The effect of sodium and calcium on physical properties and micromorphology of two red-brown earth soils

The effect of treatment with either gypsum or sodium chloride on the saturated hydraulic conductivity ( K _s) of repacked soil columns and modulus of rupture (MOR) was studied on surface samples of two red-brown earth soils from SE wheat belt in Australia.
When the exchangeable sodium percentage (ESP) of the two soils was increased to >80, K _S was substantially reduced and MOR increased relative to the untreated soil; the values of the parameters were nearly equal for these pairs of high ESP soils. However, after treatment with gypsum the Raywood soil had a K _s twice, and a MOR less than half, the corresponding values for the Glenloth soil.
Micromorphological and scanning electron microscope (SEM) observations suggest that the increase in K _s following gypsum treatment is associated with an increase in visible macropores and reduced clay dispersion; Na treatment increased dispersion at the soil surface, with the clay particles forming an impermeable surface seal and illuviation argillans.     

Amelioration on some physical properties and nutrient availability of an exposed B horizon of red-brown earth

Abstract. Following removal of the upper 40 cm of soil, the physical properties of the exposed B horizon of a red-brown earth (Goulburn clay loam) were ameliorated using a combination of gypsum (5.4 ha⁻¹) and rye grass. Phosphorus (P), nitrogen (N) and potassium (K) fertilizers were added to improve nutrient availability. The ameliorated properties of the exposed B horizon were compared with those of equivalent depths from an adjacent intact profile of Goulburn clay loam.
Initially, during the establishment phase of the rye grass, the gypsum increased the electrolyte concentration in the 0–10 cm layer, and stabilized the soil surface against mechanical dispersion. After 18 months all the gypsum in the 0–10 cm layer had dissolved. However, in the presence of rye grass, the soil surface was no longer susceptible to dispersion by the mechanical impact of water. The rye grass improved soil physical properties mainly in the upper 20 cm of the exposed B horizon. Water-stable aggregation > 2000 μm and macroporosity increased, and bulk density and penetrometer resistance of the soil decreased.
Continuous applications of P, N and K fertilizers resulted in a gradual improvement in the nutritional properties of the exposed B horizon. However, because of the large phosphorus adsorption by the exposed clay, 300 kg P ha⁻¹ was required to provide sufficient available phosphorus in the 0–10 cm layer.     

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.     

The effect of speed of wheeling on soil stresses, rut depth and soil physical properties in an ameliorated transitional red-brown earth

Soil stress measurements were made in an ameliorated transitional red-brown earth (Natric Palexeralf) during one pass of a heavily loaded (4 t) wheel. Different speeds (up to about 8 km h⁻¹ and soil water contents (close to the lower plastic limit) were used for measurements of total stress, final bulk density, air permeability and rut depth. Effective stresses appeared to decrease with speed. Increases of total stress caused by extra fluid pressure (i.e. pore-water pressure) at 20-cm depth were associated with fast deformation rates of the soil (up to about 3 m s⁻¹) just behind the leading edge of the tyre contact area. Shear stress changed very little with speed. Equations relating speed and water content to rut depth and resultant bulk density were also found. These predicted approximately 10% less mean rut depth or bulk density at 20-cm depth by increasing speed from 0.5 to 10 km h⁻¹ over this soil at water contents near the lower plastic limit.     

Effects of conservation tillage on hydraulic properties of a Griswold silt loam soil

The effects of conservation tillage (CT) systems on crop production and erosion control have been well documented, but limited information is available concerning the effects of different CT systems on the hydraulic properties of layered soils. The effects of three CT treatments: chisel (CH), no-tillage (NT) and till-plant (TP) as compared with conventional modlboard plowing (CN) were investigated on a Griswold silt loam soil (Typic Argiudoll), formed in loess overlaying glacial till. Hydraulic properties were determined in situ. In addition, hydraulic conductivity was determined in the laboratory where more detailed hydraulic conductivity changes were monitored for the lower soil moisture tension range near soil saturation.

