Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Hydrophysical characteristics in water-repellent tropical Eucalyptus, Pine, and Casuarina plantation forest soils

Hydrophysical characteristics in water-repellent tropical Eucalyptus, Pine, and Casuarina... J. Hydrol. Hydromech., 69, 2021, 4, 447–455 ©2021. This is an open access article distributed DOI: 10.2478/johh-2021-0027 under the Creative Commons Attribution ISSN 1338-4333 NonCommercial-NoDerivatives 4.0 License Hydrophysical characteristics in water-repellent tropical Eucalyptus, Pine, and Casuarina plantation forest soils 1* 1 2 1 D.A.L. Leelamanie , H.I.G.S. Piyaruwan , P.K.S.C. Jayasinghe , P.A.N.R. Senevirathne Department of Soil Science, Faculty of Agriculture, University of Ruhuna, Mapalana, Kamburupitiya 81100, Sri Lanka. Department of Information and Communication Technology, Faculty of Technology, University of Ruhuna, Karagoda-Uyangoda, Kam- burupitiya 81100, Sri Lanka. Corresponding author. Tel.: +94-71-861-4380. Fax: +94-41-2292384. E-mails: leelamanie@soil.ruh.ac.lk; leelamaniee@yahoo.co.uk Abstract: Soil water repellency (SWR) reduces the rates of wetting in dry soils and is known to interfere with water movement into as well as within the soils. The objective of this study was to investigate the hydrophysical characteristics of three water-repellent tropical exotic plantation forest soils in wet and dry seasons. The study sites were Eucalyptus grandis (EG), Pinus caribaea (PC), and Casuarina equisetifolia (CE) plantation forest soils located in the up-country intermediate zone (EG and PC), and low-country dry zone (CE). Field experiments were conducted to measure the infiltration rate, unsaturated hydraulic conductivity (k), water sorptivity (S ). Laboratory experiments were conducted to measure the potential SWR and water entry value (h ). All three soils showed higher SWR in the dry season, where CE we soils showed the highest. The EG soils showed the highest SWR in the wet season. Although SWR in all soils decreased with increasing depth in the wet season, only CE soils showed a significant decrease in SWR with soil depth in the dry season. Compared with the wet season, the k (–1 cm) was lower and hwe was higher in the dry season. However, SW did not show a significant difference between wet and dry seasons. Initial infiltration rate and k (–1 cm) showed a negative correlation with contact angle in all three soils. Soils showed positive linear correlations between k (–1 cm) and SW, and negative linear correlations between SW and hwe showing that surface water absorption is related to both subsurface unsaturated water flow and surface water entry pressure. It was clear that the water entry into soils and the subsurface water flow were hindered by the SWR. High water entry values in the dry season predict high potentials for intensified surface runoff and topsoil erosion. Future research will be required on the interactions between soil biology and soil properties such as pore structure that would influence water flow into and within soils. Keywords: Eucalyptus grandis; Pinus caribaea; Casuarina equisetifolia; Hydrophysical characteristics; Water repellency. INTRODUCTION SWR has long been considered a widespread challenge to plant growth in many regions (Doerr et al., 2000). It is not Soil water repellency (SWR) restricts the wetting of soils limited to specific climates or soil types, and is reported in and may induce preferential flow paths resulting in irregular numerous types of land uses throughout the world. Water repel- moisture or wetting patterns in soils (Šurda et al., 2020). SWR lency is repeatedly observed in soils covered by tree species is caused by either the intermixed organic substances or organic such as Japanese cypress (Chamaecyparis obtusa), Japanese coatings on the mineral soil particles of hydrophobic nature cedar (Cryptomeria japonica), eucalyptus (Eucalyptus grandis, (DeBano, 1981; Hallett, 2007). The organic substances that are Eucalyptus globulus), pine (Pinus sylvestris, Pinus pinaster, responsible for the development of SWR are usually considered Pinus caribaea), and casuarina (Casuarina equisetifolia), which to be plant roots, microbial exudates, surface waxes of leaves, are rich in various types of hydrophobic resins and waxes (Be- and any other organic substances such as long-chain aliphatic nito et al., 2019; Doerr et al., 1996; Iovino et al., 2018; Koba- acids, alcohols, wax esters (Bisdom et al., 1993). yashi and Shimizu, 2007; Keizer, et al., 2008; Leelamanie, 2016; Lichner, et al., 2013; Piyaruwan et al., 2020). Water- The basic impact of SWR can be considered as the reduction of the rates of water infiltration into soils. Water repellency repellent phenomena observed in these specific forests are reduces the wetting rates in dry soils and lowers the plant avail- known to be natural circumstances rather than being induced by able water, and is known to interfere with water movement into different external aspects such as forest fire conditions. This and within the soils affecting most of the hydrophysical proper- vegetation-induced SWR is usually associated with chemical ties and processes in soils (Lichner et al., 2012). SWR further compounds such as alkanoic acids, alkanes, and esters (Hansel leads to uneven patterns of water entry into soil generating et al., 2008). unstable and irregular water flow within the soil matrix (Rodný Forests with SWR conditions are reported to have altered et al., 2015). Hindered water entry into soils promotes surface soil hydraulic properties (Kobayashi and Shimizu, 2007; Letey runoff followed by intensified erosion, resulting in irregular et al., 1962; Lichner et al., 2013; 2020; Wahl et al., 2003). moisture patterns in the soil. Localized high and less water- Numerous impacts of SWR on soil water systems have been repellent zones lead to a selective water entry through the less recognized by studies under different land-use types and climat- water-repellent patches, stimulating preferential flow paths. ic regions. SWR tends to be highly variable spatially as well as Solute transport in soils through these specified flow channels temporally, where it often disappears following prolonged wet can lead to accelerated transport of dissolved chemicals into periods. Intensified surface runoff and erosion in water- groundwater (Lichner et al., 2013; Wessolek et al., 2008). repellent soils are reported with heavy rainfall events usually 447 D.A.L. Leelamanie, H.I.G.S. Piyaruwan, P.K.S.C. Jayasinghe, P.A.N.R. Senevirathne following long dry and hot periods (Onderka et al., 2012; The third experimental site, the CE forest (~36 ha) is a Pavelková et al., 2012). Inherent water-repellent characteristics sand dune in the Southern Dry zone, which is considered as one in soils under different types of tree species are known to influ- of the driest parts of Sri Lanka with an average annual rainfall ence soil hydrological processes more specifically following of about 900 mm. About 70% of the annual total rainfall is longer hot or dry spells (Lichner et al., 2012). received from mid-October to mid-January (wet season), and Forest plantations in Sri Lanka were mainly established us- minor proportion during mid-March to mid-May. Mid-May to ing non-native species such as Eucalyptus, Pine, and Casuarina September is considered to be the dry period (dry season) due to their faster growth rates over the indigenous species. The receiving less than 20% of the annual rainfall. The average idea of this exercise was to have an alternative timber resource annual temperature varies from 25 to 31 °C, with the highest to protect the existing natural forest and to rehabilitate the temperatures are recorded in the driest period of the year (May– environmentally damaged areas within a short period. Howev- September) (National Atlas of Sri Lanka, 2007). The soil type er, these plantations created a dialogue over its unsuitability as is identified locally as sandy Regosols, or according to USDA demonstrated by the natural evidence, such as drying out of classification as Ustic Quartzipsamments. Sandy Regosols are streams, reduction of groundwater level, the nonexistence of soils that are in general found along or within proximity to the undergrowth, and lack of animal diversity, including the pres- coastline, with no specific structural development, where both ence of SWR (Leelamanie 2016; Piyaruwan and Leelamanie, surface and subsurface soils are single-grained (National Atlas 2020; Piyaruwan et al., 2020). Although these plantations have of Sri Lanka, 2007). Soil reaction is nearly neutral (pH: proven to have some of the expected advantages, the water- 7.4±0.2). The forest floor of the studied dune is covered with a repellent aspects and their hydrophysical consequences are yet thick mat of dry leaf litter layer or phylloclades (3–10 cm of to be explored comprehensively. The objective of this study thickness). The average field soil moisture content during the was to investigate hydrophysical characteristics of three water- wet and dry seasons were 5–7% and 0.5–1.5%, respectively. repellent tropical exotic plantation forest soils (Eucalyptus, The litter layers at all three experimental sites vary in Pine, and Casuarina), considering both rainy (wet) and dry thickness interrelated with the climatic conditions, more seasons. specifically, the rainfall. The maximum litter thicknesses were observed in the driest periods, where the decomposition rate of MATERIALS AND METHODS the organic matter is very low. During these dry periods, Study area extreme levels of water-repellent nature can be observed on the soil surfaces. During the rainy season, organic matter The study was conducted at three water-repellent experi- decomposition takes place at an accelerated rate and the mental sites, namely Eucalyptus grandis (EG), Pinus caribaea thickness of the litter layer decreases. Simultaneously, the (PC), and Casuarina equisetifolia (CE) plantation forest soils. magnitude of water-repellent behavior also tends to drop. The The EG forest (06°47'45" N 80°57'58" E) and the PC forest thematic maps of normalized difference vegetation index (06°46'13" N 080°55'52" E) were located in the up-country (NDVI) for the three plantation forest sites that represent the intermediate zone (EG: IU3c; PC: IU3a, IU3b agro-ecological greenness and the relative density of the vegetation covers are regions), whereas the CE forest is located (6°06′52″ N given in Figure 1. Most of the land area in all three study sites 81°05′02″ E) in low-country dry zone (DL5 agro-ecological showed NDVI values above 0.5, indicating close to dense region) (National Atlas of Sri Lanka, 2007). vegetation cover. The first experimental site, EG forest (~100 ha) is in a slope land with considerably steep slopes ranging from ~10 to 35 °. Soil sampling The mean annual rainfall of the area is 1600–1700 mm. The highest rainfall is received in April and October to December Field experiments and laboratory experiments were (wet season), where February, June, July, and August are the conducted during the period from 2016 to 2020 dry (July, dry months (dry season) receiving less than 10% of the average August) and wet (November, December) seasons in all three annual. The mean annual temperature is in a range of 20–22.5 sites. After carefully removing the litter, both undisturbed core °C. The soil is identified as Red Yellow Podzolic according to samples and bulk samples were collected from each site at the the local classification system (National Atlas of Sri Lanka, depths of 0–5, 5–10, and 10–15 cm for laboratory experiments. 