Soil Water Research Articles

Modeling tree responses to soil water variability guides irrigation to account for soil winter reserves

AbstractHigh‐yield almond (Prunus amygdalus) production requires irrigation to support soil water availability throughout the summer. We aimed to develop tools that project almond trees’ water requirements and then integrate them into irrigation management. We postulated that deficit irrigation would limit root allocation and reduce irrigation efficiency. Thus, we monitored soil water availability (soil water content and potential evapotranspiration) and tree physiology (transpiration and trunk circumference) under 600, 900, or 1250 mm summer irrigations. A soil‐tree model was trained to predict trees’ transpiration as the soil dried between irrigation events. The model included an empirical function for tree transpiration at variable soil water potentials (50% loss by −1 MPa). Field records corroborated the soil‐tree model projections that 600 mm irrigation reduces soil water potential to −1 MPa and limits transpiration after winter soil water reserves deplete. Trees at deficit irrigation did grow deep roots to extract soil winter reserves, thus disputing our original notion. A 900 mm irrigation matched transpiration and maintained soil at −0.6 MPa. The 1250 mm irrigation exceeded transpiration and narrowed trees’ water uptake to the upper 50 cm. The reciprocity between soil water and transpiration dictates that predetermined irrigation would limit or exceed transpiration. The soil‐tree model could project transpiration responses to soil water variability, thereby supporting irrigation by trees’ transpiration. The model uses soil water dynamics, rather than insular water potential measures, to account for spatial discrepancies between water application and uptake depths. Hence, the soil‐tree model lays a computational framework for precision irrigation by automated sensory.

The LTAR Integrated Common Experiment at Southern Plains.

The Southern Plains (SP) is one of 18 Long-Term Agroecosystem Research network sites that combine strategic research projects with common measurements across multiple agroecosystems. Projects at the SP site focus on the use of indicator measurements to aid in assessment of land and nutrient management's impact on soil health, water quality, carbon and water balances, and forage biomass-quality in diversified, adaptive crop-livestock systems designed to overcome shifts in natural resources and climate. The prevailing treatment is tilled winter wheat (Triticum aestivum L.) that is grazed, hayed, harvested for grain, or grazed and harvested for grain. The alternative treatment is year-round annual cover crop forage mixes for cattle (Bos taurus) production planted in fall and spring under conservation tillage management. The area is subject to variable weather and climatic shifts that reduce the potential to diversify forage crops and limit grazing in southern tall grass prairies and small grain systems. Incorporation of fertilized, rain-fed, annual cool and warm season mixtures of cover crops could fill forage gaps. The presence of year-round ground cover reduces sediment and nutrient loading to surface waters while enhancing soil health and water holding capacity. Tools to aid agricultural producers and land and water resource managers have been developed and implemented to determine how climate, topography, and varying conservation management practices alter hydrological structures, greenhouse gas emissions, water usage, and soil resources.

Mapping soil moisture across the UK: assimilating cosmic-ray neutron sensors, remotely sensed indices, rainfall radar and catchment water balance data in a Bayesian hierarchical model

Abstract. Soil moisture is important in many hydrological and ecological processes. However, data sets which are currently available have issues with accuracy and resolution. To translate remotely sensed data to an absolute measure of soil moisture requires mapped estimates of soil hydrological properties and estimates of vegetation properties, and this introduces considerable uncertainty. We present an alternative methodology for producing daily maps of soil moisture over the UK at 2 km resolution (“SMUK”). The method is based on a simple linear statistical model, calibrated with 5 years of daily data from cosmic-ray neutron sensors at ∼ 40 sites across the country. The model is driven by precipitation, humidity, a remotely sensed “soil water index” satellite product and soil porosity. The spatial variation in the parameter describing the soil water retention (and thereby the response to precipitation) was estimated using daily water balance data from ∼ 1200 catchments with good coverage across the country. The model parameters were estimated by Bayesian calibration using a Markov chain–Monte Carlo method, so as to characterise the posterior uncertainty in the parameters and predictions. The approach reduces uncertainty by integrating multiple data sources, all of which have weaknesses but together act as a better constraint on the true soil moisture. The model explains around 70 % of the variance in the daily observations with a root-mean-square error of 0.05 m3 m−3, better than results from more complex process-based models. Given the high resolution of the inputs in time and space, the model can predict the very detailed variation in soil moisture which arises from the sporadic nature of precipitation events, including the small-scale and short-term variations associated with orographic and convective rainfall. Predictions over the period 2016 to 2023 demonstrated realistic patterns following the passage of weather fronts and prolonged droughts. The model has negligible computation time, and inputs and predictions are updated daily, lagging approximately 1 week behind real time.