At or near saturation, there was no difference in hydraulic properties for all four tillage treatments. For example, mean saturated hydraulic conductivities (from laboratory determination) were 25.5, 25.1, 24.2 and 22.8 cm day⁻¹ for CN, CH, TP and NT, respectively. However under unsaturated conditions, tillage treatments and soil layering (discontinuity between surface loess and glacial till beneath) affected hydraulic properties. In situ hydraulic conductivity (K) ranked CH>CN = NT = TP for the 0.32–0.33 m³ m⁻³ moisture content range. There were no differences in K for all treatments at other moisture ranges considered and at moisture contents 0.31 m³ m⁻³, in situ specific moisture capacity was, however, significantly lower in NT than in the other three treatments. Throughout the 20-day free drainage period for in situ K determination, the effect of layering is exhibited by the mean K values at the 50-cm depth being higher than those at 25 cm. There were negligible treatment-block interaction effects on the hydraulic properties as the soil became drier. Spatial variability in hydraulic properties was also noted for all treatments and soil depths considered.     

Effects of dolomite and gypsum on weeds

Abstract

Liming is recognized by most growers in the United States as an essential part of crop production on acid soils. Greenhouse and field studies were conducted on a sandy, siliceous, hyperthermic Ultic Hapliquod (Pomona fine sand) soil to determine the effects of dolomitic limestone and gypsum on weed populations. Under greenhouse conditions, addition of dolomite increased weed populations in pots of soil. Optimum conditions for weed growth occurred at pH 5.3 to 5.5. At pH levels greater than 5.5, weed populations were stable or showed a general decrease in number. Under field conditions, dolomite and gypsum were applied prior to plantings of three different grass species (stargrass, bahiagrass, and annual ryegrass). Addition of dolomite reduced weed populations because of a more favorable soil pH for rapid grass growth. Competition from the grasses was greater at a pH level near 5.8 to 6.0, whereas greatest weed numbers occurred at a pH of 4.8 to 4.9. Results of these studies indicate that liming is needed on acid soils for optimum crop growth, and that crops need to be established quickly as weeds are encouraged at a higher pH (5.3–5.5). Nomenclature: Stargrass, Cynodon nlemfuensis Vandersyst. var. nlemfuensis ‘Florona'; bahiagrass, Paspalum notatum Flugge ‘Pensacola'; annual ryegrass, Lolium multiflorum Lam. ‘Gulf.     

生物炭添加对矿区压实土壤水力特性的影响

中国黄土高原大型露天煤矿开采导致土壤质量下降,生物炭作为环境友好型土壤改良剂,在改善农田土壤质量中应用广泛,但在有关矿区压实土壤改良的研究中不够深入。为此,该研究通过室内试验分析不同粒径的生物炭在不同添加量下对矿区排土场压实土壤水力特性的影响。试验采用4种粒径（>1～2、>0.25～1、0.10～0.25、<0.10 mm）与4种添加量（0、4、8、16 g/kg）的生物炭,设计5种压实条件（容重分别为1.3、1.4、1.5、1.6、1.7 g/cm3）,并利用van Genuchten模型（VG模型）拟合土壤水分特征曲线。结果表明,添加生物炭后土壤水分特征曲线的相关系数均在0.960以上,标准差均小于0.015,说明VG模型适用于拟合添加生物炭后的土壤水分特征曲线。随着生物炭添加量的增加,土壤孔隙分布明显改变,形成了大量大孔隙和中孔隙,土壤的持水能力提高。在低容重（1.3、1.4 g/cm3）条件下,生物炭粒径越大（0.25～2 mm）添加量越高（8、16 g/kg）,土壤持水、保水效果越明显;在高容重（1.5、1.6、1.7 g/cm3）条件下,小粒径（<0.25 mm）和较低的生物炭添加量（4、8 g/kg）则表现出较好的持水能力。对于不同压实条件的排土场土壤,有针对性地施用生物炭,将有效提高土壤持水保水能力,提高土壤中植物的有效利用水分。     

