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In order to alleviate the shortage of water in Xinjiang cotton fields, to ensure the sustainable development of the cotton industry in southern Xinjiang, it is necessary to determine a suitable "dry sowing and wet emergence" water quantity plan for cotton fields in southern Xinjiang to change the current situation. In this study, to explore the irrigation regime of "dry sowing and wet emergence" for cotton in Korla, Xinjiang, by combining field experiments and modeling simulations, the effects of different irrigation amounts on the water–heat–salt and seedling emergence characteristics of "dry sowing and wet emergence" cotton fields were investigated; the soil, water, and salt transport under different irrigation regimes was simulated by using HYDRUS-2D, and the seedling emergence rate of the cotton under different irrigation regimes was obtained through the establishment of a regression model. The results indicated that, in the field experiment, the soil water content of the 0−40 cm soil layer showed an overall trend of first increasing and then decreasing with time, while the soil salt content showed an overall trend of first decreasing and then increasing over time. The soil water content at the drip heads and cotton rows position, as well as on the 15th day, increased by an average of 5.58 cm3·cm−3 compared to before irrigation, and the soil salt content decreased by an average of 2.74 g/kg compared to before irrigation. In the irrigation water range of 675−825 m3/hm2, reducing the irrigation water amount increased the cotton emergence rate by 3.86% and the cotton vigor index by 70.53%. After the model simulation, it is recommended to choose the cotton "dry sowing and wet emergence" irrigation regime with a low to medium water amount (300−450 m3/hm2) at 14-day intervals or a low to medium water amount (300−375 m3/hm2) at 7-day intervals, which can obtain a higher seedling emergence rate. [ABSTRACT FROM AUTHOR]

• Marula transpiration is strongly driven by both climatic and soil water content variations. • Marula can buffer daily transpiration demands via large water storage capacity. • Kei Apple transpiration is predominantly driven by climatic factors. • Whole-tree transpiration can be accurately predicted using a simple Penman-Monteith model, albeit with different parameters for each species. Conventional crop production is expected to decline in the future in sub-Saharan Africa due to the rising costs of inputs, soil degradation, and increasing water scarcity related to climate variability and change. South Africa has more than 30 species of indigenous fruit trees that are adapted to grow under harsh conditions, yet these species are currently underutilized. Their cultivation is constrained by the lack of detailed ecophysiological information required to develop effective management strategies that optimize tree performance. In this study we investigated how two species with domestication potential namely Marula (Sclerocarya birrea) and Kei apple (Dovyalis caffra) responded to climate and soil factors over a period of two years (2019–2021). Photosynthesis, transpiration, and yield were quantified for mature trees growing in experimental orchards in the Mpumalanga Province of South Africa. Leaf gas exchange data were collected at selected intervals during the growing season using an infrared gas analyser while whole tree transpiration rates were quantified using the heat ratio method of monitoring sap flow. These data were used to parameterize a big leaf Penman-Monteith (PM) model to estimate the transpiration dynamics of individual trees at the daily time step. S. birrea's transpiration responded strongly to both climatic and soil water content variations while the water use of D. caffra was driven mostly by climatic factors. Transpiration rates averaged 0.30 L/m2 of leaf area for S. birrea while that of D. caffra was around 0.45 L/m2. Both species exhibited significant alternate bearing with yield of individual trees fluctuating by more than 50 % between successive years. For the 2019/20 season, water productivity (grams of fruit per litre of water transpired) varied between 6.2 and 17.4 g/L for S. birrea and between 24.3 and 41.7 g/L for D. caffra. Whole tree transpiration by both species were accurately predicted using the PM model albeit with different parameters for each species. This study demonstrates that a simple PM model can accurately estimate the water requirements of these species in other growing regions. [ABSTRACT FROM AUTHOR]

[Objective] The aims of this study are to clarify the characteristics and influence of soil water content, soil porosity, soil nutrients and the flue-cured tobacco quality in the condition of different dosage of water retaining agent (Potassium polycalcium), to apply the important supply to relieve drought and enhance the quality of the tobacco. Methods] The random-groups design and the condition of different dosages of water retention agent were adopted to measure the indices of soil water content. soil nutrients and tobacco. quality. [Results] As the dosages of water retention agent increased the soil pH value changed from 7.4 το 7.7. total porosity, capillary porosity, soil saturated water content field capacity, capillary water content first increased then decreased. when the dosage of water retaining agent reached to 150 kg/hm, the value of soil bulk density reached to the lowest value. However, the values of total porosity, capillary porosity, soil saturated water content and capillary porosity reached to the highest values. The value of CEC showed fluctuated changes. With the increased of the dosages of water retention agent, the soil organic carbon, soil total potassium available potassium first increased then decreased. However, the total nitrogen, total phosphorus, alkali hydrolyzed nitrogen and available phosphorus showed the increasing trends. But the bulk density first decreased then increased. The chlorine and total nitrogen of the tobacco leaves showed the trends of the upper leaves < the middle leaves < the lower leaves, and as the concentrations of the water retention agent increased, the content of the chlorine of the tobacco leaves showed the fluctuating change. The potassium of middle and upper leaves of the tobacco leaves were higher than that of the lower leaves. And it increased as the concentrations of the water retention agent increased. The content of nicotine changed as the order: the upper leaves the middle leaves the lower leaves, and there existed the weak correlation between nicotine and the concentration of the water retention agents. The reducing sugar and total sugar showed the similar change trends. The ratio of potassium and chlorine changed as the order: the upper leaves > the middle leaves > the lower leaves, and showed the fluctuating change trends as the concentration of water retention agent increased. However, the ratio of nicotine and total nitrogen and the ratio of sugar and alkaline. showed the order: the upper leaves < the middle leaves < the lower leaves, and the two ratios increased as the concentration of water retention agents increased. Meanwhile, there existed the significant positive correlation between the soil total nitrogen and the chlorine contents, the potassium of the upper leaves, the reducing sugar (p<0.05). Also there existed the significant positive correlation between the soil organic carbon and the chlorine contents, the reducing sugar the potassium of the upper leaves, the nicotine of the lower leaves (p<0.05). [Conclusion Above all, the dosage of 150 kg/hm' is considered as the best dosage to soil amelioration in southwest China. Also this study can supply the basis and data supports to the anti- drought ability and enhance the flue-cured tobacco quality. [ABSTRACT FROM AUTHOR]

Nutrient addition, particularly nitrogen, often increases plant aboveground biomass but causes species loss. Asymmetric competition for light is frequently assumed to explain the biomass-driven species loss. However, it remains unclear whether other factors such as water can also play a role. Increased aboveground leaf area following nitrogen addition and warming may increase transpiration and cause water limitation, leading to a decline in diversity. To test this, we conducted field measurements in a grassland community exposed to nitrogen and water addition, and warming. We found that warming and/or nitrogen addition significantly increased aboveground biomass but reduced species richness. Water addition prevented species loss in either nitrogen-enriched or warmed treatments, while it partially mitigated species loss in the treatment exposed to increases in both temperature and nitrogen. These findings thus strongly suggest that water limitation can be an important driver of species loss as biomass increases after nitrogen addition and warming when soil moisture is limiting. This result is further supported by a meta-analysis of published studies across grasslands worldwide. Our study indicates that loss of grassland species richness in the future may be greatest under a scenario of increasing temperature and nitrogen deposition, but decreasing precipitation. [ABSTRACT FROM AUTHOR]

Monitoring soil water content (SWC) is vital for various applications, particularly in agriculture. This study compares SWC estimated by means of SCATSAR-SWI remote sensing (RS) at different depths (T-values) with Cosmic Ray Neutron Sensing (CRNS) across four agricultural sites in northern Italy. Additionally, it examines the spatial mismatch and representativeness of SWC products' footprints based on different factors within the following areas: the Normalized Difference Vegetation Index (NDVI), soil properties (sand, silt, clay, Soil Organic Carbon (SOC)), and irrigation information. The results reveal that RS-derived SWC, particularly at T = 2 depth, exhibits moderate positive linear correlation (mean Pearson correlation coefficient, R = 0.6) and a mean unbiased Root–Mean–Square Difference (ubRMSD) of 14.90%SR. However, lower agreement is observed during summer and autumn, attributed to factors such as high biomass growth. Sites with less variation in vegetation and soil properties within RS pixels rank better in comparing SWC products. Although a weak correlation (mean R = 0.35) exists between median NDVI differences of footprints and disparities in SWC product performance metrics, the influence of vegetation greenness on the results is clearly identified. Additionally, RS pixels with a lower percentage of sand and SOC and silt loam soil type correlate to decreased agreement between SWC products. Finally, localized irrigation practices also partially explain some differences in the SWC products. Overall, the results highlight how RS pixel variability of the different factors can explain differences between SWC products and how this information should be considered when selecting optimal ground-based measurement locations for remote sensing comparison. [ABSTRACT FROM AUTHOR]