A centrifuge modelling setup for dewatering, rewetting, and characterizing soil deposits

Dewatering in soils serves various purposes in the field of geotechnical engineering as well as other disciplines. In geotechnical engineering, dewatering is effective for improving stability, reducing settlements, and limiting seepage of contaminated pore fluid. This study details the development of an experimental setup that enables dewatering and rewetting soil deposits in-flight in a geotechnical centrifuge while the pore pressures/suctions and moisture contents are measured. Cone penetration tests and shear wave velocity measurements are also used to characterize the material in-flight. Detailed discussion is provided regarding the construction of the tensiometers and calibration of the moisture content probes. Tests are performed on two coal combustion products (CCPs) to exemplify the capabilities of the equipment. Illustrative test results provide time histories and profiles of soil suction and water content at different depths, agreeing well with measurements from laboratory soil-water retention curves. The results also show that dewatering of the CCP deposits leads to significant increases in strength and stiffness, and that after subsequent rewetting, the material maintains a permanent increase in stiffness. The developed system enables an economical and reliable study of the impacts related to dewatering and rewetting cycles to fulfill research purposes in a broad range of engineering disciplines.

Utilizing Data Mining Techniques in Geophysical and Biological Analysis for Assessing Environmental Risks

This study aimed to assess environmental risks using data extraction techniques. It focused on geophysical and biological factors and addressed the urgent need for effective risk management strategies to reduce soil erosion, water pollution, and air quality deterioration. A comprehensive dataset was created through the systematic collection of geophysical and biological data including temperature, soil composition, and biological abundance index. It used equipment such as satellite sensors and mountain transmitting stations. Various statistical tools used include decision trees and random forest algorithms. They were used to analyze data and identify important environmental risk factors. The results showed some interesting insights, revealing that the Neural Network has an accuracy of 95.5%, and the Random Forest algorithm predicts risk with an accuracy of 92.0%. It analyzed the classification of environmental hazard zones and identified high-risk zones, such as Zone A, which contains 10,000 people affected by erosion and Zone D, 20,000 people who were at risk from soil contamination. The study concludes that social media can significantly improve understanding and management of environmental risks. Additionally, it provides a useful framework for decision-makers and stakeholders to promote sustainable environmental practices.

An Analysis of Vertical Infiltration Responses in Unsaturated Soil Columns from Permafrost Regions

Rainfall infiltration affects permafrost-related slope stability by changing the pore water pressure in soil. In this study, the infiltration responses under rainfall conditions were elucidated. The instantaneous profile method and filter paper method were used to obtain the soil–water characteristic curve (SWCC) and hydraulic conductivity function (HCF). During the rainfall infiltration test, the vertical patters of volumetric moisture contents, total hydraulic head or suction and wetting front were recorded. Advancing displacement and rate of the wetting front, the cumulative infiltration, the instantaneous infiltration rate, and the average infiltration rate were determined to comprehensively assess the rainfall infiltration process, along with SWCC and HCF. Additionally, the effects of dry density and runoff on the one-dimensional vertical infiltration process of soil columns were evaluated. The results showed that the variation curve of wetting front displacement versus time obeys a power function relationship. In addition, the infiltration rate–time relationship curve and the unsaturated permeability curve could be roughly divided into three stages, and the SWCC and HCF calculated by volumetric moisture content are more sensitive to changes in dry density than to changes in runoff or hydraulic head height.

Native Gramineae outperform Leguminosae in enhancing ecosystem multifunctionality during semiarid desert steppe restoration

