Soil Water Capacity Research Articles

Water retention characteristics and mechanical properties of vegetated biopolymer and biochar-reinforced sandy loam

Vegetation is a sustainable strategy for erosion control and slope stabilization, though its initial cultivation can be lengthy and potentially weaken soil structures. This study compared two bio-mediated ground improvement techniques, biopolymer and biochar, known for their supportive effects on vegetation growth. Additionally, a novel treatment combining biopolymer and biochar was examined for its potential in vegetated-engineering practices. Engineering performance was assessed through soil water characteristic curve, vegetation growth, direct shear testing, and rainfall simulation. The results revealed that biopolymer and biochar treatments enhanced soil water capacity but negatively impacted vegetation germination rates and shear strength of the reinforced soil, attributed to hydrogel formation and increased soil water content from irrigation. In comparison, soil reinforced with the combined method showed a promotion in the vegetation while maintaining the soil’s mechanical performance throughout the cultivation period and exhibited only minor reductions in the shear strength compared to other reinforced soils. Moreover, the new treatment showed improved soil erodibility under a majority of rainfall occasions, regardless of the vegetation coverage. This enhanced engineering performance by the new treatment is believed to be the polymerisation between the biopolymer hydrogel, biochar and soil particles.

Unravelling the impact of drought and salt stresses on Thymus pannonicus: Morpho-physiological and biochemical insights

This research assesses the effects of drought and salt stresses applied individually or in combination on Thymus pannonicus, a resilient perennial herb native to the Pannonian vegetation region. Our experiment aimed to comprehensively evaluate morphological, physiological, and biochemical parameters of the thyme subjected to two levels of soil water capacity (SWC) - 70 % (control and salt stress) and 40 % (drought stress and combined stresses) - along with two salinity levels, 0 mM NaCl (control and drought stress) and 60 mM NaCl (salt stress and combined stresses). The plants exhibited significant responses to all the studied parameters under 40 % SWC in both treatments, demonstrating notable reductions in shoot and root parameters. In contrast, salt treatment at 60 mM had a minimal impact on growth. A stability in photosynthetic pigment composition was observed in all treatment, whereas a notable decrease (p < 0.05) in relative water content was seen in drought-stressed treatments compared to the to the control. Essential oil contents were higher in the control (0.91 ml/100g DW) but significantly declined (p < 0.05) under drought stress and combined stresses conditions (0.49 ml/100g DW and 0.53 ml/100g DW respectively). Particularly, the GC-MS analysis revealed a significant decrease (p < 0.05) in thymol and carvacrol content for the drought-stressed treatments. Substantial reductions were evident for the total polyphenol concentration and antioxidant capacity under the combined stress treatment, measuring 101.49 mg GAE/g DW and 106.57 AAE/g DW, respectively. Interestingly, the HPLC analysis indicated the highest levels of rosmarinic acid and caffeic acid in the drought-stressed treatment, while the lowest ones were recorded in the combined stress treatment. These findings indicated the responses of Thymus pannonicus to environmental stressors, emphasizing the need for further investigations for a comprehensive understanding of salinity effects.

Effects of poly‐γ‐glutamic acid addition on the transformation and distribution of soil nitrogen under different water conditions

AbstractThe impact of external poly‐γ‐glutamic acid (γ‐PGA) on soil nitrogen (N) transformation and distribution remains unclear, despite its contrasting effects on N use efficiency. Therefore, soil culture and soil column experiments were conducted using three different γ‐PGA addition rates (0%, 4% and 8% of dry soil weight, w/w) under different soil water contents (40%, 60% and 80% of field water capacity) and dry–wet cycles (0, 2, 4 and 8 times cycles; a single dry–wet cycle involved reducing soil water content from 80% to 40% of field water capacity) in sandy loam soil. The results of soil culture experiment showed that the γ‐PGA significantly increased soil –N and –N contents, as well as nitrification and transformation rates. However, these effects were observed to be influenced by both the culture time and soil water content. In addition, the results of soil column experiment showed that γ‐PGA not only significantly enhanced the soil inorganic nitrogen content within the 0–20 cm soil layer, but also improved water retention capacity. However, the differences between the γ‐PGA treatments gradually diminished with an increase in dry–wet cycle times. These results indicate that γ‐PGA addition enhanced soil inorganic N content and soil water retention by influencing soil N transformation and water distribution. However, the impact of γ‐PGA addition on soil improvement was regulated by soil water content, which should be taken into full consideration in agricultural practices.