污灌条件下土壤碱度、石膏施用以及污水过滤处理对水力传导度的影响

污水是淡水资源缺乏地区农业灌溉的重要水资源之一。该文通过室内土柱淋洗试验，研究了污水灌溉条件下土壤碱度、脱硫石膏施用以及污水过滤处理对土壤水力传导性能的影响。试验结果显示，土壤饱和水力传导度随淋出液体积的增加而减小。非碱性土壤的稳定水力传导度比碱性土壤(可交换钠百分比约为30)的大74%左右。脱硫石膏的施用降低了碱性土壤的pH值以及土壤溶液的钠吸附比。0.5%的石膏施用量可增大碱性土壤的稳定水力传导度37%左右。污水过滤处理增大了非碱性土壤的初始水力传导度，而降低了碱性土壤的初始水力传导度。在污水灌溉条件下，石膏施用可有效地改善碱性土壤的水力传导能力。     

Effects of consecutive applications of gypsum in equal,increasing, and decreasing quantities on soil hydraulic conductivity of a saline‐sodic soil

The objective of this study was to determine the effects of consecutive application of gypsum dissolved in leaching water on hydraulic conductivity of a saline‐sodic soil. Drainage type plastic columns with a 10 cm diameter were used in this laboratory experiment. Soil depth within columns was 30 cm with an average bulk density of 1.38 g cm^–3. Leaching water was applied in six equal portions. Total gypsum was applied at 1, 3, and 5 portions after dissolving in leaching water. In dissolution, equal (1.273 + 1.273 + 1.273 Mg ha^–1), increasing (0.637 + 1.273 + 1.910 Mg ha^–1) and decreasing (1.910 + 1.273 + 0.637 Mg ha^–1) quantities of gypsum were used. Results were compared with the control treatment, in which total amount of gypsum were mixed with surface layer of soil column before leaching. Hydraulic conductivity of soil increased in all treatments. The maximum hydraulic conductivity value was obtained at consecutive application of gypsum at decreasing quantities.     

Effects of cover crops on soil hydraulic properties during commodity crop growing season

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 (K_sat) 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.     

低盐再生水灌溉对亚热带红壤水力特性及微观结构的影响

低盐再生水是一种回用潜力巨大的替代性水源,为探究其灌溉亚热带红壤的适宜性,该研究以校园生活污水为再生水水源,设置再生水单一灌溉（WW）、再生水与蒸馏水交替灌溉（AWW）两种灌水模式,并以蒸馏水单一灌溉（CK）为对照。通过室外模拟土柱试验,研究了低盐再生水不同灌溉模式下红壤的盐碱度、微观结构及水力特性,并探讨了三者之间的相互作用关系。结果表明：1）低盐再生水灌溉降低了红壤的持水能力和导水能力;2）与CK处理相比,低盐再生水灌溉导致红壤田间持水率和凋萎系数降低,有效水在WW处理下增加6.33%,在AWW处理下减小27.85%;3） 两种低盐再生水灌溉模式下土壤大孔隙均增加,而有效孔隙、微小孔隙在WW处理下分别增加1.3%、5.0%,在AWW处理下分别减小4.3%、1.1%;4）与CK处理相比,低盐再生水灌溉使红壤电导率（Electrical Conductivity,EC）和Na+含量显著提高,而交换性阳离子总量（Cation Exchange Capacity,CEC）显著降低（P<0.05）。再生水两种灌溉模式中,AWW处理下土壤交换性钠百分比（Exchangeable Sodium Percentage,ESP）和钠吸附比（Sodium Adsorption Ratio,SAR）分别显著高于WW处理142.4%、120.3%（P<0.05）,从而引起更强烈的土壤黏粒分散;5）田间持水率、凋萎系数、有效水及有效孔隙和微小孔隙比例均与交换性Na+、ESP、SAR呈显著负相关,与CEC呈显著正相关。综上,低盐再生水灌溉亚热带红壤宜选择单一灌溉模式,且应定期监测土壤SAR和ESP等指标。研究结果可为再生水水质标准和灌溉制度制定提供参考。     

