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Although only representing 0.05% of global freshwater, or 0.001% of all global water, soil water supports all terrestrial biological life. Soil moisture behaviour in most models is constrained by hydraulic parameters that do not change. Here we argue that biological feedbacks from plants, macro-fauna and the microbiome influence soil structure, and thus the soil hydraulic parameters and the soil water content signals we observe. Incorporating biological feedbacks into soil hydrological models is therefore important for understanding environmental change and its impacts on ecosystems. We anticipate that environmental change will accelerate and modify soil hydraulic function. Increasingly, we understand the vital role that soil moisture exerts on the carbon cycle and other environmental threats such as heatwaves, droughts and floods, wildfires, regional precipitation patterns, disease regulation and infrastructure stability, in addition to agricultural production. Biological feedbacks may result in changes to soil hydraulic function that could be irreversible, resulting in alternative stable states (ASS) of soil moisture. To explore this, we need models that consider all the major feedbacks between soil properties and soil-plant-faunal-microbial-atmospheric processes, which is something we currently do not have. Therefore, a new direction is required to incorporate a dynamic description of soil structure and hydraulic property evolution into soil-plant-atmosphere, or land surface, models that consider feedbacks from land use and climate drivers of change, so as to better model ecosystem dynamics.

Wheat (Triticum aestivum L.) is a staple crop worldwide and yield improvement since the green revolution was attributed to chemical nitrogen (N) fertilizer application. The field experiment was performed from 2016 to 2020 in the eastern part of Loess Plateau, China, to study the effect of two sowing practices carried out before summer fallow, i.e., wide-space sowing (WS) and drill sowing (DS). The results indicated the soil water content, root length surface density (RLSD), at anthesis by drought was 44% under WS and 29% with DS, while the reduction in above-ground dry weight was 67% under WS and 56% under DS. More soil water was depleted from the deep soil layer (80–100 cm depth) than that in the shallow layer (20–60 cm depth). The average contribution rates of soil water content at sowing to grain yield under DS were 23–25%. Thus, drill sowing in summer fallow should be adopted for high water storage and yield stability. HIGHLIGHTS More soil water was depleted in the deep soil layer (80–100 cm depth) than that in the shallow layer (20–60 cm depth).; The reduction of RLSD at anthesis by drought was 44% under WS and 29% with DS, while the reduction in above-ground dry weight was 67% under WS and 56% under DS.;

The detailed evaluation of environmental parameters can be a great tool for the optimal selection and location of vegetable species, not only in vegetable production facilities and greenhouses but also in zoological and botanical gardens, which frequently maintain delicate and exotic plant species with strict environmental requirements in immersive exhibits where conditions can vary remarkably. This study, developed at an indoor zoological garden (Biodomo—Parque de las Ciencias de Granada, Spain), evaluates a sampling protocol for the determination of seven environmental parameters: daily light integral (DLI) was determined at nine different locations of the facility using a portable Light Quantum SQ-500 sensor; air temperature, atmospheric pressure, and air relative humidity were measured using a fixed ATMOS14 sensor; and soil temperature, soil water content, and soil conductivity were determined using a fixed TEROS12 sensor. Values recorded for DLI showed statistically significant variations across the nine different sampling locations, as well as between the different months in all sampling spots. Significant variations were also detected across the 12 months of study for the rest of environmental parameters evaluated, and correlations were found between the studied parameters, with the correlation between soil and air temperature the strongest (rs = 0.758) and soil temperature significantly superior to air temperature. The methodology described in this study can be easily reproduced in similar indoor zoological and botanical facilities, increasing the knowledge of the environmental conditions, and allowing corrections that could improve species selection, location, and management.

