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The filter paper (FP) method, a cost-effective, versatile, and convenient approach, has found extensive application in analyzing fine-grained soils, enabling the successful measurement of a broad spectrum of total and matric suctions. However, using the FP method in sand with a limited range of suction profiles has been notably underrepresented in the existing literature. Therefore, this study investigated the applicability of the contact FP method in establishing soil water retention curves (SWRCs) using five distinct FP calibration curves for 10 poorly graded sands. Among these calibration curves, the one presented by Chandler yielded the highest suction values, which were followed by those of ASTM. Furthermore, the FP results were subjected to fitting with a mathmatical model, which led to the observation that the overall trends in the obtained SWRCs displayed smooth sigmoidal shapes, resulting in a complete and coherent SWRCs. The SWRC results of five sand samples were assessed through validation against the hanging column technique (HCT) results, indicating a high degree of concordance and affirming the suitability of the FP method for sands characterized by a limited suction profile. Notably, the entire range of suction values fell within the 0.01–20 kPa range based on the calibration curves presented by Chandler and ASTM for all the examined sand samples, except sands 9 and 10. Furthermore, the suction values were unobtainable using the two aforementioned calibration curves within the ranges of 0.01–1.47 kPa and 0.01–0.172 kPa. [ABSTRACT FROM AUTHOR]

A positive effect of pulp and paper mill sludges as a rich source of organic substrates on soil properties was previously found for some types of sludge and soil. In this study, the effect of secondary pulp and paper sludge on water characteristics and thermal properties of Retisol, as well as the growth parameters of lettuce (Lactuca sativa L.), was tested on the basis of a pot experiment when watering plants with a 20 or 40% sludge solution. The sludge application enhanced plant growth with an increase in biomass accumulation of 21 and 53%, respectively, for 20 and 40% sludge treatments. When the sludge dose was increased from 0 to 40%, the number of leaves increased by 25%, and the leaf mass per area value increased by 42%. Due to the accumulation of more biomass in the shoots than in the roots, sludge causes a change in the allocation of plant biomass. A significant effect of the sludge application on soil particle and microaggregate sized compositions, as well as on the saturated soil hydraulic conductivity, was not found in this study. However, fitted soil water retention curves showed an increased soil water content in sludge-treated soil at all water content values exceeding field capacity. Secondary sludge application led to an increase in the saturated water content from 0.50 to 0.56 cm3 cm−3. The 40% sludge solution increased soil thermal conductivity from 0.92 to 0.98 W m−1 K−1 under saturated water content and from 0.83 to 0.92 W m−1 K−1 under field capacity. The thermal conductivity was higher in the sludge-treated than untreated soil due to a more pronounced positive effect of increased saturated water content than the negative effect of the increased organic matter content on heat transfer. The positive impact of secondary sludge application on both plant growth parameters and physical properties of Retisol, such as increased soil water-holding capacity and thermal conductivity coefficient confirms the possibility of using it to improve soil characteristics and plant productivity. [ABSTRACT FROM AUTHOR]

Mulch has been considered effective for saving water and promoting plant growth. However, little has been investigated about the effect of mulch from recycled shredded paper under different soil moisture conditions on spinach growth. A pot-grown Komatsuna spinach experiment with a factorial design was conducted under two main conditions, with and without shredded paper mulch. Each of these conditions was treated with three different soil moisture levels (SWC) 20%, 25%, and 30%. The smallest evapotranspiration amount was in the mulch-only, no-plant treatment with SWC 20% (92.88 mm), and the largest was in the plant-only, no-mulch treatment (226.19 mm). All biomass yield attributions were negatively influenced by increasing the frequency of irrigation and SWC levels. SWC 20% with shredded mulch resulted in the largest dry matter, although it was statistically non-significant. But it resulted in taller plant heights and a larger leaf area index (LAI) compared to soil with no shredded mulch (p < 0.05). For SWC 25% and 30% treatments, Komatsuna spinach with no shredded mulch resulted in slightly superior plant dry matter and plant height, compared to mulched plants. These results suggest that SWC 20% with shredded paper mulch has the highest potential for saving water among all treatments for growing spinach under limited water availability. [ABSTRACT FROM AUTHOR]

Sources of pulping red liquor, which is produced by acidic sulfite cooking in paper industry, consisted of lignosulphonate and polysaccharide, commonly considered as waste or byproducts and used in low value, such as surfactant and adhesive are wide and its price is low. Here a novel method for high value-added utilization of the pulp and paper industry waste for fabricating super-swelling biopolymer hydrogels is introduced. In contrast to other costly utilizations, which are needed to separate red liquor or purify hemicellulose and lignin before using, it is first time to directly utilize red liquor to prepare hydrogels without pretreatment. FT-IR, SEM, TGA and XRD are used to determine structure and morphology of hydrogels. It is excited the hydrogels fabricated from acrylic (AA) and industry waste exhibit super-swelling and slow release behaviors in water. Compared with synthetic materials, the hydrogels are at low price to be chosen as candidates for water retention agent for agriculture. • Super-swelling hydrogels are prepared from pulping red liquor. • The polysaccharides and lignin in the red liquor are utilized. • Hydrogels exhibit excellent swelling ratio and slow release behavior in water. • The hydrogels can be used as water retention agent for agriculture. [ABSTRACT FROM AUTHOR]

