共查询到20条相似文献，搜索用时 15 毫秒
1.
土壤饱和导水率Ks是最基本的水力参数之一,而已知实验室内其值的确定受土柱尺寸的影响.以关中的塿土为研究对象,在室内,采用定水头法,研究5～30 cm内6个不同土柱尺寸对扰动黏壤土Ka测定的影响.结果表明：随着时间的延伸,Ks逐渐减小,其值最初降幅较大,其后趋于稳定,且在5 ～ 30 cm土柱直径范围内,Ks随着土柱直径的变大,扰动黏壤土的Ks递增,二者线性相关,y=0.000 4x＋0.003 7（R2=0.965 1）.研究结果可为测定Ks合理测定时间段及合理尺寸的选择提供参考. 相似文献
2.
Cover crops (CCs) can improve soil hydraulic properties prior to termination, but their effects on soil hydraulic properties during the growing season are less known. The objective of this study was to investigate the influence of no-till CC on the soil hydraulic properties during the commodity crop growing season in Murfreesboro, USA. The CCs included hairy vetch (Vicia villosa Roth.), crimson clover (Trifolium incarnatum L.), winter wheat (Triticum aestivum L.), winter peas (Lathyrus hirsutus L.), oats (Avena sativa), triticale (Triticale hexaploide Lart.), barley (Hordeum vulgare L.) and flax (Linum usitatissimum L.). The cash crop grown was corn (Zea mays). Soil samples were collected using a cylindrical core (55 mm inside diameter, 60 mm long) at 0–10, 10–20, and 20–30 cm depths during April (prior to CC termination), May, June and July. Results showed that soil bulk density (Db) was 23%, 12%, 11% and 10% higher under no cover crop (NCC) compared with CC management during April – July, respectively. This suggests a lower rate of soil consolidation under CC management even after several rainfall events. Four months after CC termination, macroporosity and total porosity were 306 and 50% higher, respectively, under CC compared with NCC management. Therefore, saturated hydraulic conductivity (Ksat) during July was two times higher under CC management compared with NCC management and this can affect increase water infiltration and conservation during the growing season. Due to CC root-induced improvement in macroporosity, CCs had 64% higher volumetric water content (θ) at saturation during July compared with NCC management. Cover crops can improve soil hydraulic properties and these benefits can persist for up to four months after termination. 相似文献
3.
Understanding the effects of cover crops and tillage on soil physical properties is important for determining soil productivity. This study was conducted at Lincoln University's Freeman Center, USA to evaluate the effects of tillage and cover crop management on soil hydraulic properties. The field site included three replicate blocks in a randomized complete block design with each plot measuring 21.3 m in length and 12.2 m in width. Treatment factors were tillage at two levels(moldboard plow tillage vs. no tillage) and cover crop at two levels(cereal rye(Secale cereal) cover crop vs. no cover crop). Soil samples were collected in late spring/early summer from each treatment at 10-cm depth increments from the soil surface to a depth of 40 cm using cores(76.2-mm diameter and 76.2-mm length). Soil bulk density was 13% lower with tillage compared with no-tillage. Volumetric water content was significantly higher at 0.0 and -0.4 k Pa pressures with tillage compared with no tillage. Tillage increased the proportion of coarse mesopores by 32% compared with no tillage, resulting in 87% higher saturated hydraulic conductivity(K_(sat)). Cover crop increased the proportion of macropores by 24% compared with no cover crop; this can potentially increase water infiltration and reduce runoff. As a result of higher macroporosity, Ksat was higher under cover crop compared with no cover crop. This study demonstrated that tillage can benefit soil hydraulic properties in the short term, but these effects may not persist over time. Cover crops may slightly improve soil hydraulic properties, but longer term studies are needed to evaluate the long-term effects. 相似文献
4.
研究典型植被类型的土壤饱和导水率(Ks)分布及其影响因素,可为北京山区植被建设提供有力借鉴,同时加深对于土壤水分运动的理解。选取北京山区最具代表性的4种植被类型,获取不同类型、不同层次的土壤饱和导水率,调查土壤理化性质与根系生物量、石砾体积,利用Pearson相关性分析、多元逐步回归、通径分析,明晰了北京山区典型植被类型下的土壤饱和导水率分布及其影响因素。结果表明:(1)土壤饱和导水率介于0.05~2.23 mm/min,属于高度变异,随土层向下不断减小,侧柏×灌木混交林、侧柏纯林与侧柏×五角枫混交林的土壤饱和导水率存在显著差异(p＜0.05)。土壤饱和导水率与土层深度之间的关系符合对数函数关系式y=±aln x+b,R2≥0.858。(2)相关性分析结果表明,土壤饱和导水率与容重、总孔隙度、毛管孔隙度、根系生物量、有机质含量均呈极显著相关关系(p＜0.01),与非毛管孔隙度、自然含水率呈显著相关关系(p＜0.05)。(3)逐步回归分析得Y=3.42X2+0.78X6-1.333,R2=0.862。进一步通径分析可知,根系生物量主要通过直接作用影响土壤饱和导水率,而总孔隙度通过间接作用影响土壤饱和导水率。可知,侧柏×灌木混交林的导水性能最佳,后续的植被建设应重点考虑侧柏×灌木混交林,以达到减少径流、涵养水源的目的。 相似文献
5.