Assessing accuracies of satellite soil moisture (SM) products in areas with strong anthropogenic activities, abundant precipitation, and dense vegetation is important but limited. In this study, performances of nine satellite SM products, including the European Space Agency Climate Change Initiative (ESA CCI), and the ascending and descending products of the Advanced Microwave Scanning Radiometer 2 (AMSR2), Chinese Fengyun-3B (FY3B), Chinese Fengyun-3C (FY3C), and Soil Moisture Active Passive (SMAP), were evaluated against in-situ SM in the Yangtze River Delta (YRD) from 2015 to 2018. Results showed that the ESA CCI outperformed other products, with averaged correlation coefficient (R) of 0.522, correlation coefficient for SM anomalies (Rano) of 0.419, and unbiased root mean square error (ubRMSE) of 0.040 m3 m−3, followed by the SMAP_A and SMAP_D. Overestimation was observed in the AMSR2 products (Bias >0.081 m3 m−3), while underestimation was found in the FY3B and FY3C products (Bias

Introduction: Due to climate and underlying surface changes, flash floods occur frequently in northwest China, and the extreme rainstorm weather and flash floods along the eastern foot of Helan Mountain are increasing.Method: By constructing a hydrological model to simulate ten historical mountain flood events in the Suyukou watershed of the eastern foot of Helan Mountain, this study explores the constitutive relationship between rainfall and flood, evaluates accuracy, and analyzes errors. Six characteristic rain patterns were designed based on three parameters representing the position of rainfall peaks and the trend characteristics of rainfall, using 63 actual rainfall processes with a duration of 6 h selected from the rainfall stations of Suyukou watershed. Early warning indicators under different conditions were carried out based on the set of rain patterns.Results: The research results indicate that eight out of the ten simulated floods have passed the qualification test and the simulation results are good. The HEC-HMS hydrological model is suitable for simulating mountain floods in small watersheds and can provide good support for the simulation and early warning of mountain flood disasters.Discussion: Designing a rain pattern set based on actual data has put forward higher requirements for mountain flood warning and forecasting, making the warning more in line with the local actual situation and greatly improving the effectiveness of warning and forecasting.

The plant–water relationship of maize under conservation practices needs to be assessed to quantify the effectiveness of the practices in conserving soil water for crop production. This study evaluated in three trials how straw and plastic film mulching and organic manure application could potentially change water fluxes in the root zone and increase maize yield. A mathematical model HYDRUS-1D was calibrated against the observed soil water content and drainage data to predict the water fluxes in the root zone soil. The model simulated soil water dynamics in the root zone with satisfactory performance (RMSE of 0.6–2.3%, CD of 0.37–1.41, NSE of 0.18–0.88, and R2 of 0.62–0.91) during both the calibration and validation periods. The model predicted the observed drainage in a lysimeter with only a 5.5–11.7% bias and actual evapotranspiration (ETc) with a 2.6–6.7% bias for the control conditions in all three trials when the model was provided with measured plant growth, soil properties, and weather data. Both measurement and modeling confirmed that mulching augmented soil water storage by reducing ETc, i.e., 0.24–0.37 mm d-1 by straw mulching and 0.05–0.24 mm d-1 by plastic mulching during the trials. Manure application did not affect the ETc rate and resulted in the highest grain yield (6.8–8.3 Mg ha˗1) followed by plastic mulching (6.1–8.1 Mg ha˗1) and straw mulching (5.3–7.5 Mg ha˗1). Manure application increased the harvest index by optimally allocating biomass because of a steady supply of water and nutrients. The straw mulch, plastic mulch, and manure treatments increased grain yield by 13%, 24%, and 35%, respectively, compared to the control condition. Large-scale implementation of these practices would lessen blue water scarcity in agriculture.

