cover change on soil hydraulic properties and pore characteristics in a semi-arid region of central Iran

Soil & Tillage Research 197 (2020) 104478

Contents lists available at ScienceDirect

Soil & Tillage Research journal homepage: www.elsevier.com/locate/still

Effects of land-use/cover change on soil hydraulic properties and pore characteristics in a semi-arid region of central Iran

T

Eftekhar Baranian Kabira,*, Hossein Basharia, Mehdi Bassiria, Mohammad Reza Mosaddeghib a b

Department of Natural Resources, Isfahan University of Technology, Isfahan, 84156-83111, Iran Department of Soil Science, College of Agriculture, Isfahan University of Technology, Isfahan, 84156-83111, Iran

A R T I C LE I N FO

A B S T R A C T

Keywords: Tension infiltrometer Rangeland Wooding’s analytical method Saturated hydraulic conductivity Macroscopic capillary length Sorptivity

The semi-arid regions of central Iran have vastly undergone the manipulation and conversion of rangelands to dry farmlands. Soil hydraulic properties and pore characteristics may differ in various land-use/cover types. This study evaluated the effects of good and poor rangeland, dry farmland and abandoned farmland on the soil hydraulic properties and pore characteristics in a semi-arid region of central Iran. A completely randomized design was used to analyze the effects of land-use/cover on soil hydraulic properties and pore characteristics. Water infiltration into the soil at inlet matric suction (h) values of 2, 5, 10 and 15 cm was measured using a tension infiltrometer in different land-use/cover types with 18 replications. Wooding's analytical method was used to model the infiltration data and the best-fit values for Gardner’s parameters of macroscopic capillary length (λc) and saturated hydraulic conductivity (Ks) were estimated. Pore characteristics were also estimated using the Watson and Luxmoore method. The results indicated that saturated and near-saturated hydraulic conductivity values [Kh] and λc were significantly influenced by the land-use/cover type. For h < 5 cm, good rangeland and dry farmland had the highest and lowest means of hydraulic conductivity, steady-state flux and sorptivity, respectively. The K values at h lower than 5 cm were found to be as follows: good rangeland > poor rangeland > abandoned farmland > dry farmland. Good rangeland had a greater number of large pore-size class (i.e., > 0.06 cm) and total porosity. Dry farmland and good rangeland had the lowest and highest proportions of large pore-size class (> 0.06 cm), respectively. Inappropriate management practices such as overgrazing of poor rangeland, cultivation and harvesting machinery stress and soil organic carbon decomposition in the dry farmland decreased the frequency of very large pore-size classes (i.e., > 0.15 cm). Although very large and large pores contributed to less than 1% of the soil volume, more than 50% of the total water flow would happen through these pore-size classes. Preserving rangelands in good condition can maintain soil structure and stability and would enhance water infiltration into the soil. These findings can be used by decision makers and land managers for holistic management in ecosystems of semi-arid areas.

1. Introduction Land degradation is the widespread problem of unsuitable change caused by inappropriate land-use and management (Baranian Kabir et al., 2017; Li et al., 2007, 2010). Inappropriate land management can alter the soil infiltration capacity, water retention and hydraulic conductivity which would result in deterioration of soil quality (Hussen and Warrick, 1995; Schnug and Haneklaus, 2002; Zhou et al., 2008). Infiltration is an important phenomenon in the hydrology and ecosystem functions of soil because rainfall on the land surfaces may infiltrate into the soil and increase soil water storage or recharge groundwater resources or may flow overland and cause water erosion. The partitioning process is critically dependent of the physical state of ⁎

soil surface (e.g., soil texture, structure and bulk density) (Hillel, 1998; Sun et al., 2018; Zimmermann and Elsenbeer, 2008). Soil hydraulic properties (i.e., water retention and hydraulic conductivity) are required to characterize water and solute transport processes through unsaturated soils. These include runoff and infiltration, aquifer recharge, nutrient, pesticide and contaminant movement (Bagarello et al., 2005). They are subject to spatial and temporal variability and can be affected by the land-use management, and measurement scale (Martínez et al., 2014; Strudley et al., 2008; Zhou et al., 2008). The effects of land-use/cover changes on the spatial variability of soil hydraulic properties are documented in various studies (Ghimire et al., 2014; Li et al., 2010; Sun et al., 2018). The effects of tillage systems on soil hydraulic conductivity have

Corresponding author. E-mail address: [email protected] (E. Baranian Kabir).

https://doi.org/10.1016/j.still.2019.104478 Received 18 February 2019; Received in revised form 24 August 2019; Accepted 18 October 2019 0167-1987/ © 2019 Elsevier B.V. All rights reserved.

Soil & Tillage Research 197 (2020) 104478

E. Baranian Kabir, et al.

Fig. 1. Location of the study area in central Iran.

proven to be useful, water saving, and repeatable (Reynolds and Elrick, 1991; Ventrella et al., 2005; Watson and Luxmoore, 1986). Although there have been studies on the effects of land-use/cover on soil hydraulic properties (Kelishadi et al., 2014; Zimmermann et al., 2006), its impacts on soil K(h) and pore characteristics remain unclear in tillage management systems. Various rangeland conditions may occur in a given area due to their different managerial and environmental factors (Fraser and Stone, 2016). Rangeland condition refers to the present state of health of the rangeland in relation to what it could be with a given set of ecological conditions. Rangelands with good condition provide considerable forage for livestock and wildlife, and protect soil from accelerated erosion effectively (Holechek et al., 1989). Evaluating the effects of converting good rangelands to poor rangelands and dry farmlands on soil porosity and hydraulic properties are important to conserve environmental sustainability (Alletto and Coquet, 2009; Zeng et al., 2013). Although the effects of land-use change from rangelands to agricultural lands on soil hydraulic properties were investigated (Davudirad et al., 2016; Fraser and Stone, 2016; Kelishadi et al., 2014; Mirhosseini et al., 2018; Owuor et al., 2018), limited studies considered the soil pore characteristics and their contributions to overall water flow. Besides, none of these studies considered hydraulic conductivity and proportion of different soil pore size classes, and their contributions to water flow in rangelands with different conditions and abandoned farmlands. In this study, we intend to compare the soil hydraulic properties in various land-use/cover types in semi-arid areas. We hypothesized that: 1) land-use/cover changes would affect soil hydraulic properties along a rangeland conditions gradient, and 2) hydraulic conductivity and contribution of each pore-size class to water flow are different in various land-uses (e.g. rangeland and dry farmland), and in rangelands with different conditions. Therefore, the main objective of the present study was to characterize the effects of land-use/cover change on soil hydraulic properties and evaluated water-conducting porosity under different land-use/cover types. This study focused on good rangeland condition (with dense vegetation cover), poor rangeland condition (with sparse vegetation cover), dry farmland (converted

been studied in different areas such as a national wildlife area in Canada (Bodhinayake and Si, 2004), an agricultural field in Germany (Schlüter et al., 2018), and forest, pasture and croplands in Kenya (Owuor et al., 2018). Hydraulic conductivity may be significantly different under no-till or minimum tillage as compared to continuouslytilled soils but it depends on climate zone and cultivation history (Bodhinayake and Si, 2004; Buczko et al., 2006; Heard et al., 1988; Miller et al., 1998). Variability of soil hydraulic conductivity (K) can be better understood through the evaluation of soil pores and water flow (Sobieraj et al., 2002). Little research has been done on the changes in soil pore system as an explanation for the variation in soil hydraulic properties (Hu et al., 2009; Zeng et al., 2013). The K is highly controlled by soil macropores, and connectivity and continuity of the macropore network (Buczko et al., 2006). Continuous macropores are water-conducting pores for quick water flow and the ratio of their volume to the total soil volume is termed water-conducting porosity. Better insight into the effects of soil management on hydrological processes can be obtained by examination of water-conducting macropores, as characterized by tortuosity and pore connectivity. A continuous soil pore system can be re-established by plant roots in the absence of annual soil disturbance (Boizard et al., 2002). Zeng et al. (2013) evaluated the impact of alpine meadow degradation on the soil hydraulic properties in Qinghai-Tibetan Plateau, China. They stated that the presence of macropores would basically determine the infiltration capacity in the non-degraded conditions. An accelerated change of soil macropores into mesopores or micropores could occur with increasing soil degradation. In the soil layer of 0–10 cm, a great decrease in macropores has been observed which significantly reduced the proportion of total flow through mesopores and macropores. Tension infiltrometer is a well-known standard device for measuring soil hydraulic properties in order to characterize the effects of land-use change (Bodhinayake and Si, 2004), climate (Das Gupta et al., 2006), tillage practices (Mbuthia et al., 2015), manure application (Miller et al., 2002), and vegetation cover (Holden et al., 2001) on soil structure and macropores. For better understanding how different pore sizes can contribute to the total water flow, tension infiltrometers have 2

