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SOIL PHYSICS

Characterizing Soil Water-Conducting Macro and Mesoporosity as Influenced by Tillage Using Tension Infiltrometry

Departamento de Suelo y Agua, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones, Científicas (CSIC), PO Box 202, 50080 Zaragoza, Spain

^* Corresponding author (david{at}eead.csic.es).

	ABSTRACT

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
Knowledge of soil water conductive porosity is of paramount importance for understanding the water and solute movement in soil. The objective of this study was to describe and evaluate an alternative pore index, i.e., the representative mean pore radius for two consecutive soil water tensions (), for characterizing the water-transmitting macro- and mesoporosity of soil. The hydraulic conductivity (K) and related hydraulic parameters were measured using a tension disk infiltrometer at –14, –4, –1, and 0 cm water pressure heads at a soil depth of 2 cm on a long-term conservation tillage experiment (after 9 yr of trial) under conventional tillage (CT), reduced tillage (RT), and no-tillage (NT) treatments. The soil was loam (Xerollic Calciorthid). The measurements were performed within the first half of a 16- to 18-mo-long fallow period. Unlike the model based on the classical capillary rise theory, which assumes no differences between measurement sites (e.g., tillage treatments) for the corresponding equivalent pore radius (C₀) for macro- and mesopores, significant differences in values for macro- and mesopores were found between the three tillage systems tested. The number of water-transmitting macro- and mesopores per unit area estimated by means of the capillary rise approach was significantly greater than that calculated using the pore index. Although significantly higher values of for both macro- and mesopores were observed under NT, a significantly lower near-saturation K was found under NT than CT and RT treatments due to the lower density of water-transmitting macro- and mesopores.

Abbreviations: CT, Conventional tillage • NT, no-tillage • RT, reduced tillage

	INTRODUCTION

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
The measurement of soil hydraulic properties, which includes the quantification of macropores and preferential flow, is of paramount importance for many soil-related studies involving disciplines such as agriculture, forestry, and hydrology. The characterization of these properties is difficult because of the fragile and transient nature of the soil macropores and the lack of appropriate measurement techniques (Messing and Jarvis, 1993).

In recent decades, the tension disk infiltrometer (Perroux and White, 1988) has become a very popular and valuable device for studying saturated and near-saturated soil hydraulic properties. This is a relatively rapid technique that can be applied in situ. It operates in the near-zero soil water pressure head range, where the soil pores are highly hydraulically active in the transmission of water and solutes (Ankeny et al., 1991). Disk infiltrometer measurements make it possible to calculate the hydraulic conductivity, K, and sorptivity, S (Perroux and White, 1988), and estimate the flow-weighted mean pore radius, (White and Sully, 1987), of undisturbed soils. Watson and Luxmoore (1986) used the disk infiltrometer to estimate the concentration of effective macro- and mesopores on the soil surface. In this case, the minimum equivalent pore radius (C₀) for a given tension range was used to compute the maximum number of effective pores per square meter using Poiseuille's Law for flow in a capillary tube. This approach, however, involves an inconsistency because K is related to the range of pore sizes participating in water transmission, while C₀ relates to the pore size of water storage for a given tension under static conditions (Reynolds et al., 1995). Accordingly, Reynolds et al. (1995) proposed using the representative mean pore radius, , instead of C₀ to estimate the number of water-conductive pores per unit area. More recently, Bodhinayake et al. (2004) have presented a new general equation for water-conducting porosity and derived analytical solutions for the water-conducting porosity based on ponded- and tension-infiltration measurements in conjunction with four commonly used hydraulic conductivity–pressure head functions.

Soil water infiltration is directly affected by the soil tillage management. Tillage and the ensuing compaction can drastically modify the total "hydraulically active" porosity. The tension disk infiltrometer is a valuable tool for studying the effect of soil tillage practices on the soil surface hydraulic properties (Malone et al., 2003). Chan and Heenan (1993) and McGarry et al. (2000), among others, have reported higher infiltration rates under no-tillage than tilled treatments due to the greater number of macropores (Logsdon et al., 1990). Other researchers, by contrast, have found similar (Sauer et al., 1990) or lower (Miller et al., 1998; Evett et al., 1999) values of hydraulic conductivity under the no-tillage treatment. In general, the water flow of structured soils is mainly conducted by macropores even though these constitute only a very small fraction of the total porosity (Sauer et al., 1990; Reynolds et al., 1995; Angulo-Jaramillo et al., 1997; Cameira et al., 2003).