Change in rainfall pattern with longer dry period depletes soil water content (SWC) and incorrect sowing time adversely affects rainfed sorghum production in Semi-Arid Tropics (SATs). The present study was conducted to develop agricultural water management strategies for improving SWC and to evaluate sowing time as climate change agro-adaptations for sorghum production in SATs. The field experiments on two land-water management (flatbed, broad bed furrows (BBF)) and four nutrient management (application of macro-and micronutrients through combination of chemical and organic fertilizers) were conducted in 2014 and 2015 at International Crops Research Institute for the Semi-Arid Tropics, India. The average SWC in ‘BBF’ was higher over ‘flatbed’ by 0.90 cm and 1.06 cm in 0–30 cm soil depth, 0.67 cm and 1.02 cm in 30–60 cm depth, 0.51 cm and 0.84 cm in 60–90 cm depth and, 0.34 cm and 0.67 cm in 90–120 cm during 2014 and 2015, respectively. The SWC in BBF was higher over flatbed by 7.28% throughout 0–120 cm soil depth during longest dry period of 26 days in the year 2014. The simulation analyses using DSSAT Version 4.6 for Coupled Model Intercomparison Project Phase 5 with RCP 4.5 stated that postponing the normal sowing time (30 June) to 10 July resulted in lower grain yield reduction i.e. 14.75% in 2030 and 19.37% in 2050 as compared to base period (1988–2007) yield with normal sowing in Parbhani location of India. The BBF combined with macro-and micronutrients application through chemical fertilizer and postponing sowing time was found the effective climate change agro-adaptation strategies for improving sorghum production in SATs. This study indicates the need for desired policy orientation by the government to promote integrated land-water-nutrient management as the effective agro-adaptations to climate change in SATs.

ABSTRACT Clay soil results in higher crop yield and quality than sandy soil. However, irrigation causes clay soil to slump easily, increasing compactness and decreasing soil oxygen content. This study investigated the effects of dry seeding and wet emergence on the soil microenvironment and cotton growth promotion in Xinjiang silt loam fields. The experimental design included three aerated and three non-aerated treatments. The results showed that aerated irrigation decreased dry density of the 0–20 cm soil layer to different degrees, the field capacity increased to different degrees, and the dry density and field capacity of the 20-30 cm soil layer did not change among the different treatments. The dry density and field capacity of WP2 treatment changed the most, the dry density of 0-10 cm and 10-20 cm soil layer were respectively 1.28 g cm-3 and 1.27 g cm-3, and the field capacity were respectively 35.23% and 35.7%. Under the same irrigation quota, the soil water content of the aerated treatments was lower than that of the non-aerated treatments. Aerated irrigation inhibited the horizontal diffusion of water and facilitated downward water transport. The WP2 treatment had the highest peak soil temperature at depths of 10 and 20 cm, and the WP2 treatment had the highest numbers of bacteria, fungi, actinomycetes, urease, and catalase activities, seedling emergence, primary root length, plant height, and stem thickness.

Analyzing the physiological response of trees to climate change in the Qilian Mountains region is key to studying the impact of global change on forest ecosystems in the semiarid alpine region of Northwest China. The leaf area index (LAI) of the canopy of a forest is an important input parameter for simulating carbon and water cycles in forest ecosystems. Studying the relationship between LAI and environmental factors can provide a scientific basis for accurately describing the structure, function, and ecohydrological processes of forest ecosystems and theoretically guide for sustainable management of water conservation in forests. Methods: In this study, the LAI of the Picea crassifolia canopy was monitored for 2 years (2015–2016) by field observations, and its dynamic changes were analyzed. The relations between LAI and air temperature (AT), precipitation (P), soil temperature (ST), and soil water content (SWC) were studied using Pearson's correlation and multiple regression analyses. The results were as follows: seasonal variations in LAI showed a single-peak curve, which first increased, reached a maximum, remained relatively stable, and then decreased. The maximum value was 4.02 and 4.18 relatively observed in mid-August 2015 and 2016. The LAI of the P. crassifolia canopy in different months was positively correlated with AT and P. It was correlated between the LAI of the canopy with ST40−60 in May and June (p < 0.05) and was also highly positively correlated between the LAI of the canopy with ST60−80, STmean, and SWC60−80 in July and August (p < 0.01). There was a positive correlation between the LAI of the canopy with SWC0−60 and SWCmean in July and SWC0−60 and SWCmean in August (p < 0.05). The LAI of the canopy was affected by AT and ST in May and July, AT and P in June, P in August, and P and ST in September. Our study implied that the rapid increase period of the LAI of the canopy was from late May to early July. The LAI of the canopy was more influenced by temperature and water in July and August. In addition, the LAI of the canopy has significant seasonal variation although it is evergreen coniferous tree species.