This study introduces a simple and cost-effective method for the indirect determination of field capacity (FC) in soil, a critical parameter for soil hydrology and environmental modeling. The relationships between FC and soil moisture constants, specifically maximum capillary water capacity (MCWC) and retention water capacity (RWC), were established using undisturbed soil core samples analyzed via the pressure plate method and the "filter paper draining method". The aim was to reduce the time and costs associated with traditional FC measurement methods, as well as allowing for the use of legacy databases containing MCWC and RWC values. The results revealed the substantial potential of the "filter paper draining method" as a promising approach for indirect FC determination. FC determined as soil water content at −33 kPa can be effectively approximated by the equation FC33 = 1.0802 RWC − 0.0688 (with RMSE = 0.045 cm3/cm3 and R = 0.953). FC determined as soil water content at −5 or −10 kPa can be effectively approximated by both equations FC5 = 1.0146 MCWC − 0.0163 (with RMSE = 0.027 cm3/cm3 and R = 0.961) and FC10 = 1.0152 MCWC − 0.0275 (with RMSE = 0.033 cm3/cm3 and R = 0.958), respectively. Historical pedotransfer functions by Brežný and Váša relating FC to fine particle size fraction were also evaluated for practical application, and according to the results, they cannot be recommended for use. [ABSTRACT FROM AUTHOR]

There is an increasing need for accessible methods to monitor soil health. Our primary objective was to evaluate an accessible, do-it-yourself method for measuring the maximum water holding capacity – we call this the funnel, filter paper, and drainage (MWHCFFPD) method. First, we compared MWHCFFPD to the water desorption method via pressure cells (WHCPC), routinely used for generating soil water retention curves, using 10 soils from a wide range of textures (4–55% clay). Second, we tested the sensitivity of the MWHCFFPD to methodological variations likely encountered by citizen scientists. The two methods were quite comparable in precision, with mean coefficient of variances of 3.5% and 4.4% for the FFPD and water desorption method, respectively. The MWHCFFPD and WHCPC methods were comparable, with MWHCFFPD best correlating to WHCPC at −2.45 kPa (R2 = 0.98). The MWHCFFPD method is somewhat sensitive to some methodological modifications, most notably variation in water source, but with standardized protocols could be scientifically robust. Overall, MWHCFFPD can be used as a simple and affordable test of sieved soil structure and organic matter, and thus has potential to expand soil health monitoring. [ABSTRACT FROM AUTHOR]

This study examined the effect of different parameters on the collapsibility of reconstituted sandy soils. The effect of related parameters including silt content, type of fines, initial water content, drying and wetting process, and wetting pressure have been studied. Collapse potential and matric suction were measured via the single oedometer collapse test and the ASTM filter paper method, respectively. The current study revealed that matric suction has a major role in determining the collapsibility of sandy soils. The effect of parameters related to soil index properties were reflected on the initial matric suction. In addition, an equation was proposed to predict collapse potential as a function of the two stress-state variables that control the behavior of an unsaturated soil, i.e. net normal stress and matric suction before wetting. The matric suction measurements were also used to generate soil water characteristic curves (SWCCs) based on the most widely used models. Finally, a simplified relationship between initial matric suction and the degree of collapse based was established. [ABSTRACT FROM AUTHOR]

Numerous recent studies have argued that moisture limitation is leading to growth declines and mortality of black spruce (Picea mariana) and white spruce (Picea glauca) in the North American boreal forest. A parallel line of research suggests that increasingly common severe wildfires are altering successional pathways and leading to long‐term replacement of spruce forests with those dominated by paper birch (Betula papyrifera, Betula neoalaskana) and trembling aspen (Populus tremuloides). When both conifers and deciduous trees establish after fire, this biome shift hypothesis implicitly assumes that deciduous species will outcompete the conifers, owing to their more rapid vertical growth and because they might be less sensitive to warm and dry conditions.We established a research site in a white spruce‐paper birch forest on an east‐facing slope in interior Alaska and tested the hypothesis that Alaska paper birch are better adapted to warm and dry conditions than white spruce. Over 6 years (2013–2018), we made hourly measurements of microclimate and xylem sap flux of both species. We also collected increment cores and conducted climate‐growth analyses for both species.During our 6‐year study, growing seasons with low volumetric soil water content (SWC) were those that followed shallow winter snowpacks and had limited summer rainfall, not necessarily those with warm air temperature. Both species were sensitive to moisture limitation. The tree‐ring data revealed significant positive effects of cumulative water year precipitation on radial growth, with a steeper slope for paper birch than for white spruce. Radial growth of both species was also positively related to mean water year air temperature. Sap flux density declined progressively for white spruce over the range of observed SWC and abruptly for paper birch when SWC fell below ~15%.Synthesis. Our results show that, while paper birch might be less sensitive to mild drought than white spruce, it may be more sensitive to severe drought, raising questions about the ability of paper birch to outcompete co‐occurring white spruce in a drier climate. [ABSTRACT FROM AUTHOR]

Purpose: Water retention capacity (WRC) is crucial for assessing the hydro-physical behavior of unsaturated soils. Dispersive soil, erodible and found mainly in arid regions, lacks sufficient WRC knowledge, hindering its stability evaluation in unsaturated state. This study aimed to explore the WRC of dispersive soil by measuring its matric suction (ψ) under coupling effects of dry density (ρd) and soluble salt content (η). Materials and method: Compacted specimens with different ρd and η were prepared. For each ρd-η case, six levels of soil mass water content were considered and the ψ was measured via filter paper method. Soil water characteristic curves (SWCCs) were fitted by van Genuchten model. Results and discussion: The WRC of dispersive soil enhances as ρd increases. Increasing η first weakens then strengthens the WRC, showing suction dependence. The air-entry value and residual state suction range within 0.95–17.8 kPa and 15.7–98.4 MPa, respectively. As for the air-entry value, increasing η from 0.3% to 2.0% decreases it from 36.0% to 58.7% when ρd increases, and its average growth rate changes from 174.5% to 265.3% when ρd exceeds 1.53 g/cm3. Increasing ρd reduces the average water loss rate of SWCC transition stage, while the impact of η is nonmonotonic, with an inflection point at 1.0%. Conclusions: The ρd and η influenced the WRC of dispersive soil individually and interactively. The effect of ρd links to the water release sequence from pores of different sizes, whereas that of η, rather complex and non-monotonic, relates to clay electrochemistry and salt phase. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate thermal paper (TP) tickets used in Argentina as a potential source of bisphenol A (BPA) that could impact humans and the environment. BPA in TP was measured by HPLC ranging from 11.1 to 30.5 mg BPAg−1. In order to estimate the impact on humans, dermal BPA estimated daily intake was calculated as being 79.3 ± 19.5 μgd−1 for workers and 1.6 ± 0.4 μgd−1 for the general population. To evaluate TP's impact on the environment, BPA migration from TP to water and soil was studied. In the case of water, 99.6% of the BPA tickets content migrated in 30 h, while 78.0% moved into the soil in 96 h. BPA degradation kinetics in soil and water were also carried out; while in soil 61.9% of BPA degraded in 120 h, no degradation was observed up to 120 h in tap or river water. Additionally, ecotoxicological effects of BPA on the earthworm Eisenia andrei, a representative terrestrial indicator, were studied performing bioassays on lethality, avoidance, and reproductive and enzymatic activity. BPA showed to be very toxic to E. andrei (LC50 value in contact paper test of 17 μgcm−2, 95% confidence interval 6–46 μgcm−2, 24 h exposure) and also caused an increase of total cocoons for earthworms exposed to 10 and 50 mg BPA kg−1 soil. Evasion response was observed at a concentration of 50 mg BPA kg−1 soil, while no effect was observed on cholinesterases, carboxylesterases, and glutathione S-transferases activities (1, 10, and 50 mg BPA kg−1 soil). Finally, a simple BPA degradation technology using water peroxide and radish (Raphanus sativus) tissue as catalyst was explored as a simple and domestic potential treatment to avoid BPA migration to the environment. [ABSTRACT FROM AUTHOR]