The objective of this study was to propose and evaluate an alternative pore index derived from , the equivalent mean pore radius for two consecutive soil water tensions, , for characterizing and quantifying the water-conductive soil macro- and mesoporosity. To this end, measurements of soil hydraulic conductivity using the disk infiltrometry technique and the corresponding water-conductive pore analysis were performed under three different tillage systems on a long-term conservation tillage experiment in a dryland semiarid cereal-growing field in central Aragon.

	MATERIALS AND METHODS

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
Theory: Soil Water Conductive Porosity
A steady flow from a tension disk infiltrometer can be described by the simplified algebraic expression (Wooding, 1968)

[1]

where Q (m³ s^–1) is the steady-state infiltrating flux when a constant pressure head, (m of water), is applied to the tension infiltrometer membrane, R (m) is the radius of the infiltration soil surface, K (m s^–1) is the hydraulic conductivity, and (m² s^–1) is the matric flux potential (Gardner, 1958) for the infiltration surface, which is defined by

[2]

where _i (m) is the reference soil water potential.

The maximum equivalent pore radius that remains full of water under a given applied pore water pressure , C₀, is defined by the classical capillary rise theory as

[3]

where (g s^–2) is the surface tension of water, (g cm^–3) is the density of water, and g (cm s^–2) is the acceleration due to gravity. In our study, we defined macropores as those pores that drain at > –4 cm (C₀ > 0.375 mm; Clothier and White, 1981) and mesopores as those pores draining at between –4 and –14 cm (0.375 > C₀ > 0.107 mm).

White and Sully (1987) defined the representative mean pore radius, , as

[4]

This pore index represents an effective "equivalent mean" pore radius that conducts water when infiltration occurs at a given value of . However, Reynolds and Elrick (2005) have argued that cannot be an actual physical pore size, but a kind of index of "water conductiveness" that relates primarily to flow impedance and only secondarily to pore size or volume. The representative mean pore radius, , can also be expressed as

[5]

where * = K/ is the slope of the lnK vs. curve (Ankeny, 1992). The constant * value between adjacent settings is one of the main assumptions used in steady-flow analysis using tension infiltrometry (Reynolds and Elrick, 1991; Ankeny et al., 1991). When * is expressed for two consecutive soil water tensions, = _i – _i–1, the representative mean pore radius (Eq. [5]) defined for , , can be expressed as

[6]

where n is the number of measurements performed in a sequence. Note that defines a kind of pore index of "water conduciveness" that relates to the flow impedance for a soil tension range corresponding to a specific "pore size."

Using Poiseuille's Law for flow in a capillary tube, Watson and Luxmoore (1986) defined the maximum number of effective macro- and mesopores per unit area, N_C0, as

[7]

where C₀ is the minimum pore radius for the given soil tension range, and µ (g cm^–1 s^–1) is the dynamic viscosity of water. They likewise defined the effective porosity, _C0, as

[8]

However, as pointed out by Reynolds et al. (1995), this approach introduces a contradiction because K in Eq. [7] is related to the range of pore sizes participating in water transmission, while C₀ relates to the minimum pore sizes of water storage for a given tension range under static conditions. They proposed using the representative mean pore radius, , instead of C₀, to estimate the number of conductive pores per unit area, N, required to produce the measured K (Reynolds et al., 1995) as

[9]

Although N gives a general description of the soil pore concentration with the flow-weighted mean size , (Eq. [9]), this index does not allow us to distinguish the relative contributions of specific pore sizes to the soil water flow. Accordingly, on the basis of the models of Watson and Luxmoore (1986) (Eq. [7]) and Reynolds et al. (1995) (Eq. [9]), we propose the use of (Eq. [6]) to compute the number of effective water-conductive pores per unit of area for two consecutive soil water tensions, N, as

[10]

The effective water-conductive porosity for two consecutive soil water tensions, , can be expressed as

[11]

Note that , which is based on the parameter, is more likely to be dominated by flow impedances (pore tortuosity, roughness, air entrapment, and obstructions) than the pore size or volume effects. Since the physical interpretation of values to describe the total effective macro- and mesoporosity is problematic and perhaps even misleading, the use of should be taken with caution.