Abstract Spectral indices can be used as fast and non‐destructive indicators of plant water status or stress. It is the objective of the present study to evaluate the feasibility of using several spectral indices including water index (WI) and normalized spectral water indices 1–5 (NWI 1–5) to estimate water status in olive trees in arid regions in Iran. The experimental treatments involved two olive cultivars (Koroneiki and T2) and four irrigation regimes (irrigated with 100%, 85%, 70%, and 55% estimated crop evapotranspiration [ETc]). The results obtained showed that olive trees subjected to the different irrigation regimes of 85%, 70%, and 55% ETc experienced soil water content (SWC) deficits by 4.5%, 12%, and 20.5% that of the control, respectively. Significant differences were observed among the treatments with respect to measured relative water content (RWC), SWC, and the spectral indices of WI and NWI 1–5. The normalized spectral indices combining NIR and NIR wavelengths were found more effective in tracking changes in RWC and SWC than those that combine NIR and VIS or VIS and VIS wavelengths, respectively. Spectral indices were closely and significantly associated with RWC (.63**

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]

In order to explore the best irrigation and moisture conservation measures for open-air fresh grape vineyards in Northwest Hebei province, the effects of four irrigation and moisture conservation measures(drip irrigation, drip irrigation and film mulching, regulated deficit drip irrigation, and regulated deficit drip irrigation and film mulching) on soil moisture dynamics, water consumption, yield, and water use efficiency of Chunguang grape vineyards were studied with 5-year-old Chunguang grape as the test material and conventional irrigation as the control. The results showed that mulching of horticultural floor cloth (drip irrigation and film mulching, regulated deficit drip irrigation and film mulching) could increase the soil water content, the value of 0-100 cm soil layer treated by drip irrigation was the highest in the whole grape growth period, while regulated irrigation treatment had the lowest soil moisture content in the 0-100 cm soil layer. The water consumption of the five treatments was the highest from the fruit color changing stage to the mature stage and the lowest at the fruit setting stage. The water consumption of CK treatment in the whole growth period was 731.06 mm. Compared with CK, the water consumption of drip irrigation, drip irrigation film mulching, regulated deficit drip irrigation, and regulated deficit drip irrigation film mulching decreased by 4.29%, 2.99%, 8.82% and 12.07%, respectively; Compared with CK, drip irrigation and film mulching treatment increased fruit yield, while regulated deficit drip irrigation and regulated deficit drip irrigation and film mulching treatment decreased fruit yield. The irrigation water use efficiency of drip irrigation and film mulching treatment was the highest(10.69 kg/m³). Drip irrigation and film mulching treatment increased soil water content, reduced water consumption, improved fruit yield and irrigation water use efficiency, so it was the best irrigation and moisture conservation measure. [ABSTRACT FROM AUTHOR]

