对土壤主要盐分离子的分布特征及盐碱化的影响

通过田间试验,研究再生水纯灌、轮灌、重要时期灌清水等不同灌溉策略对西红柿和黄瓜地块土壤主要盐分离子的分布特征及盐碱化的影响。结果表明:对于西红柿地块,除Cl-和HCO3-在表土中的发生积累外,其他主要盐分离子均强烈受到灌溉水淋溶作用的影响,表现出向土壤深层迁移的特征,但是再生水灌溉未引起土壤剖面盐分的累积。对于黄瓜地块,土壤盐分分布对不同再生水灌溉策略的响应不同于西红柿地块,强烈的蒸发作用造成了主要盐分离子(除HCO3-外)在土壤表层中出现积累,但是未监测到盐分在深层土壤中累积。再生水灌溉对西红柿和黄瓜地块土壤的pH值和SAR值均未产生显著影响,但是较高的pH值(>8.0)说明长期灌溉再生水可能引起土壤的碱化。研究认为重要时期灌清水处理在控制土壤盐分累积方面效果明显,且未引起土壤发生碱化,可作为短期再生水灌溉果蔬菜(西红柿、黄瓜)的有益尝试。     

絮凝黄河泥沙复配生物炭对盐碱土水盐运移及水力特征参数影响

通过室内环刀试验,研究絮凝黄河泥沙复配生物炭对盐碱土水盐运移及水力特征参数的影响。将生物炭和絮凝黄河泥沙按4∶6质量比混合成土壤改良剂,再将复配后的土壤改良剂按0,1%,2%,3%,6%,10%混合到盐碱土中。结果表明:(1)随着土壤改良剂添加量的增加,土壤孔隙度及水分含量不断增大,10%添加量下的土壤孔隙度和水分含量较未添加改良剂的处理平均增加了12%;(2)土壤饱和导水率在3%的添加量下最大,较未添加处理增大68.9%;(3)土壤改良剂添加量越大水分扩散的越慢,土壤pH越大,降低盐分的效果越不明显,试验发现3%添加量下土壤盐分降低的较为明显,17 cm以上盐分降低量达到30%~50%,但土壤pH增大不明显,仅增大4%左右,波尔兹曼参数λ增加31.5%,水分扩散速率较快。综合考虑,3%添加量处理可以较为有效地提高土壤孔隙度、土壤水分含量、饱和导水率、水分扩散率,并降低土壤表层盐分。     

华北地区微咸水应用对土壤水力传导性能的影响

由于淡水资源短缺,中国华北地区微咸地下水灌溉面积逐年增多。该文通过室内土柱淋洗试验,研究了灌溉水盐分浓度和钠吸附比(SAR)对华北地区非碱土(可交换钠百分比ESP0)和碱土(ESP30)饱和水力传导性能的影响。灌溉水盐浓度分别为2.5、10和25mmolc/L,SAR分别为0、10和30(mmolc/L)0.5。去离子(盐浓度0)作为对照处理。试验包括2个土壤碱度、9个灌溉水质组合和1个去离子水处理,共20个试验处理。试验结果显示,非碱土和碱土对微咸水应用的反应机理以及反应程度不同。当黏粒弥散程度较弱时,上部土壤的饱和水力传导度显著大于下层土壤;反之,则各层土壤的水力传导度均较小。在试验水质条件下,非碱土的平均饱和水力传导度的变化范围为0.75～13.25cm/h,而碱土的变化范围为0.06～6.50cm/h。碱土的稳定饱和水力传导度随着灌溉水盐浓度的增加或/和SAR的减小而增大,但在非碱土中稳定饱和水力传导度的变化规律与此基本相反。试验结果对合理应用微咸水灌溉非碱土和碱土具有指导意义。     

Yellow River Sediment as a Soil Amendment for Amelioration of Saline Land in the Yellow River Delta