Consequences of slotting on the pore characteristics of a sandy soil in northeast Thailand

In the sandy soils of northeast Thailand, root development is generally limited to the topsoil (0–20 cm depth) but a simple slotting intervention (20–40 cm) significantly increased the root frequency in the slotted material (E_slot) compared with the undisturbed subsoil (E horizon). The aim of this study was to investigate the consequences of slotting on the soil structure by analysing at different scales the pore characteristics of the original soil profile and of the soil material inside the slot. These characteristics were studied using bulk density measurements, image analysis of thin sections and mercury porosimetry. Our results showed that the total porosity of the E horizon and E_slot material was similar when measured in 100 cm³ cylinders, but that the pore size distribution had been changed by slotting. The unaltered E horizon contained mainly small pores characterized by a narrow distribution related to close packing of the sand grains, associated with some biological macropores probably with poor continuity as they did not contain roots despite their size. On average, pores were larger in the E_slot material, with a broader distribution resulting from looser packing of the sand grains but with fewer biological macropores. Although slotting reduced the number of biological pores, the looser packing appeared to be more favourable to root development than the presence of macropores in the E horizon. Finally, the comparison of the porosity in the different horizons with the porosity of the E_slot material, indicated the significance of the closeness of the sand packing on root development.     

施用生物炭对紫色土坡耕地耕层土壤水力学性质的影响

该研究通过野外坡耕地小区施用1%秸秆生物炭1年后的对比试验,揭示生物炭对川中丘陵区紫色土耕作层土壤水力学参数、大孔隙度及其对饱和导水率的贡献率所产生的影响。试验设对照区与施用生物炭区2个处理,各处理有3个平行小区,耕作层土壤分为表层和亚表层(2~7和7~12 cm)。比较2个处理小区试验结果,可以发现:1)施用生物炭导致植物难以利用的土壤滞留水和易流失的结构性孔隙水的含量(θstr)下降,而基质性孔隙中植物有效水含量显著提高(P0.05),由(0.058±0.003)cm3/cm3增加至(0.085±0.002)cm3/cm3;2)表层和亚表层土壤中对产流起主要贡献的半径125μm的总有效孔隙度分别平均增加54%和8%,其中孔径500μm的孔隙增加最为明显,高达110%和355%;3)表层和亚表层土壤的饱和导水率分别平均增加45%和35%。研究证明,施用生物炭,一方面,能增加土壤有效水的持水量,有利于植物抗旱;另一方面,提高土壤导水率,有利于水分入渗,从而减少地表径流及土壤侵蚀的发生。     

泵轮叶片削剪对液力变矩器性能的影响

削剪泵轮叶片是优化液力变矩器性能的一种手段。为了研究泵轮叶片削剪程度对液力变矩器性能的影响规律,该研究基于计算流体动力学,采用应力混合涡湍流模型（stress-blended eddy simulation,SBES）对液力变矩器内部流场进行仿真模拟,依托外特性试验验证仿真结果的准确性。通过Q准则涡识别方法,甄选合适阈值重构叶片削剪前后泵轮流道三维涡系结构,定性分析多尺度涡动力学特性,量化提取二维流场图谱信息,揭示流速场时空演化规律。结果表明：泵轮叶片设计流线从出口处经过10%、20%和30%的削剪后,液力变矩器的变矩比逐渐增大,由原型变矩器的1.77增大到叶片削剪30%的2.33,泵轮转矩系数降幅明显,由原型变矩器的5.51降低到叶片削剪30%的3.39,叶片削剪10%后变矩比增大4.34%,泵轮转矩系数降低10.73%,降幅明显;随着泵轮叶片削剪程度加剧,叶片对流体的推动作用减弱,流体动能减小,多尺度涡运动趋势衰减,流道中部涡结构特征改变,流道出口高能小尺度“脱落涡”现象减弱;泵轮流道出口流速随叶片削剪程度增大而减小,由原型变矩器的23 m/s降低到叶片削剪30%的19 m/s,泵轮进口流速几乎不变,因进出口流速的变化,泵轮转矩系数降低。研究结果可为液力变矩器叶片设计与性能优化提供指导性建议。     