Soil & Tillage Research 197 (2020) 104478

E. Baranian Kabir, et al.

the soils are classified as Calcic Kastanozem (IUSS Working Group WRB, 2015). These sites are 2600–2900 m above sea level, with an average slope of 15–30% and located in south geographical aspect. A stratified random sampling method was used to collect samples from the surface soil (i.e., 0–5 and 5–25 cm) for analyzing the effects of land-use/cover on soil properties. At first, the study area was stratified based on landuse/cover types and then six sampling points were selected randomly in each land-use/cover area (as replications) for collection of soil samples. Field measurement and soil sampling were conducted (18 replicates in each land-use/cover type from 0–5 and 5–25 cm layers) in June and July 2014 before precipitation commenced and just after the crops were harvested in dry farmland. This coincided with maximum vegetation cover and density in the rangeland. The study area has good potential for range management but mismanagement (early and high grazing pressure) leads to rangeland deterioration and modification of good rangeland to poor rangeland. Some parts of rangelands in this areas are converted to dry farmlands (more than 30 years ago) by locals and their ecological limitations thereafter lead to dry farmlands abandonment (3–5 years ago) in many cases (Baranian Kabir et al., 2017).

from rangeland more than 30 years ago) and abandoned farmland (released from dry farming 3 to 5 years ago) in Isfahan province in central Iran. 2. Materials and methods 2.1. Study area and soil sampling The study area is located in a part of central Zagros near to the Fereidoonshahr area, 140 km northwest of the city of Isfahan at 32 °38' to 32 °57' N and 49 °58' to 50 °23' E. It covers an area of about 54 000 ha (Fig. 1). The average elevation is 2855 m above sea level; the mean annual precipitation is 538 mm and the mean annual temperature is 10.1 °C (Safaei et al., 2018). Zagros area as a main source of fresh water for agricultural, urban and industrial sectors, is located in the western part of Iran and has undergone the conversion of good rangelands to poor rangelands and dry farmlands by locals. The reason for these conversions is the fact that locals may tend to achieve more and immediate income from harvesting agricultural products of dry farmlands and overstocking in good rangelands that convert them to poor rangelands. In addition, by illegally converting rangelands to dry farmlands, locals will get the right for land acquisition. They did not pay attention to high and valuable ecological services obtained from rangelands (Baranian Kabir et al., 2017). Three sites were selected where each site had relatively homogeneous soil, topography and environmental conditions and contained adjacent examples of the relevant land-use/cover types with relatively similar land-use history. Each site contained rangelands with good and poor conditions, dry farmland (converted from rangeland more than 30 years ago) and abandoned farmland (released from dry farming 3 to 5 years ago) with at least 5 ha size each (Fig. 2). Rangeland with good condition was characterized by dense vegetation cover and regeneration of perennial, palatable and productive plant species and low soil erosion. Rangeland with poor condition had sparse vegetation cover of annuals and unpalatable species with high soil water erosion based on visual observations. This land-use/cover was found in areas close to villages and watering points where it experienced heavy grazing pressure and high trampling intensity. Dominant soil textural class in the study area is sandy clay loam and

2.2. Field measurements and methods 2.2.1. Infiltration measurements and modeling using Wooding’s (1968) analytical method The surface soil hydraulic conductivity and infiltration properties were determined using a tension infiltrometer with a disk 20 cm in diameter (Soil Measurement Systems LLC, Tucson, Arizona). This type of tension infiltrometer has been used in previous studies for the determination of soil hydraulic properties. Details of preparation of the disk tension infiltrometer and measurement procedure are described in Kelishadi et al. (2014). Matric suctions (h) of 15, 10, 5 and 2 cm were sequentially applied during the infiltration measurements in all replications. Cumulative water infiltration was measured vs. time with 20–30 s intervals, and then with 1 min intervals up to when the steady-state flux condition was reached. The steady-state flux condition was achieved when the increments in infiltration within five constant-time intervals were similar (Kelishadi et al., 2014). Required time to steady-state flux varied in the range 10–25 min depending on the soil condition and inlet h value (Ankeny et al., 1991). An undisturbed sample (near to the disk location)

Fig. 2. Studied land-use/cover types in semi-arid region, central Iran; (a) Good Rangeland, (b) Poor Rangeland, (c) Dry Farmland and (d) Abandoned Farmland. 3

Soil & Tillage Research 197 (2020) 104478

E. Baranian Kabir, et al.

q1 and q2 were estimated. The Ks was then estimated using Eq. (5) or Eq. (6). Nonlinear optimization method of Solver Tool in Microsoft Excel 2007 was used to compute the best-fit values of Ks and λc by minimizing the sum of squared errors (SSE) as:

was collected from the surface soil using core samplers of 5 cm diameter and 5.1 cm height (i.e. 100 cm3) for the measurement of bulk density (ρb). Different analytical and numerical approaches are available to model the infiltration data collected by a tension infiltrometer. In this study, Wooding’s (1968) analytical method and Gardner’s (1958) hydraulic conductivity function were used to analyze the infiltration data because they have been used in many studies due to their simplicity. Single-term Philip (1969) model was applied to model the infiltration data for early times where infiltration is mainly one-dimensional and matric forces are dominant, as follows:

SSE=

where I denotes cumulative volume of infiltrated water per disk area (L) and t denotes the time (T). The slope of the relationship between I and t0.5 was considered the soil sorptivity (S, LT−0.5) for initial times. In order to estimate S, the infiltration data of the first 200 s were used at each inlet h. The S values at h values of 2, 5, 10, and 15 cm were denoted as S2, S5, S10, and S15, respectively. Estimation of unconfined flux rate from a circular source at the steady-state condition was suggested by Wooding (1968) as follows:

4λ c ⎤ q = Kwet ⎡1 + ⎢ πr0 ⎥ ⎣ ⎦

2.2.2. Pore characteristics calculations using the Watson and Luxmoore (1986) method The maximum size of a water-filled pore class at a specific h was estimated by the capillarity equation as follows (Hillel, 1998):

d = 2r =

h ) λc

(2)

γp − g = K (hi ) − K (hi − 1 ) , i = 1, 2, …, n γCPCT %=

h ⎡ 4λ c ⎤ ) 1+ λc ⎢ πr0 ⎥ ⎣ ⎦

(3)

N=

h1 ⎡ 4λ c ⎤ ) 1+ λc ⎢ πr0 ⎥ ⎦ ⎣

K (hi ) − K (hi − 1 ) × 100 , i = 1, 2, …, n Ks

(10)

(11)

8μKh πρgr 4

(12)

where N, μ, and Kh denote the maximum number of pores per unit area, water viscosity (ML−1T−1), and hydraulic conductivity at h, respectively, and ρ, g, and r are similar to those in Eq. (9). The actively conducting pore-size class known as effective porosity (θm, cm3 cm−3) was estimated as:

θm = Nπr 2 (4)

(13)

As in Watson and Luxmoore (1986), the calculations were done for the h ranges of 0–2, 2–5, 5–10, 10–15 and > 15 cm corresponding to pore diameters of > 0.15,0.06–0.15, 0.03–0.06, 0.02–0.03 and < 0.02 cm, respectively.