Chili pepper plants are one of the horticultural commodities commonly found in Indonesia. BPS data (2022) shows that chili pepper production has increased from 2018 to 2022, with a growth rate of 15%. The increasing production of chili pepper does not indicate that market demand in Indonesia has been met. In 2022, from January to September, Indonesia will still import chili commodities totaling 35,962 tons. Market demand for chili pepper commodities is still not fulfilled, this could be because chili pepper production is still not optimal. Chili pepper plants are susceptible to water shortages, where lack of water can cause a slowdown in the growth rate of chili pepper plants and a decrease in the number of fruit produced at harvest. One of the chili pepper producers is Eptilu Education Garden. The chili pepper greenhouse at the Eptilu Education Garden may experience watering delays due to the water source being used to water another garden. Delaying watering can cause chili pepper plants to experience a lack of water. A solution that can be developed is to create several algorithm models for predicting soil water content using machine learning and comparing the accuracy values of each algorithm. The algorithms created are decision tree, support vector machine and random forest algorithms. The independent variables are greenhouse temperature (°C), relative humidity (%), soil temperature (°C), and soil water content (%). The dependent variable is soil water content (%) in the next hour. The model with the highest accuracy value is the model with the Support Vector Regression (SVR) algorithm with a linear kernel and an epsilon (ε) value of 0.1, with an accuracy value of 0.938 on test data and 0.958 on new data. [ABSTRACT FROM AUTHOR]

There is growing interest in using canopy temperature (Tc), including crop water Stress index (CWSI), for irrigation management. However, Tc varies greatly in one day, while soil water content (SWC) varies little, which may lead to different conclusions on whether irrigation is needed based on CWSI at different times. For this end, Tc of winter wheat was continuously monitored, and the data of such environmental factors as atmospheric temperature and soil water content (SWC) were simultaneously collected. CWSI was calculated based on empirical formulation and Tc and CWSI were generalized based on the normalization formulation. The correlation SWC between Tc and CWSI before and after generalization was compared and error analysis was based on SWC theoretical formula. The results showed: (1) the accuracy of SWC retrieval by Tc and CWSI increased firstly and then decreased with time during the day. The optimal time for Tc monitoring SWC was between 10:00 ~ 16:00 (R2 > 0.72) and the optimal time for CWSI monitoring SWC was between 9:00 ~ 18:00 (R2 > 0.69). (2) CWSI and Tc were mapped based on the relationship between crop water stress and soil water deficit and normalized canopy temperature expressions characterized the relationship between crop water stress and soil water deficit. (3) The accuracy of inversion of SWC by mapping Tc from 18:00 ~ 8:00 is increased from 0.5 ~ 0.6 to 0.7 ~ 0.8; the accuracy of soil water content inversion by mapping CWSI from 18:00 ~ 8:00 was improved from 0.2 ~ 0.4 to 0.4 ~ 0.6. (4) The theoretical expression of SWC deduced based on CWSI also proves that considering the relationship between crop water stress and soil water deficit change can effectively reduce the relative error from 30 to 5% in the morning and evening. This study contributes to the understanding of the reason why the correlation between Tc and SWC varies greatly during the day and solves the time-limited problem of thermal infrared remote sensing monitoring of crop water stress. [ABSTRACT FROM AUTHOR]

Increases in hydrological extremes, including drought, are expected for Amazon forests. A fundamental challenge for predicting forest responses lies in identifying ecological strategies which underlie such responses. Characterization of species-specific hydraulic strategies for regulating water-use, thought to be arrayed along an 'isohydric–anisohydric' spectrum, is a widely used approach. However, recent studies have questioned the usefulness of this classification scheme, because its metrics are strongly influenced by environments, and hence can lead to divergent classifications even within the same species. Here, we propose an alternative approach positing that individual hydraulic regulation strategies emerge from the interaction of environments with traits. Specifically, we hypothesize that the vertical forest profile represents a key gradient in drought-related environments (atmospheric vapor pressure deficit, soil water availability) that drives divergent tree water-use strategies for coordinated regulation of stomatal conductance (gs) and leaf water potentials (ΨL) with tree rooting depth, a proxy for water availability. Testing this hypothesis in a seasonal eastern Amazon forest in Brazil, we found that hydraulic strategies indeed depend on height-associated environments. Upper canopy trees, experiencing high vapor pressure deficit (VPD), but stable soil water access through deep rooting, exhibited isohydric strategies, defined by little seasonal change in the diurnal pattern of gs and steady seasonal minimum ΨL. In contrast, understory trees, exposed to less variable VPD but highly variable soil water availability, exhibited anisohydric strategies, with fluctuations in diurnal gs that increased in the dry season along with increasing variation in ΨL. Our finding that canopy height structures the coordination between drought-related environmental stressors and hydraulic traits provides a basis for preserving the applicability of the isohydric-to-anisohydric spectrum, which we show here may consistently emerge from environmental context. Our work highlights the importance of understanding how environmental heterogeneity structures forest responses to climate change, providing a mechanistic basis for improving models of tropical ecosystems. [ABSTRACT FROM AUTHOR]

Precise soil water content (SWC) measurement is crucial for effective water resource management. This study utilizes the Cosmic-Ray Neutron Sensor (CRNS) for area-averaged SWC measurements, emphasizing the need to consider all hydrogen sources, including time-variable plant biomass and water content. Near Mead, Nebraska, three field sites (CSP1, CSP2, and CSP3) growing a maize–soybean rotation were monitored for 5 (CSP1 and CSP2) and 13 (CSP3) years. Data collection included destructive biomass water equivalent (BWE) biweekly sampling, epithermal neutron counts, atmospheric meteorological variables, and point-scale SWC from a sparse time domain reflectometry (TDR) network (four locations and five depths). In 2023, dense gravimetric SWC surveys were collected eight (CSP1 and CSP2) and nine (CSP3) times over the growing season (April to October). The N0 parameter exhibited a linear relationship with BWE, suggesting that a straightforward vegetation correction factor may be suitable (fb). Results from the 2023 gravimetric surveys and long-term TDR data indicated a neutron count rate reduction of about 1% for every 1 kg m−2 (or mm of water) increase in BWE. This reduction factor aligns with existing shorter-term row crop studies but nearly doubles the value previously reported for forests. This long-term study contributes insights into the vegetation correction factor for CRNS, helping resolve a long-standing issue within the CRNS community. [ABSTRACT FROM AUTHOR]

In recent decades, distributed temperature sensing (DTS) has emerged as a robust technology for environmental applications, enabling high‐resolution temperature measurements along fibre optic cables (FOCs). The actively heated fibre optic (AHFO) method is employed to monitor soil moisture (θ$$ \theta $$, m3 m−3), wherein the soil temperature subsequent to the application of a heat pulse is measured by a DTS (AHFO‐DTS approach). Despite significant improvements in the application of AHFO‐DTS under controlled and natural conditions, the thermal behaviour of soil during multiple saturation–natural drying cycles has been insufficiently evaluated. This study aimed to address this gap by constructing an experimental horizontal soil profile in the laboratory for the application of the AHFO‐DTS method during two successive saturation–drainage–evaporation (SDE) cycles. Three heating strategies were applied to a metallic alloy in contact with a FOC, and calibration models were used to correlate θ$$ \theta $$ with the thermal conductivity (λ$$ \lambda $$), cumulative temperature increase (Tcum$$ {T}_{\mathrm{cum}} $$), and maximum temperature increase (Tmax$$ {T}_{\mathrm{max}} $$). The results indicated that during the second SDE cycle, the highest errors in θ$$ \theta $$ estimates were observed with the low power‐short heat pulse, whereas the application of the low power‐long duration and high power‐short duration pulses improved the accuracy of calculations. Additionally, errors in θ$$ \theta $$ estimates escalated under wetter conditions, attributed to a shift in soil heat transfer capacity from the first to the second SDE cycle for θ$$ \theta $$ > 0.10 m3 m−3. This behaviour was ascribed to thermal hysteresis, arising from the contact resistance of the FOC and the alloy with the surrounding soil. Furthermore, the Tmax$$ {T}_{\mathrm{max}} $$ method exhibited the least sensitivity to this effect and yielded reliable θ$$ \theta $$ estimates, thus its adoption is recommended. Moreover, the use of the low power‐long duration heating strategy is suggested as it promotes a trade‐off between energy saving and accurate estimates. We concluded that assessing soil thermal response under multiple SDE cycles enhances the comprehension of the AHFO‐DTS method. Overall, our findings provide insights into enhancing the applicability of this approach under field conditions, particularly following irrigation schedules and natural rainfall events. [ABSTRACT FROM AUTHOR]

The relationship between plant aboveground biomass and diversity typically follows a unimodal pattern, showing a positive correlation in resource‐poor habitats and a negative correlation in resource‐rich environments. Precipitation is a crucial resource for both plant biomass and diversity in terrestrial ecosystems. However, the impact of precipitation changes on the relationship between plant biomass and diversity remains unclear. We conduct a water addition field experiment in a semiarid grassland and identify a unimodal relationship between plant biomass and species richness under ambient conditions. Water addition delays the declining phase of this unimodal curve and shift it upward compared to ambient conditions. Our meta‐analysis of water addition experiments conducted across major biomes worldwide (grassland, shrubland, desert, and forest) supports this finding, while water reduction does not alter the biomass–diversity relationship. Water addition increases biomass in all climate but only increases species richness in arid and semiarid climate. Similarly, water reduction decreases biomass in all climate but only reduces species richness in arid and semiarid climate. Species richness in dry subhumid and humid climate does not change significantly. Furthermore, our field experiment shows that water addition increases plant diversity while decreasing soil inorganic nitrogen levels. The increase in one resource, such as water, leads to the scarcity of another, such as nutrient, thus postponing the declining phase of the plant biomass–diversity relationship typically observed in resource‐rich habitats. Our research contributes to predicting the plant biomass–diversity relationship under changing precipitation conditions and highlights the complex interplay between water availability, nutrient level, and plant diversity. [ABSTRACT FROM AUTHOR]