Reduction of nitrogen loss in runoff from sloping farmland by a ridged biochar permeable reactive barrier with vegetated filter strips

IntroductionEutrophication due to nitrogen (N) loss from sloping farmland has a high risk in the Three Gorges Reservoir. Biochar and vegetated filter strips (VFS) are used to control nutrient runoff and increase soil water-holding capacity, soil nutrient retention, and crop yield. However, surface biochar application has limited ability to control N loss, especially from sloping farmland.MethodsIn this study, different widths of ridged biochar permeable reactive barrier (RB-PRB) with VFS were employed to intercept N loss in runoff from sloping farmland. Adsorption characteristics of biochar for nitrate and ammonium N were evaluated using isothermal and kinetic adsorption models before field experiments. N index values for ammonium (NH4+), nitrate (NO3−), dissolved N (DTN), particulate N (PN), and total N (TN) lost through runoff were monitored from April 2019 to January 2020.ResultsNO3− and NH4+ sorption on biochar was predominantly physical adsorption with a maximum capacity of 4.51 and 4.12 mg g-1, respectively. During the research period, the dominant transportation pathway of N loss involved dissolved total N movement through subsurface flow, which accounted for 65.55% of the total loss. TN loss for CK was 1954 g·hm-2, while RB-PRB and VFS decreased N loss from sloping farmland by 36.7%. The interception efficiency of RB-PRB was highest at 0.3 m width. VFS successfully intercepted particulate N and reduced it by 32.75%. In terms of soil nutrients, the RB-PRB and VFS interventions led to a substantial 41.69% increase in the TN content of the soil at a 0.4 m width.DiscussionThe findings suggest that biochar has a favorable adsorption effect on NH4+ and NO3−, an appropriate width of RB-PRB with VFS could effectively reduce nitrogen loss from sloping farmland. Simultaneously, it enhances the water and fertilizer retention capacity of sloping cropland soil; however, the long-term implications necessitate further validation.

Effect of Humic Amendment on Selected Hydrophysical Properties of Sandy and Clayey Soils

In recent years, products containing humic acids have been increasingly used in agriculture to improve soil parameters. Quantifying their impact on soil quality is, therefore, of key importance. This study seeks to evaluate the impact of the commercial humic acid product (HA) on the hydrophysical parameters of sandy and clayey soils sampled from different sites in Slovakia. Specifically, the study hypothesizes that humic amendment will enhance particle density (ρs), dry bulk density (ρd), porosity (Φ), saturated hydraulic conductivity (Ks), soil water repellency (SWR), and water retention capacity in sandy and clayey soils. The results of the laboratory measurements were analyzed using NCSS statistical software at a statistical significance of p &lt; 0.05. In sandy soil, there was a statistically significant decrease in ρd and Ks and an increase in Φ and a contact angle (CA) after the application of 1 g/100 cm3 HA. At a dose of 6 g/100 cm3 HA, the values of ρs, ρd, and Ks decreased, and the Φ and CA values increased. In clayey soil, the Ks value significantly decreased by −35.5% only after the application of 6 g/100 cm3 HA. The addition of HA increased the full water capacity (FWC) and available water capacity (AWC) of clayey and sandy soils. The positive influence of HA on the studied soil parameters was experimentally confirmed, which can be beneficial, especially for their use in agricultural production.

