Search Results (29)

Mobile drip irrigation (MDI) systems integrate the technological advantages of center-pivot irrigation (CPI) systems and drip irrigation systems, boasting a high water-saving potential. To further enhance water use efficiency in alfalfa production in northern China, this preliminary study verified the accuracy of the HYDRUS-2D soil water movement numerical model through field experiments. Using the numerical model, four drip-line installation distances (60, 75, 90, and 105 cm), three deficit irrigation thresholds (45–50% FC, 55–60% FC, and 65–70% FC), and four irrigation depths (70% W, 85% W, 100% W, and 115% W) were set to simulate root water uptake, soil surface evaporation, total irrigation amount, and deep percolation during the entire growth cycle of alfalfa, respectively. Objective functions were constructed according to the simulation results, and the NSGA-II algorithm was used for multi-objective optimization of the deficit irrigation schedule. The preliminary results indicated that HYDRUS-2D can accurately simulate soil water movement under MDI systems, as the RMSE values of soil water content at all measured depths were less than 0.021 cm³/cm³, with the NRMSE values being below 23.3%, and the MAE values below 0.014 cm³/cm³. Increasing the deficit irrigation threshold from F1 to F3 enhanced root water uptake by 12.24–15.34% but simultaneously increased the total irrigation amount, soil surface evaporation (by up to 29.58%), and the risk of deep percolation; similar trends were observed with increasing irrigation depth. The drip-line installation distance had no significant impact on irrigation performance. The NSGA-II multi-objective optimization algorithm was used to obtain Pareto-optimal solutions that balance conflicting objectives. For this case study, a drip-line installation distance of 105 cm, a deficit irrigation threshold of 50–55% FC, and an irrigation depth of 112% W were recommended to achieve balance among the various optimization objectives. This study provides a preliminary framework for optimizing MDI systems and irrigation strategies. However, since a deeper root distribution (>80 cm) was not investigated in this study, future research incorporating deeper root zones is required for developing more comprehensive irrigation scheduling suitable for typical alfalfa cultivation scenarios. Full article

The growing divide between the capitalist mode of development promoted by the state and the participative development model suggested by the people has brought ecology, environment, and existence to the core of all contemporary debates. The Adivasi (indigenes) who constitute 8.6 percent of the entire population of India are engaged in a constant battle to save their ecology and landscape. Represented as communities whose existence is intertwined with ‘Jal, Jungle, Jameen’ (water, forest, and land), Adivasis are the most prominent communities facing dispossession and displacement from their roots to further the ideology of development in which they have no stake. The notion of Adivasis as ‘savage’, ‘primitive’, and ‘backward’ communities that are incompetent of ‘developing’ themselves, resulting in their ‘backwardness’ gets carried over from the colonial to the contemporary period. Exposed to the processes of mining and industrialisation, Adivasis and their ecological resources have been exploited since the colonial period to suit the development model of the state. The Adivasi notion of selfhood was overlooked in the process of making the areas inhabited by them zones of ‘exclusive governmentality’. The paper argues and analyses this transformation process of Adivasis into ecological warriors; a process in which they used their shared, remembered and lived past to assert their customary rights. Basing the study on three environmental movements of state of Jharkhand in Central India, namely the Koel-Karo movement of the 1980s, the Netarhat movement of the 1990s, and the Pathalgadi movement of 2017–18, the study underlines that the Adivasi of Jharkhand anchored on their customary rights as a weapon, to protect their ecology and landscape against various state-sponsored development schemes. Drawing on the methodology of field investigation, interaction with the NGOs, government reports and media reports, the article argues that these community struggles are rays of hope for a global ecological future. Full article

Arid and semi-arid areas are suffering from declines in fresh water availability, making food security in these regions strongly dependent on the adaptability of agricultural production to the minimum usage of irrigation water. In response to this critical need, efforts have been directed towards enhancing irrigation efficiency and exploring innovative clay-based subsurface irrigation systems. These systems use clay materials as porous emitters and operate on the principle of capillary water movement from the pottery to the root zone, effectively reducing water evaporation and demonstrating significant water-saving potential. This article presents the results of a systematic literature review, with a specific focus on identifying recent developments and innovations in clay-based subsurface irrigation technologies, describing cases of applicability and indicating directions for future research. This review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and involved the screening of 233 articles that were found through searches on the databases Web of Science and Science Direct combined with searches of Google Scholar and citation searches. As a result, 58 research articles were investigated. The webtool Rayyan was used for the screening of the articles and the synthesis of the results. The spectrum of clay-based irrigation systems identified in the investigated articles includes traditional methods such as clay pot and clay pipe irrigation as well as more recent advancements in the field such as Subsurface Irrigation with Ceramic Emitters (SICE), Self-regulating Low-Energy Clay-based Irrigation (SLECI), and Ceramic Patch Subsurface Drip Irrigation Line (CP-SDIL) and pottery dripper technologies. This paper offers a comprehensive analysis of each irrigation system, highlighting their main characteristics, advantages, and limitations. Particular attention is paid to the reported outcomes related to yield responses, water use efficiency, and suitability for various agricultural applications. This review indicates as a primary benefit of these systems their potential to allow water conservation, which is especially advantageous in regions with a restricted irrigation water supply. However, a major drawback is the challenge of scaling these systems effectively. Hence, the recommended areas for future research centre on the necessity of substantial economic assessments of and discussion on the potential social impact to promote the scalability of clay-based irrigation systems. Full article

