Water Infiltration Capacity Research Articles

Water provision benefits from karst ecosystems: An example for Watuputih groundwater basin, North Kendeng Mountain, Indonesia

Karst ecosystems offer a wealth of ecosystem services, but their protection is increasingly challenging due to degradation and land-use conversion, including limestone mining. This study investigates the water provision service derived from karst ecosystems threatened by limestone mining in the Watuputih groundwater basin, Central Java, Indonesia. Water supply was quantified by measuring water discharge rates from major springs around the basin. Water usage was quantified for household consumption, agriculture, and recreation. This study also measured water infiltration rates in mining and non-mining areas to indicate the effects of limestone mining to hydrological processes. This study identified three primary springs around the basin: Sumber Seribu spring, Brubulan spring, and Kalutan spring, with discharge rates of 1,080 liters per second, 85 liters per second, and 0.76 liters per second, respectively. A local water company extracts water from Sumber Seribu spring at a rate of 80 liters per second to supply approximately 57,600 individuals. The water supply from the three springs can irrigate approximately 1,594 hectares of rice fields. Water from Sumber Seribu spring also supports recreational activities in Sumber Semen recreation park, attracting an average of 19,173 visitors per year. This study revealed a complete impairment of soil's water infiltration capacity in limestone mining areas. These findings underscore the pressing need to safeguard the Watuputih groundwater basin and to mitigate the detrimental effects of limestone mining on hydrological processes. This involves designating the Watuputih karst ecosystem as a protected area, implementing Payment for Ecosystem Services (PES) programs, and restoring degraded post-mining sites.

Effects of Long-Term Fenced Enclosure on Soil Physicochemical Properties and Infiltration Ability in Grasslands of Yunwu Mountain, China

Fenced enclosures, a proven strategy for restoring degraded grassland, have been widely implemented. However, recent climate trends of warming and drying, accompanied by increased extreme rainfall, have heightened soil erosion risks. It is crucial to assess the long-term effectiveness of fenced enclosures on grassland restoration and their impact on soil physicochemical properties and water infiltration capacity. This study investigated the effects of enclosure duration on soil organic matter, aggregate composition and stability, and infiltration capacity in Yunwu Mountain Grassland Nature Reserve, comparing grasslands with enclosure durations of 2, 14, 30, and 39 years. Results showed that grasslands enclosed for 14, 30, and 39 years had infiltration rates increased by 20.66%, 152.03%, and 61.19%, respectively, compared to those enclosed for only 2 years. After 30 years of enclosure, soil quality reached its optimum, with the highest root biomass, soil organic matter, aggregate stability, and a notably superior infiltration rate. The findings suggest that long-term fenced enclosures facilitate grassland vegetation restoration and enhance soil infiltration capacity, with the most significant improvement observed at the 30-year enclosure milestone, followed by a gradual decline in this effect.

Prediction of soil texture using remote sensing data. A systematic review

Soil particle size fractions play a critical role in determining soil health attributes, including soil aeration, water infiltration and retention capacity, nutrients, and organic matter dynamics. Traditional soil mapping methods rely predominantly on ground-based surveys and laboratory analysis which are reported to be time-consuming and expensive. To address these challenges, there has been a global shift towards digital soil mapping (DSM) techniques that utilize remote sensing data. This review, conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guideline, aims to provide a comprehensive synthesis of the current state of soil texture prediction using remote sensing data. In particular, the review extract and synthesizes the satellite images used, identify the derived environmental covariates and their relative importance, and assesses the prediction models/algorithms used in the prediction of soil texture. Synthesis and analysis of 70 articles show that clay content is the most predicted of the three soil particle fractions accounting for 37% of the reviewed studies predominantly from topsoil layer (74.29%). Sentinel 2 and Landsat 8 are reported as the most frequently used satellite images. Among the covariates derived from these images, NDVI (80.4%) and SAVI (60.8%) are by far the most derived band ratios (indices). Red (37.3%), NIR (35.3%), Green (33.3%), Blue (33.3%), and SW2 (29.4%) bands were the five most incorporated as covariates for soil texture prediction amongst individual satellite bands. Regarding the DSM algorithms, Random Forest (RF) appeared in most reviewed articles followed by Support Vector Machines (SVM), and Quantile Regression Forest (QRF). The comparative model performance analysis showed that RF and Artificial neural network (ANN) had a good trade-off across validation metrics indicating their best performance in the prediction of both clay, sand, and silt. The RF performance showed a decreasing trend with increasing depth interval for clay and sand prediction and inconsistent for silt prediction.