The effects of reseeded native Gramineae and Leguminosae species on the multifunctionality of desert steppe have remained unclear. Therefore, we examined a semiarid desert steppe that was reseeded 5 years earlier with a dominant native Gramineae species, Agropyron mongolicum; a dominant native Leguminosae species, Lespedeza potaninii; and a 1:1 reseeded mixture of A. mongolicum × L. potaninii. We evaluated the changes in plant communities and soil properties and then quantified aboveground ecosystem multifunctionality (AEMF), belowground ecosystem multifunctionality (BEMF), and overall ecosystem multifunctionality (EMF) using an averaging approach. Compared with the native steppe without reseeding, both reseeded A. mongolicum and A. mongolicum × L. potaninii increased fine root volume, plant height, plant cover, aboveground biomass (AGB), belowground biomass (BGB), soil water storage (SWS), soil organic carbon, light fraction organic carbon, labile organic carbon, total nitrogen (TN), nitrate nitrogen, and total phosphorus (P), but decreased soil bulk density. However, reseeded L. potaninii increased coarse root volume, plant height, plant cover, AGB, BGB, and SWS but decreased plant richness, plant diversity, TN, and total P. In addition, reseeded A. mongolicum and A. mongolicum × L. potaninii increased AEMF, BEMF, and overall EMF, but reseeded L. potaninii only increased AEMF. Further analysis indicated that the fine roots played a crucial role in improving individual ecosystem functions and eventually in determining EMF. Therefore, the reseeding of a desert steppe with Gramineae species has greater potential than with Leguminosae species for improving EMF, since Gramineae species have greater fine roots volume than Leguminosae species.

Conservation Agriculture and Crop Residue Management

India being a populous country the intensification of the cropping system is mandatory. However, this intensification of the cropping system results in the degradation of soil and other natural resources. Considering this situation, conservation agriculture is the most suitable alternative to achieving sustainable yield and productivity. Conservation agriculture is based on three major principles those are minimum disturbance of soil, crop rotation, and maintenance of crop residue. Crop residue management plays a major role in conservation agriculture as it helps in improving soil productivity, soil organic matter content, soil structure, soil water conservation, air quality, and reduction in soil erosion. India produces 273 Mt of crop residues annually which contain a total of 7.16 Mt of nutrients (N-1.28, P2O5-1.97, K2O-3.91). In modern agriculture, green manure crops like Sesbania and sunhemp increase the quantity and quality of the crop residues in the crop field. Among various residue management practices mulching has been practiced prominently in dry lands as it increases the resource use efficiency. The residue decomposition is affected by various factors like quality of crop residue, edaphic, management, and climatic factors. In modern scientific research crop residues are being used especially for site-specific nutrient management. It is observed in most studies that zero tillage or reduced tillage with crop residue gives comparatively higher net returns, water use efficiency, and resource use efficiency than conventional agriculture. In Indian context. The management of rice residue particularly in the Indo-Gangetic Plains of India is challenging, where the rice-wheat cropping system is intensively followed and the farmers are more anxious about timely seeding of wheat in combine harvested paddy fields (Sidhu et al., 2007; Singh et al., 2020).

Simultaneous use of disulphide oil for chemical‐enhanced oil recovery by emulsion formation and stability with asphaltene deposition control

AbstractDisulphide oil (DSO) is a by‐product of oil and gas refining processes that is generated during the removal of mercaptans and the sweetening of light hydrocarbons. Asphalt deposition, especially asphaltene deposition during enhanced oil recovery methods, reduces oil recovery from the reservoir, so the use of a substance such as DSO, which has the ability to control and reduce asphaltene deposition, can be effective in increasing oil recovery from the reservoir. In this research, a micromodel with a fracture design and a matrix that represents fracture reservoirs was utilized. These tests were conducted in two groups. The first group of tests is related to adding DSO to crude oil and using 70 to 30 vol.% oil–water emulsion containing salt, surfactant, and nanoparticles. The second group involved adding DSO to both crude oil and emulsion. The first group aimed at stimulation and the second group aimed at chemical enhanced oil recovery (C‐EOR). The formation and stability of water‐in‐oil emulsion was done by analyzing the average droplet size. As a result, in the first group of tests with the presence of DSO in the oil, by measuring the average diameter before and after injection of AOS surfactant, it was observed that the average droplet size decreased from 6.89 to 4.01 μm, which indicates an increase in the emulsion stability. In the second group, where DSO was present in both oil and water emulsion in injected oil, it can be seen that the average diameter of the droplets in the surfactant decreased from 5.12 to 3.21 μm.