The contribution of both macropores and mesopores to the total saturated water flux, K_i (%), can be calculated (Cameira et al., 2003) according to

[12]

where n is the number of measurements performed in a sequence, K_i and K_i–1 the hydraulic conductivity for two consecutive tensions, and K₀ the saturated hydraulic conductivity.

Experimental Site
The site is located at the dryland research farm of the Estación Experimental de Aula Dei (CSIC) in the province of Zaragoza (41°44'N, 0°46'W, altitude 270 m). The climate is semiarid with an average annual precipitation of 390 mm and an average annual air temperature of 14.5°C. Soil at the research site is a loam (fine-loamy, mixed, thermic Xerollic Calciorthid) according to the USDA soil classification (Soil Survey Staff, 1975). Selected physical and chemical properties of the soil were given in López et al. (1996).

The study was conducted on a large block of plots, which were set up on a nearly level area (slope 0–2%) of land in 1991 within a long-term conservation tillage experiment. The field was in a winter barley (Hordeum vulgare L.)–fallow rotation. The study was conducted in the 1999 to 2000 fallow season when the field was in the 16- to 18-mo-long fallow phase of this rotation, which extends from harvest (June–July) to sowing (November–December) the following year.

Three different fallow management treatments were compared: CT, RT, and NT. The CT treatment consisted of moldboard plowing of fallow plots to a depth of 30 to 40 cm in late winter or early spring, followed by secondary tillage with a sweep cultivator to a depth of 10 to 15 cm in late spring. In the RT treatment, the primary tillage was chisel plowing to a depth of 25 to 30 cm (noninverting action), followed as in CT by a pass of the sweep cultivator in late spring. The NT treatment used exclusively herbicides (glyphosate [N-(phosphonomethyl)glycine]) for weed control throughout the fallow season.

The tillage treatments were arranged in an incomplete block design based on geostatistical concepts, with three replications for the RT and NT treatments and four for the CT treatment (López and Arrúe, 1995). In this design, each pair of treatment plots (i.e., CT–RT, RT–NT and CT–NT) forms an incomplete block in three locations. The adverse effects of soil spatial variability are reduced by making short-distance treatment comparisons, and, by keeping this distance constant, it is ensured that all contrasts are made with equal precision. More details about this design and its efficiency can be found in López and Arrúe (1995). In this study, a 7- by 7-m region was delimited within each incomplete block for field measurements at two sampling points, located in front of each other in adjacent plots (i.e., one sampling point per treatment) and separated by a distance of 5 m. In accordance with this sampling scheme, a total of 18 measurements (six per treatment) was made. The size of the basic plot was 33.5 by 10 m, with a separation of 1 m between plots.

To contrast the effects of the tillage treatments on the soil hydrophysical properties, ANOVA for the incomplete block design was used (López and Arrúe, 1995). Duncan's multiple range test was used to compare treatment means. On the other hand, a paired t-test was performed to compare the C₀ vs. , N_C0 vs. N, and _C0 vs. pore indexes for each tillage treatment.

Experimental Measurements
To analyze the soil bulk hydrophysical properties, excluding the soil surface crust effect, field measurements of soil bulk density and hydraulic conductivity were made on the 2- to 10-cm depth soil layer before the primary tillage was implemented in March.

The soil dry bulk density (_b) was determined by the core method using commercial stainless steel cylinders (50-mm diameter by 50-mm height). Core samples were taken at the 2-cm depth near the locations for the hydraulic property measurements. This sampling was made on the same day as infiltration measurements to determine the antecedent soil bulk density and moisture. The volumetric soil water content () was determined from the values for the gravimetric soil moisture (oven drying the soil at 105°C) and the bulk density.