A variety of routine methods are available for the detection of silver (I) (Ag+) ions, but most of them rely on expensive, sophisticated and desktop instruments. Herein, a low-cost, instrument-free and portable Ag+ biosensor was described by initially designing a new class of 3D origami microfluidic paper-based analytical devices (μPADs) into each of which one piece of reagent-loaded nanoporous membrane was integrated. It combines analyte-triggered self-growing of silver nanoparticles to block the membrane's pores in situ for rapid yet efficient signal amplification with a handheld personal glucose meter for a portable and sensitive quantitative readout based on the biocatalytic reactions between the glucose oxidase and glucose. Its utility is well demonstrated with the specific detection of the analyte with a limit of detection as low as ∼58.1 pM (3σ), which makes this new biosensing method one of the most sensitive Ag+ assays in comparison with many other typical methods recently reported. Moreover, the satisfactory recovery of analyzing several types of real water examples, i.e., tap water, drinking water, pond water and soil water, additionally validates its feasibility for practical applications. • A new type of 3D paper-based device is designed for biosensing of picomolar Ag+. • It integrates nanoporous membranes with self-growing for signal amplification. • It only requires a personal glucose meter for a portable, quantitative readout. • This instrument-free biosensor offers new opportunities for point-of-care uses. [ABSTRACT FROM AUTHOR]

Plastic mulch films are often used in agriculture to conserve soil moisture. Most of the plastic mulch currently used worldwide is made of non-biodegradable polyethylene, which has to be removed and disposed after harvest, incurring significant environmental costs. Biodegradable paper or plastic mulch could offer a valuable alternative to polyethylene. The objective of this study was to compare the effects of biodegradable mulches and standard polyethylene mulch on soil moisture dynamics during a growing season. A field experiment was carried out with pumpkin ( Cucurbita pepo ), which were irrigated and grown on raised beds covered with the following mulch treatments: no mulch, biodegradable paper, biodegradable plastic, and polyethylene. Soil moisture was measured at 10- and 20-cm depths. A numerical model (HYDRUS-2D) was used to simulate the moisture dynamics under the different mulch treatments, each represented by different boundary conditions at the soil surface. Polyethylene mulch, which created an impermeable surface layer, effectively reduced evaporation and maintained highest water content among the treatments. Biodegradable paper mulch, which was partially permeable to evaporation and rainfall throughout the growing season, resulted in soil moisture that was intermediate between that obtained for no mulch and polyethylene. Biodegradable plastic mulch, which was similar to that of polyethylene mulch initially in terms of effects on soil moisture, disintegrated during the growing season and allowed rainfall to penetrate and water to evaporate from the soil surface. Field data and model simulations both indicate that the biodegradable paper and plastic mulches provide comparable soil moisture dynamics as polyethylene mulch. [ABSTRACT FROM AUTHOR]

Osmotic suction affects the mechanical properties of the clay and exists as long as the solute is present in pore water of soil. Determination of osmotic suction of pore solution is significant for quantitatively explaining the mechanical behaviors of clay in saline solution. This paper aims to introduce a calculation method to determine the osmotic suction of saline solutions and the application of the osmotic suction to quantify the mechanical behaviors of clay in saline solutions. Osmotic coefficient as the bridge connecting ion concentration and osmotic suction was calculated by a simplified half-empirical equation and verified by published experimental data. Then the osmotic suctions were achieved using the calculated osmotic coefficients, and two filter paper methods were carried out to verify the calculated results. The consistency between the experimental results and the calculated ones proved the correctness of the proposed method for calculating the osmotic suction. A step further, the mechanical behaviors of clay in saline solutions were explained and quantified from the microscopic with the concept of microstructural effective stress and the macroscopic with the concept of modified effective stress, both related to the osmotic suctions. [ABSTRACT FROM AUTHOR]