The restoration of native vegetation like pines helps mitigate soil erosion, but the effects of pine needle litter on runoff, erosion, and hydrology in karst hillslopes are unclear. This study investigated these factors during the rainy season from June to August 2021 under six treatments (flat, gentle, and steep slopes with and without pine needle coverings). The results showed that pine needle litter significantly increased the soil water content, particularly on steeper slopes, by improving the water-holding capacity. It also substantially reduced runoff (by 23.8%) and soil erosion (by 92.5%). The critical rainfall threshold for generating runoff did not occur in the pine needle covering treatment, whereas it was 19.3 ± 8.8 mm in the bare soil treatment under wet conditions. These findings highlight the efficacy of pine needle cover in reducing runoff and erosion in karst areas, promoting it as a sustainable method for restoring degraded soil. [ABSTRACT FROM AUTHOR]

Aims: Soil microbial and enzymatic activity have important roles in soil health, nutrient cycle and plant growth. Biochar is an excellent biomass for increasing soil water content, but some biochar compounds, due to their high pH, are harmful to the soil. This study aimed to investigate the effect of biochar and sulfur-modified biochar on improving the soil water content and biochemical properties in a millet cropping system. Methods: The field experiment was performed in a completely random design with three replications. Experimental treatments included control, 15 t ha− 1 sunflower biochar (B), and 15 t ha− 1 sulfur-modified biochar (BS). Results: Biochar (B and BS) improved the soil water content by 47% and 35%, respectively, compared to the control. B and BS treatments improved soil biological properties, including microbial biomass carbon, basal respiration, and the activity of catalase, dehydrogenase, urease, and alkaline phosphatase enzymes compared to the control. The application of B and BS treatments decreased soil EC and sodium adsorption ratios compared to the control. The highest (8.26) and lowest (7.83) values of soil pH were related to the B and BS treatments, respectively. Treatment of soil with B and BS enhanced soil dissolved organic carbon (90% and 33%), available nitrogen (74% and 48%), and available phosphorus (60% and 96%) compared to the control. The application of B and BS treatments enhanced plant nutrients (nitrogen, phosphorus, and potassium) and the leaf relative water content by 40% and 14%, respectively. Biochar (B and BS) improved millet yield by 58% and 115%, respectively, compared to the control. Conclusion: Sulfur increased the efficiency of biochar in amending saline and calcareous soil and enhanced millet yield by improving the chemical properties (pH and CEC) of biochar. [ABSTRACT FROM AUTHOR]

In order to clarify the irrigation system of high yield and high quality cultivation of Astragalus mongholicus in arid regions in northern Shaanxi, explore the influence of different irrigation amounts on the quality and yield of Astragalus mongholicus. In this study, with Astragalus mongholicus as the experimental material, six treatments of irrigation amounts including 5 240(W1), 4 190(W2), 3 140(W3), 2 090(W4), 1 040(W5), and 0(CK) m3 /ha were set, and the differences in soil water content, dry matter mass, root crown ratio, agronomic traits, yield, and quality of Astragalus mongholicus were analyzed. The results indicated that 0-60 cm, the soil water content in the treatments of W1, W2, W3, W4, and W5 increased by 50.1%, 30%, 19.8%, 19.6%, and 14.6%, respectively compared with CK. Root crown ratio at harvest stage in the treatments of W2, W3, and W5 increased by 61%, 38% and 36% compared with CK, respectively. The plant height, stem thickness and crown amplitude of Astragalus mongholicus increased with the increase of irrigation amount, the values reached the maximum at W2 treatment, then declined. Yield in the treatments of W2 increased by 53% compared with CK. In terms of the quality of Astragalus mongholicus, in treatment W3, the Astragalus methylside content was 0.131%, the Myislavone glucoside content was 0.22%, they were higher than those in other treatments. The correlation analysis found that root dry weight, root fresh weight, stem and leaf dry weight, and crown amplitude were siginificantly positively correlated with yield. In conclusion, the suitable irrigation amounts of high yield and high quality of Astragalus mongholicus planted in the arid regions in northern Shaanxi was 3 140-4 190 m³ /ha. [ABSTRACT FROM AUTHOR]

Soil water content (θ), matric potential (h) and hydraulic conductivity (K) are key parameters for hydrological and environmental processes. Several sensors have been developed for measuring soil θ–h–K relationships. The cost of such commercially available sensors may vary over several orders of magnitude. In recent years, some sensors have been designed in the framework of Internet of Things (i.e., IoT) systems to make remote real-time soil data acquisition more straightforward, enabling low-cost field-scale monitoring at high spatio-temporal scales. In this paper, we introduce a new multi-parameter sensor designed for the simultaneous estimation of θ and h at different soil depths and, due to the sensor's specific layout, the soil hydraulic conductivity function via the instantaneous profile method (IPM). Our findings indicate that a second-order polynomial function is the most suitable model (R2 = 0.99) for capturing the behavior of the capacitive-based sensor in estimating θ in the examined soil, which has a silty-loam texture. The effectiveness of low-cost capacitive sensors, coupled with the IPM method, was confirmed as a viable alternative to time domain reflectometry (TDR) probes. Notably, the layout of the sensor makes the IPM method less labor-intensive to implement. The proposed monitoring system consistently demonstrated robust performance throughout extended periods of data acquisition and is highly suitable for ongoing monitoring of soil water status. [ABSTRACT FROM AUTHOR]

Soil moisture is among the most essential variables in hydrology and earth science. Many satellite missions, such as AMSR-E/2, have been launched to observe it in broader spatial coverage to overcome the shortage of in situ observations. However, the satellite soil moisture products have been reported to comprise errors caused by the so-called "temperature effects" widely observed in dielectrically measured in situ volumetric soil water content (SWC). In this work, we confirmed the existence of these errors in AMSR2 soil moisture products. A new algorithm was developed to remove these errors using satellite data at ascending and descending overpasses. The application of this algorithm to both satellite and in situ data of SWC and soil temperature at the Mongolia site shows that the difference between SWC values at ascending and descending overpasses caused by temperature effects is effectively removed. We assess the impact of this removal method on satellite data by comparing it with in situ data, utilizing metrics such as the correlation coefficient and other widely adopted evaluation methods. It is shown that the difference between the original and corrected in situ SWC is much smaller than that between AMSR2 and in situ SWC, either corrected or not. The results indicate that the metric values between the corrected AMSR2 and in situ SWC, after removing apparent differences caused by temperature effects, slightly improved compared to those between the original AMSR2 and in situ SWC. Though these findings imply that the removed errors may not be the most dominant, considering the current significant difference between AMSR2 and in situ SWC, the removal makes the ascending and descending data have close characteristics. It may allow using data at both ascending and descending overpasses and double the temporal resolution of AMSR2 SWC data. [ABSTRACT FROM AUTHOR]

Reducing the nitrogen (N) application rate and improving water-use efficiency (WUE) are extremely important for sustainable agricultural development in wheat–maize rotation systems in the North China Plain (NCP). We conducted a three-year experiment to investigate the effects of the N application rate on the water-use characteristics of wheat–maize rotation systems in the NCP. The experiment consisted of four N application rates: 250, 167, 84, and 0 kg hm−2, denoted by N3, N2, N1, and N0, respectively. The results showed the following: For the 0–60 cm soil layer, N deficiency could lead to reduced soil water use (SWU) in wheat seasons, but in maize seasons, N deficiency showed no significant effects on SWU in the 0–60 cm layer. For the 60–140 cm soil layer, N deficiency could lead to reduced SWU in wheat seasons, but in maize seasons, the effects of N deficiency on SWU in the 60–140 cm layer varied with the SWC in the 0–60 cm layer. Throughout the three-year experiment, the evapotranspiration (ET), leaf area index (LAI), yield, and WUE of plants receiving low N treatments decreased with the growing season due to the negative effects of low N treatment (N1 and N0) on the soil. The LAI, total ET, grain yield, and WUE were all positively correlated with each other for both wheat and maize. Considering grain yield and WUE, a single-season N application rate of 167 kg hm−2 (N2 treatment) in the NCP could meet the growth needs of the wheat–maize rotation system. [ABSTRACT FROM AUTHOR]