BACKGROUND: Undeviating climatic instabilities have increased the incidents of drought. Crop performance and yield attributes of tomatoes are negatively affected by drought stress. Biochar is an organic amendment that can increase crop yield and nutritional value under water‐deficient conditions by retaining water and providing nutrients (nitrogen, phosphorus, potassium, and other trace elements). RESULTS: The present study was designed to investigate the effects of biochar on tomato plant physiology, yield, and nutritional quality under deficit moisture regimes. Plants were subjected to two biochar levels (0.1% and 0.2%) and four moisture levels [100%, 70%, 60%, and 50% field capacities (FCs)]. Drought stress, especially 50D (50% FC), severely affected the plant morphology, physiology, yield, and fruit quality attributes. However, plants grown in biochar‐amended soil showed significant increase in the studied attributes. Plant height, root length, fresh and dry weight of root, the number of fruits per plant, fruit fresh and dry weight, ash percent, crude fat, crude fiber, crude protein, and lycopene contents were increased in plants grown in biochar‐amended soil under control and drought stress. CONCLUSION: Biochar at 0.2% application rate depicted a more pronounced increment in the studied parameters than 0.1% and can save 30% water without compromising tomato crop yield and nutritional value. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

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Understanding the response characteristics of fine roots to soil drought of different degrees is essential for revealing the ecological adaptability of trees to different water environments and diverse plant resource absorption strategies. This study focused on a Chinese white poplar (Populus tomentosa) plantation stand, which gradually experienced the process of deep soil drying. In 2019 and 2021, by measuring the fine-root length density (FRLD), mean root diameter (MRD), specific root length (SRL), and root tissue density (RTD) of 1920 root samples and continuously monitoring the soil water content (SWC) in 0–600 cm soil layers, we explored the response characteristics of fine-root distributions and morphological traits relative to soil drought of different degrees. The results showed that P. tomentosa primarily changed the fine-root vertical distribution rather than the total amount of fine roots for coping with soil drought of different degrees. Shallow soil drought induced more fine-root distributions in the deep soil layer, while drought in both shallow and deep soil further aggravated this trend. Shallow soil drought restrained shallow fine-root growth, yet deep soil drought promoted deep fine-root growth. The very deep fine roots (400–600 cm) were more sensitive to soil drought than shallow fine roots. The shallow soil drought significantly increased the SRL of very deep fine roots; in contrast, when deep soil drought also occurred, the MRD and SRL significantly increased and decreased, respectively. In addition, fine-root morphological traits exhibited significant vertical spatial and temporal variation. MRD increased and then decreased, and the RTD gradually decreased with depth, while SRL had an increased trend in the very deep soil layer (400–600 cm). When the rainy season came, MRD and SRL increased and decreased, respectively. In conclusion, when facing gradual deep soil drying, P. tomentosa will use a large range of rooting patterns to meet the water demand of the canopy. These patterns range from "drought tolerant strategies" by distributing more fine roots in the deeper soil layer where water is abundant to "drought tolerant strategies" by changing very deep fine-root morphological traits to improve water-absorbing and transporting efficiencies. Our findings provide insight into the ecological adaption strategy of tree root systems relative to soil drought of different degrees in arid and semi-arid regions and provide crucial theoretical support for developing water management technologies to cope with deep soil drying under climate change. [ABSTRACT FROM AUTHOR]

Black locust is the second-most-often planted tree worldwide, particularly for restoration plantations, but drought dieback and growth declines are being reported. Currently, we lack information on these ecosystems' water and carbon fluxes, in relation to climatic variability. Here, we employed eddy covariance to determine the gross primary production (GPP) and evapotranspiration (ET) of a black locust post-mining restoration plantation in NW Greece over c. 2.5 years. Additionally, we applied Generalized Additive Models (GAMs) to study the effects of key environmental drivers (vapour pressure deficit—VPD, soil water content—SWC, solar radiation—Rg and enhanced vegetation index—EVI) on GPP and ET during summer months. Both diurnally and seasonally, GPP increased with increasing Rg, SWC and EVI, but was saturated after certain thresholds (Rg: 400 W m−2, SWC: 25%, EVI: 0.65). In contrast, GPP declined strongly with increasing VPD. Overall, GPP was maintained at a high level, at the cost of ET, which constantly raised with increasing solar radiation and SWC and was not responsive to enhanced VPD, indicating a non-conservative water use. At present, these black locust plantations exhibit favourable productivity and no drought stress, but increasing VPD in the context of climate change may, ultimately, negatively impact these ecosystems. [ABSTRACT FROM AUTHOR]