2007) and Hapludults, according to the USDA classification Nine sampling points were sleeted (about 2 m away from trees) system (Soil Survey Staff, 2014). A dense layer of litter (3–4 per site to represent 3 blocks, in three replicates. The collected cm in thickness) was observed on the surface. The average field soil samples were tagged, sealed, and transported to the moisture content of soil in the wet and dry seasons were 12 and laboratory. 8%, respectively. The second experimental site, PC forest (~100 ha) was also Laboratory experiments located in a land with steep slopes ranging from ~10 to 40°. The mean annual rainfall of the area is 1700–1900 mm and the In the laboratory, soils were air-dried at room temperature mean annual temperature is in a range of 20–22.5 °C. The high- (27±3 °C) for 3 days and passed through a 2-mm sieve. The est rainfall in the area is received in March to May and October basic properties of the soils were measured in triplicates follow- to December (wet season). February, June, July, and August are ing standard laboratory procedures. The bulk density, the parti- the dry months (dry season) receiving less than 10% of the cle density, and the texture of soils were measured using the average annual rainfall. Similar to the EG site, the soil of the undisturbed soil core method (Blake and Hartge, 1986a), pyc- area is classified as Red Yellow Podzolic under the local classi- nometer method (Blake and Hartge, 1986b), and the hydrome- fication system and Hapludults under the USDA classification ter method (Bouyoucos, 1962), respectively. The organic matter system. A 3–12 cm thick layer of litter consisting mostly of content was measured using the loss on ignition (400 °C for 6 pine needles was observed on the surface. The average field h) method (Rowell and Coetzee, 2003; Schumacher, 2002). The moisture content of soil during the wet and dry seasons were 17 basic properties of the tested soils in the three experimental and 14%, respectively. sites are given in Table 1. 448 Hydrophysical characteristics in water-repellent forest soils (a) (b) (c) Fig. 1. Thematic maps of Normalized Difference Vegetation Index (NDVI) in 2020 for the (a) Eucalyptus, (b) Pine, and (c) Casuarina plantation forest sites. Water repellency water was placed on the surface of the soil from a height of about 10 mm using a burette. Containers were carefully covered The potential soil water repellency (SWR) was measured us- with lids to minimize the effects of evaporation during the ing the water drop penetration time (WDPT) and soil-water experiment. The time taken for water drops to completely pene- contact angle. Soil subsamples with a thickness of >5 mm were trate the soil was measured using a stopwatch (Bisdom et al. used for the WDPT test. Single drop (50±1 μL) of distilled 1993; Chenu et al., 2000; Leelamanie et al., 2008). Penetration 449 D.A.L. Leelamanie, H.I.G.S. Piyaruwan, P.K.S.C. Jayasinghe, P.A.N.R. Senevirathne Table 1. The basic properties of the plantation forest soils (mean ± standard deviation). Eucalyptus Pine Casuarina Soil property 0–5 cm 5–10 cm 10–15 cm 0–5 cm 5–10 cm 10–15 cm 0–5 cm 5–10 cm 10–15 cm –3 Bulk density (g cm ) 1.02±0.10 1.10 ±0.05 1.18 ±0.02 0.96±0.16 1.07±0.07 1.12±0.10 1.98 ±0.04 2.12 ±0.09 2.19 ±0.08 –3 Particle density (g cm ) 2.30±0.25 2.30 ±0.26 2.55 ±0.22 2.56±0.16 2.68±0.07 2.58±0.25 2.80 ±0.03 2.81 ±0.12 2.80 ±0.08 Porosity (%) 55.5 ±6.0 52.1±5.6 53.8±4.2 62.5±5.6 60.0±1.8 56.7±5.0 29.3±2.5 24.5±2.8 21.8±2.4 Sand % 80.4 ±1.8 74.8 ±2.1 79.5 ±0.1 73.7±3.9 72.6±2.3 72.6±3.2 96.7±2.1 96.9 ±4.1 97.0 ±2.9 Silt % 5.8±1.5 6.4±1.5 6.3±1.5 10.4±0.6 8.2±1.6 9.2±1.5 3.2±0.5 2.9±0.3 2.5±0.3 Clay % 13.8±4.2 17.8 ±4.4 14.2 ±2.4 15.9±3.7 19.3±3.4 18.2±1.9 0.1±0.05 0.2±0.3 0.5±0.2 Texture Loamy sand Sandy loam Sandy loam Sandy loam Sandy loam Sandy loam Sand Sand Sand Wet 9.94±0.14 7.05 ±0.04 6.92 ±0.06 15.4±4.0 12.4±2.8 10.6±1.7 1.82 ±0.15 1.29 ±0.08 0.56 ±0.04 Organic matter (%) Dry 13.2 ±1.1 9.83 ±0.72 7.95 ±0.74 19.1±1.6 15.5±1.1 12.4±0.4 2.04 ±0.06 1.64 ±0.03 1.17 ±0.03 times shorter than 0.5 s were considered as 0 s because the actu- conducted in triplicates, sectioning in the study area into three al measurement could not be taken accurately corresponding to blocks (total of nine sample points), during wet and dry the instantaneous penetration. The measurement of penetration seasons. time was terminated after 6 h. The WDPT values were deter- The actual SWR was measured using the WDPT test by mined in three replicates for nine sampling points in each site. placing a drop (50±1 μL) of distilled water on the soil surface The soil-water contact angle was measured using the modi- from a height of about 10 mm using a micropipette (Nichipet fied sessile drop method (Bachmann et al., 2000) using a digital EX II, 1–100 µL Nichiriyo, Japan). The time taken for com- microscopic camera (FS-3100-PC, Fujikoden Co. Ltd., Japan). plete penetration of the drops were measured using a stop Monolayers of soil samples fixed on double-sided adhesive watch, where the average times of 5 drops was taken as the tapes (1.5 cm × 1.5 cm) using smooth glass slides were used for WDPT for one replicate. The SWR was categorized into classes the measurements. A drop (10 μL) of distilled water was placed (both field and laboratory measurements) as wettable (WDPT ≤ on the surface of soil monolayer using a micropipette (Nichipet 5 s), slightly repellent (5–60 s), strongly repellent (60–600 s), EX II J15615241. Nichiriyo, Japan). A digital microphotograph severely repellent (600–3600 s), and extremely repellent of the water drop (horizontal view) was taken within 1–2 s. The (WDPT > 3600 s) (Bisdom et al., 1993). Penetration times contact angle was determined, in three replicates, using the shorter than 0.5 s were considered as 0 s and the measurement digital micro-photographs of the horizontal view of the drop of penetration time was terminated after 1 h. (Leelamanie, 2016). The mini-disk infiltrometer (Decagon devices, Inc.), with a suction head of 1 cm, was used for this purpose. A leveled area Water-entry value of the field at a minimum distance of 2 m to the tree trunks were selected as the sampling points and the litter layer was In water-repellent soils, low hydraulic pressures present on carefully removed without disturbing the soil before the meas- the soil surfaces are not sufficient to start the infiltration. Water urements. Before placing the The method proposed by Zhang starts to infiltrate into water repellent soils at a critical pressure (1997) was used to determine the k(–1 cm) of the tested soils showing an instantaneous breakdown of SWR (Wang et al., (Lichner et al., 2007), which requires the measuring of cumula- 2000). The critical pressure that is required for the breakdown tive infiltration with time and fitting the obtained results with of repellency and driving water into that soil can be determined the function: using the water-entry value (h ). we I = C1 t + C2 √t (1) The h of the topsoil was tested in the laboratory, in tripli- we cates, using the pressure head method (Wang et al., 2000), for –1 –1/2 where the C1 (m s ) and C2 (m s ) parameters are respective- the samples collected from the surface soils (0–5 cm). Air-dried ly related to the k (–1 cm) and the SW of the soil. The k(–1 cm) soils, in 50-g soil subsamples, were placed in the Buchner for the respective soil is then to be computed from: funnel, where the porous plate was covered with a membrane filter and filter paper. The funnel was attached to a burette k = C1/A (2) using a flexible tube. Increasing hydraulic pressure was applied to the soil sample using increasing water height by raising the where C1 is the slope of the cumulative infiltration, I (cm) ver- burette level. The starting pressure head was kept negative to 1/2 sus the square root of time (t ) curve, and A relates the van prevent initial wetting (Wang et al., 2000). The hydraulic pres- Genuchten parameters of soil to the suction rate and the sure head was increased carefully by 5 min intervals up to the infiltrometer disk radius. The slope of the cumulative infiltra- point where the water enters into the soil matrix. At this point tion versus the square root of the time curve, and the of water entry, the height of the water column (burette water k (–1 cm) were calculated based on the infiltration data gathered level compared to the reference level considering the soil) was with the support of the Microsoft Excel spreadsheet published recorded as the h of the samples (Liyanage and Leelamanie, we by Decagon (www.decagon.com/macro). The linear approxima- 2016). tion of the relationship between cumulative infiltration and the square root of time (Eq. 3) was used to estimate the water sorp- Field experiments tivity (SW). The actual SWR, infiltration rate, unsaturated hydraulic I = S √t (3) conductivity, k(–1 cm), and water sorptivity (SW) of the soils in the forest soils were determined in the field. Sampling was 450 Hydrophysical characteristics in water-repellent forest soils Data analysis Unsaturated hydraulic conductivity, k(–cm), water sorptivity (S ), contact angle, and water entry value (h ) of the tested W we The laboratory and field experiments were conducted in trip- forest soils in both wet and dry seasons are presented in Table licates and the results were statistically analyzed using linear 2. It should be noted that infiltration did not initiate in the CE regression and the analysis of variance (ANOVA) at a 5% level soils in the dry season, even with a 0.5 cm suction level in the of significance (p < 0.05) using Microsoft Excel (2016) and mini-disk infiltrometer, and therefore, it was not possible to get STATISTICA software. The mean values of the measurements the measurements for k(–1 cm) and SW in CE soils for the dry were reported, where the error bars in the figures indicate ± season. An interesting finding in the EG and PC soils in the dry standard deviation. season was the presence of very high initial infiltration rates in some locations. These can be considered as an indicator for the RESULTS AND DISCUSSION presence of preferential flow paths. The h of water-repellent we soils are in general known to be positive due to the requirement Figure 2 shows the potential (a, b, c) and actual field (d, e, f) of high hydraulic pressure for the cessation of