Although advanced production systems have been developed in the last 20 years, water scarcity is still a growing problem in agriculture. This study aims to evaluate the effect of different strategies that combine the application of seaweed and microbial biostimulants with regulated deficit irrigation (RDI) strategies on the irrigation water productivity (WPI), fruit quality parameters and soil enzymatic activity in pepper plants (Capsicum annum sp.) under two commercial greenhouse conditions. In each trial, two treatments were applied: (i) irrigation according to Farmer criteria without biostimulant applications and (ii) a combined treatment of RDI and the same biostimulation program, composed of Bacillus paralicheniformis and Ascophillum nodosum extracts. RDI was applied in different phenological stages in each greenhouse after the establishment until the 1st harvest in trial 1 or during the ripening and harvest period in trial 2. On average, the irrigation was reduced by 600 m3 ha−1 compared to the Farmer irrigation schedule. In both trials, biostimulation promoted an increase in fruit numbers, punctually in trial 1, leading to yield precocity, or generally in trial 2, obtaining a higher yield. Globally, WPI was increased when RDI was combined with biostimulation. This combined treatment also enhanced the root water absorption and improved the soil enzymatic activity in both greenhouses, suggesting that nutrients in the soil would become more available to plants. Thus, the combined action of biostimulation under different RDI strategies has been proved to be a useful strategy to improve agricultural sustainability. [ABSTRACT FROM AUTHOR]

Aims: Coffee silverskin (CS) is the most abundant waste from coffee roasting. In this research, the potential of CS as soil fertilizer for barley (Hordeum vulgare L.) cultivation was evaluated. Methods: Barley plants were grown, for 10 days from the start of germination, in soils mixed with different CS percentages (0, 2, 6 or 10%). The effects of CS addition on soil capacity to retain water and on the mold/yeast community were evaluated. Physio-morphological and biochemical responses of leaves and roots of barley plants growing in CS-enriched soil were evaluated. Results: Root and shoot length decreased in plants grown with CS, but biomass was less affected and even increased at 2% CS. Photosynthesis was higher in barley seedlings grown on CS-enriched soil than in control plants. However, Chl b was reduced in leaves of plants grown with CS. The total leaf protein content did not change with moderate CS additions in soil. However, when grown in soil with 10% CS, a significant reduction of total protein and Rubisco was observed. Extracts of barley shoots from plants grown in soil with 10% CS showed a greater antioxidant capacity with respect to all other experimental conditions. Conclusions: We conclude that CS addition to soil may improve soil property to retain water and, at low concentrations (2% w/w) positively affects barley physiology and growth. [ABSTRACT FROM AUTHOR]

Mediterranean water-stressed areas face significant challenges from higher temperatures and increasingly severe droughts. We assess the effect of climate change on rainfed barley production in the aridity-prone province of Almería, Spain, using the FAO AquaCrop model. We focus on rainfed barley growth by the mid-century (2041–2070) and end-century (2071–2100) time periods, using three Shared Socio-economic Pathway (SSP)-based scenarios: SSP1-2.6, SSP2-4.5, and SSP5-8.5. Using the paired t-test, Spearman and Pearson correlation coefficient, Root Mean Squared Error, and relative Root Mean Squared Error, we verified AquaCrop's ability to capture local multi-year trends (9 or more years) using standard barley crop parameters, without local recalibration. Starting with a reference Initial Soil Water Content (ISWC), different soil water contents within barley rooting depth were modelled to account for decreases in soil water availability. We then evaluated the efficiency of different climate adaptation strategies: irrigation, mulching, and changing sowing dates. We show average yield changes of +14% to −44.8% (mid-century) and +12% to −55.1% (end-century), with ISWC being the main factor determining yields. Irrigation increases yields by 21.1%, utilizing just 3% of Almería's superficial water resources. Mulches improve irrigated yield performances by 6.9% while reducing irrigation needs by 40%. Changing sowing dates does not consistently improve yields. We demonstrate that regardless of the scenario used, climate adaptation of field barley production in Almería should prioritize limiting soil water loss by combining irrigation with mulching. This would enable farmers in Almería's northern communities to maintain their livelihoods, reducing the province's reliance on horticulture while continuing to contribute to food security goals. [ABSTRACT FROM AUTHOR]

Gamma-ray spectroscopy (GRS) enables continuous estimation of soil water content (SWC) at the subfield scale with a noninvasive sensor. Hydrological applications, including hyper-resolution land surface models and precision agricultural decision making, could benefit greatly from such SWC information, but a gap exists between established theory and accurate estimation of SWC from GRS in the field. In response, we conducted a robust three-year field validation study at a well-instrumented agricultural site in Nebraska, United States. The study involved 27 gravimetric water content sampling campaigns in maize and soybean and 40K specific activity (Bq kg−1) measurements from a stationary GRS sensor. Our analysis showed that the current method for biomass water content correction is appropriate for our maize and soybean field but that the ratio of soil mass attenuation to water mass attenuation used in the theoretical equation must be adjusted to satisfactorily describe the field data. We propose a calibration equation with two free parameters: the theoretical 40K intensity in dry soil and a, which creates an "effective" mass attenuation ratio. Based on statistical analyses of our data set, we recommend calibrating the GRS sensor for SWC estimation using 10 profiles within the footprint and 5 calibration sampling campaigns to achieve a cross-validation root mean square error below 0.035 g g−1. [ABSTRACT FROM AUTHOR]

The subject of this study was to understand how grazing and precipitation affect the carbon cycle of grassland ecosystem. The experiment was carried out in a desert steppe of Siziwang Banner, Inner Mongolia, China, and measured CO2 flux and abiotic factors twice a month during the growing season (July to October in 2016, May to October in 2017). The experiment used a completely randomized block design, involving four different stocking rate treatments [CK, no grazing, (0 sheep unit hm –2 half year–1), light stocking rate (LG, 0.93 sheep unit hm–2 half year–1), moderate stocking rate (MG, 1.82 sheep unit hm–2 half year–1) and heavy stocking rate (HG, 2.71 sheep unit hm–2 half year–1)] with three replicates, and four precipitation treatments [50% reduced precipitation (P1), natural precipitation (P2), 50% increased precipitation (P3) and 100% increased precipitation (P4)] were set up in each stocking rate treatment plot. Results indicated that increased precipitation treatments significantly increased soil water content (SWC) and soil respiration (Rs), and significantly reduced soil temperature (Ts), grazing treatments significantly reduced Ts, the interaction between precipitation and stocking rate had no significant impact on the above indicators; Rs increased with increasing precipitation in the order: P4 > P3 > P2 > P1, Rs exhibited the following order under different stocking rates: CK > LG > MG > HG. There was a strong positive correlation between Rs and SWC, and a negative relationship between Rs and Ts. Our results demonstrate that SWC is the dominant factor affecting Rs, as SWC explained 87.12% of the variation in Rs. [ABSTRACT FROM AUTHOR]

Many studies have investigated how soil water availability in shallow soil affects forest transpiration, but how deep soil water status (below 1 m depth) alters tree water use remains poorly understood. To improve our understanding of how deep soil water changes tree transpiration dynamics, we measured soil water content (SWC) in more than 20 m depths, the radial sap flow profile and the leaf area index (LAI) in the 2017 growing season in 9-, 12-, 16-, 19- and 23-year-old afforested apple (Rosaceae) trees on the Chinese Loess Plateau. SWC was also measured in long-term cultivated farmland to derive SWC before afforestation. The results showed that there was no statistical difference in SWC in shallow soil among orchards (p > 0.05), while SWC in deep soil reduced rapidly with increasing tree age. The average SWC at 1–20 m decreased from 0.27 ± 0.02 cm3 cm−3 in farmland to 0.21 ± 0.03 cm3 cm−3 in the 23-year-old orchard. Moreover, water storage in deep soil decreased by 139 mm yr−1 between the 9- and 12-year-old stands, 105 mm yr−1 between the 12- and 16-year-old stands, 44 mm yr−1 between the 16- and 19-year-old stands, and 9 mm yr−1 from the 19- to 23-year-old stands, indicating that gradually decreased SWC in deep soil has restricted tree water use. Due to the changes in SWC, growing-season transpiration and the LAI peaked in the 16-year-old orchard and then decreased with increasing stand age. Growing-season transpiration in the 23-year-old orchard was only 77% of that in the 16-year stands, despite the older trees having larger diameters at the breast height. Our results suggest that soil water availability in deep soil plays an important role in regulating trees' transpiration. [ABSTRACT FROM AUTHOR]