Use of Geographic Information Systems to Analyze the Distribution of Water Catchment Areas in Ambon City, Indonesia

Background: Ambon City, as the capital of Maluku province, faces serious challenges in water resources management due to rapid urbanization and climate change that affects rainfall patterns. This study aims to analyze the distribution of water catchment areas using Geographic Information Systems. Methods: This study used variables of rainfall, soil type, land use, and slope which were analyzed using Geographic Information System (GIS) approach with overlay technique. Findings: The results showed that the water catchment area in Ambon City with a rather critical condition has an area of 2,350.27 ha, good condition of 13,524.39 ha, starting critical condition of 2,827.62 ha, normal natural condition of 13,636.20 ha and very critical condition of 236.12 ha. This research shows that soil characteristics, land use, slope, and rainfall in Ambon City have a significant influence on the capacity of water catchment areas. Findings from analysis using Geographic Information Systems (GIS) show that soil type, land use, and slope have a significant effect on water infiltration capacity, with alluvial soils having the best infiltration capacity. Conclusion: The results of this study emphasize the need for better management and strict implementation of spatial policies to protect water catchment areas, in order to reduce disaster risk and support sustainable development in Ambon City.

Effect of vegetation restoration type and topography on soil water storage and infiltration capacity in the Loess Plateau, China

Vegetation restoration effectively mitigates soil erosion and improves soil properties, but in drylands, it can lead to soil water scarcity and disrupt ecological balance. Until now, limited research has examined the combined effects of vegetation restoration type and topography on soil water and infiltration in the Loess Plateau of China. Here, we investigated soil water content (SWC), soil water storage (SWS), soil infiltration rates and related soil properties in typical forestland, shrubland, and grassland across five slope positions on steep slopes, and compared them with cropland. The results indicated that vegetation restoration significantly decreased SWS compared to cropland. Across the entire 0–500 cm depth, reductions were observed at 30.9 %, 33.2 %, and 20.8 % for forestland, shrubland, and grassland, respectively, with forestland and shrubland demonstrating a more pronounced decrease, particularly in deeper soil layers. Shrubland had the lowest SWS on the upper, middle, and top slopes, while forestland showed the lowest SWS on the lower and foot slopes. In terms of infiltration, vegetation restoration generally increased steady infiltration rate but resulted in reduced initial and mean infiltration rates (except for shrubland). Shrubland had the highest infiltration rates, followed by forestland, while grassland had the lowest rates. Soil infiltration rates decreased gradually along the slope, indicating that the impact of vegetation restoration on soil infiltration improvement weakened with lower slope positions. Vegetation restoration type had a stronger direct and total effects on infiltration than slope position. Yet, the indirect influence of slope position through clay content and SWC outweighed that of vegetation restoration type. Our findings highlight the comprehensive assessment of the eco-hydrological effects of vegetation restoration is essential for identifying suitable species and designing optimal spatial distribution, ultimately maximizing the ecological benefits of the restoration. These insights can offer valuable guidance for ecological restoration and land management in fragile dryland ecosystems.