By replacing consecutive matric suctions of h1 and h2 for h in Eq. (4), following equations were obtained (Ankeny's method, 1991):

q1 = Ks exp(−

(9)

where i is the number of measurements performed, K(hi) and K(hi-1) are the hydraulic conductivities obtained for the two consecutive h values and Ks is the saturated hydraulic conductivity. According to Watson and Luxmoore (1986), the water-conducting porosity is estimated as follows:

where Ks denote the saturated hydraulic conductivity (LT−1). The two unknown parameters of Ks and λc can be used for Wooding’s analytical solution. Using the multiple-head method, Ks and λc were first estimated using three sets of paired h values of 2 and 5, 5 and 10, and 10 and 15 cm. The means of predicted parameters were used as first approximations for the best-fit predictions. The following equation was achieved after substituting Eq. (3) into Eq. (2):

q = Ks exp(−

4σcosβ 0.30 ≈ ρgh h

where d and r are the pore diameter and radius (L), respectively, σ is surface tension of water (MT−2), β is soil-water contact angle, ρ is water density (ML-3), and g is acceleration due to gravity (LT−2). Therefore, the applied h values of 2, 5, 10 and 15 cm correspond to d values of 0.15, 0.06, 0.03 and 0.02 cm, respectively. Hydraulic conductivity of a pore-size class (γp-g) and the contribution of each pore-size class to total water flow (γCPCT; %) were determined using Eqs. (10) and (11), respectively (Watson and Luxmoore, 1986):

where q denotes the steady-state infiltration rate (volume of infiltrated water per disk area per unit time; LT−1), r0 denotes the disk radius (L), Kwet denotes unsaturated hydraulic conductivity (LT−1) corresponding to the inlet h of hwet (L), and λc denotes the macroscopic capillary length (L) and is equal to the inverse of the slope of K(h) function (i.e., α−1), where α is the slope of function K(h) [Eq. (3)] in the semi-logarithmic form. The measured values of q at h values of 2, 5, 10, and 15 cm were denoted as q2, q5, q10, and q15, respectively. The first and second terms on the right of Eq. (2) stand for water flow caused by gravitational force and the effects of capillary forces and water source geometry, respectively. According to Gardner's (1958) exponential model, K is assumed to vary with h as:

K (h) = Ks exp(−

(8)

where qpredicted and qmeasured were the predicted and measured q values at n inlet h values (here n = 4). Knowing the best-fit values of λc and Ks yielded the K(h) function by substituting them into Eq. (3). The K at h values of 2, 5, 10, and 15 cm, denoted by K2, K5, K10 and K15, respectively, were estimated using the K(h) function.

(1)

I = St 0.5

∑ (qmeasured − qpredicted )2

(5)

2.3. Laboratory soil measurements and degree of compactness

and

q2 = Ks exp(−

h2 ⎡ 4λ c ⎤ ) 1+ λc ⎢ πr0 ⎥ ⎦ ⎣

The disturbed/sieved samples (< 2 mm) were used for the determination of soil chemical and physical properties. The pipette method was used to determine soil texture (Gee and Bauder, 1986). The soil organic carbon (SOC) and calcium carbonate equivalent (CCE) were determined using acid dichromate wet-oxidation (Nelson et al., 1996) and back-titration methods (Erich and Ohno, 1992), respectively. Soil bulk density (ρb) was measured using the core method (Blake and Hartge, 1986). The ρb would depend on soil texture, mineralogy, particle shape and organic matter, so that it cannot accurately determine the degree of compactness regardless of soil type (Håkansson

(6)

Solving for λc after dividing Eq. (6) by Eq. (5) yielded the following equation:

λc =

|h2 − h1 | ln

( ) q2

q1

(7)

λc was directly computed from Eq. (7) since h1 and h2 were known and 4

Soil & Tillage Research 197 (2020) 104478

E. Baranian Kabir, et al.

covers (P < 0.05) (Table 1), which indicates that the land-use/cover types had intrinsically similar soil texture. Similar soil texture among the land-use/cover types indicates that perhaps land-use/cover and soil management mainly governed the changes in soil hydraulic properties and pore characteristics in the study region.

and Lipiec, 2000; Kaufmann et al., 2010; Reichert et al., 2009). Relative bulk density (ρb-rel) was used to quantify the degree of compactness irrespective of soil type (Håkansson and Lipiec, 2000) as:

ρ b−rel = ρ b ρ b−ref

(14)

where ρb-ref was computed based on the clay content (Dexter, 2004) as follows:

ρ b−ref (Mg m−3) = 1.985 − 0.00857clay (kg 100kg−1)

3.1. Impact of land-use/cover on soil physical and chemical properties

(15) Table 1 summarizes the overall mean and standard deviation (SD) of the soil physical and chemical properties in good and poor rangelands, dry farmland and abandoned farmland. The relative high SD values for most soil hydraulic properties (see Table 2) showed considerable high spatial variability for each land-use/cover. The means’ comparisons of selected soil physical and chemical properties among the land-use/cover types are shown in Table 1. The SOC varied significantly among the land-uses/covers in the both surface and subsurface soil layers (P < 0.05). The results showed that SOC in the both soil layers changed as follows: good rangeland > poor rangeland > abandoned farmland > dry farmland. In addition, the differences of SOC between good rangelands and other land-use/covers are more pronounced in the surface soil. The soil organic matter can be exposed to microbial decay as a result of the destruction of aggregates caused by tillage-induced mechanical stress. Moreover, the organic matter of surface soil can be diluted by tillage through the mixing of the surface soil rich in organic matter with the subsurface soil poor in organic matter and results in high erosion rates (Olson and Al-kaisi, 2015). The absence of livestock grazing and high vegetation cover and density (mainly Astragalus verus Olivier and Bromus tomentellus Boiss.) in the good rangeland increased the litter, vegetation residue and ultimately the SOC. Severe livestock grazing pressure (i.e., supply of forage in rangeland is less than the rate of forage removal) and low vegetation cover (less than 20%) in the poor rangeland significantly decreased the SOC in comparison with the good rangeland in the both soil layers (P < 0.05) (Table 1). Conversion of rangeland to dry farmland significantly decreased the SOC (P < 0.05) (Table 1), likely due to the fact that after-wheat harvesting in the dry farmland, postgrazing occurs which minimizes the residues returning into the soil. The CCE differed significantly among the land-use/cover types in the both surface and subsurface soil layers (P < 0.05) (Table 1). Increasing the CCE in the soil profile improves aggregation with its cementing effect and flocculation of soil particles through the release of

It was shown that ρb-ref as calculated using Eq. (15) has a strong correlation with natural ρb (Kelishadi et al., 2014; Mosaddeghi et al., 2009) and ρb-rel may be better related to plant root growth and yield (Håkansson and Lipiec, 2000; Kaufmann et al., 2010; Reichert et al., 2009) and soil physical functions such as water availability to plants and mechanical impedance to root growth (Asgarzadeh et al., 2010, 2011). Effective bulk density (ρb-eff) was also calculated using Eq. (16) indicating that clay content has a positive effect on ρb-eff (Abu-Hashim et al., 2011) as:

ρ b−eff (Mgm−3) = ρ b (Mgm−3) + 0.009 clay (kg 100kg−1)

(16)

2.4. Statistical analysis Descriptive statistics including mean and standard deviation were calculated for all the measured or estimated soil physical, chemical and hydraulic properties. The Anderson-Darling test was used to test the normality of dataset distribution. Analysis of variance (ANOVA) was performed to compare the land-uses/covers (e.g., good and poor rangelands, dry farmland and abandoned farmland) in terms of the measured or estimated soil properties using Minitab (ver. 17). CCE and some soil hydraulic properties (e.g., K(h), S(h = 5, 10 and 15) and q (h = 5 and 10)) were not normal, and we carried out the ANOVA analysis on the log-transformed data of these properties. Tukey’s honest significant difference (Tukey HSD) was used for means’ comparisons at the P < 0.05 significance (Minitab, 1991). 3. Results and discussion The dominant surface (0–5 cm) and subsurface (5–25 cm) soil texture classes were sandy clay loam, and the proportions of sand, silt and clay fractions did not significantly differ among most of the land-uses/