the SWR and SWR values as measured by the WDPT of the three plantation force water into the soils (Karunarathna et al., 2010). In all forest soils in both wet and dry seasons. Among the three plan- three soils, the dry season with higher repellency (Figure 2) tation forests, CE soils showed the highest SWR in the dry showed higher h compared with the wet season (Table 2). we season, whereas the EG soils showed the highest SWR in the The S is a measure of the ability of a soil to capture water wet season. In the wet season, all three forest soils showed a rapidly that is considered as a key parameter governing the decrease in water repellency with increasing soil depth. In early stages of entry of water into the soil through infiltration contrast, in the dry season, only CE soils showed a significant (Shaver et al., 2003). Wallis et al. (1991) pointed out that the decrease in SWR with soil depth. Both EG and PC soils main- entry of water into soils may be retarded by even minor levels tained high levels of repellency with decreasing soil depth of repellency, indicating its hydrological significance. Howev- down 15 cm in the soil profile. Both actual and potential SWR er, irrespective of the higher levels of repellency in the dry in all three tested layers of EG soils, (0–5, 5–10, 10–15 cm) season, EU and PC soils did not show any significant difference showed extreme water-repellent conditions (WDPT > 3600 s). in S for wet and dry seasons. Other than the wetting status of The two upper layers (0–5, 5–10 cm) of PC soils showed ex- soils governed by the repellency, another potential reason for treme (WDPT > 3600 s) while the 10–15 cm showed severe high rates of water absorption into soils in dry conditions is the (WDPT > 2000 s) water-repellent conditions. differences in water potential of soils between dry and moist Low SWR in the wet season seems to correspond with the conditions. As the wetting of soil with water would theoretical- thickness of the litter layer on the surface of all the forest soils. ly be accelerated when the soil is in a drier condition, it might In the wet season, the thickness of the litter layer was low, also be factored in, together with restriction for water move- which was very high in the dry season. The temperature of all ments caused by water-repellent effects, to the actual SW of the the locations is sufficient enough to maintain higher decompo- soils. These contradictory influences can be considered as the sition rates when there is enough water available. Although CE reasons for soils to show no differences in SW between dry and soils showed very high water repellency in the topsoil in the dry wet seasons. season. Interestingly water repellency dropped significantly Soils having water-repellent features are reported to resist or with the depth. It means that the highly repellent compounds retard surface water infiltration (Doerr et al., 2000; Wahl et al., added to the topsoil are not moving downward irrespective of 2003). Our results are in line with some of the previous studies the sandy nature of the soils. Furthermore, very low organic which report that water infiltration into hydrophobic soil is matter content (~1–2%) in these soils can be considered another slower than into more hydrophilic soil (Letey et al., 1962). reason for low SWR levels in the lower levels of the profile. Relation of potential SWR, as measured by soil water contact Conversely, the other two soils showed considerable high val- angle, to the initial infiltration rate during the period of first 30 ues of water repellency throughout the top 15 cm of the soil s is given in Figure 3. Initial infiltration rate showed moderate showing that the water repellent compounds transferred to the to strong negative linear correlation with soil-water contact lower levels of the profile. angle in all three soils (R = 0.55, 0.55, and 0.91, respectively in Table 2. Unsaturated hydraulic conductivity (k), water sorptivity (S ), contact angle, and water entry value (h ) of the tested forest soils in W we wet and dry seasons. k (–1 cm) S Contact angle h W we –1 –1/2 (cm h ) (cm s ) (°) (cm) Wet Dry Wet Dry Wet Dry Wet Dry Eucalyptus Minimum 1.23 0.01 0.028 0.062 119 124 3.8 6.3 Maximum 6.97 4.45 0.130 0.133 78 110 3.3 4.0 Mean 2.46 1.83 0.082 0.080 103 115 3.6 4.9 S.D. 1.63 1.35 0.025 0.018 13 4 0.3 0.9 Pine Minimum 0.47 0.02 0.021 0.019 97 107 3.4 4.4 Maximum 2.89 5.86 0.168 0.164 67 69 1.3 1.4 Mean 2.33 2.11 0.148 0.143 83 83 2.4 2.8 S.D. 0.76 1.98 0.019 0.050 10 14 1.4 1.2 Casuarina Minimum 1.66 – 0.035 – 106 119 5.3 8.2 Maximum 44.83 – 0.259 – 85 104 3.8 5.4 Mean 23.39 – 0.127 – 100 111 4.8 6.8 S.D. 17.60 – 0.095 – 7 6 0.4 0.9 451 D.A.L. Leelamanie, H.I.G.S. Piyaruwan, P.K.S.C. Jayasinghe, P.A.N.R. Senevirathne 100000 10000 Dry Dry (a) Eucalyptus (d) Eucalyptus Wet Wet 1 1 0-5 cm 5-10 cm 10-15 cm 0-5 cm 5-10 cm 10-15 cm Soil depth (cm) Soil depth (cm) (e) Pine (b) Pine Dry Dry Wet Wet 0-5 cm 5-10 cm 10-15 cm 0-5 cm 5-10 cm 10-15 cm Soil depth (cm) Soil depth (cm) (f) Casuarina Dry (c) Casuarina Dry Wet Wet 0-5 cm 5-10 cm 10-15 cm 0-5 cm 5-10 cm 10-15 cm Soil depth (cm) Soil depth (cm) Fig. 2. Potential (a, b, c) and actual (d, e, f) soil water repellency as measured by water drop penetration time (WDPT) of Eucalyptus, Pine, and Casuarina plantation forest soils in both wet and dry seasons. EU, PC, and CE soils). It was clear that the level of SWR de- soils decreased with increasing contact angle showing a nega- celerates water infiltration into all three soils at the initial level. tive exponential correlation (R = 0.34, 0.37, and 0.44, respec- The influence of SWR is reported to be more pronounced dur- tively in EU, PC, and CE soils). The results on k(–1 cm) are ing the early stages of the infiltration process. (Letey et al., comparable with Moody et al. (2009), who reported that hy- 1962; Lozano-Baez et al., 2020). This diminished water flow draulic conductivity near saturation is inversely proportional to rate into soils can be considered as a result of increased flow the SWR in fire-affected soils. resistance with increasing contact angle (Diamantopoulos and The relationship between k(–1 cm) and SW, as obtained from Durner, 2013). the linear approximation of cumulative infiltration and the Figure 4 shows the relation between the potential SWR as square root of the time, is presented in Figure 5. All three soils measured by soil-water contact angle and the k(–1 cm). Similar showed moderate to strong positive linear correlations between to the initial infiltration rate, k(–1 cm) in all the three forest k(–1 cm) and S (R = 0.82, 0.66, and 0.61, respectively in EU, WDPT (s) WDPT (s) WDPT (s) WDPT (s) WDPT (s) WDPT (s) Hydrophysical characteristics in water-repellent forest soils y = -3.12x + 344 Eucalyptus R² = 0.91 (a) Eucalyptus Pine Casuarina y = 60.91x - 0.94 R² = 0.82 y = -2.37x + 241 R² = 0.55 y = -0.47x + 73 R² = 0.55 0 0 50 70 90 110 130 0 0.05 0.1 0.15 –1/2 Soil-water contact angle (°) Sorptivity, S (cm S ) Fig. 3. Relation of Soil water repellency, as measured by soil water contact angle, to the initial infiltration rate during the period of first 30 s of infiltration in Eucalyptus, Pine, and Casuarina plantation (b) Pine forest soils. 50 6 Eucalyptus Pine Casuarina -0.09x y = 69 388.95e R² = 0.44 y = 21.56x + 0.98 R² = 0.66 -0.05x 0 0.1 0.2 0.3 y = 76.11e R² = 0.38 –1/2 Sorptivity, S (cm S ) -0.07x y = 957.72e W R² = 0.34 60 70 80 90 100 110 120 130 (c) Casuarina Contact angle (°) Fig. 4. Relationship between soil-water contact angle and the unsaturated hydraulic conductivity, k(–1 cm), in Eucalyptus, Pine, and Casuarina plantation forest soils. PC, and CE soils), which were statistically significant at 0.05 probability level. It appeared that surface sorptivity is related to 30 the subsurface unsaturated water flow in all three water- y = 234.61x - 0.50 repellent soils. R² = 0.61 The SW is the ability of soil for the rapid capture of, or to up- take, water without any influence of gravitational effects (Phil- ip, 1969). The hwe explains the critical pressure at the point of accomplishing instantaneous entry of water into soils. As both these parameters explain the entering of water into the soil at different conditions, S was plotted against h to observe the W we 00.1 0.2 0.3 interrelation. The S showed a negative linear correlation (Fig- 2 –1/2 ure 6) between h and S (R = 0.70, 0.42, and 0.65, respec- we W Sorptivity, S (cm S ) tively in EU, PC, and CE soils), where the correlation between the two parameters for all three soils was statistically signifi- Fig. 5. Relationship between unsaturated hydraulic conductivity, cant at 0.05 probability level. The result shows that the surface k(–1 cm), and water sorptivity, S , in (a) Eucalyptus, (b) Pine, and water absorption related to the critical surface water entry pres- (c) Casuarina plantation forest soils. sure that force water into the soil. –1 –1 k(–1 cm) (cm h ) Initial Infiltration rate (cm h ) –1 –1 –1 k(–1 cm) (cm h ) k(–1 cm) (cm h ) k(–1 cm) (cm h ) D.A.L. Leelamanie, H.I.G.S. Piyaruwan, P.K.S.C. Jayasinghe, P.A.N.R. Senevirathne 105–118. https://doi.org/10.1016/B978-0-444-81490-6.50013-3 Blake, G.R., Hartge, K.H., 1986a. Bulk density. In: Klute, A. (Ed.): Methods of Soil Analysis. Part 1: Physical and Miner- alogical Methods. 2nd Ed. Soil Science Society of America: Madison, WI., pp. 363–375. https://doi.org/10.2136/sssa bookser5.1.2ed.c13 Blake, G.R., Hartge, K.H., 1986b. Particle density. In: Klute, A. (Ed.): Methods of Soil Analysis. Part 1: Physical and Miner- alogical Methods. 2nd Ed. Soil Science Society of America: Madison, WI., pp. 377–382. https://doi.org/10.2136/sssaboo kser5.1.2ed.c14 Bouyoucos, G.J., 1962. Hydrometer method improved for mak- ing particle size analyses of soils. Agronomy Journal, 54, 5, 464–465. https://doi.org/10.2134/agronj1962.000219620054 00050028x Chenu, C., Le Bissonnais, Y., Arrouays, D., 2000. Organic matter influence on clay wettability and soil aggregate sta- Fig. 6. Relationship between water entry value (hwe) and water sorp- bility. Soil Science Society of America Journal, 64, 4, 1479– tivity (S ) in Eucalyptus, Pine, and Casuarina plantation forest soils. 