Soil water content is an important indicator used to maintain the ecological balance of farmland. The efficient spatial prediction of soil water content is crucial for ensuring crop growth and food production. To this end, 104 farmland soil samples were collected in the Yellow River Delta (YRD) in China, and the soil water content was determined using the drying method. A gradient boosting decision tree (GBDT) model based on a tree-structured Parzen estimator (TPE) hyperparametric optimization was developed, and then the soil water content was predicted and mapped based on the soil texture and vegetation index from Sentinel-2 remote sensing images. The results of statistical analysis showed that the soil water content had a high coefficient of variation (55.30%), a non-normal distribution, and complex spatial variability. Compared with other models, the TPE-GBDT model had the highest prediction accuracy (RMSE = 6.02% and R2 = 0.71), and its mapping results showed that the areas with high soil water content were distributed on both sides of the river and near the estuary. Furthermore, the results of Shapley additive explanation (SHAP) analysis showed that the soil texture (PC2 and PC5), modified normalized difference vegetation index (MNDVI), and Sentinel-2 red edge position (S2REP) index provided important contributions to the spatial prediction of soil water content. We found that the hydraulic physical properties of soil texture and the vegetation characteristics (such as vegetation coverage, root action, and transpiration) are the key factors affecting the spatial migration and heterogeneity of the soil water content in the study area. The above results show that the TPE algorithm can quickly capture the hyperparameters that are most suitable for the GBDT model, so that the GBDT model can ensure prediction accuracy, reduce the loss function with less training data, and accurately learn of the nonlinear relationship between soil water content and environmental factors. This paper proposes a machine learning method for hyperparameter optimization that shows considerable potential to predict the spatial heterogeneity of soil water content, which can effectively support regional farmland soil and water conservation and high-quality agricultural development. [ABSTRACT FROM AUTHOR]

The soil water supply and atmospheric humidity conditions are crucial in controlling plants' stomatal behavior and water use efficiency. When there is water stress caused by an increase in saturated water vapor pressure (VPD) and a decrease in soil water content (SWC), plants tend to close stomata to reduce water loss. This affects the gross primary productivity (GPP) and evapotranspiration (ET), subsequently leading to changes in water use efficiency (WUE) and carbon use efficiency (CUE) in plants. However, land–atmosphere interactions mean that water vapor in the atmosphere and soil moisture content causing water stress for plants are closely related. This study aims to compare and estimate the effects of VPD and SWC on the carbon cycle and water cycle for different plant functional types. Based on the fluxnet2015 dataset from around the world, the WUE and CUE of five plant functional types (PFTs) were estimated under varying levels of VPD and SWC. The results showed that high VPD and low SWC limit the stomatal conductance (Gs) and gross primary productivity (GPP) of plants. However, certain types of vegetation (crops, broad-leaved forests) could partially offset the negative effects of high VPD with higher SWC. Notably, higher SWC could even alleviate limitations and partially promote the increase in GPP and net primary production (NPP) with increasing VPD. WUE and CUE were directly affected by Gs and productivity. In general, the increase in VPD in the five PFTs was the dominant factor in changing WUE and CUE. The impact of SWC limitations on CUE was minimal, with an overall impact of only −0.05μmol/μmol on the four PFTs. However, the CUE of savanna plants changed differently from the other four PFTs. The rise in VPD dominated the changes in CUE, and there was an upward trend as SWC declined, indicating that the increase in VPD and decrease in SWC promote the increase in the CUE of savanna plants to some extent. [ABSTRACT FROM AUTHOR]

