Hydraulic Properties of a Sandy Soil at Low Water Contents

Mehta, Brijesh K.; Shiozawa, Sho; Nakano, Masashi

doi:10.1097/00010694-199404000-00002

Cited by 53 publications

(49 citation statements)

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“…This behaviour suggests that large amounts of rain moved quickly through the soils at this time. This is consistent with other studies showing that the vertical hydraulic conductivity of sands increases with soil moisture content (Mehta et al, 1994). For dune sands, these increases can be very rapid at water contents < 10% (Ritsema and Dekker, 1994).…”

Section: Rainfall Amountsupporting

confidence: 93%

“…In general, CV increases as θ decreases. A higher degree of variation at lower water contents illustrates that unsaturated hydraulic conductivity changes rapidly in response to changes in water contents under very dry conditions (Mehta et al, 1994). Soils containing low amounts of water are also more sensitive to evaporation and root water uptake.…”

Section: Rainfall Amountmentioning

confidence: 99%

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Microenvironmental and seasonal variations in soil water content of the unsaturated zone of a sand dune system at Pinery Provincial Park, Ontario, Canada

Ensign¹,

Webb²,

Longstaffe³

2006

Geoderma

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Section: Rainfall Amountsupporting

confidence: 93%

Section: Rainfall Amountmentioning

confidence: 99%

Microenvironmental and seasonal variations in soil water content of the unsaturated zone of a sand dune system at Pinery Provincial Park, Ontario, Canada

Ensign¹,

Webb²,

Longstaffe³

2006

Geoderma

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“…soil compression (Smucker and Erickson 1989), to be the most productive (Håkansson 1966, Johnson et al 1990). This has been proved particularly during drought periods, due to lower volumetric water content (Boone et al 1978, Domzal and and, thus, a weaker unsaturated hydraulic conductivity in loosely packed fine textured soils than under slightly compacted conditions (Kemper et al 1971, Voorhees et al 1979, Mehta et al 1994). On the other hand, soil compaction reduces water conductivity of coarse textured soils at matric potentials between 0 and -60 kPa (Lipiec and Tarkiewicz 1984).…”

mentioning

confidence: 98%

“…AGRICULTURAL SCIENCE This appeared to be a response to an efficient water uptake by plants under compacted soil conditions (Lipiec et al 1988(Lipiec et al , 1992 and low unsaturated hydraulic conductivity (Kemper et al 1971, Voorhees et al 1979 as a result of the lower volumetric soil water contents in loosened soils (Mehta et al 1994). Also Domzal and Hodara (1992) demonstrated this positive effect of soil compactness on volumetric soil water contents for sandy and loamy soils at matric potentials between -1 kPa and -50 kPa, and Reicosky et al (1981) for a clay loam soil at a matric potential below -10 kPa.…”

mentioning

confidence: 99%

“…At a matric potential of -10 kPa, a loose bed held less water on volume basis (31%) than a soil compacted once or four times (axle load 5.6 Mg, moisture slightly below field capacity at compaction), with water contents of 34% and 33%, respectively. According to Mehta et al (1994), this decrease of the volumetric water content in fine sand decreased its unsaturated hydraulic conductivity.…”

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Effect of soil compactness on the growth and quality of carrot