1486. https://doi.org/10.2136/sssaj2000.6441479x Debano, L.F., 1981. Water repellent soils: a state-of-the art. CONCLUSIONS General Technical Report PSW-46, Berkeley, CA: USDA Forest Service, Pacific Southwest Forest and Range Experi- All three plantation forest soils showed clear differences in ment Station, pp. 2–4. repellency between wet and dry seasons. The dry season Diamantopoulos, E., Durner, W., 2013. Physically-based model of showed higher repellency that seems to correspond to the soil hydraulic properties accounting for variable contact angle thickness of the litter layer on the surface. Positive linear corre- and its effect on hysteresis. Advances in Water Resources, 59, lations between k (–1 cm) and S , and negative linear correla- 169–180. https://doi.org/10.1016/j.advwatres.2013.06.005 tions between S and h , confirmed that the surface water W we Doerr, S.H., Shakesby, R.A., Walsh, R.P.D., 1996. Soil hydro- absorption is related to both subsurface unsaturated water flow phobicity variations with depth and particle size fraction in and surface water entry pressure. burned and unburned Eucalyptus globulus and Pinus pinas- Water entry into soils as well as the subsurface water flow ter forest terrain in the Águeda Basin, Portugal. Catena, 27, was hindered by the SWR. For the initiation of water to infil- 25–47. https://doi.org/10.1016/0341-8162(96)00007-0 trate into the soil under natural conditions, the ponding depth of Doerr, S.H., Shakesby, R.A., Walsh, R.P.D., 2000. Soil water water on the soil surface should be equal to or exceed the water repellency: Its causes, characteristics and hydro-geo mor- entry value. High water entry values in the dry season predict phological significance. Earth Sci. Rev., 51, 33–65. high potentials for intensified surface runoff and topsoil erosion https://doi.org/10.1016/S0012-8252(00)00011-8 in the dry season. Considering the localized points with very Hallett, P.D., 2007. An introduction to soil water repellency. In: high infiltration rates, presence of preferential flow paths can be th Gaskin, R.E. (Ed.): Proc. 8 Int. Symp. on Adjuvants for suggested as the possible mode of water entry into soils in Agrochem. Hand Multimedia, Christchurch, NZ. 13 p. ISBN rainfall events after strong dry spells. Future research will be 978-0-473-12388-8. required on the interactions between soil biology and soil prop- Hansel, F.A., Aoki, C.T., Maia, C.M., Cunha Jr, A. and Dede- erties such as pore structure that would influence water flow cek, R.A., 2008. Comparison of two alkaline treatments in into and within soils, and the potential runoff levels. the extraction of organic compounds associated with water repellency in soil under Pinus taeda. Geoderma, 148, 2, 167– Acknowledgements. This work was financially supported by the 172. https://doi.org/10.2134/agronj1962.000219620054000 University Grants Commission (UGC) Block grant for 50028x strengthening research [RU/PG-R/16/01]. Iovino, M., Pekárová, P., Hallett, P.D., Pekár, J., Lichner, Ľ., Mataix-Solera, J., Alagna, V., Walsh, R., Raffan, A., Conflicts of interest. As the authors of the manuscript, herewith Schacht, K., Rodný, M., 2018. Extent and persistence of soil we confirm that the study has not received any funds from inter- water repellency induced by pines in different geographic ested parties, except for the UGC Block grant [RU/PG-R/16/01] regions. Journal of Hydrology and Hydromechanics, 66, 4, and that there are no conflicts of interest in any manner. 360–368. https://doi.org/10.2478/johh-2018-0024 Karunarathna, A.K., Chhoden, T., Kawamoto, K., Komatsu, T., REFERENCES Moldrup, P., de Jonge, L.W., 2010. Estimating hysteretic soil-water retention curves in hydrophobic soil by a Bachmann, J., Ellies, A., Hartge, K.H., 2000. Development and th minitensiometer˗TDR coil probe. In: Proc. 19 World Con- application of a new sessile drop contact angle method to as- gress of Soil Science, Soil Solutions for a Changing World, sess soil water repellency. Journal of Hydrology, 231–232, Brisbane, Australia, pp. 58–61. Published on DVD. 66–75. https://doi.org/10.1016/S0022-1694(00)00184-0 Keizer, J.J., Doerr, S.H., Malvar, M.C., Prats, S.A., Ferreira, Benito, E., Varela, E., Rodríguez-Alleres, M., 2019. Persistence of R.S.V., Oñate, M.G., Coelho, C.O.A., Ferreira, A.J.D., 2008. water repellency in coarse-textured soils under various types of Temporal variation in topsoil water repellency in two recent- forests in NW Spain. Journal of Hydrology and Hydromechan- ly burnt eucalypt stands in north-central Portugal. Catena, ics, 67, 2, 129–134. https://doi.org/10.2478/johh-2018-0038 74, 192–204. https://doi.org/10.1016/j.catena.2008.01.004 Bisdom, E.B.A., Dekker, L.W., Schoute, J.F.T., 1993. Water Kobayashi, M., Shimizu, T., 2007. Soil water repellency in a repellency of sieve fractions from sandy soils and relation- Japanese cypress plantation restricts increases in soil water ships with organic material and soil structure. Geoderma, 56, 454 Hydrophysical characteristics in water-repellent forest soils storage during rainfall events. Hydrological Processes, 21, nal of Hydrology and Hydromechanics, 60, 73–86. DOI: 2356–2364. https://doi.org/10.1002/hyp.6754 10.2478/v10098-012-0007-2 Leelamanie, D.A.L., 2016. Occurrence and distribution of Philip, J., 1969. Theory of infiltration. Advances in Hydrosci- water repellency in size fractionated coastal dune sand in Sri ence, 5, 215–296. Lanka under Casuarina shelterbelt. Catena, 142, 206–212. Piyaruwan, H.I.G.S., Leelamanie, D.A.L., 2020. Existence of https://doi.org/10.1016/j.catena.2016.03.026 water repellency and its relation to structural stability of soils Leelamanie, D.A.L., Karube, J., Yoshida, A., 2008. Character- in a tropical Eucalyptus plantation forest. Geoderma, 380, izing water repellency indices: Contact angle and water drop 114679. https://doi.org/10.1016/j.geoderma.2020.114679 penetration time of hydrophobized sand. Soil Science & Piyaruwan, H.I.G.S., Jayasinghe, P.K.S.C., Leelamanie, Plant Nutrition, 54, 2, 179–187. D.A.L., 2020. Water repellency in eucalyptus and pine plan- https://doi.org/10.1111/j.1747-0765.2007.00232.x tation forest soils and its relation to groundwater levels esti- Letey, J., Osborn, J., Pelishek, R.E., 1962. The influence of the mated with multi-temporal modeling. Journal of Hydrology water-solid contact angle on water movement in soil. Hydro- and Hydromechanics, 68, 4, 382–391. logical Sciences Journal, 7, 3, 75–81. https://doi.org/10.2478/johh-2020-0030 https://doi.org/10.1080/02626666209493272 Rodný, M., Lichner, L., Schacht, K., Holko, L., 2015. Depth- Lichner, Ľ., Capuliak, J., Zhukova, N., Holko, L., Czachor, H., dependent heterogeneity of water flow in sandy soil under Kollár, J., 2013. Pines influence hydrophysical parameters grass. Biologia, 70, 11, 1462–1467. and water flow in a sandy soil. Biologia, 68, 6, 1104–1108. http://dx.doi.org/10.1515/biolog-2015-0167 https://doi.org/10.2478/s11756-013-0254-7 Rowell, M.J., Coetzee, M.E., 2003. The measurement of low Lichner, L., Hallett, P.D., Feeney, D.S., Ďurová, O., Šír, M., organic matter contents in soils. South African Journal of Tesař, M., 2007. Field measurement of soil water repellency Plant Soil, 20, 2, 49˗53. https://doi.org/10.1080/0257 and its impact on water flow under different vegetation. Bio- 1862.2003.10634907 logia, 62, 5, 537–541. https://doi.org/10.2478/s11756-007- Schumacher, B.A., 2002. Methods for the determination of total 0106-4 organic carbon (TOC) in soils and sediments. Ecological Lichner, L., Holko, L., Zhukova, N., Schacht, K., Rajkai, K., Risk Assessment Support Center Office of Research and Fodor, N., Sandor, R., 2012. Plants and biological soil crust Development, US Environmental Protection Agency, 25 p. influence the hydrophysical parameters and water flow in an Shaver, T.M., Peterson, G.A., Sherrod, L.A., 2003. Cropping aeolian sandy soil. Journal of Hydrology and Hydromechan- intensification in dryland systems improves soil physical ics, 60, 4, 309–318. DOI: 10.2478/v10098-012-0027-y properties: regression relations. Geoderma, 116, 149–164. Lichner, Ľ., Iovino, M., Šurda, P., Nagy, V., Zvala, A., Kollár, https://doi.org/10.1016/S0016-7061(03)00099-5 th J., Pecho, J., Píš, V., Sepehrnia, N., Sándor, R., 2020. Impact Soil Survey Staff, 2014. Keys to Soil Taxonomy. 12 Ed., of secondary succession in abandoned fields on some United States Department of Agriculture, Natural Resources properties of acidic sandy soils. Journal of Hydrology and Conservation Service, pp. 290–303. Hydromechanics, 68, 1, 12–18. https://doi.org/10.2478/johh- Šurda, P., Lichner, Ľ., Kollár, J., Nagy, V., 2020. Differences in 2019-0028 moisture pattern, hydrophysical and water repellency param- Liyanage, T.D.P., Leelamanie, D.A.L., 2016. Influence of eters of sandy soil under native and synanthropic vegetation. organic manure amendments on water repellency, water en- Biologia, 75, 6, 819–825. https://doi.org/10.2478/s11756- try value, and water retention of soil samples from a tropical 020-00415-z Ultisol. Journal of Hydrology and Hydromechanics, 64, 2, Wahl, N.A., Bens, O., Schäfer, B., Hüttl, R.F., 2003. Impact of 160–166. https://doi: 10.1515/johh-2016-0025 changes in land-use management on soil hydraulic properties: Lozano-Baez, S.E., Cooper, M., de Barros Ferraz, S.F., Ribeiro hydraulic conductivity, water repellency and water retention. Rodrigues, R., Lassabatere, L., Castellini, M., Di Prima, S., Physics and Chemistry of the Earth, 28, 1377–1387. 2020. Assessing water infiltration and soil water repellency https://doi.org/10.1016/j.pce.2003.09.012 in Brazilian Atlantic forest soils. Applied Sciences, 10, 6, Wallis, M.G., Scotter, D.R., Horne, D.J., 1991. An evaluation 1950. https://doi.org/10.3390/app10061950 of the intrinsic sorptivity water repellency index on a range Moody, J.A., Kinner, D.A., Úbeda, X., 2009. Linking hydraulic of New Zealand soils. Soil Research, 29, 3, 353–362. properties of fire-affected soils to infiltration and water re- https://doi.org/10.1071/SR9910353 pellency. Journal of Hydrology, 379, 3–4, 291–303. Wang, Z., Wu, L., Wu, Q.J., 2000. Water-entry value as an https://doi.org/10.1016/j.jhydrol.2009.10.015 alternative indicator of soil water-repellency and wettability. National Atlas of Sri Lanka, 2007. 2nd Ed. Survey Department Journal of Hydrology, 231–232, 76–83. of Sri Lanka. Colombo, Sri Lanka. https://doi.org/10.1016/S0022-1694(00)00185-2 Onderka, M., Wrede, S., Rodný, M., Pfister, L., Hoffmann, L., Wessolek, G., Schwärzel, K., Greiffenhagen, A., Stoffregen, Krein, A., 2012. Hydrogeologic and landscape controls of dis- H., 2008. Percolation characteristics of a water-repellent solved inorganic nitrogen (DIN) and dissolved silica (DSi) sandy forest soil. European Journal of Soil Science, 59, 14– fluxes in heterogeneous catchments. Journal of Hydrology, 23. https://doi.org/10.1111/j.1365-2389.2007.00980.x 450, 36–47. https://doi.org/10.1016/j.jhydrol.2012.05.035 Zhang, R., 1997. Determination of soil sorptivity and hydraulic Ouyang, L., Wang, F., Tang, J., Yu, L., Zhang, R., 2013. Ef- conductivity from the disk infiltrometer. Soil Science Socie- fects of biochar amendment on soil aggregates and hydraulic ty of America Journal, https://doi.org/10.2136/sssaj properties. J. Soil Sci. Plant Nutr., 13, 4, 991–1002. 1997.03615995006100040005x http://dx.doi.org/10.4067/S0718-95162013005000078 Pavelková, H., Dohnal, M., Vogel, T., 2012. Hillslope runoff Received 31 May 2021 generation-comparing different modeling approaches. Jour- Accepted 25 August 2021 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Hydrology and Hydromechanics de Gruyter

Hydrophysical characteristics in water-repellent tropical Eucalyptus, Pine, and Casuarina plantation forest soils

Loading next page...