Transpiration (Tr) is the largest continental water flux. Tr is jointly affected by biophysical factors, including atmospheric demand, soil water supply, and plant physiological features, represented by potential evapotranspiration (PET), soil water content (SWC), and leaf area index (LAI) respectively. Disentangling the independent and interacting impacts of the biophysical factors on Tr provides a better understanding on the mechanism of ecohydrological controls on forest water use. In this study, taking the black locust plantation of the Loess Plateau as an example, independent contributions of the three factors and their interactions on Tr were quantified based on field observation, model development, and factorial analysis. First, sapflow density, meteorological variables, SWC, and LAI were observed during five growing seasons. Second, a coupled Tr model (R2 = 0.85, RMSE = 5.92) was established by the long‐term observed data of Tr, PET, SWC, and LAI. Finally, factorial experiment analysis showed that contributions of LAI, PET, and SWC and their interactions (PET×LAI, LAI × SWC, and PET×SWC) on Tr accounted for 50.82%, 9.77%, 9.30%, 13.88%, 13.75%, and 2.47%, respectively. The results indicated that LAI and PET×LAI had the largest independent and interacting impact on Tr of black locust. This study suggested that regulation of canopy leaf area through forest cultivation practices could reduce forest water use, which was beneficial for soil desiccation mitigation and meeting the soil water capacity for vegetation in this region. This study also provided a methodological reference for disentangling the impacts of biophysical factors on forest transpiration. [ABSTRACT FROM AUTHOR]

Mustard cover crops can provide multiple soil health benefits but may adversely affect cash crops by depleting soil water. This was tested in a center-pivot irrigated corn cropping system in southwest Texas from 2018 to 2020. Changes in biomass growth of both the cover crops and corn, and soil water content in the root zone were monitored multiple times during the main growth periods of the crops. Upon termination, biomass production of cover crops averaged 4271 kg/ha, with equivalent nitrogen and phosphorus inputs to the soil of 92 kg/ha and 12 kg/ha, respectively. Over 2 years, water use during the main growth period of the mustard cover crops and the fallow area averaged at 1.4 mm/day and 1.1 mm/day, respectively, and water use of corn following the mustard and fallow averaged at 4.0 mm/day and 3.7 mm/day, respectively, although the differences were only marginally significant. Our data suggest that water use of cover crops was affected by their growth patterns. The mustard cover crops depleted soil water in a dry year (2019–2020), but to a less extent in a wet year (2018–2019). In either year, however, corn yield was not reduced in association with cover crop use, although the improved shoot biomass growth in corn associated with mustard cover crops was observed in the wet year but not in the dry year. Mustard cover crops tended to reduce deep drainage during the corn seasons, which has implications in preventing the leaching loss of nitrogen in the crop root zone. [ABSTRACT FROM AUTHOR]

Background: Soybeans are the main sources of oil and protein for most of the global population. As the population grows, so does the demand for soybeans. However, drought is a major factor that limits soybean growth. Methods: The nitrogen content in different parts of the soybean under drought stress and rehydration was investigated using the soybean cultivars, HN44 and HN65, at different growth stages (vegetative growth, parallel period of vegetative growth and reproductive growth and reproductive growth). Result: During the vegetative growth stage, drought decreased the plant's nitrogen content. After rehydration, all the organs showed different degrees of compensatory effects. During the parallel period of vegetative and reproductive growth, drought decreased the nitrogen content of the leaves. After rehydration, the nitrogen content was partially restored. During the reproductive growth period, drought affected the translocation of nitrogen to the sink. After rehydration, the nitrogen content increased in the pods and decreased in other parts. In summary, rehydration after drought during the vegetative growth period of soybean can lead to nitrogen accumulation, but the reproductive growth phase differs from earlier; therefore, this period should avoid drought stress. [ABSTRACT FROM AUTHOR]