Analisis Kapasitas Tanah Menahan Air (Water Holding Capacity) pada Penambahan Biochar Berbahan Pelepah Kelapa Sawit (Elaeis guineensis Jacq)

The availability of water in the soil varies and is influenced by soil properties, especially those related to the soil's capacity to retain water. Water retention capacity is one of the primary functions of soil, playing a crucial role in maintaining moisture and distributing water to plants. This research aims to analyze the effects of dosage and particle size of oil palm frond biochar on soil infiltration and water retention capacity. The study employed a Completely Randomized Factorial Design (RALF), comprising two factors: the dosage of oil palm frond biochar (A) and the biochar particle size (B). The dosage factor consisted of three levels: 0% (A1), 0.6% (A2), and 1.2% (A3), while the biochar particle size factor consisted of three levels: < 0.5 mm (B1), 0.5 - 1 mm (B2), and 1 - 2 mm (B3). Each experimental unit was replicated three times, resulting in 27 experimental units. The study utilized soil with silt loam texture. The research parameters observed included soil water content at field capacity conditions (pF 2.54) and at permanent wilting point conditions (pF 4.2), changes in water content over time, mass density, particle density, porosity, water infiltration, and water retention capacity. The findings revealed that the addition of biochar to silt loam textured soil resulted in a reduction in infiltration rate, with the most significant reduction observed when applying biochar with a particle size < 0.5 mm (B1). Furthermore, providing biochar with a size of 0.5 – 1 mm at a dosage of 0.6% (B2A2) and a dosage of 1.2% (B2A3) had the effect of increasing the soil's water retention capacity. Keysword : Infiltration, Factorial Completely Randomized Design, Silt Loam, Soil Physical Properties.

Woody species alongside earth contour bunds enhance the soil water‐infiltration capacity in the Sahel, West Africa

AbstractLand degradation, including the loss of tree, forest and vegetation cover, and its related loss of water availability are the main constraints affecting the rainfed agricultural systems in West African Sahel and dry savanna. Therefore, farmers are implementing various soil and water conservation techniques such as zaï pits, half‐moons, contour stone and earth bunds to improve crop production through reduced erosion and enhanced water retention. This study explores the effect of woody and herbaceous vegetation established along earth contour bunds on soil infiltration capacity in southern Mali. The soil infiltration measurements were carried out from September to December 2019 using single ring infiltrometers up‐slope and down‐slope of the bunds built on contour lines in 2015 and 2016 with four types of vegetation: (1) natural annual herbaceous vegetation; (2) planted Andropogon gayanus (perennial grass); (3) planted Gliricidia sepium (woody species) and (4) planted Acacia colei (woody species). The field‐saturated hydraulic conductivity (Kfs) was estimated from the infiltration data and subjected to statistical analysis to compare the effect of the four types of vegetation on soil infiltration capacity. The results revealed significant differences in infiltration rate and Kfs between the four vegetation types. The highest infiltration rate and Kfs were observed for earth contour bunds reinforced with woody species G. sepium (299.5 ± 0.6; 45.3 ± 1.4 mm h−1), followed by A. colei (232.2 ± 2; 38.2 ± 1.6 mm h−1). These were followed by the grass A. gayanus (189.4 ± 2.5; 33.0 ± 1.7 mm h−1) and natural annual herbaceous vegetation (132 ± 2.3; 20.7 ± 1.9 mm h−1). In addition, soil water‐infiltration rate and Kfs were higher for down‐slope compared to up‐slope areas for the two woody species. In practice, it is appropriate for farmers to reinforce contour bunds with woody species and perennial herbs given the beneficial effect on soil water infiltration and retention capacity and the expected socio‐economic benefit they can get from them.