Understanding the distribution of water and nitrate nitrogen in the soil profile is crucial for the reasonable operation of fertigation, and it is also fundamental for controlling and regulating nitrate nitrogen in the root zone, thereby meeting a crop's requirements. The application rates of fertilizer and water directly influence this distribution of water and nitrate nitrogen. However, the effects in Aeolian sandy soil, a type of developing soil bordering deserts, remain ambiguous. In this study, field experiments for different drip fertigation treatments in Aeolian sandy soil were conducted to investigate the soil water distribution, as well as that of nitrate nitrogen. A completely randomized experimental design was implemented, encompassing three levels of irrigation amount: low (W1), medium (W2), and high (W3), and three levels of nitrogen application rate: low (F1), medium (F2), high (F3). After the completion of each irrigation treatment, soil samples were extracted at 10–20 cm intervals. The soil water and nitrate nitrogen contents in the profiles of these samples were measured. The experimental results revealed that increasing the nitrogen application rate facilitated the retention of greater amounts of water and nitrate nitrogen in the soil profile. However, with an increase in the nitrogen application rate, both soil water and nitrate nitrogen exhibited a radial tendency to move away from the drip emitter. Some moved upward and accumulated in surface soil near a ridge furrow, while some moved downward and remained in a deeper area approximately 30 cm horizontally from the emitter at depths of 40–60 cm. The uniformity of the water distribution decreased with increasing nitrogen application under low water conditions, with a reversal of this trend observed in medium and high water treatments. The effect of nitrogen application level on the uniformity of the nitrate nitrogen distribution was not significant. There was no significant correlation between the average soil water content and nitrate nitrogen content along the horizontal direction, however, a positive correlation existed in the vertical direction. In the whole profile, increasing the nitrogen application enhanced the correlation under low water conditions, but under medium and high water conditions, this trend was the opposite. This implies that, to avoid nitrate nitrogen leaching or limiting in a specific area, a moderate nitrogen application level is advisable. Under low water conditions, nitrogen application showed a positive effect on the nitrate nitrogen content, and a higher application is recommended. In cases of substantial water irrigation or rainy years, the nitrogen application rate should be decreased. [ABSTRACT FROM AUTHOR]

Soil water content (SWC) plays a key role in the management of water and soil resources. Accurate prediction of SWC is an important issue in water and soil studies. Recently, some data mining and machine learning techniques were proposed for SWC prediction and achieved encouraging results. This paper presents four data mining predictive algorithms for SWC estimation. The used algorithms are random subspace ensemble, random tree (RT), reduced error-pruning tree (REPTree), and M5P. The motivation of this research is to investigate the performance of the popular data mining algorithms for SWC prediction. A benchmark dataset containing daily SWC parameters in three soil layers of 25 cm, 50 cm, and 100 cm from the Nebraska state station (central USA), Grand Island was used to evaluate the proposed techniques. Statistical indices of determination coefficient (R2), root-mean-square error (RMSE), mean absolute error (MAE), root relative square error (RRMSE), and relative absolute error (RAE) were utilized to measure the performance of the proposed prediction techniques. The modeling results showed that the RT algorithm with R2 = 0.97, RMSE = 0.38, MAE = 0.10, RRMSE = 7.32%, and RAE = 1.82% outperformed counterpart techniques. This study concluded that the developed models will help agricultural water users, developers, and decision-makers for achieving agricultural sustainability. [ABSTRACT FROM AUTHOR]

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

Aims: Root exudates contain polymers that form crosslinks and can create a jelly like substance known as mucilage, which adheres to soil and thus promotes the formation of rhizosheaths, i.e. soil that remains attached to the roots after gentle shaking. We hypothesized that rhizosheath formation is optimal at an intermediate chia seed mucilage concentration and water content, but that its formation is limited at both a high concentration of chia seed mucilage and under dry conditions as well as at a low concentration of chia seed mucilage and under wet conditions. We used an artificial root soil system in which soil moisture and mucilage concentrations could be varied independently from one another with respect to their effect on rhizosheath formation. Methods: Jute cords were disposed in sandy loam soil and in quartz sand. In a subsequent study, they were also amended to different moisture contents with five different concentrations of mucilage (from 0 to 0.2 g dry mucilage g−1 water), before being isolated from chia and flaxseed mucilage after swelling of the respective seeds in distilled water for 15 min. Results: We found that in dry soil, rhizosheath formation peaked at an intermediate chia seed mucilage concentration. This behavior was supported by our conceptual model of mucilage spreading and rhizosheath formation, which relies on a radial diffusion equation and assumes that at low mucilage concentration, molecule numbers are insufficient to support polymer-like networks that stick soil particles together. In a very concentrated gel, however, mucilage is too sticky to diffuse far into the soil. Increasing soil moisture promotes rhizosheath formation both in a low and a high mucilage concentration range, although only up to an intermediate volumetric water content of 0.15cm3 cm–3. Conclusions: We conclude that both water and chia seed mucilage concentration are important drivers of rhizosheath formation. The effects are not additive but can combine to an optimum range, with a maximum formation of rhizosheaths observed in this study at 0.12 g mucilage g−1 rhizosphere water. [ABSTRACT FROM AUTHOR]

Knowledge of the soil water content (SWC) is important for many aspects of agriculture and must be monitored to maximize crop yield, efficiently use limited supplies of irrigation water, and ensure optimal nutrient management with minimal environmental impact. Single-location sensors are often used to monitor SWC, but a limited number of point measurements is insufficient to measure SWC across most fields since SWC is typically very heterogeneous. To overcome this difficulty, several researchers have used data acquired from unmanned aerial vehicles (UAVs) to predict the SWC by using machine learning on a limited number of point measurements acquired across a field. While useful, these methods are limited by the relatively small number of SWC measurements that can be acquired with conventional measurement techniques. This study uses UAV-based data and thousands of SWC measurements acquired using geophysical methods at two different depths and before and after precipitation to predict the SWC using the random forest method across a vineyard in the central United States. Both multispectral data (five reflectance bands and eleven vegetation indices calculated from these bands) and thermal UAV-based data were acquired, and the importance of different reflectance data and vegetation indices in the prediction of SWC was analyzed. Results showed that when both thermal and multispectral data were used to estimate SWC, the thermal data contributed the most to prediction accuracy, although multispectral data were also important. Reflectance data contributed as much or more to prediction accuracy than most vegetation indices. SWC measurements that had a larger sample size and greater penetration depth (~30 cm sampling depth) were more accurately predicted than smaller and shallower SWC estimates (~18 cm sampling depth). The timing of SWC estimation was also important; higher accuracy predictions were achieved in wetter soils than in drier soils, and a light precipitation event also improved prediction accuracy. [ABSTRACT FROM AUTHOR]

The intensification of nitrogen deposition and the change of global rainfall pattern are important features of global change. The input of exogenous nitrogen and the change of soil water conditions will inevitably affect soil microbial diversity and community composition. Illumina Miseq high-throughput sequencing technology was used to study the effects of nitrogen addition, water change and their interaction on bacterial and fungal diversity and community composition of red soil in a modeling subtropical plantation, as well as their relationships with soil properties. The results showed that: soil bacterial diversity decreased with the decrease of water content, and the inhibition effect was enhanced by the addition of nitrogen. The Shannon index of soil fungi under medium water treatment was significantly higher than that under low water treatment. Nitrogen addition significantly decreased the relative abundance of Acidobacteria, while increased the relative abundance of Actinobacteria and Bacteroidetes. In the soil, the relative abundance of Acidobacteria and Bacteroidetes increased with the increase of soil water content, while Actinobacteria and Firmicutes were on the contrary. Drought intensified the inhibition effect of nitrogen addition on the relative abundance of Acidobacteria. Nitrogen addition and soil water interaction significantly affected the relative abundance of Cyanobacteria. But nitrogen addition, soil moisture and their interactions had no significant effects on soil fungal community composition. The results of redundancy analysis showed that the changes of soil bacterial community composition were significantly related to soil water content, pH, NO3 – -N content and TN, which accounted for 65.6%, 26.1%, 21.5% and 20.7% of the changes of soil bacterial community composition, respectively. These results suggest that nitrogen addition may alter the intensity and direction of the effects of drought on soil bacterial diversity and community composition. [ABSTRACT FROM AUTHOR]

Finding and optimizing sustainable approaches could increase yield by modifying the structural and physiological traits by reducing lodging and competition for soil water. A higher yield could be achieved by optimizing planting density under appropriate mulching. In this experiment, we studied the effect of mulching (no mulch, straw mulch, and plastic mulch) on soil water consumption, canopy structure, lodging, and yield traits of maize under different planting density rates (52,500–90,000 plants ha− 1). Results indicated that the lodging was minimum at lower planting densities while the higher density rates induced lodging by reducing the diameter and increasing the internode length. The weight of 100-grains, the number of grains per ear, ear length, and photosynthesis rate were decreased by increasing planting density but grain yield ha− 1 was increased with planting density up to 67,500 plants ha− 1 under no mulch and 75,000 plants ha− 1 under straw and plastic mulch. This showed that the higher planting density could be used by adopting plastic mulch increasing yield and saving soil moisture. The planting density at which the highest grain yield was attained under no mulch was 67,500 plants ha− 1 which was increased to 7500 plant ha− 1 under straw and plastic mulch. The yield showed 8–10% increase at plastic mulching at 75,000 plants ha− 1 as compared to no mulch at 52,500 plants ha− 1. Thus, higher density could be adopted under plastic mulching, and plastic and straw mulching decreased the lodging rate. [ABSTRACT FROM AUTHOR]