Long-term alfalfa planting mediates the coupling of soil water and organic carbon storage in a semi-arid area of the Loess Plateau, China

The key to restoring arid and semi-arid ecosystems is maintaining soil water and organic carbon contents. Alfalfa (Medicago sativa L.) is a high-yield perennial forage crop and performs ecological functions as a drought-resistance leguminous herb. It has been widely planted for reconstruction of degraded soils in the Loess Plateau in northwestern China, but long-term planting may affect soil carbon–water coupling and lead to crop yield reduction. To maximize the benefits of reconstructed grassland, this study explored the couplings of soil water, organic carbon, and alfalfa productivity along a reconstruction chronosequence in a semi-arid area of the Loess Plateau. Space-for-time substitution approach was used to select different-aged stands of reconstructed grassland (1, 5, 7, 10, 15, 20, 30 years old). Alfalfa above-ground biomass (AGB), soil water storage (SWS), organic carbon storage (SOCS), and carbon–water coupling coordination degree (D) were measured in the 0–100 cm soil profile. Alfalfa AGB reached a peak in the 7th year, and the degradation began in the 10th year. Both SWS and SOCS varied nonlinearly with stand age. The greatest loss of SWS occurred in the 15th year (80–100 cm depth), whereas the largest increase of SOCS occurred in the 30th year (0–20 cm depth). There was a negative feedback relationship between AGB and SWS over the 30-year study period (Pearson r = −0.835, P = 0.098). AGB and SOCS initially showed a trade-off within the first 10 years (Pearson r = −0.7431, P = 0.2569), in contrast to their positive feedback in the 20–30th years (Pearson r = 0.9978, P = 0.0421). A decoupling between SWS and SOCS (D < 0.6) was observed after 12 years of alfalfa planting. For agricultural production, a greater supply of water and organic fertilizer is required from the 7th year of alfalfa planting, and reseeding may be needed around the 10th year to prolong the life of alfalfa community. Alfalfa should be planted for no more than 12 consecutive years in the study area for ecological protection.

Optimizing plastic film mulch to improve the yield and water use efficiency of dryland maize in the Loess Plateau, China.

Knowledge on the variation of yield and water use efficiency under different mulching methods is important for guiding rained maize production in the Loess Plateau area. In this study, eight different plastic film mulching methods was established to analyze the maize growth, soil water content and soil temperature changes of dryland maize, and increase yield and water use efficiency (WUE). The field experiment was conducted in 2019, and eight treatments were set up, including a traditional flat planting without mulching (CK), ridge-furrow with ridges mulching black plastic film and furrows mulching straw (HJ), ridge-furrow with ridges mulching black plastic film and furrows bare (HL), ridge-furrow with ridges mulching liquid plastic film and furrows mulching straw (YJ), ridge-furrow with ridges mulching liquid plastic film and furrows bare (YL), ridge-furrow with ridges mulching biodegradable plastic film and furrows mulching straw (SJ), ridge-furrow with ridges mulching biodegradable plastic film and furrows bare (SL) and ridge-furrow with ridges bare and furrows mulching straw (NJ). Furthermore, the AHP-TOPSIS was employed to evaluate the optimal mulching method for maize. The results showed that compared with CK and NJ treatment, the soil water content and soil storage were significantly changes with other treatments in the reproductive period of maize. Among the six mulching methods, maize yield in HJ, HL, YJ, YL, SJ, and SL treatments were 46.28%, 61.95%, 70.30%, 51.02%, 52.02% and 53.53% significantly greater than CK treatment. In addition, dryland maize WUE was 66.53% and 84.01% higher in the YJ and YL treatments with ridges mulching liquid plastic film than in the CK treatment, respectively. The optimal treatments of economic benefits were YL and HJ. Through AHP-TOPSIS comprehensive analysis, the optimal mulching methods were YL and HJ treatment. Current field trials indicate that YL treatment could serve as a promising option to improve dryland maize yield, WUE, and reducing environmental risks in the Loess Plateau of China.

Functional groups of leaf phenology are key to build climate-resilience in cocoa agroforestry systems