Optimising Flood Risk Reduction in Bali's Provincial Government Center through Cultural Philosophy Approach and GIS-based Conservation of Infiltration Wells

Bali's administrative center, Renon Village, faces an increased risk of flooding due to land cover change. Conservation is needed to reduce this risk by improving water infiltration capacity. Infiltration wells are a solution to increase infiltration capacity. The Tri Hita Karana concept approach, especially Palemahan, in Balinese culture is adopted to implement infiltration well conservation with the support of GIS technology and by flood regulations and infiltration wells. The analysis showed that with a land area of 100 m2, the dimensions of the infiltration well were obtained in diameter of 1 m, and a depth of 2 m with a total of 2 pieces could absorb 2.46 m3 of rainwater. The application of infiltration wells in the study area can reduce the discharge and volume of flood peaks of 2 years, 5 years, 10 years, 25 years, 50 years, 100 years, and 200-year flood peaks, effectively reducing from 8.61% to 31.24%. This research supports the planning of sustainable drainage with a Low Impact Development approach. In addition, the construction of infiltration wells also contributes to preserving water conservation and applying green buildings that are environmentally friendly and energy efficient.

Soil water infiltration characteristics of reforested areas in the paleo-periglacial eastern Liaoning mountainous regions, China

Plantation forests (PF) and natural secondary forests (NSF) are the primary reforestation approaches. The establishment of PF can affect forest hydrological processes by changing soil structure. To date, few studies have focused on these changes and the effects on hydrological processes for the paleo-periglacial landform. To reveal reforestation approaches effects on water infiltration, including soil water infiltration capacity, retention capacity, and waterflow path pattern, we conducted field dye-tracer investigations with rainfall and laboratory infiltration experiments for the paleo-periglacial landform of eastern Liaoning mountains, China. The results showed that (1) Soil physical properties (including total porosity (TP), capillary porosity (CP), non-capillary porosity (NCP), initial soil water content (IWC), field water capacity (FWC)) and root abundance (RA) decreased with soil depth in both PF and NSF, while the soil bulk density (BD) and distribution of gravel content showed opposite changes. (2) Establishment of PF reduced the infiltration capacity and water retention capacity in the 0–20 cm layer, but enhanced the water retention capacity in 20–30 cm layer. Low IWC was conducive to increase soil water content (SWC) after infiltration. (3) Infiltration capacity parameters (including saturated hydraulic conductivity (Ks), SWC, difference between SWC and IWC (SWC–IWC), dye coverage ratio (DC)) were significantly correlated with BD, TP, CP, NCP, FWC, and fine roots RA (P < 0.05). Better connectivity gravels were more conducive to water infiltration. (4) Preferential flow was the main infiltration type, but with different waterflow paths pattern, with the 'funnel', 'finger' shape for PF, NSF, respectively. Increasing infiltration could increase flow path connectivity. Our findings show that soil physical properties, roots, and gravel occurrence affected soil infiltration, and different reforestation approaches had varying impacts on soil infiltration, water redistribution, transportation, and storage of surface and groundwater, improving the understanding of ecohydrological processes and effects of water resources management in forest ecosystems of paleo-periglacial landform.

Cracking process in expansive soil with and without vegetation covers in dry and rainy seasons at field scale

ABSTRACT The presence of desiccation cracks in the soil alters its hydromechanical behavior, increasing the soil's water infiltration capacity, mobilizing the potential for expansion. This may affect the performance of the structural elements of the construction. This study aimed to evaluate the mechanics of expansion, contraction and cracking of the expansive soil of Paulista - Pernambuco, Brazil, through field trials, subject to wetting cycles and drying. The studied soil is a sandy silty clay of high compressibility with medium to very high expansion potential. The process of formation and propagation of cracks was analyzed using digital images and the monitoring of samples subjected to drying and wetting cycles. The indices of crack geometry increased with the advancement of desiccation but did not stabilize. During the wetting period, they tend to close. The pattern of cracks in the tests varied according to the presence or absence of vegetation. It was concluded that the vegetation cover has a significant influence on the standardization and the crack formation and propagation process.