Table 1 Means’ comparisons of soil physical and chemical properties (Mean ± Standard Deviation) of surface and subsurface layers as affected by the land-use/cover type. Property*

Good Rangeland

Poor Rangeland

Dry Farmland

Abandoned Farmland

Sand (kg 100 kg−1) Silt (kg 100 kg−1) Clay (kg 100 kg−1) ρb (Mg m−3) ρb-eff (Mg m−3) ρb-rel (-) CCE (kg 100 kg−1) SOC (kg 100 kg−1)

Surface soil (0–5 cm) 13.80 ± 2.84ab 50.28 ± 5.27ab 35.93 ± 6.18ab 1.30 ± 0.11a 1.51 ± 0.10 c 1.42 ± 0.11 b 9.72 ± 1.23a 1.86 ± 0.17 a

16.39 ± 4.51a 48.06 ± 7.20ab 35.56 ± 7.50ab 1.37 ± 0.11a 1.65 ± 0.13 b 1.61 ± 0.14 ab 4.83 ± 1.03c 1.48 ± 0.24 b

15.83 ± 3.33a 45.56 ± 7.03b 38.61 ± 5.10a 1.40 ± 0.11a 1.89 ± 0.25 a 1.83 ± 0.24 a 6.83 ± 0.75b 1.00 ± 0.11 c

10.09 ± 2.65b 59.54 ± 6.34a 30.37 ± 3.09b 1.41 ± 0.15a 1.78 ± 0.33 a 1.77 ± 0.32 a 1.56 ± 0.30d 1.02 ± 0.18 c

Sand (kg 100 kg−1) Silt (kg 100 kg−1) Clay (kg 100 kg−1) ρb (Mg m−3) ρb-eff (Mg m−3) ρb-rel (-) CCE (kg 100 kg−1) SOC (kg 100 kg−1)

Subsurface soil (5–25 cm) 12.69 ± 2.20b 46.94 ± 8.66ab 40.37 ± 5.64ab 1.36 ± 0.10b 0.74 ± 0.06 a 0.67 ± 0.06 a 6.61 ± 1.22a 1.40 ± 0.20 a

16.95 ± 4.91a 40.28 ± 6.21b 42.72 ± 6.90a 1.48 ± 0.04ab 0.61 ± 0.09 b 0.58 ± 0.08 ab 3.08 ± 0.38b 1.11 ± 0.21 b

18.05 ± 5.64a 46.96 ± 2.72ab 35.00 ± 2.79b 1.60 ± 0.15a 0.56 ± 0.12 c 0.49 ± 0.11 b 7.83 ± 1.83a 0.89 ± 0.06 c

10.20 ± 1.07b 55.83 ± 6.07a 34.07 ± 4.26b 1.57 ± 0.14a 0.55 ± 0.14 c 0.53 ± 0.14 b 2.11 ± 0.42b 0.93 ± 0.15 c

*ρb, ρb-rel, and ρb-eff denote bulk density, relative bulk density and effective bulk density, respectively; CCE is calcium carbonate equivalent, and SOC is soil organic carbon content. a In each row, figures followed by similar letters are not significantly different at P < 0.05 (Tukey's HSD). 5

Soil & Tillage Research 197 (2020) 104478

E. Baranian Kabir, et al.

Table 2 Means’ comparisons of Gardner’s parameter and soil hydraulic conductivities (Mean ± Standard Deviation) among the land-use/cover types. Land use

λc cm

Good Rangeland Poor Rangeland Dry Farmland Abandoned Farmland

2.86 3.45 6.89 4.68

α cm−1 ± ± ± ±

1.78b 1.12b 2.01a 1.62ab

0.46 0.31 0.16 0.23

± ± ± ±

K15 mm h−1 0.22a 0.08a 0.05b 0.06ab

1.02 0.51 0.62 0.46

± ± ± ±

K10

1.09a 0.46a 0.45a 0.39a

2.74 1.97 1.30 1.37

K5

± ± ± ±

1.47a 1.10a 0.84 a 1.09 a

9.56 7.15 2.89 4.32

± ± ± ±

3.91 a 2.95 a 1.86b 2.31b

K2

Ks

27.06 ± 10.67 a 21.25 ± 10.18ab 4.82 ± 3.46c 8.55 ± 6.60bc

65.61 ± 24.04 a 39.82 ± 19.78ab 6.87 ± 5.46c 14.38 ± 10.82b

a In each column, figures followed by similar letters are not significantly different at P < 0.05 (Tukey's HSD); λc denotes macroscopic capillary length which is equal to the inverse of the slope of K(h) function (i.e., λc = α−1), and K15, K10, K5, K2 and Ks denote soil hydraulic conductivities at h values of 15, 10, 5, 2 and 0 cm, respectively.

Ca2+ into the soil solution. Significantly less CCE was observed in the surface soil of abandoned farmland (P < 0.05). Generally higher CCE values were observed in the subsurface soil compared with the surface soil in abandoned farmland and dry farmland (Table 1). Relatively greater CCE in the surface soil of dry farmland is related to the carbonatic B horizon brought to the surface by soil inversion and plowing (Table 1). A strong linear relationship with R2 = 99% was obtained between ρb-eff and ρb-rel for the studied soils. As implied, the soil degree of compactness in the region can be characterized interchangeably by application of ρb-eff or ρb-rel. Despite ρb in the surface soil, land-use/ cover had significant effect on ρb in the subsurface soil, and ρb-eff and ρbrel in both surface and subsurface soil layers (P < 0.05) (Table 1). While good rangeland had the lowest ρb, ρb-eff and ρb-rel values, their values in the surface soil were highest in the dry farmland (Table 1). In the good rangeland, perennial plant cover and its residue has increased SOC input, which can prevent soil compaction. High ρb-eff and ρb-rel values observed in the poor rangeland are likely as a result of overgrazing and low vegetative cover. Relatively high ρb-eff and ρb-rel values in the dry farmland can be associated with soil compaction caused by harvesting machinery traffic or intensive tillage which accelerated erosion of the surface soil (Table 1) in accordance with the findings of Havaee et al. (2014). Similarly, other studies noted the greater ρb-eff values in agricultural soils compared to forest and grassland soils (AbuHashim et al., 2011; Bodhinayake and Si, 2004).

Fig. 4. Steady-state water flux (q) at different values of matric suction (h) as affected by land-use/cover type; In each group of bars (i.e., at a specific h value), the same letters denote non-significant differences at P < 0.05 (Tukey's HSD).

3.2. Impact of land-use/cover on soil hydraulic properties According to the results, the K(h) (Table 2 and Fig. 3), q(h) (Fig. 4) and S(h) (Fig. 5) increased as h decreased (i.e., towards saturation), especially in the good rangeland. This finding indicated the high frequency of macropores that resulted from the lack of soil trampling and

Fig. 5. Soil sorptivity (S) at different values of matric suction (h) as affected by land-use/cover type; In each group of bars (i.e., at a specific h value), the same letters denote non-significant differences at P < 0.05 (Tukey's HSD).

extensive root plant systems in the good rangeland. Similarly, Kelishadi et al. (2014) found that decreasing h from 15 to 2 cm increased K(h), q (h) and S(h). They found that over-grazed pastures increased soil compaction and destructed soil macropores. In addition, Hu et al. (2009) reported that variation of K(h) increased with a decrease in h. They recorded a less than 2-fold increase in K(h) when h decreased from 3 to 0 cm, a smaller value than those reported elsewhere. Schwartz et al. (2003) found that decreasing h from 15 to 0 cm, increased K(h) by 10.1, 13, and 47 times for cropland, re-established land-use and native grassland, respectively. The lowest values for K(h), q(h) and S(h) were observed in the dry farmland (Table 2, Figs. 3, 4 and 5) likely due to plowing and

Fig. 3. Gardner’s (1958) function of unsaturated hydraulic conductivity [K(h)] as affected by land-use/cover type; inverse of macroscopic capillary length (λc−1) corresponds to the K(h) function slope (α) in a semi-logarithmic scale (log K vs. h). 6