Differences in soil water movement between the dip and anti-dip slopes of a karst trough valley

Exploring temporal and spatial variations in soil water processes is crucial for identifying the ecological water supply capacity of soil and understanding hydrologic cycles within karst catchments. However, the existing body of knowledge related to soil water dynamics across dip and anti-dip slopes in karst landscapes remains limited. To address this gap, this study investigated soil water dynamics in a karst trough valley (KTV) in southwest China, using stable isotopes (δD and δ18O) from eight sampling sites and precipitation data from April 2017 to November 2018. Our findings suggest that seasonal variations in soil water isotopes are primarily influenced by climatic factors, with soil water lagging behind rainwater isotopes by one to four months due to differences in the residence time of precipitation in different soil layers. Spatially, our results reveal the coexistence of diffuse and preferential flows on both dip and anti-dip slopes. Specifically, on the dip slope, preferential flow dominates above 20 cm, while diffuse flow prevails below this depth. In contrast, on the anti-dip slope, preferential flow is prominent above 40 cm depth, while diffuse flow dominates beneath this threshold. These spatial patterns not only impact the ecological water and nutrient supply capacity of soil but they also contribute to distinct patterns in vegetative growth on both slopes. In turn, vegetation growth facilitates preferential flow pathways, establishing a positive feedback loop between soil water movement and vegetative cover. These findings may lead to a deeper understanding of soil water processes on the dip and anti-dip slopes of KTVs and provide crucial insights into the relationship between soil water and vegetative growth in similar karst landforms.

Modeling and Forecasting the Removal of Biogenic Elements from Agricultural Lands Depending on the Soil Agrophysical Properties

Introduction. Environmental pollution prevention, including prevention of water bodies, with nutrients (nitrogen and phosphorus) when they are removed from agricultural lands with possible runoff is a topical problem that requires a timely solution. The studies have found that the removal of nutrients is a result of geochemical processes, fertilization, and other factors. In this regard, mathematical modeling of the process of removal of nutrients from agricultural lands and their possible entry into water bodies is an urgent task. Aim of the Study. The study is aimed at modeling and predicting the process of possible removal of nutrients from agricultural lands to water bodies. Materials and Methods. When conducting the study, there were used well-known modeling methods. They are the methods for calculating the removal of nutrients from agricultural objects into water bodies, based on the minimum amount of initial information for predicting the eutrophication of water bodies and agrochemical methods taking into account the structure and size of field and agricultural areas, crop yields, and removal nutrients with the harvest. Results. Based on an analysis of the literature and expert judgment, a list of the most significant indicators influencing the process of nitrogen and phosphorus removal was justified. There have been developed mathematical models to determine and predict the input of nutrients from agricultural lands to water bodies. There have been found significant indicators influencing the amount of input of nutrients, such as the amount of applied fertilizers, the volume of moisture, soil water capacity, field area, depth of cultivation, etc. There is given an example of calculating the amount of input of nutrients into water bodies with a rainfall intensity of 50 mm per hour. Discussion and Conclusion. The essence of the proposed mathematical models comes down to the synthesis of numerous indicators in the complex process of removal of nutrients and their impact on water quality. The proposed mathematical models make it possible to predict the removal of nutrients from agricultural lands and to develop and implement technical and technological solutions to prevent environmental pollution.

Benefits and pitfalls of irrigation timing and water amounts derived from satellite soil moisture