The soil hydraulic properties were characterized at each sampling point using a modified Perroux and White (1988) tension disk infiltrometer with a base radius of 125 mm (Moret et al., 2004). To consider only the effects of tillage on soil water infiltration, the surface crust, clods, and crop residues were removed from the soil surface. To ensure good hydraulic contact between the disk and the soil, a thin layer of commercial sand (80–160-µm grain size) was also poured onto the soil surface. The initial volumetric water content of the contact sand was <0.05 m³ m^–3. The base of the disk was covered with a nylon cloth of 20-µm mesh. Infiltration runs were performed at four values of soil tension, (namely, –14, –4, –1, and 0 cm, applied in this order and at the same place). Flow monitoring continued until steady-state flow from the disk was attained. The flow readings were automatically recorded every 30 s from the drop in the water level of the water supply reservoir of the infiltrometer, using the time domain reflectometry (TDR) application and procedure developed by Moret et al. (2004). To monitor during the water infiltration, a three-wire TDR probe (diameter 2 mm; length 100 mm; spacing between the outermost rods 25 mm) was horizontally inserted into the soil at 4-cm depth beneath the infiltrometer disk before the infiltration test. The TDR measurements for both cumulative infiltration and were synchronously and automatically recorded using the software WinTDR 98 (Or et al., 1998). To this end, the two TDR probes were connected to a multiplexer (Model SDMX50, Campbell Scientific, Logan, UT) (Moret et al., 2004). Steady-state values of beneath the infiltrometer disk at –14 cm of pressure head were not consistent enough. This probably was because the wetting front under the disk infiltrometer did not completely surround the area of influence of the TDR probe when steady state was attained.

The actual water pressure head on the soil surface, _s, was recalculated according to (Reynolds and Zebchuk, 1996):

[13]

where Q(₀) (m³ s^–1) is the steady flow rate out of the tension infiltrometer at a set pressure head, ₀ (m), r (m) is the radius of the contact sand layer, T_cs (m) is the thickness of the contact sand layer, and K_cs (m s^–1) is the saturated hydraulic conductivity of the contact sand layer. In our study, T_cs and K_cs were 0.0015 m and 1.05 10^–4 m s^–1, respectively. The soil hydraulic conductivity, K, at the different soil water pressure heads, _s (i.e., K₁₄, K₄, K₁, and K₀) and the matric potential, , were thus calculated from the cumulative water infiltration using the multiple-head method (Ankeny et al., 1991). The contribution of both macro- and mesopores to the total saturated water flux, K_i (%), was calculated from K₁₄, K₄, and K₀ according to Eq. [12].

	RESULTS AND DISCUSSION

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
Soil Bulk Density
Table 1 shows the soil bulk density (_b) and corresponding values measured in the 2- to 7-cm-depth soil layer for the different tillage treatments. The _b values after 9 yr of continuous NT were greater than those observed for the CT and RT treatments. Greater soil compaction under NT has also been observed in other long-term experiments (Logsdon et al., 1990; Evett et al., 1999; Lampurlanés and Cantero-Martínez, 2003). This is commonly associated with the gradual consolidation of the soil matrix with time owing to rainfall and the absence of annual tillage-induced loosening. The lower values of _b under RT than under CT can be attributed to the greater persistence of the soil loosening after chisel plowing in comparison with moldboard plowing (López et al., 1996).

View this table: [in this window] [in a new window]   Table 1. Average dry bulk density (b) and volumetric water content () of the surface soil (2–7 cm) for conventional tillage (CT), reduced tillage (RT), and no-tillage (NT).

View larger version (17K): [in this window] [in a new window]   Fig. 1. Soil hydraulic conductivity (K) vs. pressure head () relationships for conventional tillage (CT), reduced tillage (RT), and no-tillage (NT). Bars represent the shortest significant difference (P < 0.05) for comparison among tillage treatments where significant differences were found (Duncan's test).

View larger version (19K): [in this window] [in a new window]   Fig. 2. Minimum equivalent pore radius, C0 (Eq. [3], dark points), and representative mean pore radius for two consecutive soil water tensions, , (Eq. [6], white points-) estimated under conventional tillage (CT), reduced tillage (RT), and no-tillage (NT). Macropores are defined as those pores that drain at > –4 cm (C0 > 0.375 mm) and mesopores as those pores draining at between –4 and –14 cm (0.375 > C0 > 0.107 mm). Asterisks indicate significant difference between C0 and (P < 0.05, t-test).