Soil compaction and related changes of soil physical parameters are of growing importance in agricultural production. Different stresses (70, 230, 500, and 1000 kPa) were applied to undisturbed soil core samples of eight typical soils of a Saalean moraine landscape in N Germany by means of a confined compression device to determine the effect on (1) total porosity/pore‐size distribution, (2) saturated hydraulic conductivity, and (3) air conductivity to assess the susceptibility towards compaction. Different deformation behaviors after exceeding the mechanical strength particularly resulted from a combination of soil characteristics like texture and initial bulk density. The saturated hydraulic conductivity, as an indicator for pore continuity, was largely affected by the volume of coarse pores (r² = 0.82), whereas there was no relationship between bulk density and saturated hydraulic conductivity. Since coarsely textured soils primarily possess a higher coarse‐pore fraction compared to more finely textured soils, which remains at a high level even after compaction, only minor decreases of saturated hydraulic conductivity were evident. The declines in air conductivity exceeded those in hydraulic conductivity, as gas exchange in soils is, besides the connectivity of coarse pores, a function of water content, which increases after loading in dependence of susceptibility to compaction. A soil‐protection strategy should be focused on more finely textured soils, as stresses of 70 kPa may already lead to a harmful compaction regarding critical values of pore functions such as saturated hydraulic conductivity or air capacity. 相似文献
6.
Biochar has the potential to decrease salinity and nutrient loss of saline soil. We investigated the effects of biochar amendment (0–10 g kg−1) on salinity of saline soil (2.8‰ salt) in NaCl leaching and nutrient retention by conducting column leaching experiments. The biochar was produced in situ from Salix fragilis L. via a fire-water coupled process. The soil columns irrigated with 15 cm of water showed that biochar amendment (4 g kg−1) decreased the concentration Na+ by 25.55% in the first irrigation and to 60.30% for the second irrigation in sandy loam layer over the corresponding control (CK). Meanwhile, the sodium adsorption ratio (SAR) of soil after the first and second irrigation was 1.62 and 0.54, respectively, which were 15.2% and 49.5% lower than CK. The marked increase in saturated hydraulic conductivity (Ks) from 0.15 × 10–5 cm s−1 for CK to 0.39 × 10–5 cm s−1, following 4 g kg−1 of biochar addition, was conducive to salt leaching. Besides, biochar use (4 g kg−1) increased NH4+-N and Olsen-P by 63.63% and 62.50% over the CK, but accelerated NO3–-N leaching. Since 15 cm hydrostatic pressure would result in salt accumulation of root zone, we would recommend using 4 g kg−1 of biochar, 30 cm of water to ease the problem of salt leaching from the surface horizon to the subsoil. This study would provide a guidance to remediate the saline soil in the Yellow River Delta by judicious application of biochar and irrigation. 相似文献
7.
利用国际上具有代表性的9种土壤饱和导水率(Ks)传递函数模型估算了横断山地区贡嘎山不同类型森林土壤的Ks,并与实测数据进行了比较,结果表明,现有模型在横断山地区的拟合结果与实测数据的偏差极大,其在研究区的适用性差。结合研究区土壤含石率偏高的特点,增加土壤石砾含量(粒径>2 mm)作为输入变量,同时选取土壤容重、有机质含量和颗粒分布3种土壤基本特性参数作为输入变量,构建了本区域Ks传递函数模型：Ks=9.48+12.32×BD+0.29×SOM–1.94×GF+2.89×silt–5.34×sand,结果显示,模型预测值与实测值相关系数为0.67,该模型可以作为横断山地区自然林地Ks传递函数使用,从而为山地森林水文过程和自然灾害预警研究提供实用的参数估算工具。 相似文献
8.