Despite the key role of irrigation in the Earth system, we lack fundamental information regarding the distribution of irrigated fields, irrigation timing and the amount of water utilized. In the past years, the SM_Delta and SM_Inversion approaches have been independently developed to provide estimates of irrigation timing and water amounts based on satellite soil moisture data. The SM_Delta approach retrieves irrigation from variations in soil moisture between an individual pixel and the surrounding rainfed area, while the SM_Inversion approach estimates the total amount of water entering the soil, then irrigation is derived by subtracting precipitation. In this study, we perform a comprehensive assessment of irrigation estimates from the SM_Delta and SM_Inversion algorithms based on Sentinel-1 surface soil moisture retrievals at 1 km resolution. Our analysis focuses on the Ebro basin, an irrigated region in Spain covering 83000 km2, during the period 2017–2019. We assess the ability of the two methods to discriminate irrigated and rainfed pixels, then we quantify the agreement of irrigation timing and water volumes with reference irrigation data. An inter-comparison between estimates from the SM_Delta and SM_Inversion methods is carried out considering both temporal and spatial features, i.e., monthly irrigation peaks and spatial irrigation patterns. Finally, we explore two potential applications of satellite-derived irrigation estimates: attributing irrigation water volumes to specific irrigation systems and to individual crops. We observe that both methods erroneously retrieve irrigation over rainfed pixels, and are therefore not suitable to map irrigated and rainfed fields. However, when auxiliary information on irrigated fields is available, we find a satisfactory agreement between district-scale reference data and satellite-retrieved irrigation, using both the SM_Delta and SM_Inversion approaches (Pearson R equal to 0.67 and 0.71, bias equal to −4.99 and −4.75 mm/15 days, respectively). When aggregated in space or time, the irrigation estimates exhibit coherent temporal dynamics and spatial patterns. For instance, estimates from both SM_Delta and SM_Inversion capture the delayed irrigation that occurred in 2018 due to wetter than usual conditions in spring. However, at the pixel-scale, limited consistency exists between irrigation estimates from the two methods due to different assumptions and parameterizations, e.g., use of constant vs pixel-specific soil water capacity (in the SM_Delta and SM_Inversion, respectively). Overall, the study demonstrates the reliability of irrigation estimates derived from the SM_Delta and SM_Inversion approaches, especially when shifting from small spatial and short temporal scales (pixel level, sub-weekly) to larger and longer scales (district level, seasonal). Hence, satellite-based irrigation estimates could inform water resources managers and basin authorities, as well as serve the modelling community by providing reliable information on the timing and the amounts of water employed at the basin level.

Population-level responses of aphids to pulsed drought stress

The first aim of this study was to test the pulsed stress hypothesis on a system consisting of young spring wheat (Triticum aestivum L.) and the rose-grain aphid Metopolophium dirhodum (Walker) by following the age-stage, two-sex life table theory. This hypothesis predicts that fluid-feeding insects benefit from feeding on plants intermittently stressed by drought due to the increased nutrient availability and restored cell turgor. Our second aim was to illustrate the risk of drawing different conclusions if based on a single or a small subset of parameters or if the entire lifespan of a generation is not covered compared to if the study was conducted at the population level. We applied periods of drought stress (soil water capacity, SWC = 40%) on four occasions relative to the population development of the aphids and compared those treatments with well-watered (SWC = 70%) and continuous stress conditions (SWC = 40%). The timing of the stresses appeared to be important in determining the effect on aphid performance. Although we found some improvement in fecundity when the stress occurred before the aphids were placed on the plants, the overall effect of the early-timed pulsed stress treatments on the rate of increase was negative compared to the well-watered control, which was mainly due to prolonged nymph development. The drought pulse that was timed late (the second week of aphid reproduction) did not show any effect relative to the well-watered control. This study therefore provides no clear support for the validity of the pulsed stress hypothesis.

Winter wheat irrigation parameters in the Brazilian Cerrado

Wheat is the second most produced cereal in the world. The gap between production and consumption in Brazil shows that wheat production must be increased to meet the domestic demand. In this context, the objective of this study was to determine the crop coefficient of wheat and the ideal moment for irrigation, based on the soil water depletion rate (f). The study was carried out in the tropics, on an Oxisoil (Typic Haplustox), in an experimental field of Embrapa Cerrados in Planaltina, Federal District of Brazil. The experimental design consisted of randomized blocks with three replications. The treatments were differentiated by the soil water depletion index (f) of 0.2, 0.4, 0.6, and 0.8. In other words, irrigation was initiated when 20, 40, 60 and 80% of the available soil water capacity (AWC) at a soil depth of 0.4 m was consumed by the crop. Wheat yield and yield components were evaluated. The phenological development was monitored based on Zadok’s scale, in days after emergence, and the management parameters crop coefficient (Kc) and irrigation timing were determined. The results indicated a soil water depletion index of 0.4 as the best indicator for beginning wheat irrigation. Under this condition, Kc can be estimated daily as a function of days after emergence (DAE) by the quadratic polynomial regression or curve fitting method, adjusted as follows: Kc = −0.000298 × DAE² + 0.036695 × DAE + 0.332486. Alternatively, the means of Kc of each phenological crop phase can be used: Kc = 0.45 (establishment); 0.81 (tillering); 1.21 (booting); 1.43 (flowering); 1.27 (grain formation); and 0.89 (maturation). Thus, there is a limit of consumption of soil available water, at which wheat still achieves the full yield potential, with a rational use of water which varies according to the development phase.