Number of Effective Water-Conductive Pores per Unit Area for Two Consecutive Soil Water Tensions
The number of water-transmitting macro- and mesopores per unit area calculated according to the Watson and Luxmoore (1986) model, N_C0 (Eq. [7]), was significantly greater than that estimated using the N index (Eq. [10]; Fig. 3 ). This is because the pore radius, C₀, used to calculate N_C0 is significantly smaller than the values used for estimating N (Fig. 2). We may thus conclude that, while N_C0 estimates the theoretical maximum number of macro- and mesopores per unit area, N characterizes the actual concentration of the soil's water-conductive macro- and mesoporosity. Differences between N_C0 and N are more evident under NT, where greater differences between and C₀ are found (Fig. 2). The number of water-conductive mesopores per unit area, N, was 99% greater than that calculated for macropores (Fig. 3). As regards the different tillage treatments, significantly lower values of N for mesopores were observed under NT than under the CT and RT systems (Fig. 3).

View larger version (11K): [in this window] [in a new window]   Fig. 3. Maximum number of effective pores per unit area, NC0, (Eq. [7], black points) and number of effective water-transmitting pores per unit area, N, (Eq. [10], white points) for two consecutive water soil tensions measured under conventional tillage (CT), reduced tillage (RT), and no-tillage (NT). Macropores are defined as those pores that drain at > –4 cm and mesopores as those pores draining at between –4 and –14 cm. Asterisks indicate significant difference between NC0 and N (P < 0.05, t-test).

View larger version (12K): [in this window] [in a new window]   Fig. 4. Effective porosity,C0, calculated using the minimum equivalent pore radius (C0) for a given tension range (Eq. [8], dark points) and effective porosity, , computed from the representative mean pore radius for two consecutive soil water tensions, , (Eq. [11], white points) measured under conventional tillage (CT), reduced tillage (RT), and no-tillage (NT). Macropores are defined as those pores that drain at > –4 cm and mesopores as those pores draining at between –4 and –14 cm. Asterisks indicate significant difference between C0 and (P < 0.05, t-test).

Analysis of Representative Mean Pore Radius and Number of Effective Water-Conducting Pores
The and N vs. K relationships for structured soil conditions (Fig. 5 ) were similar to those reported by Reynolds et al. (1995). The effective equivalent mean pore radius, , was relatively constant at its minimum value of about 0.05 mm for low K values, but then increased as K rose to higher levels. This behavior could be the result of constrictions (e.g., pore necks, entrapped air bubbles) and discontinuous pores within the range where is constant (Reynolds et al., 1995). On the other hand, N, which is inversely related to , increases when K decreases (Fig. 5). For all three tillage treatments, and throughout the entire range of , varied between about 0.05 and 0.25 mm, as reported by other researchers (Sauer et al., 1990; Reynolds et al., 1995; Angulo-Jaramillo et al., 1997). Likewise, N values for the three tillage systems varied between 1000 and 17000 pores m^–2 for = 0 and –14 cm, respectively. Both and N were affected by the different tillage treatments. For K₁₄ and K_4, was smaller and N was greater under NT than under CT and RT. These results are consistent with the higher soil bulk density found under NT (Table 1) as a consequence of the gradual consolidation of the soil matrix with time due to rainfall and the absence of annual tillage-induced loosening (Reynolds et al., 1995).

View larger version (21K): [in this window] [in a new window]   Fig. 5. Number of effective water-transmitting pores per unit area (N) and representative mean pore radius () vs. soil hydraulic conductivity (K) under conventional tillage (CT), reduced tillage (RT), and no-tillage (NT).

Contribution of Macropores and Mesopores to the Total Saturated Water Flux
On average and regardless of the tillage system, 75% of the total saturated water flux (Eq. [12]) was controlled by the macropores, and the remaining 16% by the mesopores. As Messing and Jarvis (1993) and Cameira et al. (2003) observed, these results indicate that the soil macropores have a larger influence on water flow than mesopores, even though they are a much smaller fraction of total soil water-conducting porosity. The contribution of macropores to the total saturated water flux under NT (79%) was significantly greater than that observed for the CT (69%) and RT (77%) treatments. In contrast, the contribution of mesopores to the total saturated water flux under CT (21%) was significantly higher than that estimated for RT (15%) and NT (13%).