Assessment of short- to medium-term impacts of bench terrace construction on soil water repellency in north-central Portugal

Agrarian terraces are surely recognized as a traditional soil and water conservation technique, however the use of these methods in forestry are poorly studied, especially the hydrological impacts of bench terracing for forest plantations. The employment of heavy machinery in forests have been described to increase soil bulk density and compaction which might reduce soil water infiltration capacity, and thus, increase runoff generation. However, in the case of terraces, the flattening of the terrain may increase the infiltration and re-infiltration of runoff due to consecutive slope discontinuity. The present study assesses the short to medium-term impacts of bench terrace construction on soil water repellency and soil water infiltration in eucalypt forest plantations. A chrono-sequence approach was used to analyse a time series of sites terraced at different periods with neighbouring mature long-undisturbed sites. Therefore, Methanol droplet test was employed in-situ in four different periods of time-since-terracing (0, 5, 10 and 17 years after terracing). Three pairs of nearby terraced and non-terraced eucalypt plantations were studied for each period, counting a total of 24 study sites. Our results revealed clear differences in SWR between terraced and non-terraced eucalypt plantations, with all non-terraced sites showing extreme SWR values while at the terraced sites highly variable values were found. In addition, the median SWR increase with time elapsed since terrace construction, i.e. from very wettable immediately and 5 years after terracing, and increase to strong and moderate water repellent at 10 and 17 years following terracing. The infiltration variables were observed inversely correlated with SWR following terrace construction and were watched to decrease with time-since-terracing. The litter and the Oh humified layer were found positively correlated to the SWR as well as the stone and bulk density variables, while the percentage of organic matter and the soil moisture content in the soil were poorly correlated.

The anecic earthworm Lumbricus terrestris can persist after introduction into permanent grassland on sandy soil

Grasslands are important water-regulating agro-ecosystems. Their ability to store and retain water is of vital importance under the current trend of increasing peak rains and droughts, which are events that can result in economic damage to infrastructure and crops. The presence of the anecic earthworm Lumbricus terrestris has a positive effect on the water regulation of the soil. This earthworm creates semi-permanent burrows with a depth of up to 2 m, which increase the water infiltration rate and capacity of the soil. The burrows can also facilitate plant root penetration into deeper soil layers, thus increasing drought resistance. The objective of this research was to explore the ability of L. terrestris to survive and reproduce after introduction into grasslands on sandy soils where they had been absent.We introduced L. terrestris into mesocosms on sandy soil under permanent grassland at two dairy farms in the Netherlands. Results showed that while L. terrestris was able to survive and produce cocoons, survival rate was low (32% after seven months, 6% after fifteen months) and the number of juveniles was low (2.6 and 2.7 ind. m−2 after seven and fifteen months, respectively). The causes of this low survival rate may be related to the life history of the earthworms introduced, the effects of soil moisture, interspecific competition for food with the native population of epigeic earthworms, and the risk of predation.We conclude that L. terrestris can survive and produce cocoons after introduction into permanent grassland on sandy soil, but only further experimental trials over greater time spans and in non-enclosed plots will determine whether there is realistic potential for L. terrestris to develop a stable population.

Spatial pattern of hydrological and erosion behaviour along a dolomite hillslope in Southwest China

Dolomite hillslopes are highly vulnerable to rocky desertification, but the linkages among soil type, runoff mechanisms, and soil erosion remain unclear. During four hydrological years (2018–2021), soil type, plot-scale hydrological and erosion behavior at the upper, middle, and lower slopes along the dolomite hillslope in karst regions of Southwest China were investigated. The results indicated that along the downward slope direction, the degree of soil development gradually increased, forming a typical soil catena pattern. The soil types along the downward direction on the dolomite hillslope gradually transitioned from Entisol to Inceptisol and to Semi-Alfisol. The Entisol was thin and gravelly, with the highest volume ratio of gravel of 75 %. In contrast, Semi-Alfisol was thick and clayey, with the highest volume ratio of fine soil of 97 %. The surface runoff coefficient of the upper slope was only 2.3 % because of the high water infiltration capacity of shallow and rocky soil, and the runoff generation mode was dominated by discontinuous infiltration–excess runoff occurring on rock outcrop patches. Due to the higher soil water content (mean value of 37 %) and frequently occurring lateral flow, the lower slope exhibited the highest surface runoff coefficient of 21 %, mainly as saturation-excess runoff. Catenary soils and their correspondingly divergent hydrological regimes led to average annual soil losses of 0.4, 0.8, and 2.8 t·ha−1·yr−1 at the upper, middle, and lower slopes, respectively. These results advance the understanding of the relationship between hydrology and erosion on karst hillslopes and provide theoretical support for further rocky desertification control.