Highlights • Plastic film (PF) mulching increased both soil temperature (ST) and moisture (SM). • Biodegradable paper (BP) mulching reduced ST but increased SM. • Bio-based film (BB) mulching reduced both ST and SM. • BP mulching enhanced plant growth and increased fruit quality and yield. Abstract Plastic film (PF) is a common soil mulching material used worldwide in crop production. In recent years there is an increasing demand for reducing the use of PF because of potential environmental- and ecological-risks. Although biodegradable paper (BP) and bio-based film (BB) have been used as alternatives to PF, little information is available regarding their efficiency in summer crop production, which is often restricted by the combination of heat stress and drought stress. To meet this need, PF (silver-gray plastic film made from polyethylene), BP (biodegradable paper made from plant straw) and BB (bio-based film made from plant straw combined with decomposed coal) were used as soil mulching materials to investigate their influence on soil properties (temperature, moisture, pH, electricity conductivity (EC), nutrients and enzymes), plant growth (root morphology, the relative growth rate (RGR), plant biomass and the root/shoot ratio), fruit yield and fruit quality. The un-mulched soil served as control. The trial was conducted in a five-year-old commercial greenhouse located in Helan county, Ningxia, China, with the mean air temperatures of about 32 °C and 31 °C during the summer season in 2016 and 2017, respectively. In general, although PF mulching increased soil moisture, it increased soil temperature, pH and EC and decreased available P, resulting in the reduction of plant growth (root length and diameter, the RGRs of plant height and leaf area, and shoot and root biomass) and fruit yield. The BB mulching decreased soil temperature, however, it decreased soil moisture and invertase and increased soil EC, leading to reduced root growth (root diameter and biomass, and the root/shoot ratio). The BP mulching not only decreased soil temperature, but also increased soil moisture. As a result, it showed several advantages such as decreasing soil EC, increasing soil enzyme activities, improving plant growth (root length, the RGRs of plant height and leaf area, plant biomass and the root/shoot ratio) and increasing fruit yield. Moreover, the fruit quality was partly improved by BP mulching due to reduced nitrate but increased vitamin C. Our results infer that BP was a potential mulching material that could be used for summer tomato production. [ABSTRACT FROM AUTHOR]

A biodegradable mulch paper (BMP) was made from pea starch and brown kraft paper. Brown kraft paper (KP) was brushed with pregelatinized starch solution on one side evenly at 0.095 kg starch solution per square meter and dried at room temperature for 48-72 h. The BMP, uncoated KP, and commercial plastic weed barrier (WB) had similar thicknesses, from 0.15 to 0.22 mm. However, the tensile strength (TS) of KP was much higher than BMP and WB, whereas the tensile strengths of BMP and WB were similar. The KP had the highest values in elastic modulus (EM), indicating brittleness and rigidity. The WB had the lowest elastic modulus value. Water vapor permeability (WVP) of BMP was lower than that of KP, resulting in 4.57 and 10.28 g mm kPa-1h-1m-2, respectively. Both the BMP and KP could keep the soil more humid than the WB did. Soil temperature under BMP and KP was lower than those of WB and bare soil. The field experiment results also showed that BMP and KP prevented the growth of weeds. [ABSTRACT FROM AUTHOR]

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Abstract: Paper birch (Betula papyrifera Marsh.) is routinely chemically or mechanically weeded from Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) plantations to increase conifer productivity, but these practices are controversial because of unknown effects on forest health and diversity. This study examined effects of paper birch density reduction treatments on productivity and disease incidence of Douglas-fir saplings in the southern interior of British Columbia. Five paper birch density treatments (0, 400, 1111, 4444 stems ha−1 and an un-thinned control of >7000 stems ha−1), where paper birch was manually cut at the root collar in 1999, were replicated on four sites in a randomized block design. After 2 years, Douglas-fir survival did not differ significantly among treatments, but where Armillaria ostoyae (Romagn.) Herink was present in untreated stands, mortality due to root disease increased significantly with increasing paper birch thinning intensity. Mean diameter increment and height:diameter ratio of Douglas-fir improved where paper birch was completely removed or partially thinned compared with the control. Mean light transmittance and soil moisture content increased with decreasing paper birch density, but Douglas-fir foliar N status was unaffected. Our results suggest that Douglas-fir growth can be improved and root disease incidence minimized by thinning paper birch to 4444 stems ha−1 in young mixed stands, but that subsequent release treatments may be necessary to maintain Douglas-fir growth rates. [Copyright &y& Elsevier]

Soil water characteristic curve (SWCC) is a very important property of unsaturated soil and by extension tropical red earth soils. This is because several other important soils' properties can be related to it. The Filter paper method was employed in the determination of the A-7-5(5) tropical red earth WCC. The gravimetric water content was utilized in the computation of the SWCC. Four models, Fredlund and Xing (1994), FX; Van Genuchten (1980), VG; Brooks and Corey (1964), BC; and Kosugi (1996), K were used to estimate the SWCCs of the soil and the minimum SSEnorm (MSSE), Average Relative Error (ARE), and R² values were used to determine the most suitable model for predicting the SWCC. Results show that all four models can be used to predict A-7-5(5) WCC as they all had R2 value greater than 89% although BC and K models perform best with coefficient of determination of over 97%. MSSE and ARE% were also significantly low for BC and K models. [ABSTRACT FROM AUTHOR]

Infrastructures are mostly built on unsaturated soil in the tropical region such as Nigeria, yet soil investigations and designs are based on saturated soil mechanics owing to difficulties associated with soil suction measurements using direct methods such as pressure plate extractor, triaxial testing equipment for testing unsaturated soil, etc. Soil water characteristic curve is an important parameter for estimating unsaturated soil property function. This research considered an indirect method (filter paper) of laboratory soil suction measurement (which is relatively simple, fast and inexpensive) and predictive correlation equations for estimating soil water characteristic curve from index properties of soil for four unsaturated tropical soils of Nigeria, three predictive correlation equations were used in this research namely; Navid et al model (2012), Zapata et al model (2000) and Witczak model (2006), the soil water characteristic curve constant parameters computed from these models were fitted through either Van Genuchten model (1980) or Fredlund & Xing model (1994). Results of air entry values of soils from experimental work and predictive correlation equations were in close range which indicated that in spite of the difficulties experienced in performing laboratory suction test, the predictive correlation equations such as the ones used in this research were found to be proper for estimating soil water characteristic curve. [ABSTRACT FROM AUTHOR]