该文利用单环入渗的概化解,对不同土地利用方式下烟台棕壤土的饱和导水率进行了研究,同时分析了不同单环直径对求解饱和导水率产生的影响。研究结果表明：草地、裸地和道路的入渗速率、累积入渗量和饱和导水率呈现依次降低的变化趋势,利用直径为20、30和45 cm的入渗环得到的饱和导水率具有明显的差异性。根据求解的饱和导水率计算的累积入渗量非常接近实测值,整体相对误差很小,草地、裸地和道路,在5、7和40 m in后浮动在5%以内;在15、43和55 m in后变化幅度小于1%。20、30和45 cm入渗环累积入渗量计算值的相对误差初始阶段波动较大,随后逐渐趋于平稳。 相似文献
9.
The large dryland area of the Loess Plateau (China) is subject of developing strategies for a sustainable crop production, e.g., by modifications of nutrient management affecting soil quality and crop productivity. A 19 y long‐term experiment was employed to evaluate the effects of fertilization regimes on soil organic C (SOC) dynamics, soil physical properties, and wheat yield. The SOC content in the top 20 cm soil layer remained unchanged over time under the unfertilized plot (CK), whereas it significantly increased under both inorganic N, P, and K fertilizers (NPK) and combined manure (M) with NPK (MNPK) treatments. After 18 y, the SOC in the MNPK and NPK treatments remained significantly higher than in the control in the top 20 cm and top 10 cm soil layers, respectively. The MNPK‐treated soil retained significant more water than CK at tension ranges from 0 to 0.25 kPa and from 8 to 33 kPa for the 0–5 cm layer. The MNPK‐treated soil also retained markedly more water than the NPK‐treated and CK soils at tensions from 0 to 0.75 kPa and more water than CK from 100 to 300 kPa for the 10–15 cm layer. There were no significant differences of saturated hydraulic conductivity between three treatments both at 0–5 and 10–15 cm depths. In contrast, the unsaturated hydraulic conductivity in the MNPK plot was lower than in the CK plot at depths of 0–5 cm and 10–15 cm. On average, wheat yields were similar under MNPK and NPK treatments and significantly higher than under the CK treatment. Thus, considering soil‐quality conservation and sustainable crop productivity, reasonably combined application of NPK and organic manure is a better nutrient‐management option in this rainfed wheat–fallow cropping system. 相似文献
10.
黄土高原坡地表层土壤饱和导水率和水分含量空间变异特征 总被引：8，自引：0，他引：8
表层土壤水分含量和饱和导水率对深层土壤水分的动态的变化具有重要的决定作用。在黄土高原坡地（50m×360 m）范围内进行网格（10 m×10 m）取样,用地统计学方法研究表层（0～30 cm）土壤饱和导水率和水分含量的空间变异特征。结果表明：1）坡地表层土壤密度变化规律为坡下位大于坡上位,土壤饱和导水率变异系数为0.37,属于中等变异强度;2）饱和导水率和自然对数化的饱和导水率在360 m尺度内均不具备空间结构特征,是纯随机变量,线性有基台模型适用于描述表层土壤水分的分布特征,水分分布存在明显的块金效应,并且随滞后距离的增加半方差变大;3）饱和导水率和水分含量从坡上位到坡下位均呈现波浪式变化,饱和导水率大的采样点土壤水分含量低,反之则高。 相似文献
11.
石灰岩与白云岩坡地土壤饱和导水率对比研究 总被引：1，自引：0，他引：1
[目的]对比研究不同下垫面特征和土地利用方式对两类坡地表层土壤性质及其土壤饱和导水率(Ks)的影响。[方法]以喀斯特地区不同岩性下垫面的石灰岩和白云岩两类坡地表层土壤为研究对象,采用Guleph稳定入渗仪和土壤分析的方法。[结果](1)石灰岩和白云岩表层土壤在受到放牧作用影响后,土壤均呈现显著退化趋势,其容重、黏粒含量增大,孔隙度、有机质含量降低。(2)石灰岩和白云岩两类坡地表层土壤在未受到人为干扰的自然植被条件下,由于表层岩溶带的发育,Ks都很高,平均值分别为328.6和257.2mm/h。其中,石灰岩坡地相比白云岩坡地,Ks具有更高的空间变异性,二者Ks变异系数变化范围分别为90.71%~95.62%和59.60%~67.32%。(3)受到放牧作用影响后,石灰岩和白云岩坡地表层土壤Ks相比自然植被状态下呈显著降低趋势,Ks分别降低52.2%和86.7%,白云岩坡地Ks降低程度大,高于石灰岩坡地。 相似文献
12.
13.