Soil & Tillage Research 197 (2020) 104478

E. Baranian Kabir, et al.

on pore radii greater than 300 μm. Fig. 4 compares unsaturated steady-state flux (q) at different h values by land-use/cover type. Clearly, q followed a similar trend as K and decreased as h increased for all land-use/cover types because the conducting macropores would govern the near-saturated water flow. The extent of increase in q from h of 15 to 2 cm in the good rangeland was greater than that for the dry farmland. The results revealed that at higher values of h (i.e., 10 and 15 cm), q did not differ significantly among the land-use/cover types (Fig. 4). Poor rangeland had lower values of q than good rangeland (Fig. 4) likely due to overgrazing and the decrease in vegetation cover in accordance with the results of Owuor et al. (2018). In most cases, the lowest values of q were observed in the dry farmland because of decrement in the size of soil pores due to high degree of compactness (ρb-eff and ρb-rel, see Table 1). Abu-Hashim et al. (2011) reported the following order for infiltration rate by landuse: forest soil > grassland soil > agricultural soil for which the SOC content of forest soil was greatest. Compared to land cultivation for long-term periods, a recently cultivated pasture had greater initial and final rates of saturated infiltration as measured by a double-ring infiltrometer (Mielke and Wilhelm, 1998). Additionally, conventional tillage was noted by Lipiec et al. (2006) to provide the greatest water infiltration in a silt loam soil. In contrast, Kelishadi et al. (2014) observed that qh values for dryland farming were significantly greater than those for pastures which were associated with over-grazing and lowest SOC of pasture soils and with the creation of heterogeneous pores by tillage in dryland farming. The effects of land-use/cover on soil sorptivity (S) at different h values are shown in Fig. 5. The S(h) followed a trend similar to those of K(h) and q(h) and showed a decrease with an increase in h for all of the land-use/cover types. The results showed that S did not differ significantly at higher values of h (i.e., 10 and 15 cm) for all the land-use/ cover types (P < 0.05) (Fig. 5). The S(h) is influenced by the integrated effects of size and frequency of soil pores. The soils with greater matric forces, water retention and pore space would have higher values of S at a specific value of h. The least variation in S(h) was recorded for the dry farmland (Fig. 5), probably due to soil compaction during the harvesting had altered the macropores to micropores (i.e., reduced size of soil pores) and resulted in a lower pore space. Similar to our findings, Moosavi and Sepaskhah (2012) found that S increased as h decreased. Fallow and dryland farming were found by Kelishadi et al. (2014) to have greater S values than pastures and irrigated farms perhaps due to creation of macropores by tillage and annual soil loosening. In general, the hydraulic properties of abandoned farmland (i.e., λc, K, q and S) fall between those for rangeland and dry farmland (see Table 2, Figs. 3–5). This finding suggests that abandoning the use of dry farming and the decrease in soil manipulation will allow establishment of invasive perennial species, improvement of soil structure and pore size distribution. Since infiltrating water in the topsoil (0–25 cm) may not address the impact of vertical soil property heterogeneity on water fluxes at greater depths, it is unlikely that the soil property analyses from the topsoil layers are sufficient to accurately characterize water fluxes and conductivity occurring at deeper depths.

harvesting that could increase soil compaction and resulted in deterioration of soil structure and macropores in this land-use/cover type. Intensive tillage, especially under wet conditions, can also result in excessive soil compaction and poor structure (Kargas et al., 2016). The increased power of tractors and harvesters leads to heavier loads that cause subsoil compaction in the dry farmland. As a consequence, compacted plow pans are usually formed beneath the plow layer (Blanco-Canqui et al., 2017; Mossadeghi-Björklund et al., 2016). Means’ comparisons of macroscopic capillary length (λc), α and hydraulic conductivity (K) values among the land-use/cover types are shown in Table 2. The λc differed significantly between the land-use/ cover types (P < 0.05). The values for λc were significantly greater in the dry farmland than in the rangeland and abandoned farmland (P < 0.05) that is likely a result of disturbance of large and very large pore-size classes. Radcliffe and Šimůnek (2010) showed that λc had a positive relation with soil bulk density. Similarly, the results of the current study showed that despite of ρb in the surface soil, the degree of compactness in the subsoil (i.e., ρb, ρb-eff and ρb-rel; Table 1) was significantly greater in the dry farmland which might result in a higher λc value. By increasing the λc value, the relative contribution of gravitational force versus capillary force to water flow in soil decreased (Kelishadi et al., 2014; Radcliffe and Šimůnek, 2010). The K in all of the land-use/cover types increased as h decreased but it was more evident in the rangeland (especially in the good rangeland) than in the dry farmland and abandoned farmland (Table 2). The differences of K values among the land-use/cover types became greater and significant (P < 0.05) as h decreased (i.e., for K2 and Ks Table 2). Good rangeland had the highest values for K at all h values (from 1.01 mm h−1 at h = 15 cm to 65.61 mm h−1 at h = 0 cm). Dry farmland had the lowest values of K at h = 0 and 2 cm and these values were significantly different from the other land-use/cover types (P < 0.05). The low values of K may be related to higher values of ρb-eff and ρb-rel in the dry farmland (Table 1). Although the values of K at lower h values (i.e., 0 and 2 cm) differed significantly (P < 0.05) among the land-use/ cover types, the differences were not significant at higher values of h (i.e., 10 and 15 cm). The lowest values for K were observed in the abandoned farmland at h values of 5 and 15 cm and in the dry farmland at h = 10 cm (Table 2). Abu-Hashim et al. (2011) also observed that agricultural soils had a lower Ks with greater variation compared with grassland and forest soils. Yu et al. (2015) reported that land-use type significantly affected saturated and near-saturated K values, but had no significant impact on unsaturated K (P < 0.05). By contrast, Kelishadi et al. (2014) showed that pasture soil (with high grazing pressure) had higher λc and lower Kh values when compared with cultivated land. Fig. 3 shows the K(h) function of Gardner (1958) as affected by land-use/cover type. In the semi-logarithmic scale (log K vs. h), the inverse of macroscopic capillary length (α = λc−1) corresponds to the slope of K(h) function. Rangelands (especially good rangeland) had greater α values than other land-use/cover types, which is an indicator of macropore flow or gravitational force at low values of h (i.e., 0–5 cm). An increase in h decreased the differences between the K curves among the land-use/cover types (Fig. 3). This means that the effect of land-use/cover on Kh values is more evident at lower values of h. Accordingly Bodhinayake and Si (2004) reported that increasing h led to a considerable decrease in K in grassland ecosystems compared to arable lands. In accordance with our findings, these researchers found that at low values of h, there were significant differences between K(h) values among the land-use types (P < 0.05). They found significant differences for K3 values (grassland soil > arable soil), while K7, K15 and K22 were not significantly different (P < 0.05) among the land-use types. Schwartz et al. (2003) compared hydraulic properties of cropland with re-established and native grassland in Southern Great Plains. They observed that the Kh values in re-established grassland were lower than those in native grassland and cropland at low h values due to lower macroporosity and SOC content. They also found that long-term soil structural development on native grassland had considerable influence

3.3. Impact of land-use/cover on soil pore characteristics Means’ comparisons of hydraulic conductivity of soil pore-size classes (γp-g) as affected by the land-use/cover type are shown in Fig. 6. Although the effect of land-use/cover type on the hydraulic conductivities of large and intermediate pore classes was significant (i.e., macropores and mesopores; > 0.02 cm), this influence was not significant for the micropores (< 0.02 cm). The variation in K values at low values of h (Fig. 3) being related to soil geometry and pore sizes supports the findings about the impact of land-use/cover on γp-g. Poor and good rangelands did not differ significantly in terms of γp-g (P < 0.05); however, the proportion of very large pores (> 0.147 cm) 7

Soil & Tillage Research 197 (2020) 104478

E. Baranian Kabir, et al.

Table 4 Means’ comparisons of soil pore-size class porosities (θm, %) corresponding to different matric suction ranges, and total porosity as affected by the land-use/ cover type. Matric suction (cm)

Pore-size range (cm)

0–2 > 0.15 2–5 0.06–0.15 5–10 0.03–0.06 10–15 0.02–0.03 > 15 < 0.02 Total Porosity

Fig. 6. Means’ comparisons of hydraulic conductivities of soil pore-size (cm) classes (γp-g, mm h−1) as affected by the land-use/cover type; In each class of soil pores, the same letters denote non-significant differences among the landuse/cover types at P < 0.05 (Tukey’s HSD).