 
/lp/de-gruyter/hydrophysical-characteristics-in-water-repellent-tropical-eucalyptus-mw6njRuguz
Publisher
de Gruyter
Copyright
© 2021 D.A.L. Leelamanie et al., published by Sciendo
ISSN
0042-790X
eISSN
1338-4333
DOI
10.2478/johh-2021-0027
Publisher site
See Article on Publisher Site

Abstract

J. Hydrol. Hydromech., 69, 2021, 4, 447–455 ©2021. This is an open access article distributed DOI: 10.2478/johh-2021-0027 under the Creative Commons Attribution ISSN 1338-4333 NonCommercial-NoDerivatives 4.0 License Hydrophysical characteristics in water-repellent tropical Eucalyptus, Pine, and Casuarina plantation forest soils 1* 1 2 1 D.A.L. Leelamanie , H.I.G.S. Piyaruwan , P.K.S.C. Jayasinghe , P.A.N.R. Senevirathne Department of Soil Science, Faculty of Agriculture, University of Ruhuna, Mapalana, Kamburupitiya 81100, Sri Lanka. Department of Information and Communication Technology, Faculty of Technology, University of Ruhuna, Karagoda-Uyangoda, Kam- burupitiya 81100, Sri Lanka. Corresponding author. Tel.: +94-71-861-4380. Fax: +94-41-2292384. E-mails: leelamanie@soil.ruh.ac.lk; leelamaniee@yahoo.co.uk Abstract: Soil water repellency (SWR) reduces the rates of wetting in dry soils and is known to interfere with water movement into as well as within the soils. The objective of this study was to investigate the hydrophysical characteristics of three water-repellent tropical exotic plantation forest soils in wet and dry seasons. The study sites were Eucalyptus grandis (EG), Pinus caribaea (PC), and Casuarina equisetifolia (CE) plantation forest soils located in the up-country intermediate zone (EG and PC), and low-country dry zone (CE). Field experiments were conducted to measure the infiltration rate, unsaturated hydraulic conductivity (k), water sorptivity (S ). Laboratory experiments were conducted to measure the potential SWR and water entry value (h ). All three soils showed higher SWR in the dry season, where CE we soils showed the highest. The EG soils showed the highest SWR in the wet season. Although SWR in all soils decreased with increasing depth in the wet season, only CE soils showed a significant decrease in SWR with soil depth in the dry season. Compared with the wet season, the k (–1 cm) was lower and hwe was higher in the dry season. However, SW did not show a significant difference between wet and dry seasons. Initial infiltration rate and k (–1 cm) showed a negative correlation with contact angle in all three soils. Soils showed positive linear correlations between k (–1 cm) and SW, and negative linear correlations between SW and hwe showing that surface water absorption is related to both subsurface unsaturated water flow and surface water entry pressure. It was clear that the water entry into soils and the subsurface water flow were hindered by the SWR. High water entry values in the dry season predict high potentials for intensified surface runoff and topsoil erosion. Future research will be required on the interactions between soil biology and soil properties such as pore structure that would influence water flow into and within soils. Keywords: Eucalyptus grandis; Pinus caribaea; Casuarina equisetifolia; Hydrophysical characteristics; Water repellency. INTRODUCTION SWR has long been considered a widespread challenge to plant growth in many regions (Doerr et al., 2000). It is not Soil water repellency (SWR) restricts the wetting of soils limited to specific climates or soil types, and is reported in and may induce preferential flow paths resulting in irregular numerous types of land uses throughout the world. Water repel- moisture or wetting patterns in soils (Šurda et al., 2020). SWR lency is repeatedly observed in soils covered by tree species is caused by either the intermixed organic substances or organic such as Japanese cypress (Chamaecyparis obtusa), Japanese coatings on the mineral soil particles of hydrophobic nature cedar (Cryptomeria japonica), eucalyptus (Eucalyptus grandis, (DeBano, 1981; Hallett, 2007). The organic substances that are Eucalyptus globulus), pine (Pinus sylvestris, Pinus pinaster, responsible for the development of SWR are usually considered Pinus caribaea), and casuarina (Casuarina equisetifolia), which to be plant roots, microbial exudates, surface waxes of leaves, are rich in various types of hydrophobic resins and waxes (Be- and any other organic substances such as long-chain aliphatic nito et al., 2019; Doerr et al., 1996; Iovino et al., 2018; Koba- acids, alcohols, wax esters (Bisdom et al., 1993). yashi and Shimizu, 2007; Keizer, et al., 2008; Leelamanie, 2016; Lichner, et al., 2013; Piyaruwan et al., 2020). Water- The basic impact of SWR can be considered as the reduction of the rates of water infiltration into soils. Water repellency repellent phenomena observed in these specific forests are reduces the wetting rates in dry soils and lowers the plant avail- known to be natural circumstances rather than being induced by able water, and is known to interfere with water movement into different external aspects such as forest fire conditions. This and within the soils affecting most of the hydrophysical proper- vegetation-induced SWR is usually associated with chemical ties and processes in soils (Lichner et al., 2012). SWR further compounds such as alkanoic acids, alkanes, and esters (Hansel leads to uneven patterns of water entry into soil generating et al., 2008). unstable and irregular water flow within the soil matrix (Rodný Forests with SWR conditions are reported to have altered et al., 2015). Hindered water entry into soils promotes surface soil hydraulic properties (Kobayashi and Shimizu, 2007; Letey runoff followed by intensified erosion, resulting in irregular et al., 1962; Lichner et al., 2013; 2020; Wahl et al., 2003). moisture patterns in the soil. Localized high and less water- Numerous impacts of SWR on soil water systems have been repellent zones lead to a selective water entry through the less recognized by studies under different land-use types and climat- water-repellent patches, stimulating preferential flow paths. ic regions. SWR tends to be highly variable spatially as well as Solute transport in soils through these specified flow channels temporally, where it often disappears following prolonged wet can lead to accelerated transport of dissolved chemicals into periods. Intensified surface runoff and erosion in water- groundwater (Lichner et al., 2013; Wessolek et al., 2008). repellent soils are reported with heavy rainfall events usually 447 D.A.L. Leelamanie, H.I.G.S. Piyaruwan, P.K.S.C. Jayasinghe, P.A.N.R. Senevirathne following long dry and hot periods (Onderka et al., 2012; The third experimental site, the CE forest (~36 ha) is a Pavelková et al., 2012). Inherent water-repellent characteristics sand dune in the Southern Dry zone, which is considered as one in soils under different types of tree species are known to influ- of the driest parts of Sri Lanka with an average annual rainfall ence soil hydrological processes more specifically following of about 900 mm. About 70% of the annual total rainfall is longer hot or dry spells (Lichner et al., 2012). received from mid-October to mid-January (wet season), and Forest plantations in Sri Lanka were mainly established us- minor proportion during mid-March to mid-May. Mid-May to ing non-native species such as Eucalyptus, Pine, and Casuarina September is considered to be the dry period (dry season) due to their faster growth rates over the indigenous species. The receiving less than 20% of the annual rainfall. The average idea of this exercise was to have an alternative timber resource annual temperature varies from 25 to 31 °C, with the highest to protect the existing natural forest and to rehabilitate the temperatures are recorded in the driest period of the year (May– environmentally damaged areas within a short period. Howev- September) (National Atlas of Sri Lanka, 2007). The soil type er, these plantations created a dialogue over its unsuitability as is identified locally as sandy Regosols, or according to USDA demonstrated by the natural evidence, such as drying out of classification as Ustic Quartzipsamments. Sandy Regosols are streams, reduction of groundwater level, the nonexistence of soils that are in general found along or within proximity to the undergrowth, and lack of animal diversity, including the pres- coastline, with no specific structural development, where both ence of SWR (Leelamanie 2016; Piyaruwan and Leelamanie, surface and subsurface soils are single-grained (National Atlas 2020; Piyaruwan et al., 2020). Although these plantations have of Sri Lanka, 2007). Soil reaction is nearly neutral (pH: proven to have some of the expected advantages, the water- 7.4±0.2). The forest floor of the studied dune is covered with a repellent aspects and their hydrophysical consequences are yet thick mat of dry leaf litter layer or phylloclades (3–10 cm of to be explored comprehensively. The objective of this study thickness). The average field soil moisture content during the was to investigate hydrophysical characteristics of three water- wet and dry seasons were 5–7% and 0.5–1.5%, respectively. repellent tropical exotic plantation forest soils (Eucalyptus, The litter layers at all three experimental sites vary in Pine, and Casuarina), considering both rainy (wet) and dry thickness interrelated with the climatic conditions, more seasons. specifically, the rainfall. The maximum litter thicknesses were observed in the driest periods, where the decomposition rate of MATERIALS AND METHODS the organic matter is very low. During these dry periods, Study area extreme levels of water-repellent nature can be observed on the soil surfaces. During the rainy season, organic matter The study was conducted at three water-repellent experi- decomposition takes place at an accelerated rate and the mental sites, namely Eucalyptus grandis (EG), Pinus caribaea thickness of the litter layer decreases. Simultaneously, the (PC), and Casuarina equisetifolia (CE) plantation forest soils. magnitude of water-repellent behavior also tends to drop. The The EG forest (06°47'45" N 80°57'58" E) and the PC forest thematic maps of normalized difference vegetation index (06°46'13" N 080°55'52" E) were located in the up-country (NDVI) for the three plantation forest sites that represent the intermediate zone (EG: IU3c; PC: IU3a, IU3b agro-ecological greenness and the relative density of the vegetation covers are regions), whereas the CE forest is located (6°06′52″ N given in Figure 1. Most of the land area in all three study sites 81°05′02″ E) in low-country dry zone (DL5 agro-ecological showed NDVI values above 0.5, indicating close to dense region) (National Atlas of Sri Lanka, 2007). vegetation cover. The first experimental site, EG forest (~100 ha) is in a slope land with considerably steep slopes ranging from ~10 to 35 °. Soil sampling The mean annual rainfall of the area is 1600–1700 mm. The highest rainfall is received in April and October to December Field experiments and laboratory experiments were (wet season), where February, June, July, and August are the conducted during the period from 2016 to 2020 dry (July, dry months (dry season) receiving less than 10% of the average August) and wet (November, December) seasons in all three annual. The mean annual temperature is in a range of 20–22.5 sites. After carefully removing the litter, both undisturbed core °C. The soil is identified as Red Yellow Podzolic according to samples and bulk samples were collected from each site at the the local classification system (National Atlas of Sri Lanka, depths of 0–5, 5–10, and 10–15 cm for laboratory experiments. 