Estimating irrigation requirement and scheduling for major crops: Case study in Kampong Thom, Cambodia

The situation is the outcome of both increased water demand and climate change, the shortage of water resources is increasing in Cambodia. In this regard, efficient irrigation water management for vegetable production is a crucial need for farmers. The main crops farmed in Chroab commune, Santuk district, Kampong Thom province, Cambodia, are cabbage, potato, and tomato. This article uses the CROPWAT model to predict the water requirement. The pressure plant was used to measure the soil’s soil water capacity, and the findings ranged from 45.65 to 234.159 mm/m. The analysis showed that the overall CWR for crop water for the entire growing season for cabbage, potato, and tomato was 589.4 mm/165 days; 442.5 mm/130 days; and 585.4 mm/145 days, respectively. The findings of the study contribute to investigating the irrigation water requirements with scientific soil and climate inputs.

Genome wide association study of Ethiopian barley for terminal drought stress tolerance under field and climate chamber conditions

In order to detect markers for drought stress tolerance, field experiments in Ethiopia were conducted for three years at two naturally drought-prone locations and two optimum moisture locations using 239 Ethiopian barley landraces and 21 barley breeding lines. Furthermore, a climate chamber experiment applying drought stress at different water regimes (70% soil water capacity (WC) for control and 20% WC for drought stress conditions) after flowering was conducted for selected 196 accessions. Results revealed reduced grain biomass by 47% and 80% under field and climate chamber conditions, respectively, as well as significantly (p < 0.05) reduced days to maturity and plant height, in both experimental designs. Based on 10,644 SNP markers, GWAS was conducted to identify marker trait associations (MTA) for drought stress tolerance. For days to maturity, relative chlorophyll content, plant height, number of seeds per spike, thousand kernel weight, and harvest index under field and climate chamber drought stress treatments, 58 significant MTAs were identified. In total, 41.4% of the MTAs were located on chromosome 2H, of which one is very close to the Ppd-H1 flowering locus. These findings underpin the importance of this genome region for drought tolerance. Another MTA on chromosome 1H was detected for days to maturity under field drought stress treatment in the vicinity of the known flowering time ELF3 gene. Additionally, 13 and 3 Ethiopian landraces that tolerate severe and moderate drought stress in climate chamber and field experiments were identified, respectively, using drought indices. The results highlight the tolerance of Ethiopian landraces to different levels of drought stress as well as their potential to be considered in future barley improvement programs.

Effects of Land Use on Soil Physical-Hydric Attributes in Two Watersheds in the Southern Amazon, Brazil

Changes in land use can cause degradation of soil physical quality with negative effects on the environment and agricultural production. The effects of different land uses on soil physical-hydric attributes were studied in the Renato River and Caiabi River watersheds in the southern Brazilian Amazon. Three conditions of land use were evaluated: native forest, crops, and pasture in the headwater, middle, and mouth of each watershed. Particle size, particle density, bulk density, total porosity, macroporosity, microporosity, water contents at field capacity and permanent wilting point, and available water capacity in soil were evaluated in three soil layers down to 0.4 m. Data collected were subjected to the Kruskal–Wallis nonparametric test and Pearson’s correlations. Multivariate analyses were also performed using the principal component method. In the Renato watershed, in comparison with native forest, conventional management of pasture and crops caused soil physical degradation, increasing soil density in the surface layer and reducing macroporosity and total porosity. In the Caiabi watershed, converting native forest areas into pasture and crops altered water quality, influencing the water dynamics in the soil, by reducing soil water conductivity. Soil attributes varied by watershed, with texture variations between the headwater and mouth, indicating that changes in soil properties result from both management and the granulometric composition of the soil in different regions of the same watershed. Adoption of crop and pasture conservation practices can improve soil physical attributes in regions bordering agricultural areas in the southern Amazon.