Background and aims: The abandonment of alfalfa fields is increasing in a semi-arid region. To determine the change of soil physicochemical properties and plant diversity in abandoned alfalfa fields for a long-term is essential for vegetation restoration. This study surveyed alfalfa fields of different planting ages in 2003 (1–30 years), 2014 (12–41 years), and 2022 (20–49 years) to explore the change in various indicators using a space-for-time method. Results: The results suggested that abandoned alfalfa fields converted into natural grasslands after 15 years, where the abundances of Gramineae and Asteraceae (59.1–84.0%) increased, whereas those of legumes decreased (16.5–9.4%). As the plant composition changed, the soil water content (SWC) decreased by 19.0% 1–15 years after abandonment, but increased by 54.5% 15–49 years after abandonment. The plant diversity (Margalef, Pielou, Simpson, and Shannon–Wiener indices), and soil organic carbon (SOC), and total nitrogen (TN) contents increased by 0.5% to 51.5% with the number of years alfalfa planting. Furthermore, the plant composition significantly affected the SWC through the soil physicochemical characteristics and plant diversity. Conclusions: This study demonstrated that the longest time of alfalfa planting was 15 years. Furthermore, the plant composition changed from alfalfa to local grasses due to the natural succession of abandoned alfalfa fields, with increases in SWC, SOC, TN, and plant diversity in the semi-arid region. [ABSTRACT FROM AUTHOR]

Soil erosion is a key factor in soil quality degradation and carbon balance in arid ecosystems. However, many models ignore the soil erosion process in arid regions, which may lead to limits in our understanding of ecosystem processes in arid regions. In this study, we added the soil erosion process according to field observed data of soil hydrothermal regimes and carbon flux. We validated this coupling version of IBIS (Integrated Biosphere Simulator) and RUSLE (RU–IBIS) by examining four different vegetation types and the carbon budget in the arid region on the Loess Plateau (LP). Our results indicated that the coupling model (RU–IBIS) produced more reliable simulations of the soil water content (with the r from 0.23–0.90 to 0.71–0.97) and evaporation (ET) (the average r was 0.76) and significantly improved the simulation of the leaf area index (LAI) (the average r was 0.95) and net primary production (NPP) (the average r was 0.95). We also conducted sensitivity experiments to determine how soil texture and aerodynamic roughness (Z0m) affect the soil water content. Moreover, it was revealed that specific leaf area (SLA) plays a key role in the simulation of NPP and NEE. Our study suggests that the coupled soil erosion process and parameterization can effectively improve the performance of IBIS in arid regions. These results need to be considered in future Earth system models. [ABSTRACT FROM AUTHOR]

In an upland forested micro-catchment during the growing season, we tested soil responses to precipitation events as well as soil water content (SWC). We asked ourselves if what is the difference of SWC response to precipitation events depending on the presence and proximity of a tree? The environmental heterogeneity of the small 7.5-ha headwater area was captured by soil probes at specific locations: (i) probe measurements of SWC at 10-, 30-, 60-, and 100-cm depths; (ii) resolution of near-tree (NT) and between-tree (BT) positions; and (iii) resolution of four slope classes. The results revealed significant differences between the hydrological responses of the soil. NT soils had faster infiltration but were also faster to dry out when compared to BT soils, which were less affected by the presence of trees. Water input threshold values, measured as the precipitation amount needed to cause a significant increase in SWC, were also significantly different, with NT positions always lower than BT positions. Total infiltration of the topmost NT and BT soil layers reached 185 and 156 mm during the study period, corresponding to 43% and 36% of the total 434 mm of precipitation, respectively. Infiltration into the deepest horizon was significantly higher in NT soils, where it reached 114 mm (26%) as opposed to 9 mm (2%) in BT soils, and was indicative of significant vertical hydraulic bypass flow in the proximity of trees. These observations contribute to better understanding the hydrological processes, their nonlinearity, and the expansion of conceptual hydrological models. [ABSTRACT FROM AUTHOR]

For wheat (Triticum aestivum), sustained crop yield at limited soil water availability has been linked to osmotic adjustment (OA) – a physiological mechanism that aids maintenance of leaf hydration status, turgor (P) and growth. 'Canada Western Red Spring' (CWRS) wheat cultivars are typically grown in rainfed areas with milder climates, but ongoing climate change is increasesing the frequency and intensity of drought events. The overarching goal of this study was to elucidate if commercially used CWRS cultivars ('Superb', 'Stettler', 'AAC Viewfield') have the ability for leaf OA. Measurements of leaf water relation parameters (water potential, Ψ ; solute potential, Ψ s; stomatal conductance, g s; relative water content, RWC) showed that all three cultivars reached zero P (= Ψ – Ψ s) at a leaf Ψ of −1.1 MPa. Prior to that, P maintenance in 'Superb' and 'AAC Viewfield' was associated with a significant reduction in leaf Ψ s and OA contributed 0.53 MPa ('Superb') and 0.73 MPa ('AAC Viewfield'). Our data analyses provided no support for the existence of OA in 'Stettler'. Under water deficit, leaf g s was significantly higher in 'AAC Viewfield' compared to 'Stettler'; it was intermediate in 'Superb'. Together, drought tolerance in CWRS wheat cultivars is most likely linked to the degree of OA. 'Canada Western Red Spring' wheat cultivars are typically grown in rainfed areas with milder climates, but drought is increasing with climate change. Wheat can maintain yield under dry conditions through the physiological mechanism of osmotic adjustment. We show that two of three studied cultivars of 'Canada Western Red Spring' are capable of osmotic adjustment, permitting a degree of drought tolerance. [ABSTRACT FROM AUTHOR]

Biochar has been shown to improve soil properties and plant productivity in soils with inherently low fertility. However, little has been reported for upland corns under dry and wet precipitation regimes. This study investigates the effect of biochar addition on a range of soil physicochemical, biological, and hydrological properties, and corn growth and productivity under agrometeorological drought and wet conditions. Here, experiments were laid out in a randomized complete block design with three replications at two sites during 2017 and 2018 in South Korea. Treatments included (i) CN: control (ii) IF: inorganic fertilizer (N–P–K) at 145–30–60 kg ha−1; (iii) BS: barley straw at 5 t ha−1; (iv) CWBC: corn waste biochar at 5 t ha−1; (v) CWBC + IF: corn waste biochar + inorganic fertilizer; (vi) CWBC + BS: corn waste biochar + barley straw. The year 2017 was relatively dry, whereas the year 2018 was wet. Despite drought conditions in the year 2017, biochar facilitated soil water conservation. However, higher precipitation in 2018 increased the quantity and distribution of soil water and nutrients in the top 15 cm. Biochar reduced soil bulk density, and increased porosity, cation exchange capacity and total organic carbon in both years but increased total bacterial counts during the dry year only. Bacterial population was generally higher under wet conditions. Similarly, more soil CO2 was emitted in the wet year than in the dry year. Results further indicated that biochar can enhance corn biomass and grain yield regardless of precipitation conditions. The grain index was, however, affected by rainfall and was significantly different across treatments in the year 2018 only. All biomass, grain yield, and grain index were highest in CWBC + IF treatment and lowest under CN treatment. Indeed, biochar addition appeared to improve soil quality and soil conditioning effects in the drought and wet years, ameliorating soil and plant properties. Overall, biochar can improve water and nutrients storage, availability, and uptake, and therefore corn productivity during hydrological extremes. Highlights: Biochar application consistently increased soil water content. Biochar improved soil physicochemical characteristics in the drought and wet year. Biochar increased bacterial population during the drought year. Grain yield was higher in the wet year than in the drought year. Grain yield and grain index was highest under CWBC + IF and lowest under CN treatment. [ABSTRACT FROM AUTHOR]

[Objective] The study aims to clarify the dynamic changes and differences in water balance elements between Robinia pseudoacacia woodland and apple orchard, and to provide theoretical guidance for ecological sustainable development. [Methods] This study used the dual pore model and calibrated parameters in Hydras-1D to simulate the dynamic changes of various elements of water balance in Robinia pseudoacacia woodland and apple orchard from 2012 to 2021. [Results] The R² and RMSE of the two hole model in the optimization and validation periods of Hydras-1D were 0.61 and 0.76, respectively, and 0.026 and 0.048 cm³/cm³, respectively. The water balance errors in the simulation period were 0.18% and 0.04%, respectively; The transpiration of Robinia pseudoacacia forestland and apple orchard were (372±70) mm and (320±34) mm, respectively, and the evaporation was (256±44) mm and (288±36) mm. Variation of soil water storage was (-0.61±96) mm and (-3.26±87) mm, and deep leakage was (34±45) mm and (59±48) mm. [Conclusion] The model can better simulate the dynamic changes of water balance elements in Robinia pseudoacacia woodland and apple orchard. Compared with apple fields, Robinia pseudoacacia forest has a larger transpiration, a smaller evaporation and deeper leakage, and a more significant fluctuation in soil water storage. [ABSTRACT FROM AUTHOR]