2007) and Hapludults, according to the USDA classification Nine sampling points were sleeted (about 2 m away from trees) system (Soil Survey Staff, 2014). A dense layer of litter (3–4 per site to represent 3 blocks, in three replicates. The collected cm in thickness) was observed on the surface. The average field soil samples were tagged, sealed, and transported to the moisture content of soil in the wet and dry seasons were 12 and laboratory. 8%, respectively. The second experimental site, PC forest (~100 ha) was also Laboratory experiments located in a land with steep slopes ranging from ~10 to 40°. The mean annual rainfall of the area is 1700–1900 mm and the In the laboratory, soils were air-dried at room temperature mean annual temperature is in a range of 20–22.5 °C. The high- (27±3 °C) for 3 days and passed through a 2-mm sieve. The est rainfall in the area is received in March to May and October basic properties of the soils were measured in triplicates follow- to December (wet season). February, June, July, and August are ing standard laboratory procedures. The bulk density, the parti- the dry months (dry season) receiving less than 10% of the cle density, and the texture of soils were measured using the average annual rainfall. Similar to the EG site, the soil of the undisturbed soil core method (Blake and Hartge, 1986a), pyc- area is classified as Red Yellow Podzolic under the local classi- nometer method (Blake and Hartge, 1986b), and the hydrome- fication system and Hapludults under the USDA classification ter method (Bouyoucos, 1962), respectively. The organic matter system. A 3–12 cm thick layer of litter consisting mostly of content was measured using the loss on ignition (400 °C for 6 pine needles was observed on the surface. The average field h) method (Rowell and Coetzee, 2003; Schumacher, 2002). The moisture content of soil during the wet and dry seasons were 17 basic properties of the tested soils in the three experimental and 14%, respectively. sites are given in Table 1. 448 Hydrophysical characteristics in water-repellent forest soils (a) (b) (c) Fig. 1. Thematic maps of Normalized Difference Vegetation Index (NDVI) in 2020 for the (a) Eucalyptus, (b) Pine, and (c) Casuarina plantation forest sites. Water repellency water was placed on the surface of the soil from a height of about 10 mm using a burette. Containers were carefully covered The potential soil water repellency (SWR) was measured us- with lids to minimize the effects of evaporation during the ing the water drop penetration time (WDPT) and soil-water experiment. The time taken for water drops to completely pene- contact angle. Soil subsamples with a thickness of >5 mm were trate the soil was measured using a stopwatch (Bisdom et al. used for the WDPT test. Single drop (50±1 μL) of distilled 1993; Chenu et al., 2000; Leelamanie et al., 2008). Penetration 449 D.A.L. Leelamanie, H.I.G.S. Piyaruwan, P.K.S.C. Jayasinghe, P.A.N.R. Senevirathne Table 1. The basic properties of the plantation forest soils (mean ± standard deviation). Eucalyptus Pine Casuarina Soil property 0–5 cm 5–10 cm 10–15 cm 0–5 cm 5–10 cm 10–15 cm 0–5 cm 5–10 cm 10–15 cm –3 Bulk density (g cm ) 1.02±0.10 1.10 ±0.05 1.18 ±0.02 0.96±0.16 1.07±0.07 1.12±0.10 1.98 ±0.04 2.12 ±0.09 2.19 ±0.08 –3 Particle density (g cm ) 2.30±0.25 2.30 ±0.26 2.55 ±0.22 2.56±0.16 2.68±0.07 2.58±0.25 2.80 ±0.03 2.81 ±0.12 2.80 ±0.08 Porosity (%) 55.5 ±6.0 52.1±5.6 53.8±4.2 62.5±5.6 60.0±1.8 56.7±5.0 29.3±2.5 24.5±2.8 21.8±2.4 Sand % 80.4 ±1.8 74.8 ±2.1 79.5 ±0.1 73.7±3.9 72.6±2.3 72.6±3.2 96.7±2.1 96.9 ±4.1 97.0 ±2.9 Silt % 5.8±1.5 6.4±1.5 6.3±1.5 10.4±0.6 8.2±1.6 9.2±1.5 3.2±0.5 2.9±0.3 2.5±0.3 Clay % 13.8±4.2 17.8 ±4.4 14.2 ±2.4 15.9±3.7 19.3±3.4 18.2±1.9 0.1±0.05 0.2±0.3 0.5±0.2 Texture Loamy sand Sandy loam Sandy loam Sandy loam Sandy loam Sandy loam Sand Sand Sand Wet 9.94±0.14 7.05 ±0.04 6.92 ±0.06 15.4±4.0 12.4±2.8 10.6±1.7 1.82 ±0.15 1.29 ±0.08 0.56 ±0.04 Organic matter (%) Dry 13.2 ±1.1 9.83 ±0.72 7.95 ±0.74 19.1±1.6 15.5±1.1 12.4±0.4 2.04 ±0.06 1.64 ±0.03 1.17 ±0.03 times shorter than 0.5 s were considered as 0 s because the actu- conducted in triplicates, sectioning in the study area into three al measurement could not be taken accurately corresponding to blocks (total of nine sample points), during wet and dry the instantaneous penetration. The measurement of penetration seasons. time was terminated after 6 h. The WDPT values were deter- The actual SWR was measured using the WDPT test by mined in three replicates for nine sampling points in each site. placing a drop (50±1 μL) of distilled water on the soil surface The soil-water contact angle was measured using the modi- from a height of about 10 mm using a micropipette (Nichipet fied sessile drop method (Bachmann et al., 2000) using a digital EX II, 1–100 µL Nichiriyo, Japan). The time taken for com- microscopic camera (FS-3100-PC, Fujikoden Co. Ltd., Japan). plete penetration of the drops were measured using a stop Monolayers of soil samples fixed on double-sided adhesive watch, where the average times of 5 drops was taken as the tapes (1.5 cm × 1.5 cm) using smooth glass slides were used for WDPT for one replicate. The SWR was categorized into classes the measurements. A drop (10 μL) of distilled water was placed (both field and laboratory measurements) as wettable (WDPT ≤ on the surface of soil monolayer using a micropipette (Nichipet 5 s), slightly repellent (5–60 s), strongly repellent (60–600 s), EX II J15615241. Nichiriyo, Japan). A digital microphotograph severely repellent (600–3600 s), and extremely repellent of the water drop (horizontal view) was taken within 1–2 s. The (WDPT > 3600 s) (Bisdom et al., 1993). Penetration times contact angle was determined, in three replicates, using the shorter than 0.5 s were considered as 0 s and the measurement digital micro-photographs of the horizontal view of the drop of penetration time was terminated after 1 h. (Leelamanie, 2016). The mini-disk infiltrometer (Decagon devices, Inc.), with a suction head of 1 cm, was used for this purpose. A leveled area Water-entry value of the field at a minimum distance of 2 m to the tree trunks were selected as the sampling points and the litter layer was In water-repellent soils, low hydraulic pressures present on carefully removed without disturbing the soil before the meas- the soil surfaces are not sufficient to start the infiltration. Water urements. Before placing the The method proposed by Zhang starts to infiltrate into water repellent soils at a critical pressure (1997) was used to determine the k(–1 cm) of the tested soils showing an instantaneous breakdown of SWR (Wang et al., (Lichner et al., 2007), which requires the measuring of cumula- 2000). The critical pressure that is required for the breakdown tive infiltration with time and fitting the obtained results with of repellency and driving water into that soil can be determined the function: using the water-entry value (h ). we I = C1 t + C2 √t (1) The h of the topsoil was tested in the laboratory, in tripli- we cates, using the pressure head method (Wang et al., 2000), for –1 –1/2 where the C1 (m s ) and C2 (m s ) parameters are respective- the samples collected from the surface soils (0–5 cm). Air-dried ly related to the k (–1 cm) and the SW of the soil. The k(–1 cm) soils, in 50-g soil subsamples, were placed in the Buchner for the respective soil is then to be computed from: funnel, where the porous plate was covered with a membrane filter and filter paper. The funnel was attached to a burette k = C1/A (2) using a flexible tube. Increasing hydraulic pressure was applied to the soil sample using increasing water height by raising the where C1 is the slope of the cumulative infiltration, I (cm) ver- burette level. The starting pressure head was kept negative to 1/2 sus the square root of time (t ) curve, and A relates the van prevent initial wetting (Wang et al., 2000). The hydraulic pres- Genuchten parameters of soil to the suction rate and the sure head was increased carefully by 5 min intervals up to the infiltrometer disk radius. The slope of the cumulative infiltra- point where the water enters into the soil matrix. At this point tion versus the square root of the time curve, and the of water entry, the height of the water column (burette water k (–1 cm) were calculated based on the infiltration data gathered level compared to the reference level considering the soil) was with the support of the Microsoft Excel spreadsheet published recorded as the h of the samples (Liyanage and Leelamanie, we by Decagon (www.decagon.com/macro). The linear approxima- 2016). tion of the relationship between cumulative infiltration and the square root of time (Eq. 3) was used to estimate the water sorp- Field experiments tivity (SW). The actual SWR, infiltration rate, unsaturated hydraulic I = S √t (3) conductivity, k(–1 cm), and water sorptivity (SW) of the soils in the forest soils were determined in the field. Sampling was 450 Hydrophysical characteristics in water-repellent forest soils Data analysis Unsaturated hydraulic conductivity, k(–cm), water sorptivity (S ), contact angle, and water entry value (h ) of the tested W we The laboratory and field experiments were conducted in trip- forest soils in both wet and dry seasons are presented in Table licates and the results were statistically analyzed using linear 2. It should be noted that infiltration did not initiate in the CE regression and the analysis of variance (ANOVA) at a 5% level soils in the dry season, even with a 0.5 cm suction level in the of significance (p < 0.05) using Microsoft Excel (2016) and mini-disk infiltrometer, and therefore, it was not possible to get STATISTICA software. The mean values of the measurements the measurements for k(–1 cm) and SW in CE soils for the dry were reported, where the error bars in the figures indicate ± season. An interesting finding in the EG and PC soils in the dry standard deviation. season was the presence of very high initial infiltration rates in some locations. These can be considered as an indicator for the RESULTS AND DISCUSSION presence of preferential flow paths. The h of water-repellent we soils are in general known to be positive due to the requirement Figure 2 shows the potential (a, b, c) and actual field (d, e, f) of high hydraulic pressure for the