Agroforestry has the potential to enhance climate change adaptation. While benefits from agroforestry systems consisting of cash crops and shade trees are usually attributed to the (shade) trees, the trees can also have negative impacts due to resource competition with crops. Our hypothesis is that leaf phenology and height of shade trees determine their seasonal effect on crops. We test this hypothesis by categorizing shade tree species into functional groups based on leaf phenology, shade tree canopy height and shade tree light (wet and dry season) interception as well as the effects. To this end, leaf phenology and the effects on microclimate (temperature, air humidity, intercepted photoactive radiation (PAR)), soil water, stomatal conductance and cocoa yield were monitored monthly during wet and dry seasons over a two-year period on smallholder cocoa plantations in the northern cocoa belt of Ghana. Seven leaf phenological groups were identified. In the wet season, highest buffering effect of microclimate was recorded under the trees brevi-deciduous before dry season. During dry season, high PAR and lowest reduction in soil moisture were observed under the trees in the group of completely deciduous during dry season. The evergreen groups also showed less reduction in soil water than the brevi-deciduous groups. In the wet season, shade tree effects on cocoa tree yields in their sub canopy compared to the respective control of outer canopy with full sun ranged from positive (+10 %) to negative (-15 %) for the deciduous groups, while yield reductions for the evergreen groups ranged from −20 % to −33 %. While there were negative yield impacts for all phenological groups in the dry season, the trees in completely deciduous during dry season group recorded least penalties (-12 %) and the trees with evergreen upper canopy the highest (-35 %). The function of shade trees in enhancing climate resilience is therefore strongly dependent on their leaf phenological characteristics. Our study demonstrates how the key trait leaf phenology can be applied to successful design of climate-resilient agroforestry systems.

Woody Encroachment Modifies Subsurface Structure and Hydrological Function

ABSTRACTWoody encroachment—the expansion of woody shrubs into grasslands—is a widely documented phenomenon with global significance for the water cycle. However, its effects on watershed hydrology, including streamflow and groundwater recharge, remain poorly understood. A key challenge is the limited understanding of how changes to root abundance, size and distribution across soil depths influence infiltration and preferential flow. We hypothesised that woody shrubs would increase and deepen coarse‐root abundance and effective soil porosity, thus promoting deeper soil water infiltration and increasing soil water flow velocities. To test this hypothesis, we conducted a study at the Konza Prairie Biological Station in Kansas, where roughleaf dogwood (Cornus drummondii) is the predominant woody shrub encroaching into native tallgrass prairie. We quantified the distribution of coarse and fine roots and leveraged soil moisture time series and electrical resistivity imaging to analyse soil water flow beneath shrubs and grasses. We observed a greater fraction of coarse roots beneath shrubs compared to grasses, which was concurrent with greater saturated hydraulic conductivity and effective porosity. Half‐hourly rainfall and soil moisture data show that the average soil water flow through macropores was 135% greater beneath shrubs than grasses at the deepest B horizon, consistent with greater saturated hydraulic conductivity. Soil‐moisture time series and electrical resistivity imaging also indicated that large rainfall events and greater antecedent wetness promoted more flow in the deeper layers beneath shrubs than beneath grasses. These findings suggest that woody encroachment alters soil hydrologic processes with cascading consequences for ecohydrological processes, including increased vertical connectivity and potential groundwater recharge.

The water vapor distribution profile in dry soil layer during evaporating with high spatial resolution monitored by distributed fibre-optic sensing technology

The dry soil layer (DSL) typically forms on the surface of sandy soils during the evaporation process, with water in the DSL moving solely as vapor. Understanding the DSL thickness and its water vapor distribution is crucial for accurately estimating soil water flux, improving evaporation mechanisms, and enhancing ecological conservation efforts. This study employed distributed fibre-optic sensing (DFOS) technology to achieve high spatial resolution measurements (up to 1 mm) of the water vapor distribution within the DSL. We measured soil water vapor profiles in a sand column subjected to evaporation over 24 days using a 60 cm long relative humidity sensing probe and an optical frequency domain reflection (OFDR) interrogator. We effectively captured the downward migration of the evaporating surface from the sand surface and quantified the inhibitory effect of DSL thickness on evaporation using a logarithmic function. Additionally, we identified a linear distribution of water vapor with depth in the DSL. Our findings offer novel insights into the role of DSL in the hydrological behaviour of unsaturated soils and demonstrate the potential of our approach for investigating dynamic changes in in-situ DSLs, particularly in arid and semi-arid regions.

Production Law of Shielding Oil in Fractured Carbonate Reservoirs: A Case Study of Northwest Oilfield, China