Effects of urea solution concentration on soil hydraulic properties and water infiltration capacity

Elucidating the effect of fertigation on soil hydraulic parameters and water-solute transportation is fundamental to the design of farmland irrigation systems and their sustainable utilization. Few studies have focused on soil hydraulic parameters or water infiltration characteristics or how they are influenced by urea solution concentration. In this study, the clay loam and sandy loam in Yangling District of Shaanxi Province, China, were used as test soil, and experiments involving seven urea solution concentrations (0.2, 0.4, 0.6, 0.8, 1, 3, and 5 g/L) and a control treatment (0 g/L) were conducted to explore the influence of the various urea solution concentrations on soil hydraulic parameters and water infiltration characteristics. The results indicated that the cumulative infiltration and wetting front migration depth increased with urea solution concentration, as accurately estimated using the Kostiakov model and a power function, respectively. In addition, the coefficients of the Kostiakov model and the power function increased with urea solution concentration. Treatment with multiple concentrations of urea solution resulted in an increase in the volume of macro pores in the soil but a reduction in the volume of mesopores and micro pores in the soil, leading to increases in the saturated water content, saturated hydraulic conductivity, soil water diffusivity, and infiltration capacity and a reduction in the water-holding capacity of the soil. The effect of urea solute potential on the inhibition of soil water movement is small, and this inhibitory effect is far weaker than the improvement effect of the urea solution on soil structure, and hence enhance the soil water infiltration capacity. Our results increase the understanding of soil hydrological mechanisms and may be usefully applied for improving the management of fertigation.

Effects of Land Use and Cropping on Soil Erosion in Agricultural Frontier Areas in the Cerrado-Amazon Ecotone, Brazil, Using a Rainfall Simulator Experiment

Agricultural soils provide ecosystem services, but the removal of natural vegetation reduces water infiltration capacity, increasing surface runoff. Thus, monitoring erosion is critical for sustainable agricultural management. Sediment losses and surface runoff were evaluated using a simulated rainfall of 75 mm/h in areas with crops and pastures in both the Caiabi River and Renato River sub-basins of the Teles Pires River watershed in Mato Grosso State, Brazil. In both the Caiabi and Renato sub-basins, data were collected from 156 observations in the upper, middle, and lower regions where (1) soybeans, (2) maize, and (3) pasture were grown alone, with another crop, or with soil that was scarified. Erosion occurred independent of soil texture and was closely related to the management and use of systems involving fewer crops and more soil scarification, regardless of sub-basin location. In uncovered, scarified soil, the soil losses from erosion were greater compared to covered soil, regardless of sub-basin and sub-basin region. In the Renato River sub-basin, soil losses in cultivated areas not planted with crops but with scarification were 66.01, 90.79, and 60.02 g/square meter in the upper, middle, and lower regions, respectively. Agricultural producers need to increase the planting of crops throughout the year and minimize soil disturbance, which will reduce soil erosion and improve sustainability.