cessation of the SWR and SWR values as measured by the WDPT of the three plantation force water into the soils (Karunarathna et al., 2010). In all forest soils in both wet and dry seasons. Among the three plan- three soils, the dry season with higher repellency (Figure 2) tation forests, CE soils showed the highest SWR in the dry showed higher h compared with the wet season (Table 2). we season, whereas the EG soils showed the highest SWR in the The S is a measure of the ability of a soil to capture water wet season. In the wet season, all three forest soils showed a rapidly that is considered as a key parameter governing the decrease in water repellency with increasing soil depth. In early stages of entry of water into the soil through infiltration contrast, in the dry season, only CE soils showed a significant (Shaver et al., 2003). Wallis et al. (1991) pointed out that the decrease in SWR with soil depth. Both EG and PC soils main- entry of water into soils may be retarded by even minor levels tained high levels of repellency with decreasing soil depth of repellency, indicating its hydrological significance. Howev- down 15 cm in the soil profile. Both actual and potential SWR er, irrespective of the higher levels of repellency in the dry in all three tested layers of EG soils, (0–5, 5–10, 10–15 cm) season, EU and PC soils did not show any significant difference showed extreme water-repellent conditions (WDPT > 3600 s). in S for wet and dry seasons. Other than the wetting status of The two upper layers (0–5, 5–10 cm) of PC soils showed ex- soils governed by the repellency, another potential reason for treme (WDPT > 3600 s) while the 10–15 cm showed severe high rates of water absorption into soils in dry conditions is the (WDPT > 2000 s) water-repellent conditions. differences in water potential of soils between dry and moist Low SWR in the wet season seems to correspond with the conditions. As the wetting of soil with water would theoretical- thickness of the litter layer on the surface of all the forest soils. ly be accelerated when the soil is in a drier condition, it might In the wet season, the thickness of the litter layer was low, also be factored in, together with restriction for water move- which was very high in the dry season. The temperature of all ments caused by water-repellent effects, to the actual SW of the the locations is sufficient enough to maintain higher decompo- soils. These contradictory influences can be considered as the sition rates when there is enough water available. Although CE reasons for soils to show no differences in SW between dry and soils showed very high water repellency in the topsoil in the dry wet seasons. season. Interestingly water repellency dropped significantly Soils having water-repellent features are reported to resist or with the depth. It means that the highly repellent compounds retard surface water infiltration (Doerr et al., 2000; Wahl et al., added to the topsoil are not moving downward irrespective of 2003). Our results are in line with some of the previous studies the sandy nature of the soils. Furthermore, very low organic which report that water infiltration into hydrophobic soil is matter content (~1–2%) in these soils can be considered another slower than into more hydrophilic soil (Letey et al., 1962). reason for low SWR levels in the lower levels of the profile. Relation of potential SWR, as measured by soil water contact Conversely, the other two soils showed considerable high val- angle, to the initial infiltration rate during the period of first 30 ues of water repellency throughout the top 15 cm of the soil s is given in Figure 3. Initial infiltration rate showed moderate showing that the water repellent compounds transferred to the to strong negative linear correlation with soil-water contact lower levels of the profile. angle in all three soils (R = 0.55, 0.55, and 0.91, respectively in Table 2. Unsaturated hydraulic conductivity (k), water sorptivity (S ), contact angle, and water entry value (h ) of the tested forest soils in W we wet and dry seasons. k (–1 cm) S Contact angle h W we –1 –1/2 (cm h ) (cm s ) (°) (cm) Wet Dry Wet Dry Wet Dry Wet Dry Eucalyptus Minimum 1.23 0.01 0.028 0.062 119 124 3.8 6.3 Maximum 6.97 4.45 0.130 0.133 78 110 3.3 4.0 Mean 2.46 1.83 0.082 0.080 103 115 3.6 4.9 S.D. 1.63 1.35 0.025 0.018 13 4 0.3 0.9 Pine Minimum 0.47 0.02 0.021 0.019 97 107 3.4 4.4 Maximum 2.89 5.86 0.168 0.164 67 69 1.3 1.4 Mean 2.33 2.11 0.148 0.143 83 83 2.4 2.8 S.D. 0.76 1.98 0.019 0.050 10 14 1.4 1.2 Casuarina Minimum 1.66 – 0.035 – 106 119 5.3 8.2 Maximum 44.83 – 0.259 – 85 104 3.8 5.4 Mean 23.39 – 0.127 – 100 111 4.8 6.8 S.D. 17.60 – 0.095 – 7 6 0.4 0.9 451 D.A.L. Leelamanie, H.I.G.S. Piyaruwan, P.K.S.C. Jayasinghe, P.A.N.R. Senevirathne 100000 10000 Dry Dry (a) Eucalyptus (d) Eucalyptus Wet Wet 1 1 0-5 cm 5-10 cm 10-15 cm 0-5 cm 5-10 cm 10-15 cm Soil depth (cm) Soil depth (cm) (e) Pine (b) Pine Dry Dry Wet Wet 0-5 cm 5-10 cm 10-15 cm 0-5 cm 5-10 cm 10-15 cm Soil depth (cm) Soil depth (cm) (f) Casuarina Dry (c) Casuarina Dry Wet Wet 0-5 cm 5-10 cm 10-15 cm 0-5 cm 5-10 cm 10-15 cm Soil depth (cm) Soil depth (cm) Fig. 2. Potential (a, b, c) and actual (d, e, f) soil water repellency as measured by water drop penetration time (WDPT) of Eucalyptus, Pine, and Casuarina plantation forest soils in both wet and dry seasons. EU, PC, and CE soils). It was clear that the level of SWR de- soils decreased with increasing contact angle showing a nega- celerates water infiltration into all three soils at the initial level. tive exponential correlation (R = 0.34, 0.37, and 0.44, respec- The influence of SWR is reported to be more pronounced dur- tively in EU, PC, and CE soils). The results on k(–1 cm) are ing the early stages of the infiltration process. (Letey et al., comparable with Moody et al. (2009), who reported that hy- 1962; Lozano-Baez et al., 2020). This diminished water flow draulic conductivity near saturation is inversely proportional to rate into soils can be considered as a result of increased flow the SWR in fire-affected soils. resistance with increasing contact angle (Diamantopoulos and The relationship between k(–1 cm) and SW, as obtained from Durner, 2013). the linear approximation of cumulative infiltration and the Figure 4 shows the relation between the potential SWR as square root of the time, is presented in Figure 5. All three soils measured by soil-water contact angle and the k(–1 cm). Similar showed moderate to strong positive linear correlations between to the initial infiltration rate, k(–1 cm) in all the three forest k(–1 cm) and S (R = 0.82, 0.66, and 0.61, respectively in EU, WDPT (s) WDPT (s) WDPT (s) WDPT (s) WDPT (s) WDPT (s) Hydrophysical characteristics in water-repellent forest soils y = -3.12x + 344 Eucalyptus R² = 0.91 (a) Eucalyptus Pine Casuarina y = 60.91x - 0.94 R² = 0.82 y = -2.37x + 241 R² = 0.55 y = -0.47x + 73 R² = 0.55 0 0 50 70 90 110 130 0 0.05 0.1 0.15 –1/2 Soil-water contact angle (°) Sorptivity, S (cm S ) Fig. 3. Relation of Soil water repellency, as measured by soil water contact angle, to the initial infiltration rate during the period of first 30 s of infiltration in Eucalyptus, Pine, and Casuarina plantation (b) Pine forest soils. 50 6 Eucalyptus Pine Casuarina -0.09x y = 69 388.95e R² = 0.44 y = 21.56x + 0.98 R² = 0.66 -0.05x 0 0.1 0.2 0.3 y = 76.11e R² = 0.38 –1/2 Sorptivity, S (cm S ) -0.07x y = 957.72e W R² = 0.34 60 70 80 90 100 110 120 130 (c) Casuarina Contact angle (°) Fig. 4. Relationship between soil-water contact angle and the unsaturated hydraulic conductivity, k(–1 cm), in Eucalyptus, Pine, and Casuarina plantation forest soils. PC, and CE soils), which were statistically significant at 0.05 probability level. It appeared that surface sorptivity is related to 30 the subsurface unsaturated water flow in all three water- y = 234.61x - 0.50 repellent soils. R² = 0.61 The SW is the ability of soil for the rapid capture of, or to up- take, water without any influence of gravitational effects (Phil- ip, 1969). The hwe explains the critical pressure at the point of accomplishing instantaneous entry of water into soils. As both these parameters explain the entering of water into the soil at different conditions, S was plotted against h to observe the W we 00.1 0.2 0.3 interrelation. The S showed a negative linear correlation (Fig- 2 –1/2 ure 6) between h and S (R = 0.70, 0.42, and 0.65, respec- we W Sorptivity, S (cm S ) tively in EU, PC, and CE soils), where the correlation between the two parameters for all three soils was statistically signifi- Fig. 5. Relationship between unsaturated hydraulic conductivity, cant at 0.05 probability level. The result shows that the surface k(–1 cm), and water sorptivity, S , in (a) Eucalyptus, (b) Pine, and water absorption related to the critical surface water entry pres- (c) Casuarina plantation forest soils. sure that force water into the soil. –1 –1 k(–1 cm) (cm h ) Initial Infiltration rate (cm h ) –1 –1 –1 k(–1 cm) (cm h ) k(–1 cm) (cm h ) k(–1 cm) (cm h ) D.A.L. Leelamanie, H.I.G.S. Piyaruwan, P.K.S.C. Jayasinghe, P.A.N.R. Senevirathne 105–118. https://doi.org/10.1016/B978-0-444-81490-6.50013-3 Blake, G.R., Hartge, K.H., 1986a. Bulk density. In: Klute, A. (Ed.): Methods of Soil Analysis. Part 1: Physical and Miner- alogical Methods. 2nd Ed. Soil Science Society of America: Madison, WI., pp. 363–375. https://doi.org/10.2136/sssa bookser5.1.2ed.c13 Blake, G.R., Hartge, K.H., 1986b. Particle density. In: Klute, A. (Ed.): Methods of Soil Analysis. Part 1: Physical and Miner- alogical Methods. 2nd Ed. Soil Science Society of America: Madison, WI., pp. 377–382. https://doi.org/10.2136/sssaboo kser5.1.2ed.c14 Bouyoucos, G.J., 1962. Hydrometer method improved for mak- ing particle size analyses of soils. Agronomy Journal, 54, 5, 464–465. https://doi.org/10.2134/agronj1962.000219620054 00050028x Chenu, C., Le Bissonnais, Y., Arrouays, D., 2000. Organic matter influence on clay wettability and soil aggregate sta- Fig. 6. Relationship between water entry value (hwe) and water sorp- bility. Soil Science Society of America Journal, 64, 4, 1479– tivity (S ) in Eucalyptus, Pine, and Casuarina plantation forest soils. 