Imidacloprid (IDP) products are applied via soil drenching in the citrus critical root zone (CCRZ) at 0–60 cm soil depth. This study aimed to determine the uptake and leaching of IDP in the CCRZ of a Florida Entisol. The treatments include: (1) a control with no IDP applied, (2) 1.6 g of active ingredient (a.i.) per tree (×2), and (3) 3.2 g a.i. per tree of IDP (×4). The treatments were applied to two trees within each experiment unit, replicated five times, and completely randomized. The IDP concentration in the Entisol was affected by the amount of water received within the sampling intervals. IDP movement in the Entisol was evident for the field trials in Fall 2021 and 2022, irrespective of the treatment. A total of 10 mm of daily irrigation was the major driver of IDP movement in Fall 2021 (September–December 2021), while 11.7 cm of cumulative rainfall plus 10 mm of daily irrigation were the major drivers for IDP in Fall 2022 (November–December 2022). The IDP uptake level by leaves was relatively low probably because of the relatively low temperature and humidity. More applications of IDP did not result in its higher uptake by citrus leaves in the Entisol. Given the persistence of IDP, there is a possibility of leaching, which could potentially contaminate the groundwater, surface water, and non-target organisms. Therefore, it is crucial to carefully manage the use of IDP in citrus production systems to mitigate the unintended environmental impacts. Full article

Background: root-zone water transport is crucial in the water transformation from precipitation to groundwater, directly influencing soil moisture distribution and resource acquisition for wetland plants. Methods: This study investigated the movement mechanism of root-zone (0–80 cm) soil water in the Poyang Lake wetland, China, during a dry year. Hydrological observation and stable isotopes (δ¹⁸O and δD) were utilized. Results: The root-zone soil water content was low (2.9–12.6%) at the high site covered by Artemisia capillaris, while it remained high (25.2–30.2%) at the median and low sites covered by Phragmites australis and Carex cinerascens, respectively. The isotopic values of shallow soil water (0–40 cm) in the A. capillaris site followed the seasonal pattern of rainfall isotopes, indicating predominantly rainfall recharge. Rainfall was primarily transported by piston flow, with an infiltration depth of approximately 60 cm. Conversely, depleted water isotopes measured at certain depths in P. australis and C. cinerascens sites closely resembled those of rainfall, suggesting that preferential flow dominated. The average groundwater contribution proportions in root-zone soil water were 65.5% and 57.4% in P. australis and C. cinerascens sites, respectively, while no contribution was detected in A. capillaris site. Conclusions: Preferential flow and groundwater recharge occurred in the P. australis and C. cinerascens sites. They enhance the hydrological connection at the profile scale and are useful for maintaining a favorable root-zone moisture environment for wetland ecosystems in dry years. However, the hydrological connectivity between root-zone soil and groundwater was found to be obstructed in the A. capillaris site. This might be the main reason for vegetation degradation at high elevations in the Poyang Lake wetland. Full article

Climate change and human activities lead to freshwater shortage, soil salinization, and food security crises in arable land. To explore the natural and irrigation factors on soil water and salt movement, this study quantitatively analyzed the dynamic characteristics of soil water and salt movement under precipitation, groundwater irrigation, and brackish water irrigation conditions for the next 30 years using Hydrus-1D model-based parameters obtained from the winter wheat–summer maize rotation experiments in the Yellow River Irrigation District. The results showed that precipitation was the key factor of climate change affecting soil water and salt migration, especially in the 0–20 cm soil layer. Under both SSP585 and SSP245 climate scenarios, rainfall in normal and wet years promoted salt leaching up to 1 m below the surface soil. But in dry years, salt washing treatment was required for the tillage layer to prevent salt accumulation. The higher the groundwater level was, the higher the soil water and salt content was in the 0–100 cm soil layer. In this soil layer, a 2 m groundwater level contributed 30% to wheat water needs, while a 3 m groundwater level contributed 18%, and no significant contribution was observed for a 4 m groundwater level. The salinity of the soil profile showed an overall increasing trend with irrigation using 1–3 g/L brackish water for 30 years. However, the salinity in the 0–100 cm soil layer was below the salt tolerance threshold of winter wheat and summer maize with salts accumulated in the 1–2 m soil layer. Considering the salinization of the root zone and crop water needs, it is recommended that the safe groundwater level for brackish water irrigation should be 3 m in the study region. This study provides scientific reference for groundwater–farmland ecosystems to utilize brackish water and treat saline–alkali lands. Full article