Cover crops (CCs) can affect the cropping systems’ N dynamics and soil water content (SWC), but optimizing their potential effects requires knowledge of their growth pattern, N accumulation, and mineralization. For this purpose, a 3-year field experiment was initiated in northeast Italy involving a maize-soybean rotation. The objectives of this study were to (i) evaluate the use of time series vegetation indices (VIs) obtained from the Sentinel-2 satellite for monitoring the growth of CCs and estimating their biomass and N uptake at termination; (ii) investigate the effects of different CCs on cash crop yield and SWC; and (iii) use the simulation model CC-NCALC to predict the nitrogen contribution of CCs to subsequent cash crops. Three CC systems were tested: a fixed treatment with triticale; a 3-year succession of rye, crimson clover, and mustard; and a control with no CCs. Satellite imagery revealed that rye and triticale grew faster during the winter season than clover but slower compared to mustard, which suffered a frost winterkilling. Both grasses and mustard produced greater biomass at termination compared to clover, but none of the CC species affected SWC or yield and N uptake of the cash crop. A net N mineralization of all the CC residues was estimated by the model (except for the N immobilization after triticale roots residues). During the subsequent cash crop season, the estimated clover and mustard N released was around 33%, and the triticale around 3% of their total N uptake, with a release peak 2 months after their termination. The use of remote sensing imagery and a prediction model of CC residue decomposition showed potential to be used as instruments for optimizing the CCs utilization and enhancing cropping water and N fertilization management efficiency; however, it must be further analyzed with other CCs species, environmental conditions, and cropping systems. [ABSTRACT FROM AUTHOR]

Despite the mounting attention being paid to vegetation growth and their driving forces for water-limited ecosystems, the relative contributions of atmospheric and soil moisture dryness stress on vegetation growth are an ongoing debate. Here we comprehensively compare the impacts of high vapor pressure deficit (VPD) and low soil water content (SWC) on vegetation growth in Eurasian drylands during 1982–2014. The analysis indicates a gradual decoupling between atmospheric dryness and soil dryness over this period, as the former has expanded faster than the latter. Moreover, the VPD–SWC relation and VPD–greenness relation are both non-linear, while the SWC–greenness relation is near-linear. The loosened coupling between VPD and SWC, the non-linear correlations among VPD–SWC-greenness and the expanded area extent in which SWC acts as the dominant stress factor all provide compelling evidence that SWC is a more influential stressor than VPD on vegetation growth in Eurasian drylands. In addition, a set of 11 Earth system models projected a continuously growing constraint of SWC stress on vegetation growth towards 2100. Our results are vital to dryland ecosystems management and drought mitigation in Eurasia. [ABSTRACT FROM AUTHOR]

Background and Aims Plant nitrogen (N) acquisition via arbuscular mycorrhizal fungi (AMF) serves as a dominant pathway in the N nutrition of many plants, but the functional impact of AMF in acquisition of N by wetland plants has not been well quantified. Subtropical lake–wetland ecosystems are characterized by seasonal changes in the water table and low N availability in soil. Yet, it is unclear whether and how AMF alters the N acquisition pattern of plants for various forms of N and how this process is influenced by soil water conditions. Methods We performed a pot study with Carex thunbergii that were either colonized by AMF or not colonized and also subjected to different water conditions. We used 15N labelling to track plant N uptake. Key Results Colonization by AMF had little effect on the biomass components of C. thunbergii but did significantly affect the plant functional traits and N acquisition in ways that were dependent on the soil water conditions. The N uptake rate of AMF-colonized plants was significantly lower than that of the non-colonized plants in conditions of low soil water. A decreased NO3− uptake rate in AMF-colonized plants reduced the N:P ratio of the plants. Although C. thunbergii predominantly took up N in the form of NO3−, higher water availability increased the proportion of N taken up as NH4+, irrespective of the inoculation status. Conclusions These results emphasize the importance of AMF colonization in controlling the N uptake strategies of plants and can improve predictions of N budget under the changing water table conditions in this subtropical wetland ecosystem. [ABSTRACT FROM AUTHOR]

Soil moisture profile sensors (SMPSs) have a high potential for climate-smart agriculture due to their easy handling and ability to perform simultaneous measurements at different depths. To date, an accurate and easy-to-use method for the evaluation of long SMPSs is not available. In this study, we developed laboratory and field experiments to evaluate three different SMPSs (SoilVUE10, Drill&Drop, and SMT500) in terms of measurement accuracy, sensor-to-sensor variability, and temperature stability. The laboratory experiment features a temperature-controlled lysimeter to evaluate intra-sensor variability and temperature stability of SMPSs. The field experiment features a water level-controlled sandbox and reference TDR measurements to evaluate the soil water measurement accuracy of the SMPS. In both experiments, a well-characterized fine sand was used as measurement medium to ensure homogeneous dielectric properties in the measurement domain of the sensors. The laboratory experiments with the lysimeter showed that the Drill&Drop sensor has the highest temperature sensitivity with a decrease of 0.014 m3 m−3 per 10 °C, but at the same time showed the lowest intra- and inter-sensor variability. The field experiment with the sandbox showed that all three SMPSs have a similar performance (average RMSE ≈ 0.023 m3 m−3) with higher uncertainties at intermediate soil moisture contents. The presented combination of laboratory and field tests were found to be well suited to evaluate the performance of SMPSs and will be used to test additional SMPSs in the future. [ABSTRACT FROM AUTHOR]

An isotope-enabled module of Hydrus-1D was applied to a potted olive tree to trace water parcels originating from 26 irrigation events in a glasshouse experiment. The soil hydraulic parameters were optimized via inverse modelling by minimizing the discrepancies between observed and simulated soil water content and soil water isotope (18O) values at three soil depths. The model's performance was validated with observed sap flow z-scores and xylem water 18O. We quantified the source and transit time of irrigation water by analysing the mass breakthrough curves derived from a virtual tracer injection experiment. On average, 26% of irrigation water was removed by plant transpiration with a mean transit time of 94 hours. Our proof of concept work suggests that transit time may represent a functional indicator for the uptake of irrigation water in agricultural ecosystems. [ABSTRACT FROM AUTHOR]

Improving soil fertility by adopting several sustainable management practices that are a prime concern for plant growth. Organic waste addition to agricultural soil is becoming a common practice that improves physical, chemical and hydrodynamic properties and minimizes environmental impact. The use of some alternative nutrition sources as biochar and compost has been tested on two-year-old olive varieties 'Chemlali' and 'Koroneiki.' Three treatments were established "Cont" soil didn't amended, "Comp" soil amended with Compost (90% soil+10% compost), and "Bioc" soil amended with biochar (90% soil+10% biochar). All treatments were conducted under deficit irrigation receiving 50% of daily evapotranspiration. We evaluated soil–plant water status and relationships between all studied parameters. Results showed that soil water content was the lowest in non-amended treatments and did not exceed 10%. During experiment, compost amendment induced a better water plant status for both studied varieties less than −2 MPa for mean seasonal leaf water potential, while the biochar amendment induced a weak stress level indicated by the lower potential that reached a minimum value equal to −2.9 MPa. Crop Water Stress Index on biochar-amended soil was more important than that measured on other treatments which confirms the sensitivity of biochar treatment to hard conditions. High negative relationships have been found between soil water statuses and plant water statuses. The highest determination coefficient was between crop water stresss index and leaf water potential was about 0.85. In conclusion, the use of organic amendment is an approach for sustainable olive orchards under low water avaibility. [ABSTRACT FROM AUTHOR]

Plant species in alpine swamp meadow which is a successional stage of dried alpine wetland, is sensitive to changes in soil water content, and thus it is important to understand the responses of common species of alpine swamp meadow to changed soil water condition. In order to determine the effects of different soil water content on plants of alpine swamp meadow, we transplanted 17 common species from an alpine swamp meadow to a manipulated environment located in Maqu county of Gansu Province, eastern Qinghai-Tibetan Plateau. These plants were then subjected to three soil moisture regimes: flooding (FD), control treatment (CK), and slightly drought (SD). The net photosynthesis （A）, stomatal conductance (g) and leaf dry mass per unit area (LMA) were measured for leaves from 6 plants each species per treatment. We calculated the difference of A, g and LMA between FD or SD and CK for each species, and the relationships between A and g or LMA was analyzed. Results are as follows. (1) The LMA of alpine swamp meadow common species was significantly affected by soil water condition, and there were different responses among different species. (2) Significant habitat-specific responses of gas exchange to water condition were found among the species. (3) There were significant correlations between A and g under both treatments, but it was not for A and LMA. As a conclusion, the common species of alpine swamp meadow was strongly influenced by soil water content, in additional; there was significant habitat-specific responses of the morphological traits or physiological taints to different soil water condition. Our findings suggested that the species composition of alpine swamp meadow was very sensitive to change in soil water condition. In the context of global climate change, which is predicted to alter the precipitation regime of alpine area, will be significantly influence the composition and structure of alpine swamp meadow community in the future. This should be considered carefully for protection and restoration of alpine grassland. [ABSTRACT FROM AUTHOR]