Karakteristike černozemolike karbonatne livadske crnice Oglednog polja za soju i šećernu repu u Starom Bečeju (Srbija)

In this study, Fluvisol from the area of Stari Beĉej (Serbia) was investigated with the aim of evaluating selected chemical and physical indicators of soil quality affter its long-term use in crop production. Ten bulk soil samples (soil depth: 0-210 cm) were collected to analyze soil chemical properties (humus, CaCO3, pH, P2O5, K2O), texture (six samples, soil depth: 0-130 cm), dry-stable aggregate distribution and stability of soil aggregates (four samples, soil depth: 0-80 cm). Additional undisturbed core samples (100 cm3 volume) were also collected to determine soil bulk density, total porosity, field air capacity, and field water capacity. Water infiltration capacity was also measured in the field using a double ring infiltrometer. The results indicated that the soil had a two-layer profile and a silty loam texture (with a physical clay content of 41-42% and a colloidal clay content of 27-28%). The humus horizon has quite favorable chemical properties up to a depth of 60 cm, and at a depth of 60-80 cm it is alkalized under the influence of saline groundwater. From an agronomic point of view, the structure of this soil is favorable. The results of determining the stabillity soil aggregates show that the soil structure in the Ahp and Ah horizons at depth (0-40 cm) with a content of 41% of water-stable aggregates &lt; 0.25 mm is significantly worse (less favorable) than in the surface part of the AhBca horizon (40-60 cm) with a content of ~58% of waterstable aggregates &lt; 0.25 mm. The main physical properties are not particularly favorable in the Ah and AhBca horizons to a depth of 80 cm. The Ah horizon is very compact (bulk density: 1.33-1.38 g/cm3 ), and the air-filled porosity is very low (less than 5%) and small (5-10%) at all depths up to 80 cm, and it is lowest in the surface 0-20 cm layer, only 3.8%. Infiltration capacity is low. The reserves of soil moisture available for plant growth in the soil layer 0-100 cm are very good (&gt; 160 mm water depth). In summary, the results of this study show that perennial tillage can lead to a loss of soil productivity and serious soil degradation.

Plant-soil interactions in response to grazing intensity in a semi-arid ecosystem from NE Spain

Livestock grazing is an important element in ecosystem regulation since it may affect essential ecosystem functions, such as nutrient acquisition, organic matter decomposition, or litter accumulation in the soil. Overgrazing can threaten the conservation of ecosystems through excessive defoliation of plants or trampling. On the contrary, moderate grazing can have benefits on ecosystem dynamics by favoring nutrient cycling or the soil microbial activity. The aim of this study was to analyze these effects in a semi-arid Mediterranean shrubland located in NE Spain. We established six study sites including three grazing intensities, where we sampled vegetation biomass and soil properties: nitrogen content, microbial biomass, water infiltration capacity, porosity, and gypsum content. These parameters were included in a plant-soil interaction model tested through Structural Equation Modeling. Grazing had a direct negative effect on plant biomass (p < 0.01) and water infiltration capacity (p < 0.05) affecting soil nitrogen content (p < 0.001) and microbial biomass (p < 0.5), respectively. Infiltration capacity and porosity were primary drivers of plant biomass (p < 0.05, both cases), and plant biomass was the main contributor to the soil nitrogen pool. Microbial biomass was dependent on infiltration capacity (p < 0.05), porosity (p < 0.01), and nitrogen (p < 0.01). Grazing directly or indirectly affected the functioning of the ecosystem through effects on plant and soil attributes, which may result in changes in plant growth, litter decomposition, or plant nutrient acquisition. This study revealed that moderate grazing can maintain optimal ecosystem features and prevent ecosystem degradation.