Soil reinforcement using synthetic fibers is a proven technique for enhancing engineering properties to meet the requirements of subgrade materials for pavement projects. The safe and economical design of fiber-reinforced pavement layers requires better insights into their unsaturated behavior. The soil–water characteristic curve (SWCC) is a measure of the water content inside soil pores at a given suction and is considered an essential property to better understand or predict the behavior of unsaturated fiber-reinforced soils. This paper centers on investigating the soil–water characteristic curves for typical expansive clay reinforced with two different types of polypropylene fibers having different surface morphological properties. The effect of an increase in the fiber dosage (0.2% and 0.6% by dry weight of soil) and fiber lengths (6 and 12 mm) on the resultant SWCC patterns is investigated. The addition of lime is considered to enhance the bonding between clay particles and fiber elements to ensure better friction mobilization levels. SWCCs were determined for all experimental mixtures using a combination of axis translation and filter paper techniques that cover the entire matric suction range during measurements. Volume changes undergone during suction measurements have been duly highlighted and discussed. Furthermore, the one-dimensional deformation (swelling/consolidation) characteristics of these lime-blended fiber-reinforced mixtures at different levels of initial matric suction are studied, and the correlations between initial matric suction with both compression index (Cc) and swell index (Cs) are established. The results indicate a significant change in the shape of the SWCC for lime-blended fiber-reinforced mixtures compared with the shape of the SWCC for natural clay. The contribution of fiber inclination to altering the shape of the SWCC curve is observed as slight regardless of the type, length, and dosage of fiber. Compression and swell indices for tested mixtures increased proportionately with an increase in initial matric suction levels. Doubling the length of the fiber also induced an increase in the compression index. Under no stress conditions did both fiber type and fiber length have a marginal effect on the swell potential and SWCCs. [ABSTRACT FROM AUTHOR]

This study presents a series of model experiments conducted on single pile embedded in saturated and unsaturated expansive soil. A soil composed of 70% bentonite and 30% sand which represents a very high expansive soil is employed in this study. Soil suction (total and matric) was measured using the filter paper technique and calibrated electrical resistance gauges to study the behavior of the soil water retention curve (SWRC) and initial suction and their influence on the results. The results showed that the ultimate skin resistance is increased about 49% when the initial degree of saturation decreases from 90 to 70%. However, the adhesion factor (α, used in calculating the skin friction) increases as the unconsolidated undrained cohesion decreases and as the initial matric suction decreases. The adhesion factor reached a value of 1.3 when the undrained cohesion is 36 kPa, initial degree of saturation of 100% and initial matric suction of 10 kPa. The sharing ratio of the ultimate shaft capacity to the ultimate pile capacity of a single pile changes from 91 to 81% when the degree of saturation decreases from 100 to 70%. [ABSTRACT FROM AUTHOR]

In the present scenario, soil mechanics plays a vital role. In the past few decades there is a wide range of exposure to the unsaturated soils as a significant portion of earth is consisting of arid and semi-arid climatic conditions. Unsaturated soils frequently undergo wetting and drying process due to seasonal variations. Due to this process, expansive soil may undergo swelling-shrinkage process. Considering the similarity between wetting-drying and freezing-thawing process, this study was an attempt to analyse the effect of the freezingthawing process on suction behaviour of expansive soil. Suction is the basic and most important parameter which influences the behaviour of soil. Filter Paper method is used to for the study as an economical approach to evaluate suction. For the experimental study, samples were moulded to achieve full compaction (100% of Proctor density) for different degree of saturation. The moulded samples were passed through required number of the freezing-thawing cycles (0, 1, 3, & 5 nos.) and soil-water characteristic curves (SWCC) are formulated for all F-T cycles. [ABSTRACT FROM AUTHOR]

Throughfall (TF) is an important water input of rainfall redistribution into floor, and its spatial-temporal variability under some species' canopies has been documented to evaluate effect on splash erosion. However, the understanding of TF variability under large broad-leaved canopy remains insufficient. In this study, the spatial heterogeneity, temporal stability and drop size of TF were quantified using variogram fitting, normalised ranking and filter paper staining, respectively, under banana (Musa nana Lour.) canopy comprising long and wide leaves. Results indicated TF pattern showed strong spatial correlation at a range of 3-5 m. High spatial variability of TF was found, which was affected by rainfall event size and was accompanied by great canopy disturbance. TF plots revealed high time variability, which was mainly controlled by unstable banana canopy structure. TF drop size from leaf dripping points varied in 3-10 mm and showed significant differences (p,0.05) among five kinds of leaf shapes, implying that concave and broken banana leaves were involved in the variability of TF drop size. Overall, results demonstrate the spatial-temporal variability of TF is dramatically induced by banana canopy with broad leaves, which may result in non-uniform soil water content and splash erosion under the canopy. [ABSTRACT FROM AUTHOR]

Iron oxide-coated filter paper (Pi) can estimate labile phosphorus (P) in soil by acting as a P sink. The mechanism of Pi extraction may be more analogous to P sorption by plants than extraction with chemical extractants. The objective of this work was to compare strips of paper prepared by the Chardon method with Olsen, ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA), Bray 1, and Mehlich 1 methods in determining available P in alfalfa (Medicago Sativa) and surface samples of 15 soils of the Hamadan province, western Iran. A pot experiment was carried out in a randomized block design with two P levels (0 and 200 mg P kg-1) and three replications. Plants were harvested in three cuttings in a period of 25 weeks and were used to measure plant-available soil P. The following soil tests for P had increasingly higher average amounts of P: paper strips, Bray 1, Olsen, AB-DTPA, and Mehlich 1. The P extracted by paper strips was significantly correlated with P extracted by Olsen and AB-DTPA. In the first cutting, P uptake was not significantly correlated with the P extracted by the three methods. In the second and third cuttings, plant indices were significantly correlated with P extracted by paper strips, Olsen, and AB-DTPA. The results of the present study showed that the strip paper method can be used to detrmine available P of the studied calcareous soils. [ABSTRACT FROM AUTHOR]