Organic fertilizers are an important source of nutrients for improving farmland fertility. To explore high-yield, efficient and green production technology for oilseed flax in dryland agricultural areas, a field split plot experiment was conducted in the semi-arid area of the Loess Plateau in northwest China from April to August in 2020 and 2021. The study compared and analyzed the effects of different nutrient sources and their application rates on water consumption characteristics, grain yield and water use efficiency of oilseed flax. The main plots were fertilizer types (sheep manure, chicken manure and chemical fertilizer), while the subplots were fertilizer application rates (sheep manure: S1-12,500 kg·hm−2 and S2-25,000 kg·hm−2; chicken manure: C1-5800 kg·hm−2 and C2-11,600 kg·hm−2; chemical fertilizer: F1-N 112.5 kg·hm−2, P 75 kg·hm−2, K 67.5 kg·hm−2 and F2-N 225 kg·hm−2, P2O5 150 kg·hm−2, K2O 135 kg·hm−2). The results showed that compared with chemical fertilizers, organic fertilizers significantly increased the soil water storage capacity of the 0–160 cm soil layer during the whole growth period of oilseed flax and significantly reduced water consumption. During two growing seasons, the application of 25,000 kg·hm−2 sheep manure significantly reduced water consumption during the seedling-bud period and green fruit period-maturity period of oilseed flax by 16.13% and 23.19% compared with CK, respectively. Thousand-grain weight, yield and water use efficiency were significantly increased by 14.70%, 48.32% and 61.29%, respectively. These results indicate that the application of 25,000 kg·hm−2 sheep manure can significantly increase soil water storage capacity of the 0–160 cm soil layer, reduce water consumption during the whole growth period of oilseed flax and thus improve grain yield and water use efficiency of oilseed flax. It is a suitable fertilization technology for the high-yield, efficient and green production of oilseed flax in the semi-arid areas of northwest Loess Plateau. [ABSTRACT FROM AUTHOR]

Kale (Brassica oleracea, var. Acephala) contains complete nutrients that are very useful for health. The cultivation of kale plant requires adequate water. However, climate change results in erratic soil water supply and decreases plant productivity. This study investigated the effect of soil water content on morphology and physiology of kale and to determine optimum soil water content level for kale cultivation (100, 80, 60, 40 or 20%). Soil water content affected growth, fresh weight, kale plant biomass, and water use efficiency, but did not affect transpiration rate and leaf relative water content. Optimum soil water content for kale was 60% field capacity or 21.50% actual water content on a dusty loam soil, with a biomass of 12.35 g and water use efficiency of 106.38%. [ABSTRACT FROM AUTHOR]

Unlike traditional ridging, mulching broad ridges with a woven polypropylene fabric (WPF) can reduce soil evaporation during the drought season and avoid long saturation time in the root zone of pear trees during the rainy season. In this study, field experiments were conducted from 2017 to 2020 in a pear orchard in the North China Plain to investigate the effects of mulching broad ridges (0.3 m in height and 2 m in width) with WPF on soil temperature and moisture, nitrogen leaching, vegetative and reproductive growth of young pear trees (Pyrus bretschneideri Rehd. 'Yuluxiang'). The experiments involved two treatments, namely, control (traditional no-ridge planting without mulching) and mulching broad ridges with WPF (RM treatment). The results showed that the RM treatment increased soil moisture and temperature and decreased nitrogen leaching, resulting in vigorous growth of the young pear trees. Moreover, the RM treatment increased the tree trunk cross-sectional area and height of the young pear trees by 37% and 8% in 2020, respectively. The nitrate nitrogen content at the soil layer depth of 0e30 cm was significantly higher in the RM than that in control. Furthermore, the RM treatment significantly increased the fruit yield due to larger tree size. In addition, compared with control, significantly higher fruit soluble solid content of RM treatment was detected in 2020. High precipitation (423 mm) occurred during fruit enlargement stage in 2020, RM treatment decreased the rainfall infiltration in the ridge and the soil moisture in root region, resulting in the improvement of fruit quality, compared with control. Therefore, mulching broad ridges with WPF can be implemented to increase soil moisture during drought season, soil temperature, and nitrate nitrogen content, thereby improving the growth and fruit yield of young pear trees. Additionally, it can reduce soil moisture in the root zone during the rainy season and improve the fruit quality of the trees. Finally, it can reduce nitrate nitrogen leaching, thereby reducing environmental pollution. [ABSTRACT FROM AUTHOR]

Agriculture is a major consumer of freshwater and is often associated with low water productivity. To prevent drought, farmers tend to over-irrigate, putting a strain on the ever-depleting groundwater resources. To improve modern agricultural techniques and conserve water, quick and accurate estimates of soil water content (SWC) should be made, and irrigation timed correctly in order to optimize crop yield and water use. In this study, soil samples common to the Maltese Islands having different clay, sand, and silt contents were, primarily, investigated to: (a) deduce whether the dielectric constant can be considered as a viable indicator of the SWC for the soils of Malta; (b) determine how soil compaction affects the dielectric constant measurements; and (c) to create calibration curves to directly relate the dielectric constant and the SWC for two different soil types of low and high density. The measurements, which were carried out in the X-band, were facilitated by an experimental setup comprising a two-port Vector Network Analyzer (VNA) connected to a rectangular waveguide system. From data analysis, it was found that for each soil investigated, the dielectric constant increases notably with an increase in both density and SWC. Our findings are expected to aid in future numerical analysis and simulations aimed at developing low-cost, minimally invasive Microwave (MW) systems for localized SWC sensing, and hence, in agricultural water conservation. However, it should be noted that a statistically significant relationship between soil texture and the dielectric constant could not be determined at this stage. [ABSTRACT FROM AUTHOR]

[Objective] Water resources are shortage in the Loess Plateau. Exploring the impact of the individual rainfall on the change of soil water content in different land uses is of great significance to the theoretical exploration of the optimal allocation of regional water resources. [Methods] Based on the measured data of natural rainfall in runoff field of Nanxiaohegou in Qingyang. Gansu Province, and the observed data before and after rainfall under four land use patterns (agriculture, forest, grass and bare), the characteristics of soil water content changes in five different rainfall levels under different land use patterns were analyzed. [Results] (1) The dynamic change of soil water content is closely related to land use pattern. Among the four land use patterns, forest land has better water storage capacity than bare land, but the soil water content in bare land fluctuates the most under different rainfall levels. With the increase of soil depth, the response of surface soil moisture to rainfall is obvious, and there is a certain lag between the middle layer and the deep layer. (2) Under specific rainfall conditions, the water exchange at different depths of soil has obvious demarcation point of water active layer. Under heavy rain and rainstorm conditions, there is an obvious demarcation point of water active layer at 4() cm depth. Under moderate rain conditions, except for the significant difference in soil water content after rain, under other land uses, soil water content appeares obvious demarcation point of water active layer from 6() cm. (3) Under different land use patterns, rainfall characteristic factors had the lowest correlation with surface soil water content, but had the highest correlation with middle and deep soil water content. Compared with bare land, forestland, grassland and agricultural land have the greater regulation effects on soil water. Conclusion] The difference of soil infiltration response to rainfall under different land use patterns is closely related to the distribution of surface vegetation cover and underground vegetation root system. The gray correlation analysis of soil moisture changes provides the theoretical basis for the study of soil and water conservation in the Loess Plateau. [ABSTRACT FROM AUTHOR]

The change of soil water content in crop root system is the basis for the designing of water-saving irrigation scheduling. In order to explore the dynamic changes of soil water content, our study carried out long-term monitoring on the soil content at different depths in a typical citrus orchard. In this concern, water contents, salinities, and nitrate concentrations were measured weakly and were compared with the model predictions. One of the important perspectives is the growth restricting factor in the soil water, yield, and fruit quality of citrus. Combined with the meteorological data, the changing characters of soil water content and its responses to evapotranspiration and precipitation during the whole growth period were investigated. And then the changing process of soil moisture was simulated through the soil water balance model. The results showed that during the whole growth period of the citrus, the soil water content buried at 40 cm depth had the best correlation with that in the main active layer of citrus root system (0–60 cm), between which the correlation coefficient reached 0.988. Therefore, the depth of 40 cm could be used as the representative depth of soil water content monitoring. Under the combined effects of precipitation and evapotranspiration, soil depth could influence the changing process of soil water content, of which the effect weakened with the increase in depth. The water balance model within 1-week timescale was appropriate to simulate the changing process of soil water content. [ABSTRACT FROM AUTHOR]

Large area of soil moisture status diagnosis based on plant canopy spectral data remains one of the hot spots of agricultural irrigation. However, the existing soil water prediction model constructed by the spectral parameters without considering the plant growth process will inevitably increase the prediction errors. This study carried out research on the correlations among spectral parameters of the canopy of winter wheat, crop growth process, and soil water content, and finally constructed the soil water content prediction model with the growth days parameter. The results showed that the plant water content of winter wheat tended to decrease during the whole growth period. The plant water content had the best correlations with the soil water content of the 0-50 cm soil layer. At different growth stages, even if the soil water content was the same, the plant water content and characteristic spectral reflectance were also different. Therefore, the crop growing days parameter was added to the model established by the relationships between characteristic spectral parameters and soil water content to increase the prediction accuracy. It is found that the determination coefficient (R²) of the models built during the whole growth period was greatly increased, ranging from 0.54 to 0.60. Then, the model built by OSAVI (Optimized Soil Adjusted Vegetation Index) and Rg/Rr, two of the highest precision characteristic spectral parameters, were selected for model validation. The correlation between OSAVI and soil water content, Rg/Rr, and soil water content were still significant (p<0.05). The R², MAE, and RMSE validation models were 0.53 and 0.58, 3.19 and 2.97, 4.76 and 4.41, respectively, which was accurate enough to be applied in a large-area field. Furthermore, the upper and lower irrigation limit of OSAVI and Rg/Rr were put forward. The research results could guide the agricultural production of winter wheat in northern China. [ABSTRACT FROM AUTHOR]