Moistube irrigation is an efficient method that accurately irrigates and fertilizes agricultural crops. Investigation into the mechanisms of infiltration behaviors under an adjusted working head (WKH) benefits a timely and artificially regulating moisture condition within root zones, as adapted to evapotranspiration. This study explores the laws of Moistube irrigated soil water movement under constant and adjusted working heads. Lysimeter experiments were conducted to measure Moistube irrigation cumulative infiltration, infiltration rate, and to observe wetting front area and water content distribution using digital image processing and time domain reflectometry, respectively. Treatments of constant heads (0, 1, and 2 m), increasing heads (0 to 1, 0 to 2 and 1 to 2 m) and deceasing heads (1 to 0, 2 to 0 and 2 to 1 m) were designed. The results show that (1) under constant heads, the cumulative infiltration increases linearly over time. The infiltration rate and cumulative infiltration are positively correlated with the pressure head. When WKH is increased or decreased, the infiltration rate and cumulative infiltration curves significantly change, followed by a gradual stabilization. The more the head is increased or decreased, the more evident this tendency will be. (2) When WKH is increased, the wetting front migration rate and the wetted soil moisture content marked increase; when WKH is decreased, the wetting front migration rate sharply decelerates, and the water content of the wetted soil slowly grows. They both tend to equilibrium with time. (3) By regarding the same cumulative infiltration of increased WKH and constant WKH treatments as a similar initial condition, we proposed a cumulative infiltration empirical model for Moistube irrigation under variable working head. Additionally, we treat the Moistube as a clayey porous medium and construct a HYDRUS-2D numerical model to predict the infiltration behaviors under variable WKH. The validity of the two models were well proven, with MRE and NRMSE close to 0 and NSE greater than 0.867, indicating good agreements with the experimental results. This model breaks through the limitation of constant boundary of traditional numerical model and applies variable head boundary to the boundary of the Moistube pipe, which can also effectively simulate the response mechanism of Moistube irrigation to variable WKH. The research results further confirmed the feasibility of manually adjusting the WKH to regulate the discharge of the Moistube pipe and soil moisture state. Based on the HYDRUS-2D numerical model simulation results and the root distribution and water demand of typical facility crops, the selection range of placement depth and the adjustable range of WKH of Moistube irrigation were proposed. The research results provide a theoretical reference for manual adjustment or automatic control of Moistube irrigation WKH to adapt to real-time crop water demand in agricultural production. Full article

Processes in hillslope soils present a particular challenge for agricultural production and soil management due to their hydropedological specifics and high soil erosion risk. Soil heterogeneities can cause preferential and/or lateral flow on the entire hillslope resulting in the off-site movement of water, fertilizers and chemicals used in crop production. A study was conducted under controlled conditions in a laboratory with undisturbed soil cores (250 cm³), which were used to estimate the soil hydraulic properties (SHP) using HYPROP and WP4C devices, while undisturbed soil columns (diameter = 16 cm, length = 25 cm) were used for the evaluation of preferential flow pathways using potassium bromide and Brilliant Blue. Samples were excavated in triplicate from the hilltop, backslope and footslope regions within the inter-rows of a vineyard from a critical zone observatory, SUPREHILL, in Croatia in Dystric Luvic Stagnosol. The aim of this study was to determine if the erosion-affected hillslope position affected the physical, chemical and hydraulic properties of soil and to identify water flow and possible preferential flow using dye and bromide tracers. The results of the sensor measurements and estimated SHPs were in agreement, showing a faster leaching of the irrigated rainwater in the footslope column. The tracer experiments showed variability even in the columns taken from the same position on the hillslope, which can be linked to plant roots and soil fauna activity. Altogether, the results showed a deeper loose layer at the footslope as a consequence of the soil erosion, which then resulted in higher hydraulic conductivity and the leached mass of the bromide due to better soil structure and pore connectivity. Thus, due to significant differences in the leached mass of bromide, this research should be later expanded in field experiments to reveal the impact of surface runoff, subsurface preferential and lateral flow on a larger scale. Full article