Pietola¹

1995

AFSci

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Field experiments were performed in Southern Finland on three soil types: fine sand (1989-1991), clay (1989) and mull (1990-1991). The following soil mechanical treatments were applied to autumn ploughed land: soil loosening by ridge preparation (ridge distance 45 cm), rotary harrowing (to a depth of 20 cm, clay 15 cm), and soil compaction track by track by a tractor weighing 3 Mg (1 or 3 passes, wheel width 33 cm) before seed bed preparation. One plot was untreated. These treatments were set up in April (on clay in May) under moist soil conditions. Sprinkler irrigation (one application of 30 mm) was applied to clay and fine sand when soil moisture in top soil had decreased to around 50% of plant-available water capacity. PVC cylinders (r = 15 cm, h = 60 cm) were fixed in the experimental areas during the growing periods. At harvest, these cylinders were removed for specific analysis of tap and fibrous roots of carrot. Length and width of fibrous roots were quantified by image analysis in the USA. The impacts of soil loosening and partial compaction were determined by measuring soil physical parameters to a depth of 25 cm in mineral soils, and to greater depths in organic soil. Dry bulk densities of the plough layers increased with increasing tractor passes by 8%, 10% and 13% for fine sand, mull and clay soils, respectively. The lowest dry soil bulk density in the plough layer was obtained by rotary harrowing to a depth of 20 cm. Comparison of gamma ray transmission and gravimetric analysis indicated that dry soil bulk density was slightly lower when determined by gravimetric analysis. Increased soil bulk densities were reflected by increased water retention capacity (matric suction ≤ 10 kPa) and greater penetrometer resistance. Relatively similar increases in bulk density increased the penetrometer resistance much less in mull than in fine sand. In contrast, greater bulk densities in the mull soil affected soil air composition adversely by decreasing the O2 content to 10% when the subsoil had high wetness. In other soils, the lowest soil oxygen contents of 16-18% were recorded in early summer (compacted clay) and during periods of vigorous plant growth (fine sand) when soil water contents were high. Even though the highest degree of soil compactness (D) in a plough layer approached 93 (gravimetric) in all soils, only clay soil was compacted to a soil macro-porosity below 10% (pore diameter > 30 μm). Soil compaction promoted crop establishment and early growth as compared with loose soil beds. Optimum soil compactness for carrot yield (D = 82) was observed only in clay field where excess loosening or compaction affected yield quantity adversely at different stages of growth. During biomass accumulation, excessive penetrometer resistances limited tap root growth in compacted fine sand without irrigation. Water applications promoted shoot growth, but did not affect final shoot and tap root yield. Among the three soil types tested in this study, compaction of mull soil had the least effect on carrot growth and external quality. This paper presents evidence that the internal quality of carrots is only slightly affected by changes in soil physical properties, while the adverse effects of soil compaction on carrot external quality (short, deformed and conical tap roots with greater maximum diameters) are clear. Even though compacted clay soil greatly limited the biomass accumulations in the tap root, which had a high crude fibre content, the carotene (10 mg/100 g carrots) and sugar contents (5%) reached acceptable levels. The lowest carotene contents (4 mg/100 g carrots) were observed in loose mull, following a cool late summer in 1990. The effect of irrigation on carotene content varied from one year to another. High sugar and carotene contents appeared to respond to the high below-ground absorption surface. The fibrous root system of carrots, consisting of mostly very fine roots (diameter 0.15 mm), had total lengths of 150 m in loose fine sand at a soil depth of 0-50 cm (rotary harrowed), 200 m and 300 m in fine sand and mull soils subjected to 3 passes by a tractor wheel. The maximum dry weight (60 μg), length (1.2 cm) and surface area (0.05 cm2) of the fibrous root system per soil volume (cm3) were observed in compacted or irrigated soil to a depth of 30 cm, and also in relation to tap root dry weight. This suggests a capacity of carrot plant for high below-ground absorption potential and optimal biochemial maturation of tap root tissue even when surface soils are compacted. This is supported by higher leaf area, as the early shoot growth was promoted by partial soil compaction. Soil compaction affected the soil physical properties and carrot external quality in agreement with previous studies. Carotene and sugar contents appeared to be unaffected or were slightly increased in riper and firmer carrots of compacted soils. This is consistent with the earlier information about the internal quality of carrot which is shown to be highly dependent on genetic factors and developmental stage of carrot. The present study emphasizes the surface area of carrot fibrous root system as a beneficial factor for maintaining high levels of carotene and sugar contents in tap roots after partial soil compaction.

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Numerical study of evaporation‐induced salt accumulation and precipitation in bare saline soils: Mechanism and feedback

Zhang

Lockington

2014

Water Resources Research

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Evaporation from bare saline soils in coastal wetlands causes salt precipitation in the form of efflorescence and subflorescence. However, it is not clear how much the precipitated salt in turn affects the water transport in the soil and hence the evaporation rate. We hypothesized that efflorescence exerts a mulching resistance to evaporation, while subflorescence reduces the pore space for water vapor to move through the soil. A numerical model is developed to simulate the transport of water, solute, and heat in the soil, and resulting evaporation and salt precipitation with the hypothesized feedback mechanism incorporated. The model was applied to simulate four evaporation experiments in soil columns with and without a fixed shallow water table, and was found to replicate well the experimental observations. The simulated results indicated that as long as the hydraulic connection between the near surface soil layer and the water source in the interior soil layer exists, vaporization occurs near the surface, and salt precipitates exclusively as efflorescence. When such hydraulic connection is absent, the vaporization plane develops downward and salt precipitates as subflorescence. Being more substantial in quantity, efflorescent affects more significantly evaporation than subflorescence during the soil-drying process. Different evaporation stages based on the location of the vaporization plane and the state of salt accumulation can be identified for characterizing the process of evaporation from bare saline soils with or without a fixed shallow water table.

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Hydraulic Properties of a Sandy Soil at Low Water Contents

Cited by 53 publications

References 0 publications

Microenvironmental and seasonal variations in soil water content of the unsaturated zone of a sand dune system at Pinery Provincial Park, Ontario, Canada

Microenvironmental and seasonal variations in soil water content of the unsaturated zone of a sand dune system at Pinery Provincial Park, Ontario, Canada

Effect of soil compactness on the growth and quality of carrot

Numerical study of evaporation‐induced salt accumulation and precipitation in bare saline soils: Mechanism and feedback

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