Change in the hydraulic properties of a Brazilian clay Ferralsol on clearing for pasture

Ferralsols under native vegetation have a weak to moderate macrostructure and a well-developed microstructure corresponding to subrounded microaggregates that are usually 80 to 300 μm in size. The aim of this study was to analyze how the hydraulic properties of a clay Ferralsol were affected by a change of structure when the native vegetation is cleared for pasture. We studied the macrostructure in the field and microstructure in scanning electron microscopy. The water retention properties were determined by using pressure cell equipment. We determined the saturated hydraulic conductivity, K_s, by applying a constant hydraulic head to saturated core samples, and the unsaturated hydraulic conductivity, K(Ψ), by applying the evaporation method to undisturbed core samples. Results showed a significant decrease in the water retained at −1 and −10 hPa from 0- to 40-cm-depth when the native vegetation is cleared for pasture. That decrease in the water retained was related to a smaller development of microaggregation and greater proportion of microaggregates in close packing. For smaller water potential, there was no difference of water retained at every depth between native vegetation and pasture. Pedotransfer functions established earlier for Brazilian Ferralsols and using clay content as single predictor gave pretty good results but the precision of the estimation decreased when the water potential increased. This decrease in the precision was related to the lack of predictor taking structure into account. K_s and K(Ψ) showed an upward trend with depth under native vegetation and pasture. Except at 0–7-cm depth between the Brachiaria clumps in the pasture where smaller K_s and K(Ψ) than at the other depth was recorded whatever land use, we did not record any significant difference of K_s and K(Ψ) at every depth between native vegetation and pasture. The upward trend shown by the hydraulic conductivity with depth was related to the increase in the development of microaggregation with depth.     

Long-term cultivation effects on hydraulic properties of a Walla Walla silt loam

Hydraulic properties of a Walla Walla silt loam were significantly changed by 50 years or more of cultivation under either a wheat-peas rotation (tillage depth 30 cm) or a wheat-summerfallow rotation (tillage depth 15 cm) as compared with no cultivation. Soil pH was reduced to depths as great as 60 cm in the cultivated sites; dry bulk density was increased to depths as great as 40 cm. Expressions of these changes were greater in the wheat-peas rotation because tillage was deeper than in the wheat-summerfallow rotation. Small reductions in soil organic matter were also noted in the cultivated sites. In the 60- to 90-cm depth, all three sites had similar bulk density, pH, cation exchange capacity, soil texture, desorption water characteristic, and hydraulic conductivity. In the upper 40-cm layer the desorption water characteristic showed that cultivation produced more smaller pores at the expense of large pores; in the upper 30-cm layer of the cultivated soils hydraulic conductivity was reduced at least 10-fold for water potentials > −100 cm of H₂O. Steady-state drainage profiles and associated assumptions suggest that long-term cultivation increased the hydraulic gradient in the upper 35 cm, and that the low saturated conductivity of the 0- to 15-cm layer had an overall drying effect on the 15- to 35-cm layer. In the cultivated soils increased runoff and denitrification in the plow layer should both be expected and water relations in the 15- to 35-cm layer should favor microorganisms sensitive to high water potentials. Simulations suggested that long-term cultivation decreased evaporation rates an estimated 40% and in wet soil, increased the drying time needed to attain optimum moisture for tillage.     