Good Rangeland

Poor Rangeland

Dry Farmland

Abandoned Farmland

0–2 2–5 5–10 10–15

> 0.15 0.06–0.15 0.03–0.06 0.02–0.03

64.8a 1500.6a 9466.8a 11807.8a

40.8b 1209.1b 6997.2ab 10418.7a

4.6c 162.9c 2195.2c 4862.0b

13.0c 360.2c 3978.8b 6251.2b

Dry Farmland

Abandoned Farmland

0.01a 0.04a 0.06a 0.04a 50.79a 50.94a

0.01b 0.03b 0.05ab 0.03a 47.05b 47.17b

0.00c 0.01c 0.02c 0.02b 47.14b 47.17b

0.00c 0.01c 0.03b 0.02b 47.11b 47.17b

In each row, figures followed by similar letters are not significantly different at P < 0.05 (Tukey's HSD).

Fig. 7. Means’ comparisons of contributions of soil pore-size (cm) classes to water flow (γCPCT, %) as affected by the land-use/cover type; In each class of soil pores, the same letters denote non-significant differences among the landuse/cover types at P < 0.05 (Tukey’s HSD).

by land-use/cover type is shown in Fig. 7. In spite of low θm value of large pores (see Table 4), γCPCT of large pores is dominant (Fig. 7). Therefore, small fraction of large pores could significantly affect water flow processes such as infiltration, runoff and water transport in soil especially under saturated and near-saturated conditions. The contribution (γCPCT) of large pores (i.e., pore-size > 0.15 cm) to water flow decreased from 52% in the good rangeland to 30% in the dry farmland (Fig. 7). Inappropriate management practices such as over-grazing in the poor rangeland, cultivation and harvesting machinery traffic led to greater variations of the γCPCT values for very large pore-size class (> 0.15 cm) among the land-use/cover types when compared to the other pore-size classes. The γCPCT values of smaller pore-size classes (i.e., 0.03–0.02 and < 0.02 cm) in the dry farmland were significantly greater than those in the other land-use/cover types (Fig. 7). Although very large and large pores (i.e., > 0.15, 0.15–0.06 cm) contributed to less than 1% of the soil volume (see Table 4), more than 50% of the total water flow would happen through these pore-size classes (Fig. 7). Therefore, this finding highlights the dominant contribution of macropores to increased infiltration and prevention of accelerated runoff and erosion. Similarly, the dominance of water flow through the macropores was reported by Watson and Luxmoore (1986) implying the importance of large soil pores in water flow processes. It suggests that converting rangeland to dry farmland decreased the pore-size range. Grazing pressure has been recognized as a factor that modifies macropores to micropores due to compaction and decreases Ks in alpine meadows (Zeng et al., 2013) and pastures (Zhou et al., 2008).

Table 3 Means’ comparisons of maximum numbers of soil pores from different size classes (N, m−2) corresponding to different matric suction ranges as affected by the land-use/cover type. Pore-size range (cm)

Poor Rangeland

a

was considerably less in the poor rangeland than in the good rangeland (Fig. 6) likely due to severe over-grazing, trampling and the decrease in soil physical quality. Moreover, the difference in γp-g between the poor and good rangelands decreased as the size of the soil pores decreased (Fig. 6). The effect of land-use/cover type on the maximum numbers of soil pores of different size classes (N) was also examined. The results revealed that a decrease in pore-size was coincided with a power-like increase in the number of pores (Table 3). The N differed significantly among the land-use/cover types (P < 0.05) and this difference was greater for the macropores (0.06–0.15 and > 0.15 cm; Table 3). The N among the land-use/cover type declined as follows: good rangeland > poor rangeland > abandoned farmland > dry farmland. The lowest numbers of macropores and mesopores were observed in the dry farmland which were significantly different from the rangeland and abandoned farmland (P < 0.05). High degree of compactness (ρb-eff and ρb-rel; see Table 1), structural deterioration and the alteration of macropores to mesopores and micropores are possible reasons for the low N value of macropores in the dry farmland (Table 3). This implies that soil manipulation by machinery would destroy macropores in dry farmland, and decreased the hydraulic conductivity of corresponding pore-size class (Fig. 6). The effective porosity of different pore-size classes (θm) and total porosity differed significantly among the land-use/cover types (P < 0.05); Good rangeland had the greatest values of θm and total porosity (i.e., 50.94%; Table 4). In other studies, the effects of various land-use treatments on the soil pore size distribution were denoted (Afyuni and Mosaddeghi, 2001; Haghighi et al., 2010; Schwartz et al., 2003). Similarly, they reported that soil macroporosity is greater in long-term no-tillage system compared to conventional tillage system and in native rangelands (with dense vegetation). The contribution of each pore-size class (γCPCT) (> 0.15, 0.15–0.06, 0.06–0.03, 0.03–0.02 and < 0.02 cm) to the soil water flow as affected

Matric suction (cm)

Good Rangeland

3.4. Management implication

In each row, figures followed by similar letters are not significantly different at P < 0.05 (Tukey's HSD).

Understanding the effects of land-use/cover change on the hydrological properties of soil is essential for sustainable land-use/cover,

a

8

Soil & Tillage Research 197 (2020) 104478

E. Baranian Kabir, et al.

References

effective land management and soil quality improvement. This study indicates that rangeland (especially good rangelands) have crucial importance for conserving hydrological status of the ecosystem. These valuable ecosystems offer various services for humans such as food and water production, and groundwater recharge (Hartel et al., 2018). Although the effects of land-use/cover on soil hydraulic properties are investigated in various ecosystems around the world, land managers and policy makers did not pay enough attention to the results of these studies and their managements are aimed to achieve more short-term benefits. Investigating the soil hydraulic properties and especially their pore characteristics in various land-use/cover types can facilitate decision makers to evaluate field-scale water-cycle processes, such as nutrient transport, runoff and infiltration that are important for the evaluation of ecosystem services and initiating successful global strategies addressing challenges of water and food security, loss of biodiversity and human health (Hirmas et al., 2018). By increasing pore space and improving pore size distribution in the surface soil, there are more chances for rapid capture of rainfall. This would decrease water runoff and evaporation, and increasing water availability to plants; hence, system precipitation use efficiency will be increased (Shaver et al., 2002). Identifying best management practices (e.g., combination of cropping system that could increase crop residue production) for enhancing pore space in the surface soil is extremely important in dry land agriculture where water shortage is the most challenging factor for end-users.