Soil salinization and sedimentation in the Yellow River Delta pose significant environmental concerns in China. This study demonstrated for the first time that the Yellow River sediment can be used as a soil amendment to remediate the salt‐affected soil. Four treatments including the control (CK), Yellow River sediment application at 70 Mg ha⁻¹ (S70) and 140 Mg ha⁻¹ (S140), and crop residue application at 3 Mg ha⁻¹ (P3) were replicated in two blocks in the field. Cotton, one of the most common crops in the Yellow River Delta, was planted. Soil physical properties and electrical conductivity (EC) were measured. The results indicated that mixing the Yellow River sediment, a poorly graded sand, with the clayed saline soil improved soil texture, macroporosity, and saturated hydraulic conductivity. Mean EC of treated soils was significantly lower than for the control. Improved cotton emergence and stand establishment were observed along with a significant treatment effect on cotton yield. The effects of S140 and P3 on soil macroporosity, hydraulic conductivity, soil EC, and cotton growth were comparable. This study concluded that applying Yellow River sediment in the saline land is a technically feasible and environmentally sustainable approach for saline soil remediation in the Yellow River Delta. Copyright © 2014 John Wiley & Sons, Ltd.     

Short-term effects of biochar and gypsum on soil hydraulic properties and sodicity in a saline-alkali soil

Salt and sodicity of saline-alkali soil adversely affect the construction of ecological landscapes and negatively impact crop production. The reclamation potential of biochar (BC, wheat straw biochar applied at 1% by weight), gypsum (G, 0.4% by weight), and gypsum coupled with biochar (GBC) was examined in this laboratory-based study by evaluating their effects on a saline-alkali soil (silt loam) with no amendment as a control (CK). Saline ice and fresh water (simulated rainfall) were leached through soil columns to investigate changes in salt content, sodium adsorption ratio (SAR), alkalinity, and pH of the leachate and the soil. Results showed that saturated water content and field water capacity (FWC) significantly increased by 4.4% and 5.6%, respectively, in the BC treatment after a short incubation time. Co-application of biochar and gypsum (GBC) increased soil saturated hydraulic conductivity (Ks) by 58.4%, which was also significantly higher than the sole addition. Electrical conductivity (EC) of the leachate decreased sharply after saline ice leaching; subsequent freshwater leaching accelerated the removal of the rest of the salts, irrespective of the amendment application. However, the application of gypsum (G and GB) significantly enhanced the removal of exchangeable Na+ and reduced leachate SAR. After leaching, the soil salt content decreased significantly for all treatments. The application of gypsum resulted in a significantly lower soil pH, exchangeable sodium percentage (ESP), SAR, and alkalinity values than those recorded for the CK and BC treatments. These results demonstrated that the co-application of gypsum and biochar could improve saline-alkali soil hydraulic conductivity and decrease leaching-induced sodicity over a short period.     

再生水灌溉对土壤理化性质影响的试验研究

通过室内土柱模拟试验的方法，研究了再生水灌溉对土壤理化性质的影响。结果表明：再生水灌溉对土壤扩散率和饱和导水率的影响与连续灌溉再生水的次数有关，短时间灌溉有降低的作用，但随着灌溉次数的增加，土壤扩散率和饱和导水率有增加的趋势；同时，随着灌溉次数的增加，土壤pH值降低，土壤有机质和全盐量增加；土壤溶液中各离子浓度有显著变化。灌溉5次之后，除0～10cm土层全盐量为0．107％外，其他各层均低于0．1％的限度；0～10，10～20，30～40cm土层的ESP均在5％～10％范围之内，20～30cm土层的ESP基本保持在原始的水平。再生水灌溉对土壤次生盐渍化的影响不显著。     

Field and laboratory approaches for determining sodicity effects on saturated soil hydraulic conductivity