Tillage effects on near-surface soil hydraulic properties

The processes for the formation of porosity are thought to differ between tilled and non-tilled cropping systems. The pores are created primarily by the tillage tool in the tilled systems and by biological processes in non-tilled systems. Because of the different methods of pore formation, the pore size distribution, pore continuity and hydraulic conductivity functions would be expected to differ among tillage systems. The objective of this study was to determine effects of three tillage systems — mold-board plow (MP), chisel plow (CP), and no-till (NT) — on hydraulic properties of soils from eight long-term tillage and rotation experiments. Tillage effects on saturated and unsaturated hydraulic conductivity, pore size distribution, and moisture retention characteristics were more apparent for soils with a continuous corn (CC) rotation than for either a corn-soybean (CS) rotation or a corn-oats-alfalfa (COA) rotation. Pore size distributions were similar among tillage systems for each soil except for three soils with a CC rotation. The MP system increased volume of pores >150 μm radius by 23% to 91% compared with the NT system on two of the soils, but the NT system increased the volume of the same radius pore by 50% on one other soil. The NT system had 30 to 180% greater saturated hydraulic conductivity than either the CP or MP systems. The NT system with a CC rotation showed a greater slope of the log unsaturated hydraulic conductivity; log volumetric water content relationship on two of the soils indicating greater water movement through a few relatively large pores for this system than for either the CP or MP systems.     

Surface measurements of the hydraulic properties of a tilled and untilled soil

The surface characteristics of soil can have a profound effect on the hydrology of tilled land. Apposite measurements of the surface hydraulic properties of Plainfield sand (Wisconsin, U.S.A.), a Typic Udipsamment, were used to assess the hydrologic impact of 5 years tillage by either moldboard plow or no-till. The crop was always corn (Zea mays L.). The “mean” pore size (λ_m), weighted in a way relevant to the flow of water through the soil surface, was computed here from saturated and unsaturated measurements of sorptivity (S₀) and hydraulic conductivity (K₀). Disc permeameters of dissimilar radii were used at two unsaturated supply-potential heads of ψ₀=−100 mm and −20 mm to find S₀ (ψ₀) and K₀ (ψ₀). At saturation (ψ₀=0), infiltration rings of contrasting radii were employed. The saturated and unsaturated values for S₀ and K₀ of the plowed soil were either the same as, or greater than the corresponding values for the no-till soil. Combination of the values for the saturated S₀ and K₀ showed that the no-till soil had a λ_m=1.34 (±0.67) mm, while in the plowed soil the “mean” pore size during saturated flow was only 0.19 (±0.18) mm. The large λ_m, and the high coefficient of variation, for the no-till soil was presumed to be related to the macropore network associated with the decay of crop residue in the less-sorptive matrix. The small homogeneous λ_m of both the saturated and unsaturated plowed soil reflects the annual pulverization of the soil surface by tillage.     

小麦玉米秸秆掺土还田量对土壤水分运动特性的影响

为探求小麦、玉米秸秆还田对土壤水分运动特性的影响,利用非饱和导水率测定仪测定土壤水分特征曲线,采用van-Genuchten模型拟合土壤水分特征曲线。试验以不掺加任何秸秆为对照,另设计分别掺加小麦或玉米秸秆的4个处理,掺加量分别为干土质量的1.0%、1.6%、2.25%、3.2%,比较各处理土壤水分运动参数和水分有效性差异。结果表明,掺加秸秆后模型进气值倒数值均小于对照;在秸秆掺加量为1%~2.25%时,形状系数值随着秸秆掺加量的增大而增大,当掺加量为3.2%时反而减小;秸秆的掺入还影响到土壤水分特征曲线的土壤残余含水率和土壤饱和含水率,掺加2种秸秆后,土壤饱和含水率均比未掺时小;土壤残余含水率变化规律与形状系数值一致,掺加小麦秸秆后,土壤残余含水率略低于对照,而掺加玉米秸秆后,土壤残余含水率略高于对照。掺加秸秆能减少土壤重力水19.3%~73.3%,在掺加小麦秸秆3.2%、掺加玉米秸秆2.25%时,土壤中易利用水比例系数最大,分别为26.3%、30.6%,所以通过掺加秸秆能显著提高土壤的保水性。研究可为阐明秸秆还田后土壤水分运动规律提供理论依据。