Abu-Hashim, M.S.D., Schöniger, B.P.D.M., Schnug, E., 2011. Impact of Land-Use and Land-management on the Water Infiltration Capacity of Soils on a Catchment Scale. T.U. Braunschweig, pp. 184. Afyuni, M., Mosaddeghi, M.R., 2001. Impact of tillage system on soil physical properties and bromide leaching. J. Water Soil Sci. 5 (2), 39–53 In Persian with English Abstract. Alletto, L., Coquet, Y., 2009. Temporal and spatial variability of soil bulk density and near-saturated hydraulic conductivity under two contrasted tillage management systems. Geoderma 152 (1), 85–94. Ankeny, M.D., Ahmed, M., Kaspar, T.C., Horton, R., 1991. Simple field method for determining unsaturated hydraulic conductivity. Soil Sci. Soc. Am. J. 55 (2), 467–470. Asgarzadeh, H., Mosaddeghi, M.R., Mahboubi, A.A., Nosrati, A., Dexter, A.R., 2010. Soil water availability for plants as quantified by conventional available water, least limiting water range and integral water capacity. Plant Soil 335 (1–2), 229–244. Asgarzadeh, H., Mosaddeghi, M.R., Mahboubi, A.A., Nosrati, A., Dexter, A.R., 2011. Integral energy of conventional available water, least limiting water range and integral water capacity for better characterization of water availability and soil physical quality. Geoderma 166 (1), 34–42. Bagarello, V., Castellini, M., Iovino, M., 2005. Influence of the pressure head sequence on the soil hydraulic conductivity determined with tension infiltrometer. Appl. Eng. Agric. 21 (3), 383–391. Baranian Kabir, E., Bashari, H., Mosaddeghi, M.R., Bassiri, M., 2017. Soil aggregate stability and organic matter as affected by land-use change in central Iran. Arch. Agron. Soil Sci. 63 (13), 1823–1837. Blake, G.R., Hartge, K.H., 1986. Bulk density. In: Klute, A. (Ed.), Methods of Soil Analysis. Part 1. Physical and Mineralogical Properties. ASA/SSSA, Madison, WI, pp. 363–375. Blanco-Canqui, H., Wienhold, B.J., Jin, V.L., Schmer, M.R., Kibet, L.C., 2017. Long-term tillage impact on soil hydraulic properties. Soil Tillage Res. 170, 38–42. Bodhinayake, W., Si, B.C., 2004. Near saturated surface soil hydraulic properties under different land uses in the St Denis National Wildlife Area, Saskatchewan, Canada. Hydrol. Process. 18 (15), 2835–2850. Boizard, H., Richard, G., Roger-Estrade, J., Dürr, C., Boiffin, J., 2002. Cumulative effects of cropping systems on the structure of the tilled layer in northern France. Soil Tillage Res. 64 (1), 149–164. Buczko, U., Bens, O., Hüttl, R., 2006. Tillage effects on hydraulic properties and macroporosity in silty and sandy soils. Soil Sci. Soc. Am. J. 70 (6), 1998–2007. Das Gupta, S., Mohanty, B.P., Köhne, J.M., 2006. Soil hydraulic conductivities and their spatial and temporal variations in a vertisol. Soil Sci. Soc. Am. J. 70 (6), 1872–1881. Davudirad, A.A., Sadeghi, S.H., Sadoddin, A., 2016. The impact of development plans on hydrological changes in the Shazand Watershed, Iran. Land Degrad. Dev. 27 (4), 1236–1244. Dexter, A., 2004. Soil physical quality: part I. Theory, effects of soil texture, density, and organic matter, and effects on root growth. Geoderma 120 (3), 201–214. Erich, M.S., Ohno, T., 1992. Titrimetric determination of calcium carbonate equivalence of wood ash. Analyst 117 (6), 993–995. Fraser, G.W., Stone, G.S., 2016. The effect of soil and pasture attributes on rangeland infiltration rates in northern Australia. Rangeland J. 38 (3), 245–259. Gardner, W., 1958. Some steady-state solutions of the unsaturated moisture flow equation with application to evaporation from a water table. Soil Sci. 85 (4), 228–232. Gee, G.W., Bauder, J.W., 1986. Particle-size analysis. In: Klute, A. (Ed.), Methods of Soil Analysis. Part 1. Physical and Mineralogical Methods. ASA/SSSA, Madison, WI, pp. 383–411. Ghimire, C.P., Bruijnzeel, L.A., Bonell, M., Coles, N., Lubczynski, M.W., Gilmour, D.A., 2014. The effects of sustained forest use on hillslope soil hydraulic conductivity in the Middle Mountains of Central Nepal: sustained forest use and soil hydraulic conductivity. Ecohydrology 7, 478–495. Haghighi, F., Gorji, M., Shorafa, M., Sarmadian, F., Mohammadi, M.H., 2010. Evaluation of some infiltration models and hydraulic parameters. Span. J. Agric. Res. 8 (1), 210–217. Håkansson, I., Lipiec, J., 2000. A review of the usefulness of relative bulk density values in studies of soil structure and compaction. Soil Tillage Res. 53 (2), 71–85. Hartel, T., Fagerholm, N., Torralba, M., Balázsi, Á., Plieninger, T., 2018. Social-Ecological system archetypes for European rangelands. Rangeland Ecol. Manage. 71 (5), 536–544. Havaee, S., Ayoubi, S., Mosaddeghi, M., Keller, T., 2014. Impacts of land use on soil organic matter and degree of compactness in calcareous soils of central Iran. Soil Use Manage. 30 (1), 2–9. Heard, J.R., Kladivko, E.J., Mannering, J.V., 1988. Soil macroporosity, hydraulic conductivity and air permeability of silty soils under long-term conservation tillage in Indiana. Soil Tillage Res. 11 (1), 1–18. Hillel, D., 1998. Environmental Soil Physics. Academic Press, New York, USA, pp. 771. Hirmas, D.R., Giménez, D., Nemes, A., Kerry, R., Brunsell, N.A., Wilson, C.J., 2018. Climate-induced changes in continental-scale soil macroporosity may intensify water cycle. Nature 561 (7721), 100. Holden, J., Burt, T., Cox, N., 2001. Macroporosity and infiltration in blanket peat: the implications of tension disc infiltrometer measurements. Hydrol. Process. 15 (2), 289–303. Holechek, J.L., Pieper, R.D., Herbel, C.H., 1989. Range Management. Principles and Practices. Prentice-Hall. Hu, W., Shao, M., Wang, Q., Fan, J., Horton, R., 2009. Temporal changes of soil hydraulic properties under different land uses. Geoderma 149 (3), 355–366. Hussen, A., Warrick, A., 1995. Tension infiltrometers for the measurement of vadose zone hydraulic properties. In: Wilson, L.G., Everett, L.G., Cullen, S.J. (Eds.), Handbook of

4. Conclusions 1) The results showed that the changes in land-use/cover type (from rangeland to dry farmland) had a negative influence on soil hydraulic properties. At matric suction lower than 5 cm, good rangeland and dry farmland recorded the highest and lowest values of hydraulic conductivity, steady-state flux and sorptivity, respectively. Hydraulic conductivity values were ordered as follows: good rangeland > poor rangeland > abandoned farmland > dry farmland. These findings are related to the higher SOC content in the good rangeland, and lower SOC and a higher degree of compactness caused by machinery traffic in the dry farmland. 2) Good rangeland had a greater number of large pore-size classes and total soil porosity. The contribution of the very large pore-size class (i.e., > 0.15 cm) to soil water flow decreased from 52% in the good rangeland to 30% in the dry farmland. Inappropriate management practices (i.e., over-grazing in poor rangeland, and cultivation and machinery traffic in dry farmland) increased the frequency of smaller pores. 3) Although poor rangeland lacks dense vegetation and experiences the negative impact of over-grazing, converting this type of land-use/ cover to dry farmland to achieve short-term benefits would distort soil hydraulic properties and decrease water-conducting porosity. Because dry farmland usually loses its production value and is released from cultivation to become abandoned farmland, the soil hydraulic properties gradually improve in the abandoned farmland in this area. It can be concluded that less manipulation of natural land-use can improve the soil structure and hydraulic properties, and prevent consequences that are observed under unsustainable land-use modification.

Acknowledgments We would like to thank Isfahan University of Technology for its support and laboratory facilities. The authors are also thankful to anonymous reviewers for their constructive comments.