Dilution of high-sodicity soil water by low-sodicity rainfall or irrigation water can cause declining soil hydraulic conductivity (K) by inducing swelling, aggregate slaking and clay particle dispersion. Investigations of sodicity-induced reduction in K are generally restricted to repacked laboratory cores of air-dried and sieved soil that are saturated and equilibrated with sodic solution before tests are conducted. This approach may not yield a complete picture of sodicity effects in the field, however, because of loss of antecedent soil structure, small sample size, detachment of the sample from the soil profile, reliance on chemical equilibrium, and differing time scales between laboratory and field processes. The objectives of this study were to: (i) compare the electrical conductivity (EC), exchangeable sodium percentage (ESP), and sodium adsorption ratio (SAR) in laboratory cores of intact field soil that had, or had not, undergone prior saturation and equilibration with sodic solution; (ii) compare the pressure infiltrometer (PI) field method with the intact laboratory soil core (SC) method for assessing sodicity effects on saturated soil hydraulic conductivity; and (iii) characterize hydraulic conductivity reduction in a salt-affected sandy loam soil and a salt-affected clay soil in Sicily as a result of diluting high-sodicity soil water with low-sodicity water.In terms of EC, ESP and SAR, quasi-equilibrium between soil and infiltrating solution was attainable in 0.08 m diameter by 0.05 m long laboratory cores of intact clay soil, regardless of whether or not the cores were previously saturated and equilibrated with solutions of SAR=0 or 30. In the sandy loam soil, the PI and SC methods produced statistically equivalent linear reductions in K as a result of diluting increasingly sodic soil water (SAR=0, 10, 20, 30) with deionised water. In the clay soil, the PI method produced no significant correlation between initial soil water SAR and K reduction, while the SC method produced a significant log-linear decline in K with increasing soil water SAR. Sodicity-induced reductions in K ranged from 3–8% (initial soil water SAR=0) to 85–94% (initial soil water SAR=30) in the sandy loam, and from 9–13% (initial soil water SAR=0) to 42–98% (initial soil water SAR=30) in the clay. The reductions in K were caused by aggregate slaking and partial blocking of soil pores by dispersed clay particles, as evidenced by the appearance of suspended clay in the SC effluent during infiltration of deionised water. As a result, maintenance of K in these two salt-affected soils will likely require procedures to prevent or control the build-up of sodicity.     

黄河三角洲柽柳周边土壤钠吸附比分布特征及影响因素分析

  目的  黄河三角洲是极具特色的滨海盐生湿地,为探究该区域关键木本植物柽柳周围土壤钠吸附的特征及其影响因素。  方法  运用同心圆布点采样和相关分析等方法,对黄河三角洲柽柳周边土壤盐分离子、钠吸附比的空间分布及离子相互关系进行了分析。  结果  Cl?和Na+是柽柳周边土壤盐分构成的主要离子。Na+、Cl?和Mg2+在距离柽柳较近的表层土壤中含量较少,其含量随土壤深度增加而上升,呈现底聚现象,在距离柽柳较远的土壤中呈现表聚现象。Ca2+、SO₄2?和K+的表聚现象不受距离柽柳远近的影响。相关分析表明,柽柳周边土壤钠吸附比与Cl?、Na+、K+和Mg2+离子关系密切,与Na+的相关性最强。在0 ~ 40 cm土层中,距离柽柳100 cm以内的钠吸附比远低于150 cm以外区域。钠吸附比的变异系数随土层加深而减小,深层土壤钠吸附比与盐离子的相关性均不显著。  结论  柽柳对钠吸附比的影响在100 cm以内的0 ~ 40 cm土层中更为显著。土壤盐分与钠吸附比的空间分布受柽柳冠幅范围、植物根系吸收、凋落物堆积和降水淋溶等作用的影响。     