Multi-scale fractures in Northwest Oilfield are extremely developed. Fractures in both oil flow channels and water channels lead to the phenomenon of water channeling in the later stages of reservoir development, which may be affected by the bottom water cone. Gel plugging agents are widely used in the treatment of this phenomenon because of their low cost and high-water plugging efficiency. However, because there is often residual oil in small-scale fractures, the pressure law of different grades of differential fractures on gel is not clear, thus leading to low gel application efficiency and low oil recovery. There is still a lack of effective means through which to understand the regularity of shielding the remaining oil with gel strength and fractures of different grades. In this study, we conducted a novel analysis of the law of shielding oil production in fractured reservoirs. The gelling and rheological properties of anti-temperature gels (ATGs) with different strengths were studied. The plugging rate of oil phase was 96.39%, and that of water phase was 25.37%. ATG showed good oil–water selectivity. The influences of different grades of differential fractures on the production law of shielding the remaining oil were also studied, as well as the corresponding influence law chart. When the gel strength was in the range of 2.0–28.1 Pa and the fracture grade difference was 5–10, the recovery ratio was increased by 10.6–24%. The enhanced oil recovery can be quantitatively predicted by the scale of reservoir fractures and the strength of gel used. It has a certain guiding role for the field application of gel to efficiently shield residual oil in differential fractures.

The essence of soil and soil formation in accordance with soil water regime

The obtaining of new data on the transformation of parent materials into soil and on soil as a set of essential properties is provided on the basis of previously conducted fundamental studies of soils formed on loess-like loams in Belarus (15,000 numerical indicators). The study objects are autochthonous soils of uniform granulometric texture. The basic properties without which soils cannot exist are comprehensively considered. Interpolation of factual materials is given, highlighting the essential properties of soils. Soil formation is analyzed as a natural phenomenon depending on the life activity of biota and the water regime. Models for differentiation of the chemical profile and bioenergy potential of soils are presented. The results of the represented study interpret the available materials taking into account publications on the biology and water regime of soils over the past 50 years into three issues: the difference between soil and soil-like bodies; the soil formation as a natural phenomenon of the mobilization of soil biota from the energy of the sun, the atmosphere, and the destruction of minerals in the parent materials; and the essence of soil as a solid phase and as an ecosystem. The novelty of the article study is determined by the consideration of the priority of microorganisms and water regime in soil formation, chemical-analytical identification of types of water regime, and determination of the water regime as a marker of soil genesis.

Effect of Grasses on Native Tree Seedling Establishment Along a Water Stress Gradient: Results of Forest and Greenhouse Experiments

ABSTRACTAnthropogenic activities such as cattle grazing and forest clearing have led to the establishment of early successional grass layers in some native forests, which may inhibit or entirely prevent native tree regeneration. We hypothesize that increased grass coverage reduces or eliminates the establishment of native tree seedlings by limiting water availability to seeds and seedlings. This study aims to evaluate the impact of grass cover on tree seedling survival under varying levels of soil water stress. We conducted a field experiment using 36 experimental exclosures in two northwest Patagonian valleys, representing a regional gradient in altitude, rainfall, and tree canopy openness. Additionally, a greenhouse experiment was performed with 36 pots, manipulating four levels of grass cover and three levels of water stress. Results from both experiments showed similarities: in the field, the likelihood of finding a live tree seedling was approximately 2.78 times higher in areas without grass compared with grass‐covered sites. In the greenhouse, the presence of grass reduced the final number of established seedlings by an average of 43% across all irrigation levels, indicating significant water competition. These findings suggest that management practices promoting grass invasion could severely hinder tree regeneration in forests not adapted to large herbivore intensive grazing. Such situation may be exacerbated in regions suffering water limitation in the growing season or where the climate change would intensify water stress.

Superabsorbent hydrogels: A new tool for vineyard water management?

New superabsorbent hydrogels (SH) could be groundbreaking technologies for the adaptation of agriculture to climate change, but knowledge about their physio-chemical traits, their effects on soil hydrology, and their efficacy on tree crop physiology is very limited. In this work, two potassium polyacrylate SH (SH1 and SH2) and an organic material derived SH (SH3) were tested for their water holding capacity and the capability to improve soil hydrology according to the water demands of cultivated grapevine, one of the most relevant rainfed tree crops. All SH absorbed a significant amount of water as compared to their relative weight (from 9.19 g H2O/g polymer of SH3, to 369.64 g H2O/g polymer of SH2) and made it available at water potential (Ψ) levels compatible with grapevine root system uptake. When incorporated to the soil, all SH successfully increased soil field capacity, affecting also wilting point, and increasing maximum plant available water (from +43 % of SH2 to +84 % of SH1). All SH increased stem Ψ of potted vines subjected to a progressive water deficit, as compared to controls (+0.25 MPa at four days from irrigation suspension, +0.2 MPa at eight days from water suspension, when Control vines showed a stem Ψ of −1.63 MPa).Our work demonstrated for the first time the potentialities of three different SH and their positive effects on soil water relations. Both synthetic and organic-derived SH could improve vine water status under limited water supply. While other studies are needed to clarify effects according to different rootstocks and soils, the results pave the way for the integration of SH in vineyard water management.