Many empirical approaches have been developed to analyze changes in hydraulic conductivity due to concentration and composition of equilibrium solution. However, in swelling soils these approaches fail to perform satisfactorily, mainly due to the complex nature of clay minerals and soil–water interactions. The present study describes the changes in hydraulic conductivity of clay (Typic Haplustert) and clay‐loam (Vertic Haplustept) soils with change in electrolyte concentration (TEC) and sodium‐adsorption ratio (SAR) of equilibrium solution and assesses the suitability of a model developed by Russo and Bresler (1977) to describe the effects of mixed Na‐Ca‐Mg solutions on hydraulic conductivity. Four solutions encompassing two TEC levels viz., 5 and 50 mmolc L–1 and two SAR levels viz., 2.5 and 30 mmol1/2 L–1/2 were synthesized to equilibrate the soil samples using pure chloride salts of Ca, Mg, and Na at Ca : Mg = 2:1. Diluting 50 mmolc L–1 solution to 5 mmolc L–1 reduced saturated hydraulic conductivity of both soils by 66%, and increasing SAR from 2.5 to 30 mmol1/2 L–1/2 decreased saturated hydraulic conductivity by 82% and 79% in clay and clay‐loam soils, respectively. Near saturation, the magnitude of the change in unsaturated hydraulic conductivity due to the change in TEC and SAR was of 103‐ and 102‐fold, and at volumetric water content of 0.20 cm3 cm–3, it was of 1014‐ and 106‐fold in clay and clay‐loam soils, respectively. Differences between experimental and predicted values of saturated hydraulic conductivity ranged between 0.6% and 11% in clay and between 0.06% and 2.1% in clay‐loam soils. Difference between experimental and predicted values of unsaturated hydraulic conductivity widened with drying in both soils. Predicted values were in good agreement with the experimental values of hydraulic conductivity in clay and clay‐loam soils with R2 values of 0.98 and 0.94, respectively. The model can be satisfactorily used to describe salt effects on hydraulic conductivity of swelling soils in arid and semiarid areas, where groundwater quality is poor. 相似文献
14.
15.
土壤水力学性质和功能的变化是评价长期施肥是否维持土壤可持续健康发展的重要方面。该研究通过采取\"国家黄土肥力与肥料效益监测基地\"的表层原状土壤,分析测定了撂荒(LH)、休闲(XX)、不施肥(CK)、单施氮肥(N)、氮磷钾肥(NPK)和有机肥与氮磷钾肥配施(MNPK)6个处理的土壤水分特征曲线、饱和导水率和紧实度等指标,评价了长期定位施肥对土壤基本物理性质和水力学性质的影响。结果表明:1)与CK、N和NPK处理相比,MNPK处理显著提高了土壤有机碳、饱和导水率和孔隙度,而降低了土壤容重和紧实度(P0.05)。2)不同施肥处理之间的土壤水分特征曲线表现出一定的差异,其土壤持水能力强弱为:XXN≈NPKCKMNPKLH;MNPK处理较CK、N和NPK处理持水能力分别提高2.57%、3.33%和7.34%;V-G模型拟合结果表明残余含水量(θ_r)、饱和含水量(θ_s)和进气值倒数(a)都存在一定程度的差异,θ_r在MNPK处理最大,XX最小;θ_s在N处理最大,MNPK次之,CK最小。进气值(1/a)在XX处理最大,LH最小。3)当量孔隙的分布主要在9μm大孔隙范围内,其次是0.2μm小孔隙范围,0.2～9μm之间的中孔隙分布较少。综上,MNPK有助于改善土壤结构,提高土壤持水性,降低土壤容重和紧实度,有助于作物生长和高产,是关中地区较为适宜的施肥措施。 相似文献
16.
为了探究太原东山试验林场不同坡向条件土壤性质及饱和导水率变化的规律,选取东山林场无植被覆盖裸地和油松林地的阳坡、阴坡、半阴半阳坡共6个样地进行土壤采样,测定了土壤基本性质及养分含量,并用环刀分层取土,测定土壤饱和导水率,对比分析了土壤性质、养分及饱和导水率的坡向分异规律。结果表明:坡向对土壤密度无影响;裸地土壤含水率表现为阴坡 > 半阴半阳坡 > 阳坡;油松林地土壤含水率、土壤养分元素含量、土壤饱和导水率表现为阳坡 > 半阴半阳坡 > 阴坡,阳坡表层土壤（0—30 cm）石砾含量少于其他坡向,总孔隙度高于其他坡向。坡向对土壤性质及饱和导水率的影响是通过植被产生作用。在今后对林地土壤性质及水分入渗的研究中不能忽略坡向的影响。 相似文献
17.