Physio-morphological trait and bioactive constituents of Ocimum species under drought stress

The genus Ocimum, which belongs to the Lamiaceae family, encompasses a wide variety of herbs and shrubs, with over 60 species originating from tropical regions. These plants are widely cultivated for their essential oils, which are used in culinary, medicinal, and aromatic applications. However, prolonged exposure to water scarcity can negatively impact the growth and essential oil production of Ocimum species. There is limited information available on how Ocimum basilicum ‘Ohře’ and O. americanum respond to drought stress. Consequently, two-year studies (2021 and 2022) were conducted to investigate the physiological, morphological, and biochemical changes occurring in those two basil plants under three different soil water regimes (70%, 50%, and 30% of soil water capacities ‘SWC’). The findings of these studies demonstrated that drought stress significantly affected physiological indicators, hindered the growth and development of the examined Ocimum species, and altered their essential oil production. Due to severe drought stress both basil plants lost over 14% of their leaf relative water content and more than 60% reduction in water potential. Consequently, basil plants lost over 45% of their biomass (dry and fresh) and essential oil yield when the soil became drier (30% SWC). Conversely, dry soil conditions enhanced water use efficiency, SPAD value, glandular hair density (increased by over 60%), essential oil concentration (increased by 10%), and phenol concentration. Additionally, the essential oil constituents were mildly affected, with the effects dependent on factors such as species, production year, drought intensity, and specific essential oil compounds. In conclusion, these studies have demonstrated that prolonged exposure to water scarcity limits growth and alters the biochemical constituents of both Ocimum species. Therefore, to secure maximum biomass and essential oil yield under protected cultivation, it is recommended to maintain at least 70% soil water capacity.

Influence of the biochar application on the thermal properties of soddy-podzolic soil and on the energy balance fluxes of spring wheat in the Leningrad region under various soil moisture conditions

The article presents the results of a field experiment to assess the effect of pre-sowing application of the biochar on the thermal properties of the arable horizon of soddy-podzolic sandy loam soil, on the energy balance components, on the crop surface temperature and on the leaves temperature of spring wheat (variety “Daria”) under various conditions of soil moisture in 2022. The experiment took place at the Menkovo Experimental Station of the Agrophysical Research Institute, located in the Gatchinsky District of the Leningrad Region. The experiment included the plot with the biochar application at the dose of 21.9 t ha-1 and the control plot. The soil thermal properties were measured by the heat pulse method. The components of the energy balance were determined using agrometeorological measurements, radiation balance measurements, crop surface temperature, and phenological measurements. The crop surface temperature was measured by a non-contact method using pyrometers. The soil moisture conditions and available water for wheat were characterized by volumetric soil moisture and evapotranspiration. The volumetric soil moisture was measured using a capacitive soil moisture sensor. The evapotranspiration was determined using the residual term of the energy balance equation through the latent heat flux. According to the results of field experiments, a significant effect (p &lt; 0.05) of the biochar application on the soil thermal properties was found, however, under different moisture conditions, the effect was multidirectional. At zero soil moisture, the biochar application reduced thermal conductivity by 29.7%, reduced volumetric heat capacity by 18.5%, reduced diffusivity by 13.7%, and reduced thermal inertia by 24.3%. Under the conditions of field capacity, the biochar application increased thermal conductivity by 9.4%, reduced volumetric heat capacity by 2.6%, increased diffusivity by 12.3%, and increased thermal inertia by 3.2%. The biochar application significantly (p &lt; 0.05) increased the turbulent heat flux – by 35.5%, which is due to an increase in the crop surface temperature (by 6.4%). Resulting from the decrease in soil evaporation, the biochar application reduced the latent heat flux by 17.0%, and the evapotranspiration by 13.9%. Leaf temperature is related to transpiration. Transpiration can increase when biochar is applied on light-textured soils due to an increase in soil water capacity. The biochar application did not result in significant changes of leaf temperature. The study results are confirmed by numerous articles of both foreign and Russian researchers.