	CONCLUSIONS

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
This study evaluated an alternative pore index, , to characterize the water-conducting soil macro- and mesopores. The index has been tested under three different soil tillage management conditions in a long-term tillage experiment in central Aragon. The results indicate that is physically consistent. Unlike the Watson and Luxmoore (1986) model, which calculates the maximum concentration of water-conducting macro- and mesopores (C₀) by assuming no differences in pore sizes between tillage treatments, significant differences in were found among the three tillage systems. The concentration of water-transmitting macro- and mesopores estimated by the capillary rise approach (Watson and Luxmoore, 1986) was too high if compared with the number of pores per unit area calculated using the pore index. The soil water-conducting macro- and mesoporosity are more properly characterized using and N instead of and N.

Although the largest values of for macropores were observed under NT, the soil hydraulic conductivity near saturation under NT was significantly lower than under CT and RT, due to the lower density of water-transmitting macro- and mesopores (N). Regardless of the tillage system, the soil water flow at the soil surface was mainly regulated by macropores, even though this pore size represents a very small fraction of total soil porosity.

	ACKNOWLEDGMENTS

 
This research was supported by the Comisión Interministerial de Ciencia y Tecnología of Spain (Grants no. AGF98-0261-C02-02 and AGL 2001-2238-CO2-01 and PNFPI predoctoral fellowship and research contract awarded to D. Moret) and the European Union (FEDER funds). We acknowledge M.V. López, R. Gracia, and M.J. Salvador for their help in various aspects of this study.

	NOTES

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
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Received for publication March 17, 2006.