Expansive soils often pose as a potential geo-hazard for structures built on them due to the volumetric changes associated with moisture variation. Soil water characteristic curve (SWCC) is a direct representation of the pore and grain distribution of clays while the variation of in situ soil matric suction governs the hydration processes. In the present research, five natural expansive clays were studied at their 95% of maximum dry unit weight. Swell behavioral evaluations are conducted using standard test procedures. Both desorption and adsorption SWCC's were determined using pressure cell apparatus and filter paper method. Adsorption paths are utilized for analysis study as swelling behavior is the main scope of the research. A novel path traversed by the soil specimen on the void ratio-moisture content-log (soil suction) plot, and the corresponding slope, namely the modified specific moisture capacity, 'α', is identified as the main influential parameter. This modified specific moisture capacity exhibited direct relationship to swelling strains and swelling pressure of all five natural clays. A simple model for predicting one dimensional swell strain and swell pressure was established based on reliable predictions obtained using the modified specific moisture capacity of clays. [ABSTRACT FROM AUTHOR]

The application of organic materials is an environmental practice in soil restoration, but the use of sugarcane pith, a by-product of the paper industry, as an amendment in soil reclamation has not been tested so far. The objective of this study was to quantify the effects of the application of sugarcane pith on various hydrophysical properties of saline-sodic soil. A 4-month incubation pot trial under stagnant water and leaching conditions was carried out. Application of 5, 10 and 20 t ha−1 pith led to a decrease in bulk density by 19, 41 and 42%, respectively, and a corresponding increase in drainable porosity. Likewise, soil structure expressed in terms of aggregate stability was enhanced substantially from 0.5 to 0.9. Water-saturated hydraulic conductivity ( Ks) and available water content were also positively affected by the amendments with pith; these changes were attributed to its spongy nature and the increase in organic matter with its decomposition. The doubling of Ks to 1.4 cm hour−1 with the application of 20 t ha−1 pith was considered crucial because it resulted in larger rates of leaching of salt. The fast decomposition of pith released Ca2+, Mg2+ and K+ ions, which accelerated the leaching of Na+. We recommend that saline-sodic soil of the type that we investigated in this study should be amended with sugarcane pith powder up to a rate of 10 t ha−1. Future work should investigate the effects of pith amendments in field trials on a wide range of types of saline-sodic soil. Highlights Is fresh sugarcane pith effective as an amendment for saline-sodic soil?, Sugarcane pith could play a vital role in the management and reclamation of saline-sodic soil., Application of 10-20 t ha−1 sugarcane pith positively affected soil physicochemical properties., Sugarcane pith applied to saline-sodic soil improves the hydrophysical characteristics. [ABSTRACT FROM AUTHOR]

Abstract: The preparation and evaluation of a simple paper-based device for the determination of reactive phosphate in natural and soil waters based on the formation of phosphomolybdenum blue is reported. Hydrophilic reagent zones were defined by printing filter paper with a hydrophobic paper-sizing agent using an inkjet printer. The molybdate/potassium antimony(III)-tartrate reagent and ascorbic acid reductant merged together from adjacent hydrophilic zones after spotting the liquid sample onto the paper. The colour intensity of the phosphoantimonylmolybdenum blue complex produced was measured using a flat bed scanner. Under optimal conditions, the paper-based device is characterised by a working range of 0.2–10mgL−1 P, limits of detection and quantitation of 0.05 and 0.16mgL−1 P, respectively, and repeatability of less than 2% RSD at 1 and 5mgL−1 P (n=10 and 8). There was no significant difference between the results obtained using the paper-based device and reference methods (t=0.0135, P (T≤t) two-tail=0.9892, df=38). In its optimum form, the paper-based device was stable for up to 15 day under ambient conditions, and up to 122day when stored at ≤−20°C. The small dimensions, minimal reagent consumption, low cost (a few cents), ease of operation and favourable analytical performance make the proposed paper-based device attractive for on-site environmental monitoring and analysis. [Copyright &y& Elsevier]

The Internet of Things (IoT) is transforming the agriculture industry and enabling farmers to contend with the enormous challenges they face. Livestock monitoring, conservation monitoring, and plant & soil monitoring are the challenges for which IoT can provide solutions. Innovative IoT applications address agricultural issues, enhancing the quality, quantity, sustainability, and cost-effectiveness of production. Today's large and local farms can leverage IoT to remotely monitor sensors detecting soil moisture, crop growth, pests, and control smart connected harvesters and irrigation equipment. This paper aims to monitor soil parameters such as moisture, temperature, and electrical conductivity, and automate the irrigation process. Decision-making is executed through a microcontroller. Users are notified via android apps when there are deviations from expected values, ensuring system health. Greenhouses are controlled environments for plant growth. The main aim of this paper is to design a simple, low-cost, IoT-based system to continuously monitor and control environmental parameters to achieve optimal plant growth and yield. [ABSTRACT FROM AUTHOR]

Pollution of air, water, and soil is a pressing global issue with significant implications for environmental and human health. This research paper explores the various methods and technologies employed for the monitoring and remediation of pollutants in these three crucial environmental compartments. It discusses the challenges associated with pollution, the importance of effective monitoring, and the diverse strategies available for pollutant remediation. By synthesizing current research and technologies, this paper aims to provide insights into the state-of-the-art approaches for addressing pollution and promoting environmental sustainability [ABSTRACT FROM AUTHOR]