亚热带土壤导水特征对钠盐溶液浓度的响应

再生水中高浓度钠盐溶液入渗对土壤水力特性的影响是长期低质水灌溉引起土壤生态环境退化的关键问题之一。该文采用定水头渗透法、一维水平土柱吸渗法测定不同浓度钠盐溶液条件下亚热带地区黏性潮土、沙性潮土、红壤、水稻土、紫色土共5种土壤的水动力学参数,分析了土壤理化性质和钠盐溶液浓度对土壤导水特征的影响及其作用机制。结果表明:土壤粉粒、交换性钙及交换性镁含量具有促进土壤水分运动的作用,而土壤黏粒、交换性铁及交换性铝含量则表现出抑制作用。与蒸馏水处理相比较,钠盐加快了土壤水分黏性潮土、沙性潮土及水稻土中的土壤水分运动速率,分别可最高提升其土壤水分扩散率为22.0%、37.3%、39.7%;钠盐减缓了红壤和紫色土的水分扩散速率,溶液钠盐浓度越高,其抑制作用越明显。土壤饱和导水率随溶液盐浓度升高呈先降后升的趋势,1~10 g/L钠盐浓度范围内土壤饱和导水率与钠盐浓度具有良好的抛物线关系(R^2>0.807),各土壤导水率最小极值点的钠盐浓度在5 g/L左右。因此,再生水灌溉利用时其盐浓度适度控制低于其极值点浓度。     

Effectiveness of Pyrites in Reclaiming Sodic Clay Soil under Laboratory Conditions

In a laboratory experiment pyrites at the rate equivalent to 75% of gypsum requirement was surface applied and mixed with a sodic black clay soil (Vertisol) at 15, 30, 45 and 60% soil moisture content. The soil samples were then incubated for 60, 120, 240 and 360 hours. A separate set of similarly treated soil packed in permeameters was used to estimate saturated hydraulic conductivity. After incubation, FeS₂ was oxidised, soil pH and percentage of exchangeable sodium (ESP) decreased and water soluble sulphate and calcium increased with soil moisture content up to 45% and with time of incubation up to 120 hours. The surface application of pyrites proved superior as compared to mixed with soil. Leaching of the soil following incubation with three pore volumes of demineralised water removed most of the water soluble sodium and thus improved the effectiveness of the pyrites in lowering down the soil ESP. The saturated hydraulic conductivity also increased as a result of improved physico-chemical properties of the soil.     

废水灌溉对芦苇地土壤水文特征的影响

为研究造纸废水灌溉对黄河三角洲内陆盐碱芦苇地土壤水文特征的影响,通过设置芦苇地不同废水灌溉次数下的随机区组试验,采用田间测量土壤入渗过程和实验室内测定水文物理参数相结合的方法,分析造纸废水灌溉前后土壤pH值、含盐率及土壤水文物理参数的变化。结果表明：1）废水灌溉后,土壤pH均值降低6.0%;废水灌溉1～2次,土壤含盐率降低11.7%,废水灌溉3～4次后,增壤含盐率增加12.6%。2）废水灌溉后土壤体积质量均值减小6.5%,总孔隙度均值增大18.1%;随着废水灌溉次数的增多,土壤体积质量和总孔隙度分别有减小和增大的趋势。3）Horton模型比较适合描述废水灌溉后芦苇群落的土壤入渗过程,废水灌溉降低了初渗率,但随着废水灌溉次数的增多,稳渗率增加明显。4）废水灌溉增强了土壤贮蓄水分的能力,废水灌溉3次吸持贮水量达到最高（90.15 mm）,灌水4次滞留贮水量达到最高（4.51 mm）。与未灌溉相比,废水灌溉具有明显的压碱抑盐、改良土壤水文物理性状、提高土壤入渗和贮水能力的作用,但不同灌溉次数处理间差异性显著。该研究为黄河三角洲内陆盐碱地区芦苇群落在造纸废水灌溉下的适宜灌溉次数和灌溉水量的确定提供了科学依据,有利于造纸废水资源的合理化开发利用。     

Changes in selected soil physical properties caused by sodicity of soil and irrigation water

Abstract

Sodic water and spring water percolated through clay, clay loam, and sandy loam (SL) soils with exchangeable sodium percentages (ESPs) of 0, 10, 30, and 50. Reduction in saturated hydraulic conductivity and water stable aggregates recorded at higher ESPs. At ESP ≈30, application of sodic and spring water to clay soil (C) reduced saturated hydraulic conductivity from 1.2 to 3 mm hr^?1, whereas in SL soil, the values were 2.8 and 6.2 mm hr^?1, respectively. Results indicated that at any ESP and water source, the highest free swelling obtained was in the C soil. This study has practical importance to the management of irrigation water quality with respect to soil deterioration.