Effect of Replacing Mineral Fertilizer with Manure on Soil Water Retention Capacity in a Semi-Arid Region

The long-term and excessive use of mineral fertilizers in a semi-arid region with severe water shortage will lead to soil compaction and poor water-holding capacity. The fertilization method of manure instead of mineral fertilizer has attracted wide attention. It has adverse consequences for the growth and development of crops. Hence, the objective of this study was to determine how replacing mineral fertilizer with manure affects the soil water retention curve, soil water constant, soil water availability, and soil equivalent pore size distribution, and to seek the best scheme of applying manure in semi-arid area and provide theoretical a basis for improving soil water retention capacity. Here, 0% (CK), 25% (M25), 50% (M50), 75% (M75), and 100% (M100) of 225 kg ha−1 nitrogen from mineral fertilizer were replaced with equivalent nitrogen from manure in the Loess Plateau of China under semi-arid conditions. The centrifuge method was used to determine the soil volumetric water content under different water suction levels, and the Gardner model was used to fit and draw its soil water retention curve, and then calculate the soil water constant and equivalent pore size distribution. The results showed that the Gardner model fitted well. The soil saturated water content with the M100 treatment was the highest, whereas the specific water capacity, water availability, and soil porosity with the M75 treatment were the highest. The soil saturated water content showed a downward trend with the increase in nitrogen from manure instead of nitrogen from mineral fertilizer in the partial replacement treatments. This downward trend slowed down over time. The M75 treatment increased field capacity. The M100 treatment increased soil capillary porosity, soil available water porosity, and soil water availability compared with CK from the fifth fertilization. Replacement treatments increased the specific water capacity, soil saturated water content, soil water availability, soil porosity, and reduced the wilting point over time. In the replacement treatments, specific soil water capacity, soil water availability, and soil porosity first rose and then declined with the increase in nitrogen provided by manure replacing that provided by mineral fertilizer. Therefore, the soil water holding capacity and water supply capacity with the M75 treatment were the best.

Response of total belowground soil biota in Alhagi sparsifolia monoculture at different soil vertical profiles in desert ecosystem

The soil organisms are extremely important for the land-based ecosystem. There is a growing interest in studying the variety and composition of the entire underground soil organism community at a large ecological scale. Soil organisms show different patterns in relation to soil physiochemical properties (SPPs) in various ecosystems. However, there is limited knowledge regarding their response to soil vertical profiles (SVPs) in monoculture of Alhagi sparsifolia, which is the primary shrub in the deserts of China, and is well-known for its contributions to sand dune stabilization, traditional Chinese medicine, and forage. Here, we investigated the population dynamics of soil bacteria, fungi, archaea, protists and metazoa across six different SVPs ranging from 0 to 100 cm in monoculture of A. sparsifolia, in its natural desert ecosystem. Our findings indicate that the soil biota communities displayed a declining pattern in the alpha diversity of bacteria, protists, and metazoa with an increase in soil depth. However, the opposite trend was observed for fungi and archaea. The beta diversity of soil biota was significantly affected by SVPs, particularly for metazoa, fungi and protists as revealed by Non-Metric Dimensional Scaling. The most prevalent soil bacterial, fungal, archaeal, protist, and metazoa classes were Actinobacteria, Sordariomycetes, Nitrososphaeria, Filosa-Sarcomonadea, and Nematoda, respectively. The correlation among vertical distribution of the most abundant biotic communities and variations in SPPs exhibited that the variations in total carbon (TC) and total nitrogen (TN) had the most significant influence on bacterial changes, while available potassium (AK) had an impact on fungi. Archaea were affected by TC and pH, protists by the C/N-Ratio and TP, and metazoa by TN, AK, and soil water capacity (SWC). Collectively, our findings provide a new perspective on the vertical distribution and distinct response patterns of soil biota in A. sparsifolia monoculture under natural desert ecosystem of China.