	REFERENCES

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 

• Angulo-Jaramillo, R., F. Moreno, B.E. Clothier, J.L. Thony, G. Vachaud, E. Fernández-Boy, and J.A. Cayuela. 1997. Seasonal variation of hydraulic properties of soils measured using a tension disk infiltrometer. Soil Sci. Soc. Am. J. 61:27–32.[Web of Science]
• Ankeny, M.D. 1992. Methods and theory for unconfined infiltration measurements. p. 123–141. In G.C. Topp et al. (ed.) Advances in measurement of soil physical properties: Bringing theory into practice. SSSA Spec. Publ. 30. SSSA, Madison, WI,
• Ankeny, M.D., M. Ahmed, T.C. Kaspar, and R. Horton. 1991. Simple field method for determining unsaturated hydraulic conductivity. Soil Sci. Soc. Am. J. 55:467–470.[Web of Science]
• Bodhinayake, W., B.C. Si, and C. Xiao. 2004. New method for determining water-conducting macro- and mesoporosity from tension infiltrometer. Soil Sci. Soc. Am. J. 68:760–769.[Abstract/Free Full Text]
• Cameira, M.R., R.M. Fernando, and L.S. Pereira. 2003. Soil macropore dynamics affected by tillage and irrigation for a silty loam alluvial soil in southern Portugal. Soil Tillage Res. 70:131–140.
• Chan, K.Y., and D.P. Heenan. 1993. Surface hydraulic properties of a red earth under continuous cropping with different management practices. Aust. J. Soil Res. 31:13–24.
• Clothier, B.E., and I. White. 1981. Measurement of sorptivity and soil water diffusivity in the field. Soil Sci. Soc. Am. J. 45:241–245.[Web of Science]
• Evett, S.R., F.H. Peters, O.R. Jones, and P.W. Unger. 1999. Soil hydraulic conductivity and retention curves from tension infiltrometer and laboratory data. p. 541–551. In M.Th. van Genuchten et al. (ed.) Characterization and measurement of the hydraulic properties of unsaturated porous media. Part 1. U.S. Soil Salinity Lab., Riverside, CA.
• Gardner, W.R. 1958. Some steady-state solutions of the unsaturated moisture flow equation with application to evaporation from a water table. Soil Sci. 85:228–232.
• Green, R.T., L.R. Ahuja, and J.G. Benjamin. 2003. Advances and challenges in predicting agricultural management effects on soil hydraulic properties. Geoderma 116:3–27.[CrossRef][Web of Science]
• Lampurlanés, J., and C. Cantero-Martínez. 2003. Soil bulk density and penetration resistance under different tillage and crop management systems and their relationships with barley root growth. Agron. J. 95:526–536.[Abstract/Free Full Text]
• Logsdon, S.D., R.R. Allmaras, L. Wu, J.B. Swan, and G.W. Randall. 1990. Macroporosity and its relation to saturated hydraulic conductivity under different tillage practices. Soil Sci. Soc. Am. J. 54:1096–1101.
• Logsdon, S.D., and T.C. Kaspar. 1995. Tillage influences as measured by ponded and tension infiltration. J. Soil Water Conserv. 50:571–575.
• López, M.V., and J.L. Arrúe. 1995. Efficiency of an incomplete block design based on geostatistics for tillage experiments. Soil Sci. Soc. Am. J. 59:1104–1111.
• López, M.V., J.L. Arrúe, and V. Sánchez-Girón. 1996. A comparison between seasonal changes in soil water storage and penetration resistance under conventional and conservation tillage systems in Aragón. Soil Tillage Res. 37:251–271.
• Malone, R.W., S. Logsdon, M.J. Shipitalo, J. Weatherington-Rice, L. Ahuja, and L. Ma. 2003. Tillage effect on macroporosity and herbicide transport in percolate. Geoderma 116:191–215.[CrossRef][Web of Science]
• McGarry, D., B.J. Bridge, and B.J. Radford. 2000. Contrasting soil physical properties after zero and traditional tillage of an alluvial soil in the semi-arid subtropics. Soil Tillage Res. 53:105–115.
• Messing, I., and N.J. Jarvis. 1993. Temporal variation in the hydraulic conductivity of a tilled clay soil as measured by tension infiltrometers. J. Soil Sci. 44:11–24.
• Miller, J.J., N.J. Sweetland, F.J. Larney, and K.M. Volkmar. 1998. Unsaturated hydraulic conductivity of conventional and conservation tillage soils in southern Alberta. Can. J. Soil Sci. 78:643–648.
• Moreno, F., F. Pelegrín, J.E. Fernández, and J.M. Murillo. 1997. Soil physical properties, water depletion and crop development under traditional and conservation tillage in southern Spain. Soil Tillage Res. 41:25–42.
• Moret, D., M.V. López, and J.L. Arrúe. 2004. TDR application for automated water level measurement from Mariotte reservoirs in tension disc infiltrometers. J. Hydrol. 297:229–235.
• Or, D., B. Fisher, R.A. Hubscher, and J. Wraith. 1998. WinTDR 98, Version 4.0. User's guide. Dep. of Plants, Soil and Biometeorology, Utah State Univ., Logan.
• Perroux, K.M., and I. White. 1988. Designs for disc permeameters. Soil Sci. Soc. Am. J. 52:1205–1215.
• Reynolds, W.D., and D.E. Elrick. 1991. Determination of hydraulic conductivity using a tension infiltrometer. Soil Sci. Soc. Am. J. 55:633–639.[Web of Science]
• Reynolds, W.D., and D.E. Elrick. 2005. Measurement and characterization of soil hydraulic properties. p. 197–252. In J. Alvarez-Benedi and R. Munoz-Carpena (ed.) Soil–water–solute process characterization: An integrated approach. CRC Press, Boca Raton, FL.
• Reynolds, W.D., E.G. Gregorich, and W.E. Curnoe. 1995. Characterization of water transmission properties in tilled and untilled soils using tension infiltrometers. Soil Tillage Res. 33:117–131.
• Reynolds, W.D., and W.D. Zebchuk. 1996. Use of contact material in tension infiltrometer measurements. Soil Technol. 9:141–159.
• Sauer, T.J., B.E. Clothier, and T.C. Daniel. 1990. Surface measurements of the hydraulic properties of a tilled and untilled soil. Soil Tillage Res. 15:359–369.
• Soil Survey Staff. 1975. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. USDA-SCS Agric. Handb. 436. U.S. Gov. Print. Office, Washington, DC.
• Watson, K.W., and R.J. Luxmoore. 1986. Estimating macroporosity in a forest watershed by use of a tension infiltrometer. Soil Sci. Soc. Am. J. 50:578–582.
• White, I., and M.J. Sully. 1987. Macroscopic and microscopic capillary length and time scales from field infiltration. Water Resour. Res. 23:1514–1522.
• Wooding, R.A. 1968. Steady infiltration from a shallow circular pond. Water Resour. Res. 4:1259–1273.

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