9

Soil & Tillage Research 197 (2020) 104478

E. Baranian Kabir, et al.

33–37. Owuor, S.O., Butterbach-Bahl, K., Guzha, A.C., Jacobs, S., Merbold, L., Rufino, M.C., Pelster, D.E., Díaz-Pinés, E., Breuer, L., 2018. Conversion of natural forest results in a significant degradation of soil hydraulic properties in the highlands of Kenya. Soil Tillage Res. 176, 36–44. Philip, J., 1969. Theory of infiltration. Adv. Hydrosci. 5, 215–296. Radcliffe, D.E., Šimůnek, J., 2010. Soil Physics with HYDRUS: Modeling and Applications. CRC Press, Boca Raton, FL. Reichert, J.M., Suzuki, L.E.A.S., Reinert, D.J., Horn, R., Håkansson, I., 2009. Reference bulk density and critical degree of compactness for no-till crop production in subtropical highly weathered soils. Soil Tillage Res. 102 (2), 242–254. Reynolds, W., Elrick, D., 1991. Determination of hydraulic conductivity using a tension infiltrometer. Soil Sci. Soc. Am. J. 55 (3), 633–639. Safaei, M., Jafari, R., Bashari, H., Esfahani, S.F., 2018. Mapping and monitoring of the structure and function of rangeland ecosystems in central Zagros, Iran. Environ. Monit. Assess. 190 (11), 662. Schnug, E., Haneklaus, S., 2002. Agricultural production technique and infiltration significance of organic farming for preventive flood protection. Landbauforschung Volkenrode 52 (4), 197–203. Schlüter, S., Großmann, C., Diel, J., Wu, G.M., Tischer, S., Deubel, A., Rücknagel, J., 2018. Long-term effects of conventional and reduced tillage on soil structure, soil ecological and soil hydraulic properties. Geoderma 332, 10–19. Schwartz, R.C., Evett, S.R., Unger, P.W., 2003. Soil hydraulic properties of cropland compared with reestablished and native grassland. Geoderma 116 (1), 47–60. Shaver, T.M., Peterson, G.A., Ahuja, L.R., Westfall, D.G., Sherrod, L.A., Dunn, G., 2002. Surface soil physical properties after twelve years of dryland no-till management. Soil Sci. Soc. Am. J. 66 (4), 1296–1303. Sobieraj, J.A., Elsenbeer, H., Coelho, R.M., Newton, B., 2002. Spatial variability of soil hydraulic conductivity along a tropical rainforest catena. Geoderma 108 (1–2), 79–90. Strudley, M.W., Green, T.R., Ascough, J.C., 2008. Tillage effects on soil hydraulic properties in space and time: state of the science. Soil Tillage Res. 99 (1), 4–48. Sun, D., Yang, H., Guan, D., Yang, M., Wu, J., Yuan, F., Jin, C., Wang, A., Zhang, Y., 2018. The effects of land use change on soil infiltration capacity in China: a meta-analysis. Sci. Total Environ. 626, 1394–1401. Ventrella, D., Losavio, N., Vonella, A., Leij, F., 2005. Estimating hydraulic conductivity of a fine-textured soil using tension infiltrometry. Geoderma 124 (3), 267–277. Watson, K., Luxmoore, R., 1986. Estimating macroporosity in a forest watershed by use of a tension infiltrometer. Soil Sci. Soc. Am. J. 50 (3), 578–582. Wooding, R., 1968. Steady infiltration from a shallow circular pond. Water Resour. Res. 4 (6), 1259–1273. Yu, M., Zhang, L., Xu, X., Feger, K.H., Wang, Y., Liu, W., Schwärzel, K., 2015. Impact of land-use changes on soil hydraulic properties of Calcaric Regosols on the Loess Plateau, NW China. J. Plant Nutr. Soil Sci. 178 (3), 486–498. Zeng, C., Zhang, F., Wang, Q., Chen, Y., Joswiak, D.R., 2013. Impact of alpine meadow degradation on soil hydraulic properties over the Qinghai-Tibetan Plateau. J. Hydrol. 478, 148–156. Zhou, X., Lin, H., White, E., 2008. Surface soil hydraulic properties in four soil series under different land uses and their temporal changes. Catena 73 (2), 180–188. Zimmermann, B., Elsenbeer, H., 2008. Spatial and temporal variability of soil saturated hydraulic conductivity in gradients of disturbance. J. Hydrol. 361, 78–95. Zimmermann, B., Elsenbeer, H., De Moraes, J.M., 2006. The influence of land-use changes on soil hydraulic properties: implications for runoff generation. Forest Ecol. Manage. 222 (1), 29–38.

Vadose Zone Characterization & Monitoring. Lewis Publ., Boca Raton, pp. 189–201. IUSS Working Group WRB, 2015. World Reference Base for Soil Resources 2014, Update 2015; International Soil Classification System for Naming Soils and Creating Legends for Soil Maps. World Soil Resources Reports No. 106. FAO, Rome. Kargas, G., Kerkides, P., Sotirakoglou, K., Poulovassilis, A., 2016. Temporal variability of surface soil hydraulic properties under various tillage systems. Soil Tillage Res. 158, 22–31. Kaufmann, M., Tobias, S., Schulin, R., 2010. Comparison of critical limits for crop plant growth based on different indicators for the state of soil compaction. J. Plant Nutr. Soil Sci. 173 (4), 573–583. Kelishadi, H., Mosaddeghi, M., Hajabbasi, M., Ayoubi, S., 2014. Near-saturated soil hydraulic properties as influenced by land use management systems in Koohrang region of central Zagros, Iran. Geoderma 213, 426–434. Li, J., Mendoza, A., Heine, P., 2010. Effects of land-use history on soil spatial heterogeneity of macro- and trace elements in the Southern Piedmont USA. Geoderma 156 (1), 60–73. Li, X.G., Li, F.M., Zed, R., Zhan, Z.Y., 2007. Soil physical properties and their relations to organic carbon pools as affected by land use in an alpine pastureland. Geoderma 139 (1), 98–105. Lipiec, J., Kuś, J., Słowińska-Jurkiewicz, A., Nosalewicz, A., 2006. Soil porosity and water infiltration as influenced by tillage methods. Soil Tillage Res. 89 (2), 210–220. Martínez, G., Pachepsky, Y.A., Vereecken, H., 2014. Temporal stability of soil water content as affected by climate and soil hydraulic properties: a simulation study. Hydrol. Process. 28 (4), 1899–1915. Mbuthia, L.W., Acosta-Martínez, V., DeBruyn, J., Schaeffer, S., Tyler, D., Odoi, E., Mpheshea, M., Walker, F., Eash, N., 2015. Long term tillage, cover crop, and fertilization effects on microbial community structure, activity: implications for soil quality. Soil Biol. Biochem. 89, 24–34. Mielke, L., Wilhelm, W., 1998. Comparisons of soil physical characteristics in long-term tillage winter wheat–fallow tillage experiments. Soil Tillage Res. 49 (1), 29–35. Miller, J., Sweetland, N., Chang, C., 2002. Hydrological properties of a clay loam soil after long-term cattle manure application. J. Environ. Qual. 31 (3), 989–996. Miller, J., Sweetland, N., Larney, F., Volkmar, K., 1998. Unsaturated hydraulic conductivity of conventional and conservation tillage soils in southern Alberta. Can. J. Soil Sci. 78 (4), 643–648. Minitab, I., 1991. MINITAB Reference Manual. Minitab. Mirhosseini, M., Farshchi, P., Noroozi, A.A., Shariat, M., Aalesheikh, A.A., 2018. Changing land use a threat to surface water quality: a vulnerability assessment approach in Zanjanroud watershed, central Iran. Water Resou. 45 (2), 268–279. Moosavi, A.A., Sepaskhah, A.R., 2012. Spatial variability of physico-chemical properties and hydraulic characteristics of a gravelly calcareous soil. Arch. Agron. Soil Sci. 58 (6), 631–656. Mosaddeghi, M., Morshedizad, M., Mahboubi, A., Dexter, A., Schulin, R., 2009. Laboratory evaluation of a model for soil crumbling for prediction of the optimum soil water content for tillage. Soil Tillage Res. 105 (2), 242–250. Mossadeghi-Björklund, M., Arvidsson, J., Keller, T., Koestel, J., Lamandé, M., Larsbo, M., Jarvis, N., 2016. Effects of subsoil compaction on hydraulic properties and preferential flow in a Swedish clay soil. Soil Tillage Res. 156, 91–98. Nelson, D.W., Sommers, L.E., 1996. Total carbon, organic carbon, and organic matter. In: Sparks, D., Page, A., Helmke, P., Loeppert, R., Soltanpour, P., Tabatabai, M., Johnston, C., Sumner, M. (Eds.), Methods of Soil Analysis. Part 3. Chemical Methods. ASA/SSSA, Madison, WI, pp. 961–1010. Olson, K.R., Al-Kaisi, M.M., 2015. The importance of soil sampling depth for accurate account of soil organic carbon sequestration, storage, retention and loss. Catena 125,

10