Greater moisture impacts on radial growth of Larix sibirica in the eastern Altay Mountains since the 1990s.

Against the background of climate warming and humidification, the so-called 'divergence problem' reduces the stability of tree rings in response to climate, and affects the reliability of tree-ring reconstruction. Investigation of the divergence problem is crucial to improve our understanding of the response patterns of trees to climate warming, and provide a scientific basis for accurate climate reconstruction. Based on tree-ring width data for Siberian larch (Larix sibirica Ledeb.) growing at low elevations in the eastern Altay Mountains, we analyzed the relationship between radial growth of trees and climatic factors in the context of abrupt climate change in this region. We calculated the proportional contribution of five climatic factors to the radial growth of trees, and discussed the response mechanism of radial growth of L. sibirica in combination with large-scale atmospheric circulation patterns. The radial growth of L. sibirica was mainly constrained by water availability. Before climate warming (1961-1990), the radial growth of L. sibirica was mainly limited by temperature in the previous June. After abrupt climate warming (1991-2020), there was a significant positive correlation between growth and soil moisture in the previous winter, suggesting that high temperatures in the following spring would limit tree radial growth if water availability was low. The attribution analysis results revealed that, before 1990, the proportional of relative contribution of temperature to radial growth of trees exceeded 60%. Since 1990, the proportional of relative contribution of water (precipitation and volumetric soil water) to growth of L. sibirica increased. This might reflect the combined effects of local climatic conditions and changes in large-scale atmospheric circulation.

Sugarcane bagasse derived biochar potential to improve soil structure and water availability in texturally different soils

Low organic matter content is one of the main constraints in arid and semiarid regions. This constraint and its negative influences on soils and plant growth may be alleviated by biochar (BC). Furthermore, improving soil physical and hydraulic attributes by application of biochar has received increased attention. Therefore, in the present study, the effects of sugarcane bagasse-derived biochar on the structural stability, water availability, and pore-size distribution (PSD) of three texturally different calcareous soils collected from different agro-climatologically regions were examined during a long-term experiment. Low and high-temperature biochars, produced in a muffle furnace by the traditional slow pyrolysis method at 300 °C (BC300) and 600 °C (BC600) were evaluated. Pots (15 kg) were filled with three different silty-clay Inceptisols (SCInc), silty-clay-loam Alfisols (SCLAlf), and loam Aridisols (LArid) soils mixed with 0 (control), 1, 2, and 3 w/w% of BC300 and BC600 during 540 days of incubation. The high energy moisture characteristic (HEMC) data was modeled using a modified van Genuchten function to quantify aggregate stability through stability ratio (SR) and structural stability index (SSI). The plant available water (PAW), least limiting water range (LLWR), and integral water capacity (IWC) were calculated with two matric suctions (h) of 330 cm for field capacity (FC) and 15,000 cm for permanent wilting point (PWP). Then the integral energy (EI) values were calculated (EIIWC). Results indicated that the incorporation of 3 w/w% biochar significantly (p < 0.01) increased SR (35 to 100%) and SSI (21 to 28%) indices in all three soils. Biochar significantly increased modal suction (MS) in LArid soils (5 to 158%); whereas, decreased MS of the other soils (3 to 43%). MS, SR, and SSI of BC300 and BC600-treated soils were not significantly different. PAW, LLWR, and IWC significantly decreased in the SCInc (18 to 61%, 8 to 44%, and 6 to 35%) and SCLAlf (8 to 44%, 18 to 35%, and 20 to 47%) soils and increased in LArid (4 to 54%, 3 to 61%, and 24 to 111%) soil with increasing biochar doses. There were no changes in EIIWC in biochar-treated LArid soil where PAW, LLWR, and IWC increased. Biochar increased EIIWC across the studied soil from 1% to 3.38 folds, thereby increasing the gradient of water potential to absorb the available water. Soil and soil-biochar mixtures exhibited heterogeneous and multimodal pore-size distribution (PSD). Biochar promoted the PSD peaks related to water-transmitting pores in SCInc and SCLAlf soils while decreased in LArid soil. In conclusion, results indicated that among the applied levels of biochar, the application of 3 w/w% biochar is suggested as a suitable way to improve soil physical behavior and structural stability.