Although crop residue management is known to affect near‐surface soil physical quality, little is known about the temporal variability of these indicators over short time intervals. This study evaluates the temporal changes of nine indicators of soil physical quality. These are organic carbon content, structural stability index, bulk density, macroporosity, air capacity, relative field capacity, plant available water capacity, Dexter's S‐index and saturated hydraulic conductivity. A second set of soil physical indicators, based on the distribution of soil pore volume, was also evaluated. The indicators were determined in three different times during the growing cycle of winter durum wheat cultivated within a long‐term field research carrying out in Southern Italy and comparing two types of crop residue management, that is, burning (B) and soil incorporation (I). Only the bulk density changed over time for both treatments, although the air capacity also changed for the incorporation of wheat residues. Residual effects of the autumnal soil tillage and soil compaction were a common source of variability, irrespective of which treatment was used. Based on the existing guidelines for evaluating the physical quality of these agricultural soils, optimal or near‐optimal values were detected in about half of the cases under consideration. This suggests that both B and I create sufficiently good conditions for crop growth during the crop cycle. The comparison between observed and optimal soil pore distribution function was always poor. The pore volume distributions showed lower densities of small pores and relatively higher densities of large pores than the proposed optimal distribution. This study also suggests that the considered optimal or references curves probably cannot be applied successfully to a wide range of agricultural soils. 相似文献
18.
土壤质量、土壤蓄水保肥能力和土壤养分吸收利用与土壤物理性质有密切联系。在甘肃省河西走廊民乐县至高台县自东向西的天然降水梯度上,选择荒漠区的7个研究点对土壤表层(0—20cm)和亚表层(20—40cm)分别采集42个土壤样品,在野外采用张力入渗仪测定饱和导水率,室内采用常规方法对土壤容重、孔隙度、颗粒组成等项目进行了测定。结果表明,在360～100mm的降水梯度上,荒漠土壤粉粒和黏粒含量降低,砂粒含量增加;伴随着土壤的粗粒化,引起土体的风散和结构的破坏,使土壤容重增加、孔隙度降低、持水性能下降等一系列物理性质的恶化。土壤表层、亚表层饱和导水率Ksat和变异系数Cv分别为70.0%和86.3%,均是土壤表层和亚表层各物理性质中变异系数最高的。 相似文献
19.
为研究渝东北紫色土理化性质在垂直空间上的分布情况以及对饱和导水率的影响,进而建立饱和导水率与各理化性质间的关系函数,推求饱和导水率的传递函数,选择渝东北开州区、云阳县等7个区县内45个紫色土典型田块为研究区域,运用Excel 2013和Matlab 2015b软件统计分析后,利用多元非线性回归法推求并验证了渝东北紫色土饱和导水率传递函数模型和模型参数。研究表明:①研究区土壤饱和导水率变化范围在0.16～195.68 cm/d,变化范围广,空间变异系数大,变异性较强;同一采样点深度越大,饱和导水率越小;②土壤饱和导水率与有机质含量有显著的指数函数关系,与饱和含水量有较强的二次函数关系,与土壤容重和土壤颗粒的相关性不大;③本次试验建立的土壤饱和导水率传递函数模型及模型系数检验合格,预测值与实际测算值误差较小,精度良好,可用于渝东北紫色土饱和导水率的预测工作。 相似文献
20.
滨海盐渍土土壤物化性质与水动力学性质变异 总被引：1，自引：0，他引：1
为分析不同梯度盐渍土土壤的物理性质与水动力学性质变异状况,在江苏沿海连云港市徐圩新区开展了试验研究。对5种不同盐渍化级别土壤进行取样,测定其pH、ECe、容重、总孔隙度、含水率和饱和导水率等,分析不同级别滨海盐渍土壤物化特性参数和水动力学性质变化规律。结果表明:(1)不同级别盐渍土0—50 cm剖面土壤ECe先变小后增大,但40—50 cm剖面ECe明显大于0—10 cm剖面。非盐渍土和极重度盐渍土0—50 cm剖面土壤ECe变化较小,轻度盐渍土、中度盐渍土、重度盐渍土的0—50 cm剖面土壤ECe值变化较大。(2)土壤ECe和容重呈极显著负相关关系,与毛管孔隙度、非毛管孔隙度、总孔隙度、含水率、毛管持水量、田间持水量、最大持水量呈极显著正相关关系。土壤孔隙度和持水量呈极显著正相关关系。(3)极重度盐渍土饱和导水率明显小于其他级别的盐渍土,且0—20 cm剖面土壤饱和导水率大于20—50 cm剖面。研究结果可为滨海盐渍土水盐管理和生态环境建设提供理论参考依据。 相似文献