The accurate prediction of soil moisture content helps to evaluate the quality of farmland. Taking the black soil in the Nanguan District of Changchun City as the research object, this paper proposes a stacking ensemble learning model integrating hybrid neural networks to address the issue that it is difficult to improve the accuracy of inversion soil moisture content by a single model. First, raw hyperspectral data are processed by removing edge noise and standardization. Then, the gray wolf optimization (GWO) algorithm is adopted to optimize a convolutional neural network (CNN), and a gated recurrent unit (GRU) and an attention mechanism are added to construct a hybrid neural network model (GWO–CNN–GRU–Attention). To estimate soil water content, the hybrid neural network model is integrated into the stacking model along with Bagging and Boosting algorithms and the feedforward neural network. Experimental results demonstrate that the GWO–CNN–GRU–Attention model proposed in this paper can better predict soil water content; the stacking method of integrating hybrid neural networks overcomes the limitations of a single model's instability and inferior accuracy. The relative prediction deviation (RPD), root mean square error (RMSE), and coefficient of determination (R2) on the test set are 4.577, 0.227, and 0.952, respectively. The average R2 and RPD increased by 0.056 and 1.418 in comparison to the base learner algorithm. The study results lay a foundation for the fast detection of soil moisture content in black soil areas and provide a data source for intelligent irrigation in agriculture. [ABSTRACT FROM AUTHOR]

This work investigates the effect of filler type on the rate of biodegradation of thermoplastic starch-based films in water and soil environments. The authors applied the casting method to create films of thermoplastic starch, based on waste paper, filled with clays or organic fillers. Since such materials made from cellulose tend to absorb water, we hydrophobized the surfaces of the filled thermoplastic starch samples. The structures of the blends were characterized by infrared spectroscopy, while atomic-force microscopy was applied to observe change in surface topography and the distribution of the filler. We also studied moisture resistance of the blends. Biodegradation tests revealed that surface topography, distribution of the filler and starch-to-filler interactions were non-critical to the rate and degree of biodegradation of the blends. The biodegradation rate of the blends was strongly affected by the environmental conditions (relative humidity 54%, 100%, respectively; temperature 25 °C, 37 °C, respectively). Under anaerobic conditions, it was the mixtures that biodegraded to the greatest extent, whereas the hydrophobized mixtures did so the least. [ABSTRACT FROM AUTHOR]

In this study, an attempt is made to investigate the load transfer in pile groups constructed in saturated and unsaturated soil using aluminum model piles of 20 × 20 mm in cross section and 200 mm in length with six group configurations, single, 2 × 1 , 3 × 1 , 2 × 2 , 3 × 2 , and 3 × 3 , groups in addition to pull-out test. The samples are prepared at three different soil properties: two models with the same degree of saturation and two with different dry unit weights and the third is unsaturated soil model with. A relationship between the soil suction and water content is introduced using a digital monitor, accompanied by eight suction probes planted in CBR molds. This relationship is used to predict the value of suction when conducting tests on models of the unsaturated soil. Further, the soil suction is measured using a filter paper method. Results of ultimate load capacity obtained from the load–displacement curves reveal an increase in the ultimate load with increasing the number of piles in the group for the same soil properties, and also an increase in the soil dry unit weight. Further, the results indicate an increase in pile capacity when the soil becomes in unsaturated state compared with saturated soil for the same pile group tested. On the other hand, the pull-out test gives a maximum load carrying capacity when the single pile tested was in saturated soil with high dry density, and minimum results are obtained when tested in unsaturated condition with the percentage of increase being about 463 and 34% for two saturated soils, compared with that for unsaturated soil. [ABSTRACT FROM AUTHOR]

This work presents a simple and innovative protocol employing a microfluidic paper-based analytical device (µPAD) for equipment-free determination of mercury. In this method, mercury (II) forms an ionic-association complex of tetraiodomercurate (II) ion (HgI42−(aq)) using a known excess amount of iodide. The residual iodide flows by capillary action into a second region of the paper where it is converted to iodine by pre-deposited iodate to liberate I2(g) under acidic condition. Iodine vapor diffuses across the spacer region of the µPAD to form a purple colored of tri-iodide starch complex in a detection zone located in a separate layer of the µPAD. The digital image of the complex is analyzed using ImageJ software. The method has a linear calibration range of 50–350 mg L−1 Hg with the detection limit of 20 mg L−1. The method was successfully applied to the determination of mercury in contaminated soil and water samples which the results agreed well with the ICP-MS method. Three soil samples were highly contaminated with mercury above the acceptable WHO limits (0.05 mg kg−1). To the best of our knowledge, this is the first colorimetric µPAD method that is applicable for soil samples including mercury contaminated soils from gold mining areas. [ABSTRACT FROM AUTHOR]

Most Penman-Monteith-Leuning (PML) evapotranspiration (ET) modeling studies are dominated by consideration of meteorological, energy, and land use information, etc., but the dynamic coupling of soil moisture content (SM), especially in terms of improving accuracy through assimilation, lacks sufficient attention. This paper proposes a research framework for the dynamic coupling simulation of PML model and SM based on data assimilation, i.e., the remote sensing monitored SM is combined with soil evaporation of PML to obtain high-precision time-continuous SM data through data assimilation; simultaneously, dynamical soil evaporation coefficients are generated based on the assimilated SM to improve the simulation accuracy of the PML model. The new scheme was validated at a typical irrigation zone in north China and showed obvious improvements in both SM and ET simulations. Moreover, the effect of the assimilation of SM on the simulation accuracy of ET for different crop growth periods is further analyzed. This research provides a new idea for the coupling simulation of the SM and PML models. [ABSTRACT FROM AUTHOR]

Loess is susceptible to large and sudden volume reduction induced by loading or wetting. The work in this paper focused on compression and collapse behaviour of the intact loess under isotropic stress condition. To this purpose, an improved technique was introduced for the unsaturated triaxial apparatus that was capable of precise injecting know the amounts of water into the specimen, while continuously monitoring the suction. Tests were performed under two separate hydro-mechanical paths: isotropic compression at various suctions and wetting in steps at various net isotropic stresses. Experimental measurements indicated that the compression behaviour of the intact loess was highly affected by the extent of the level of the suction. The wetting-induced collapse behaviour depended on both the extent of applied net isotropic stress and the hydro-mechanical path. The collapse potential reached a maximum when the specimen was wetted at the initial yield stress. No unique of yield curve was identified from loading and wetting paths in a suction–net mean stress plane. For the same plastic volumetric strain, the suction decrease yield curve identified from wetting path appeared under the loading–collapse yield curve identified from loading path. Interestingly, the uniqueness of the yield curve was identified from loading and wetting paths in a suction–mean effective stress plane. An elastoplastic model of the intact loess under isotropic stress condition incorporating soil water retention behaviour was proposed, using the mean effective stress as constitutive stress. This model is able to reproduce the volumetric behaviour of the intact loess along constant suction paths and wetting paths quite well, using a single-valued compressibility index. [ABSTRACT FROM AUTHOR]