The simple leaves of deciduous forest trees in temperate zones have more irregular and asymmetric shapes than comparable non-deciduous leaves of trees in the tropics and subtropics. These shapes manifest as the irregular lobes and sinuses of temperate species of Quercus and Acer, as well as the greater bilateral asymmetry of Ulmaceae and Betulaceae, the serrated margins of many species, and the greater frequency of compound leaves generally (Fraxinus and Carya). These modifications may contribute to an early transition from laminar to turbulent flow, thus reducing the lateral movement of leaves when they drop during the onset of either winter or the dry season, or when they are simply shed for replacement. Such leaves are more likely to drop over the critical root zone than large, thin, broadly elliptic, and symmetric leaves. Here, we evaluate evidence for and against self-mulching as an explanation for differences in leaf shape between temperate and tropical forests. We suggest that the main evolutionary trade-offs are between competition for (1) light among tropical trees and temperate subcanopy trees, and (2) competition for water and soil nutrients among temperate canopy trees. Full article

The interplay of surface and shallow subsurface fluxes plays a critical role in controlling water movement in hillslope agroecosystems and impacting soil and plant health during prolonged dry periods, demonstrating a need for in-field monitoring. This study was conducted for two years (2021–2022) by combining field monitoring of the grass-covered inter-row area (passive wick lysimeter, surface runoff, and meteorological data), laboratory determination of soil hydraulic properties (SHPs), and numerical modeling with the aim to explore near-surface fluxes at the SUPREHILL Critical Zone Observatory (CZO) located on a hillslope vineyard. Additionally, sensitivity analysis for basic root water uptake (RWU) parameters was conducted. The model was evaluated (R², RMSE, and NSE) with lysimeter (hillslope) and runoff (footslope) data, producing good agreement, but only after the inverse optimization of laboratory estimated hydraulic conductivity was conducted, demonstrating that adequate parameterization is required to capture the hydropedological response of erosion-affected soil systems. Results exhibit the dependence of runoff generation on hydraulic conductivity, rainfall, and soil moisture conditions. The data suggest different soil-rewetting scenarios based on temporal rainfall variability. Sensitivity analysis demonstrated that Leaf Area Index (LAI) was the most responsive parameter determining the RWU. The study offers an approach for the investigation of fluxes in the topsoil for similar sites and/or crops (and covers), presenting the methodology of self-constructed soil–water collection instruments. Full article

In arid and semi-arid areas, water vapor transport is an important form of soil water movement and plays a crucial role in the overall water and energy balance. For better prediction of soil water and heat fluxes and understanding of root zone soil water dynamics for effective crop management, soil moisture, temperature, soil texture and micrometeorological data have been collected from field trials. Based on the data collected, a Hydrus 1D model was established to simulate the coupled transport of liquid water, water vapor and heat under summer maize (summer maize treatment; SMT) and bare soil (bare soil treatment; BT) for a 100 cm soil profile. Calibration and validation data for the model revealed a good level of agreement between simulated and measured data. Results indicated that the isothermal vapor flux was close to zero throughout the profile, while the isothermal water flux dominated the soil water movement for both SMT and BT. The vapor flux was mainly contributed by thermal vapor flux and increased with soil desiccation. Evaporation and transpiration showed two distinct phases, increasing immediately after irrigation and decreasing gradually as soil water content decreased. SMT had lower evaporation rates due to the protection provided by crop canopy. Irrigation significantly altered the dynamic characteristics of thermal liquid water and thermal vapor fluxes in the vadose, emphasizing the importance of considering the coupled transport of liquid water, vapor, and heat transport at interfaces in the soil–plant–atmosphere continuum for accurate estimates of water flux, especially under prolonged drought conditions. Full article

Estimating crop evapotranspiration (ET_a) is an important requirement for a rational assessment and management of water resources. The various remote sensing products allow the determination of crops’ biophysical variables integrated in the evaluation of ET_a by using surface energy balance (SEB) models. This study compares ET_a estimated by the simplified surface energy balance index (S-SEBI) using Landsat 8 optical and thermal infra-red spectral bands and transit model HYDRUS-1D. In semi-arid Tunisia, real time measurements of soil water content (θ) and pore electrical conductivity (EC_p) were made in the crop root zone using capacitive sensors (5TE) for rainfed and drip irrigated crops (barley and potato). Results show that HYDRUS model is a fast and cost-effective assessment tool for water flow and salt movement in the crop root layer. ET_a estimated by S-SEBI varies according to the available energy resulting from the difference between the net radiation and soil flux G₀, and more specifically according to the assessed G₀ from remote sensing. Compared to HYDRUS, the ET_a from S-SEBI was estimated to have an R² of 0.86 and 0.70 for barley and potato, respectively. The S-SEBI performed better for rainfed barley (RMSE between 0.35 and 0.46 mm·d⁻¹) than for drip irrigated potato (RMSE between 1.5 and 1.9 mm·d⁻¹). Full article