The Effect of Land Use and Land Cover Changes on Flood Occurrence in Teunom Watershed, Aceh Jaya

The change in land use and land cover in upstream watersheds will change the features of drainage systems such that they will impact surface overflow and affect the infiltration capacity of a land surface, which is one of the factors that contributes to flooding. The key objective of this study is to identify vulnerable areas of flooding and to assess the causes of flooding using ground-based measurement, remote sensing data, and GIS-based flood risk mapping approaches for the flood hazard mapping of the Teunom watershed. The purposes of this investigation were to: (1) examine the level and characteristics of land use and land cover changes that occurred in the area between 2009 and 2019; (2) determine the impact of land use and land cover changes on the water overflow and infiltration capacity; and (3) produce flood risk maps for the Teunom sub-district. Landsat imagery of 2009, 2013, and 2019; slope maps; and field measurement soil characteristics data were utilized for this study. The results show a significant increase in the use of residential land, open land, rice fields, and wetlands (water bodies) and different infiltration rates that contribute to the variation of flood zone hazards. The Teunom watershed has a high and very high risk of ~11.98% of the total area, a moderate risk of 56.24%, and a low and very low risk of ~31.79%. The Teunom watershed generally has a high flood risk, with a total of ~68% of the area (moderate to very high risk). There was a substantial reduction in forest land, agricultural land, and shrubs from 2009 to 2019. Therefore, the segmentation of flood-risk zones is essential for preparation in the region. The study offers basic information about flood hazard areas for central governments, local governments, NGOs, and communities to intervene in preparedness, responses, and flood mitigation and recovery processes, respectively.

Direct and indirect plant-soil interactions in a semi-arid Mediterranean shrubland (NE Spain)

Dynamics between plants and soil control important processes such as community succession, nutrient cycling or resilience to environmental change. Until now, most research on plant-soil interactions has focused on uni-directional and species-specific effects of plants on soil and vice-versa, under controlled-conditions experiments, but little is known about the direct and indirect interactions between the plant community and the underlying soil under field conditions. We investigated these interactions in a semi-arid shrubland from NE Spain. We sampled plant biomass, nitrogen availability in soil, soil microbial biomass C, soil water infiltration capacity, soil bulk density and quality of plant tissue. These parameters were related to each other to build a statistical plant soil interaction model that was analyzed through regression and Structural Equation Modeling analyses. This statistical model was hypothesized to reveal important mechanisms for community regulation. Plant biomass was fundamentally dependent on water infiltration capacity and microbial biomass C was fundamentally dependent on nitrogen availability. Plant biomass interacted indirectly with microbial biomass C by directly affecting nitrogen stock and quality of plant tissue. Similarly, plant biomass modulated the soil bulk density. We demonstrated that vegetation has a preeminent role in the regulation of biological processes in this ecosystem through control on nutrient status, microbial biomass and mechanical soil conditions. Conclusions extracted from this study can be valuable in restoring and conserving similar ecosystems at risk of disappearing due to desertification.

Erodibility improvement and scour mitigation of beach sand by enzymatic induced carbonate precipitation

The main objective of this study was to evaluate the use of enzymatic induced carbonate precipitation (EICP) treatment for erodibility improvement, scour mitigation, and water infiltration capacity of beach sand at one, two, and three cycles of treatment. EICP is a biochemical process that produces calcium carbonate precipitation within a soil matrix to improve the geotechnical properties of the soil. Direct shear test (DST) was used to examine the shear behavior of bio-cemented beach sand after one and two cycle treatment, the results of which showed that the cohesion was increased substantially, especially after the second cycle; conversely, the friction angle was decreased. The mineralogy of treated soil was also assessed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The mini-jet test has been used to adequately measure the soil erosion characteristics of the biotreated sand (1–3 treatment cycles) in the laboratory, the results of which indicated a significant improvement compared to the control specimen after the third cycle of EICP treatment, with reduced erosion rate and scour depth in the order of approximately 88-fold and 23-fold respectively. After three treatment cycles, the seepage rate was decreased to 71 times lower than the untreated specimens. Strong positive correlations were found between CaCO3, seepage rate, erosion rate, and soil cohesion. The results of this study have confirmed that there is strong evidence for improving erodibility behavior and shear strength of beach sand via EICP treatment. The results of this study would be beneficial to engineers in better understanding bio-cementation techniques and their implementations.