1486. https://doi.org/10.2136/sssaj2000.6441479x Debano, L.F., 1981. Water repellent soils: a state-of-the art. CONCLUSIONS General Technical Report PSW-46, Berkeley, CA: USDA Forest Service, Pacific Southwest Forest and Range Experi- All three plantation forest soils showed clear differences in ment Station, pp. 2–4. repellency between wet and dry seasons. The dry season Diamantopoulos, E., Durner, W., 2013. Physically-based model of showed higher repellency that seems to correspond to the soil hydraulic properties accounting for variable contact angle thickness of the litter layer on the surface. Positive linear corre- and its effect on hysteresis. Advances in Water Resources, 59, lations between k (–1 cm) and S , and negative linear correla- 169–180. https://doi.org/10.1016/j.advwatres.2013.06.005 tions between S and h , confirmed that the surface water W we Doerr, S.H., Shakesby, R.A., Walsh, R.P.D., 1996. Soil hydro- absorption is related to both subsurface unsaturated water flow phobicity variations with depth and particle size fraction in and surface water entry pressure. burned and unburned Eucalyptus globulus and Pinus pinas- Water entry into soils as well as the subsurface water flow ter forest terrain in the Águeda Basin, Portugal. Catena, 27, was hindered by the SWR. For the initiation of water to infil- 25–47. https://doi.org/10.1016/0341-8162(96)00007-0 trate into the soil under natural conditions, the ponding depth of Doerr, S.H., Shakesby, R.A., Walsh, R.P.D., 2000. Soil water water on the soil surface should be equal to or exceed the water repellency: Its causes, characteristics and hydro-geo mor- entry value. High water entry values in the dry season predict phological significance. Earth Sci. Rev., 51, 33–65. high potentials for intensified surface runoff and topsoil erosion https://doi.org/10.1016/S0012-8252(00)00011-8 in the dry season. Considering the localized points with very Hallett, P.D., 2007. An introduction to soil water repellency. In: high infiltration rates, presence of preferential flow paths can be th Gaskin, R.E. (Ed.): Proc. 8 Int. Symp. on Adjuvants for suggested as the possible mode of water entry into soils in Agrochem. Hand Multimedia, Christchurch, NZ. 13 p. ISBN rainfall events after strong dry spells. Future research will be 978-0-473-12388-8. required on the interactions between soil biology and soil prop- Hansel, F.A., Aoki, C.T., Maia, C.M., Cunha Jr, A. and Dede- erties such as pore structure that would influence water flow cek, R.A., 2008. Comparison of two alkaline treatments in into and within soils, and the potential runoff levels. the extraction of organic compounds associated with water repellency in soil under Pinus taeda. Geoderma, 148, 2, 167– Acknowledgements. This work was financially supported by the 172. https://doi.org/10.2134/agronj1962.000219620054000 University Grants Commission (UGC) Block grant for 50028x strengthening research [RU/PG-R/16/01]. Iovino, M., Pekárová, P., Hallett, P.D., Pekár, J., Lichner, Ľ., Mataix-Solera, J., Alagna, V., Walsh, R., Raffan, A., Conflicts of interest. As the authors of the manuscript, herewith Schacht, K., Rodný, M., 2018. Extent and persistence of soil we confirm that the study has not received any funds from inter- water repellency induced by pines in different geographic ested parties, except for the UGC Block grant [RU/PG-R/16/01] regions. Journal of Hydrology and Hydromechanics, 66, 4, and that there are no conflicts of interest in any manner. 360–368. https://doi.org/10.2478/johh-2018-0024 Karunarathna, A.K., Chhoden, T., Kawamoto, K., Komatsu, T., REFERENCES Moldrup, P., de Jonge, L.W., 2010. Estimating hysteretic soil-water retention curves in hydrophobic soil by a Bachmann, J., Ellies, A., Hartge, K.H., 2000. Development and th minitensiometer˗TDR coil probe. In: Proc. 19 World Con- application of a new sessile drop contact angle method to as- gress of Soil Science, Soil Solutions for a Changing World, sess soil water repellency. Journal of Hydrology, 231–232, Brisbane, Australia, pp. 58–61. Published on DVD. 66–75. https://doi.org/10.1016/S0022-1694(00)00184-0 Keizer, J.J., Doerr, S.H., Malvar, M.C., Prats, S.A., Ferreira, Benito, E., Varela, E., Rodríguez-Alleres, M., 2019. Persistence of R.S.V., Oñate, M.G., Coelho, C.O.A., Ferreira, A.J.D., 2008. water repellency in coarse-textured soils under various types of Temporal variation in topsoil water repellency in two recent- forests in NW Spain. Journal of Hydrology and Hydromechan- ly burnt eucalypt stands in north-central Portugal. Catena, ics, 67, 2, 129–134. https://doi.org/10.2478/johh-2018-0038 74, 192–204. https://doi.org/10.1016/j.catena.2008.01.004 Bisdom, E.B.A., Dekker, L.W., Schoute, J.F.T., 1993. Water Kobayashi, M., Shimizu, T., 2007. Soil water repellency in a repellency of sieve fractions from sandy soils and relation- Japanese cypress plantation restricts increases in soil water ships with organic material and soil structure. Geoderma, 56, 454 Hydrophysical characteristics in water-repellent forest soils storage during rainfall events. Hydrological Processes, 21, nal of Hydrology and Hydromechanics, 60, 73–86. DOI: 2356–2364. https://doi.org/10.1002/hyp.6754 10.2478/v10098-012-0007-2 Leelamanie, D.A.L., 2016. Occurrence and distribution of Philip, J., 1969. Theory of infiltration. Advances in Hydrosci- water repellency in size fractionated coastal dune sand in Sri ence, 5, 215–296. Lanka under Casuarina shelterbelt. Catena, 142, 206–212. Piyaruwan, H.I.G.S., Leelamanie, D.A.L., 2020. Existence of https://doi.org/10.1016/j.catena.2016.03.026 water repellency and its relation to structural stability of soils Leelamanie, D.A.L., Karube, J., Yoshida, A., 2008. Character- in a tropical Eucalyptus plantation forest. Geoderma, 380, izing water repellency indices: Contact angle and water drop 114679. https://doi.org/10.1016/j.geoderma.2020.114679 penetration time of hydrophobized sand. Soil Science & Piyaruwan, H.I.G.S., Jayasinghe, P.K.S.C., Leelamanie, Plant Nutrition, 54, 2, 179–187. D.A.L., 2020. Water repellency in eucalyptus and pine plan- https://doi.org/10.1111/j.1747-0765.2007.00232.x tation forest soils and its relation to groundwater levels esti- Letey, J., Osborn, J., Pelishek, R.E., 1962. The influence of the mated with multi-temporal modeling. Journal of Hydrology water-solid contact angle on water movement in soil. Hydro- and Hydromechanics, 68, 4, 382–391. logical Sciences Journal, 7, 3, 75–81. https://doi.org/10.2478/johh-2020-0030 https://doi.org/10.1080/02626666209493272 Rodný, M., Lichner, L., Schacht, K., Holko, L., 2015. Depth- Lichner, Ľ., Capuliak, J., Zhukova, N., Holko, L., Czachor, H., dependent heterogeneity of water flow in sandy soil under Kollár, J., 2013. Pines influence hydrophysical parameters grass. Biologia, 70, 11, 1462–1467. and water flow in a sandy soil. Biologia, 68, 6, 1104–1108. http://dx.doi.org/10.1515/biolog-2015-0167 https://doi.org/10.2478/s11756-013-0254-7 Rowell, M.J., Coetzee, M.E., 2003. The measurement of low Lichner, L., Hallett, P.D., Feeney, D.S., Ďurová, O., Šír, M., organic matter contents in soils. South African Journal of Tesař, M., 2007. Field measurement of soil water repellency Plant Soil, 20, 2, 49˗53. https://doi.org/10.1080/0257 and its impact on water flow under different vegetation. Bio- 1862.2003.10634907 logia, 62, 5, 537–541. https://doi.org/10.2478/s11756-007- Schumacher, B.A., 2002. Methods for the determination of total 0106-4 organic carbon (TOC) in soils and sediments. Ecological Lichner, L., Holko, L., Zhukova, N., Schacht, K., Rajkai, K., Risk Assessment Support Center Office of Research and Fodor, N., Sandor, R., 2012. Plants and biological soil crust Development, US Environmental Protection Agency, 25 p. influence the hydrophysical parameters and water flow in an Shaver, T.M., Peterson, G.A., Sherrod, L.A., 2003. Cropping aeolian sandy soil. Journal of Hydrology and Hydromechan- intensification in dryland systems improves soil physical ics, 60, 4, 309–318. DOI: 10.2478/v10098-012-0027-y properties: regression relations. Geoderma, 116, 149–164. Lichner, Ľ., Iovino, M., Šurda, P., Nagy, V., Zvala, A., Kollár, https://doi.org/10.1016/S0016-7061(03)00099-5 th J., Pecho, J., Píš, V., Sepehrnia, N., Sándor, R., 2020. Impact Soil Survey Staff, 2014. Keys to Soil Taxonomy. 12 Ed., of secondary succession in abandoned fields on some United States Department of Agriculture, Natural Resources properties of acidic sandy soils. Journal of Hydrology and Conservation Service, pp. 290–303. Hydromechanics, 68, 1, 12–18. https://doi.org/10.2478/johh- Šurda, P., Lichner, Ľ., Kollár, J., Nagy, V., 2020. Differences in 2019-0028 moisture pattern, hydrophysical and water repellency param- Liyanage, T.D.P., Leelamanie, D.A.L., 2016. Influence of eters of sandy soil under native and synanthropic vegetation. organic manure amendments on water repellency, water en- Biologia, 75, 6, 819–825. https://doi.org/10.2478/s11756- try value, and water retention of soil samples from a tropical 020-00415-z Ultisol. Journal of Hydrology and Hydromechanics, 64, 2, Wahl, N.A., Bens, O., Schäfer, B., Hüttl, R.F., 2003. Impact of 160–166. https://doi: 10.1515/johh-2016-0025 changes in land-use management on soil hydraulic properties: Lozano-Baez, S.E., Cooper, M., de Barros Ferraz, S.F., Ribeiro hydraulic conductivity, water repellency and water retention. Rodrigues, R., Lassabatere, L., Castellini, M., Di Prima, S., Physics and Chemistry of the Earth, 28, 1377–1387. 2020. Assessing water infiltration and soil water repellency https://doi.org/10.1016/j.pce.2003.09.012 in Brazilian Atlantic forest soils. Applied Sciences, 10, 6, Wallis, M.G., Scotter, D.R., Horne, D.J., 1991. An evaluation 1950. https://doi.org/10.3390/app10061950 of the intrinsic sorptivity water repellency index on a range Moody, J.A., Kinner, D.A., Úbeda, X., 2009. Linking hydraulic of New Zealand soils. Soil Research, 29, 3, 353–362. properties of fire-affected soils to infiltration and water re- https://doi.org/10.1071/SR9910353 pellency. Journal of Hydrology, 379, 3–4, 291–303. Wang, Z., Wu, L., Wu, Q.J., 2000. Water-entry value as an https://doi.org/10.1016/j.jhydrol.2009.10.015 alternative indicator of soil water-repellency and wettability. National Atlas of Sri Lanka, 2007. 2nd Ed. Survey Department Journal of Hydrology, 231–232, 76–83. of Sri Lanka. Colombo, Sri Lanka. https://doi.org/10.1016/S0022-1694(00)00185-2 Onderka, M., Wrede, S., Rodný, M., Pfister, L., Hoffmann, L., Wessolek, G., Schwärzel, K., Greiffenhagen, A., Stoffregen, Krein, A., 2012. Hydrogeologic and landscape controls of dis- H., 2008. Percolation characteristics of a water-repellent solved inorganic nitrogen (DIN) and dissolved silica (DSi) sandy forest soil. European Journal of Soil Science, 59, 14– fluxes in heterogeneous catchments. Journal of Hydrology, 23. https://doi.org/10.1111/j.1365-2389.2007.00980.x 450, 36–47. https://doi.org/10.1016/j.jhydrol.2012.05.035 Zhang, R., 1997. Determination of soil sorptivity and hydraulic Ouyang, L., Wang, F., Tang, J., Yu, L., Zhang, R., 2013. Ef- conductivity from the disk infiltrometer. Soil Science Socie- fects of biochar amendment on soil aggregates and hydraulic ty of America Journal, https://doi.org/10.2136/sssaj properties. J. Soil Sci. Plant Nutr., 13, 4, 991–1002. 1997.03615995006100040005x http://dx.doi.org/10.4067/S0718-95162013005000078 Pavelková, H., Dohnal, M., Vogel, T., 2012. Hillslope runoff Received 31 May 2021 generation-comparing different modeling approaches. Jour- Accepted 25 August 2021

Journal

Journal of Hydrology and Hydromechanicsde Gruyter

Published: Dec 1, 2021

Keywords: Eucalyptus grandis; Pinus caribaea; Casuarina equisetifolia; Hydrophysical characteristics; Water repellency

There are no references for this article.