Arsenic is a metalloid widely distributed in the environment and of global concern for human health. In a promising breakthrough for sustainable arsenic soil remediation, a fern, Pteris vittata L., was discovered to take up arsenic from the soil and accumulate it in its fronds at up to ~100 times soil concentrations. Successively harvesting the fronds removes, or phytoextracts, arsenic from the soil with potential environmental and economic benefits including low site disturbance and low cost. The practical use of P. vittata for soil remediation faces challenges largely stemming from the complex nature of the soil. Here, we review soil geochemical processes governing the transport of arsenic from soil to the roots of arsenic-hyperaccumulating ferns. We find that phytoextraction is a soil-dependent process, but that key soil attributes including texture are often not reported. We show that rhizosphere processes play a crucial role in arsenic phytoextraction, and that nutrient management is most successful with ecologically based approaches including sparingly soluble nutrient forms. We conclude that a multi-scale ecological approach is needed to validate P. vittata behavior across controlled and field conditions, and arsenic movement between soil, water, and plant compartments. Our synthesis suggests that phytoextraction as currently practiced is limited to soils with low arsenic concentrations and that P. vittata cultivation is climate-limited to a zone smaller than its range as a wild species. Full article

Soil water and salt movement during the freeze–thaw period facilitate soil and water conservation and agroecological environment maintenance in the desert–oases transition zone of the Hexi Corridor; however, our understanding of soil salinization and the shifting water, heat, and salt states in soil ecosystems of Haloxylon ammodendron forests at different ages is poor. We analyzed the soil moisture, temperature, and salinity characteristics of Haloxylon ammodendron forests of different ages in the Hexi Corridor of Northwest China and determined their coupling. Our results indicated that shallow (0–120 cm) soil temperatures significantly correlated with air temperatures. With increased forest age, the soil freezing period shortened and the permafrost layer shallowed. Changes in soil temperature lagged those in air temperature, and this lag time increased with forest age and soil depth. With increases in forest age and planting years, the water in the shallow soil layer gradually declined, and the surface aggregation of salt increased. In deep soils (120–200 cm), both soil moisture and salinity increased with the number of planting years. Accordingly, the clay layer and deep root system of Haloxylonammodendron greatly influenced the transport of soil water and salt; and temperature is a key driving force for their transport. Thus, water, temperature, and salt content dynamics were synergetic. Full article

Soil salinization is a major eco-environmental problem in irrigated agro-ecosystems. Understanding regional soil salinity spatial patterns and seasonal dynamics and their driving factors under changing environments is beneficial to managing soil salinity to maintain agricultural production in arid agricultural areas. To better investigate this topic, soil salinity was measured, ranging from topsoil to the depth of 1.8 m in an irrigation district with 68 sampling sites before and after the crop growing seasons of the dry year of 2017 and wet year of 2018. Soil texture, groundwater table depth, groundwater salinity, and crop type were monitored. The results indicated that an increase in soil salinity in the root zone (0–0.6 m) was accompanied by a decrease in soil salinity in the deep soil (0.6–1.8 m) through the crop growing season due to water movement from the deep layer to shallow layer, whereas the opposite trend was observed during the fallow seasons. During the dry year, the area with soil desalted was measured to be 19.89%, 14.42%, and 2.78% lower at depths of 0–0.6 m, 0.6–1.2 m, and 1.2–1.8 m than that during the wet year. The groundwater table depth in the crop growing season had the least impact on the change in root zone soil salinity (p > 0.05). Interactions between crop types and groundwater table depth had a significant effect on the change of soil salinity in the root zone during the growing season of the dry year, but were insignificant during the wet year. Crop types, groundwater table depth, and climate conditions determined the contribution of shallow groundwater to crop water consumption and, to a greater extent, soil salinity. Regression tree analysis showed that groundwater salinity and soil texture had a greater influence on soil salinity than groundwater table depth and land elevation. The effect of groundwater on soil salinity is strongly related to soil texture, and the salinity of fine-textured soil was 36–54% greater than that of coarse-textured soil due to large capillary action. Therefore, we suggest strengthening groundwater management in areas with fine-textured soil to relieve soil salinization, particularly during dry years. Full article