In the paper of [6], maps of suitability predictions for a handful relevant tree species in 30 × 30 m resolution are presented based on ecograms that are linked with interpolated, modeled soil data (subsoil pH, subsoil texture and derived plant available water to 160 cm). We ignore statistical principles if we accept interpolated tree species suitability predictions based on limited sets of soil properties without verifying them with observed, local site and soil data. Commentary to the paper by Roell, Nord-Larsen et al. 'Mapping tree species ecograms based on soil pH and soil water availability across Denmark'. [Extracted from the article]

The concept of utilizing handmade wastepaper refuse for synthesis of nanocellulose and later converting it into nanourea incorporated carboxymethylcellulose (NU@CMC) hydrogel has been visualized as a sustainable solution to manage solid wastepaper and simultaneously enrich plant growth by providing nanourea. Various characterization techniques like Fourier-transform infrared spectroscopic (FTIR), Field emission scanning electron microscopic (FESEM), High-Resolution Transmission Electron Microscopy (HRTEM) analysis and Brunauer-Emmett-Teller (BET) analysis confirmed that the NU@CMC hydrogel was rich in functional groups, having porous and rough surface morphology. Swelling ratio was found to be 1457% at pH 7 due to the presence of polar group and porous surface of hydrogel. Maximum water holding capacity (54.45%) was obtained at 2 wt% NU@CMC hydrogels, and it retained moisture in the soil for more than 2 weeks. NU@CMC hydrogel was used as a control release vehicle for the release of nanourea for plants at different pH ranges, and results indicated that this process followed the Fickian diffusion mechanism at pH 7 and 46.71% release efficiency was observed in 18 days. Maximum stem length was observed with NU@CMC hydrogels compared to CMC hydrogel and soil. Thus, eco-friendly, versatile NU@CMC hydrogel with 39.8% biodegradability within 32 days establishes its dual promise for water transport under water-limited conditions and as a fertilizer release vehicle for sustainable plant growth. [Display omitted] • NU@CMC hydrogel has been synthesized form waste paper for slow release of nanourea. • Maximum swelling ratio of the hydrogel was found to be 1457% at a pH 7. • Release behavior of hydrogel shows the Fickian diffusion mechanism. • Maximum stem length was observed with NU@CMC hydrogels compared to soil. • The NU@CMC hydrogel shows 39.8% biodegradability in 32 days. [ABSTRACT FROM AUTHOR]

Soil suction is one of the most important parameters describing soil moisture conditions for unsaturated soils used in landfill liners. However, few studies have been conducted on the suction characteristics of compacted zeolite–bentonite mixtures (ZBMs) and sand–bentonite mixtures (SBMs), which are proposed for use as liner materials. Nevertheless, zeolite is known for its microporous skeleton containing cages and tunnels and it has a great physical affiliation to water uptake. Zeolite and bentonite, in a mixture, are thought to be in competition for water uptake and this may alter the distribution of water content for each soil in the mixture. The present study investigated the suction properties of compacted ZBMs and SBMs for varying mixing ratios and compaction water contents. The soil suction measurement technique chosen was the filter-paper method. The suction characteristics of powdered, granular, and block zeolites, as well as 0, 10, and 20% bentonite in ZBMs and SBMs were measured and compared with each other. Contaminated compacted ZBMs are compared with those of uncontaminated compacted ones at the optimum water content for the 10% and 20% mixtures. The results show that suction capacity of zeolite increases with grain size. As bentonite content increases, both matric and total suction increase for both mixtures. ZBMs have higher matric suction values than SBMs, but not total suction values. Contaminated total suction values are found to be higher than those of uncontaminated samples due to an increase in dissolved ion concentration. [ABSTRACT FROM AUTHOR]

Soil hydraulic properties significantly affect the occurrence and development of collapsing gully walls. The effect of temperature on the hydraulic properties of soil in collapsing gully walls remains unclear. In this study, the hydraulic properties of the red soil layer, the sandy soil layer and the detritus layer in a collapsing gully wall were investigated using the filter paper method, and the soil water retention curves of the different soil layers at 25 and 40 °C were determined. The aim of this study was to investigate the impact of temperature on the soil hydraulic properties of different soil layers in collapsing gully walls. The study found that when the water content in the red soil layer and sandy soil layer exceeded 20% and in the detritus layer exceeded 10%, the soil's matric suction significantly decreased as the temperature increased from 25 to 40 °C. Additionally, the parameters of θ s , α , n and m all exhibited a decreasing trend, and the soil water content in the detritus layer was primarily influenced by the temperature change, which resulted in a decrease of 38.10%. The unsaturated hydraulic conductivity of the detritus layer exhibited higher values than that of the sandy layer and red soil layer under identical temperature conditions. Moreover, the unsaturated hydraulic conductivity of the red soil layer, sandy soil layer and detritus layer increased with increasing temperature. It was observed that the unsaturated hydraulic conductivity of the detritus layer increased by 0.18 cm h−1 at a soil water content of 44%. This increase in conductivity was more pronounced than the corresponding changes in the red soil layer and sandy soil layer. An elevated temperature caused the water-holding capacity of the different soil layers of the collapsing gully wall to decrease and the unsaturated hydraulic conductivity to increase. However, the influence of the clay particle content within the soil of the collapsing gully wall rendered the temperature effect more distinct. Therefore, the destabilizing deformation of the soil in the collapsing gully wall during the summer under high temperatures and precipitation may have played a key role in its collapse. [ABSTRACT FROM AUTHOR]