Effects of Agricultural Cropping Systems on Soil Water Capacity: The Case in Cross-Border Altai

Temperate grasslands are called the breadbaskets of the world. Due to most continental climate conditions, humus-rich soils have been developed. These soils are very well suited for grain production. This is why extensive conversions from natural steppe to arable land have been implemented in this biome. The Kulunda Steppe, in Southwest Siberia and Central Asia, occupies large parts of the driest regions of the Eurasian Steppe Belt. It was one of the sites of the Virgin Land Campaign realized in the former Soviet Union in the 1950s and 1960s. Intensive agricultural practices have caused significant soil degradation, mainly through humus loss and soil erosion. This results in the degradation of organic carbon, altering the physical and chemical structure of the chestnut soils and impacting their water storage capacity. Against the background of climatic changes, a further intensification of these processes and conditions is to be expected. To stabilize soil carbon and optimize moisture utilization, it is necessary to extensively introduce worldwide experiences in conservation cropping technologies (such as no-till, min-till, and direct seeding) in the area. This study aimed to determine the effects of different cropping systems on soil water storage and water availability. The study’s initial hypothesis was that the soil conservational cropping system has advantages against the traditional deep tillage (24 cm). This hypothesis was based on extensive global experience studying the effects of different agricultural management systems on soil-water balance. In 2013–2016, an experiment was conducted for the first time in the Kulunda steppe to instrumentally measure soil moisture and matrix potential at 30–60–120 cm depth under traditional and conservation technology using innovative meteorological and soil hydrological stations. Statistically significant advantages of no-till over deep tillage (24 cm) in terms of moisture retention were found, confirming the hypothesis of this study. Besides, this groundbreaking study reveals new possibilities for soil monitoring in the region. The acquired data are applicable for predictive models using remote sensing. Moreover, the results on the management effects for the soil water balance provide basic approaches to soil water monitoring, offering important data for evaluating model results and remote sensing products for the region.

Effect of oil and surfactants on changes in some physical properties of soils

The paper shows that oil pollution of gray forest and soddy-podzolic soils led to a decrease in capillary water capacity, plasticity and solid phase of soils. As a result of the introduction of the nonionic surfactant tween-80 into the oil-contaminated soil, these indicators were partially restored, but their values remained lower than in soil samples subjected to oil treatment. The obtained materials allow us to speak about the fundamental possibility of using surfactants for the remediation of oil-contaminated soils.

Walnut in Sweden: effects of nurse trees, weed control and fertilization on five-year survival and growth of planted Juglans × intermedia NG23 and NG38

ABSTRACT This study quantified the effects of different establishment practices on survival, dieback and early growth of Juglans × intermedia NG23 and NG38 planted in a statistically designed field experiment on glacial till in southern Sweden. Establishment practices included the use or absence of nurse trees (Populus maximowiczii × trichocarpa var. OP42 planted one year before J. × intermedia), weed control (2 m2·tree−1) and fertilization (+25 g N·tree−1·year−1). NG23 transplants were smaller than NG38 at the time of planting. The overall survival rate was 97%. NG23 suffered marginally more mortality than NG38. Leader shoot dieback occurred in all treatment combinations but was most severe in the presence of nurse trees. NG23 suffered less dieback than NG38. Annual height growth of trees unaffected by dieback increased with increasing levels of precipitation during the growing season (194–407 mm) and with increasing soil quality in terms of nitrogen (94·10−3–607·10−3 g·g−1), base saturation (14–99%) or available soil water capacity (8.6–30.6 l·m−3). It was negatively influenced by poplar nurse trees and positively by fertilization. Weed control had no impact on height growth, possibly due to inefficient implementation. With nurse trees, NG23 had stronger growth than NG38. The opposite was true without nurse trees. It was hypothesized that less growth and more dieback resulted from competition for water.