The retrieval of crop growth status using Global Navigation Satellite System Interferometric Reflectometry (GNSS-IR) has become a major area of interest within the field of vegetation remote sensing in recent years. Using only a single GNSS antenna, it is difficult to determine the crop growth status and soil water content (SWC) in vegetation-covered regions due to plenty of multi-path signals. Based on the empirical mode decomposition and the spectrum difference, this study presents an algorithm that can decompose and separate signals reflected by the soil surface or corn canopy. Because the low-roughness soil surface is isotropic while the corn canopy is anisotropic, the signals reflected by the soil surface have a higher proportion of coherent components than those reflected by the corn canopy. The moduli between the retrieved heights and the actual heights (for the same interval from different satellites) have the least variance. In this study, the signals reflected by the soil surface and the corn canopy are separated using the variance of retrieved heights. When the corn grows taller than the GNSS antenna, the vegetation water content (VWC) of the corn leaves becomes the primary factor affecting the direct signal's intensity, as the leaves obstruct the signal. Hence, the VWC of corn leaves can be calculated through the power attenuation of signals. An experiment performed on a plot of land covered with corn shows that, after multi-GPS-satellite fusion, the correlations between the retrieved corn canopy height, leaf VWC, soil water content (SWC), and in situ data reach 0.94, 0.92, and 0.88, respectively. The corresponding root mean square errors are 0.195 m, 0.0055 kg/cm 2 , and 0.0484 cm 3 /cm 3 , respectively. [ABSTRACT FROM AUTHOR]

The purpose of the research was to study the soil water content (SWC) and water use efficiency (WUE) of sugar beet (Beta vulgaris L.) and its aftercrop spring barley (Hordeum vulgare L.) under the influence of crop rotation, fertilisation system, and weather conditions. A long-term field experiment was established in the Central Forest Steppe zone of Ukraine. The experiment included the following six-field crop rotations: (i) cereal, fodder, and tilled, (ii) tilled, and (iii) cereal and tilled. In the experimental field, sugar beet fertilisation was mineral (N100P90K90) and organic-mineral (40 t ha-1 cattle manure + N100P90K90). Regardless of crop rotation, sugar beet plants used water more efficiently under mineral and organic-mineral fertilisation with the WUE reaching 67-76 m³ t-1, which is 2.1-2.5 times lower compared to zero fertilisation (control). The WUE of spring barley was 277-372 m³ t-1 under residual effect of mineral and organic-mineral fertilisation and 428-458 m³ t-1 under zero fertilisation of sugar beet. Fertilisers applied to sugar beet provided an additional 100-122 mm of SWC (0-150 cm soil layer) for its aftercrop spring barley, while with zero fertilisation the SWC was only 58-79 mm. It can be concluded that organic-mineral fertilisation applied to sugar beet is more effective compared to mineral fertilisation, as it provides a significant additional water reserve to the aftercrop spring barley. [ABSTRACT FROM AUTHOR]

As climate change progresses, the frequency and duration of drought stress events are increasing. While the mechanisms of drought acclimation of trees has received considerable attention in recent years, the recovery processes remain critically understudied. We used a unique throughfall exclusion experiment in a mature temperate mixed forest consisting of the more isohydric Norway spruce and more anisohydric European beech, to study the recovery and resilience after drought release. We hypothesized that pre-dawn water potential (ΨPD) of both species will increase within 1 day after watering, while the recovery of stomatal conductance (g s) and the reversal of osmoregulation will be significantly delayed in the more isohydric spruce. Furthermore, we hypothesized that the xylem sap flow density (u daily) will not fully recover within the growing season due to the strong drought impact. After 5 years of summer drought, trees showed significantly reduced ΨPD, u daily and increased osmoregulation in leaves, but only isohydric spruce displayed increased leaf abscisic acid concentrations. In line with our hypothesis, ΨPD and g s recovered within 1 day in beech. Conversely, isohydric spruce showed delayed increases in ΨPD and g s. The delay in recovery of spruce was partially related to the replenishment of the stem water reservoir, as indicated by the missing response of u daily at the crown base compared with DBH level upon watering. However, u daily fully recovered only in the next growing season for beech and was still reduced in spruce. Nevertheless, in both species, osmotic acclimations of leaves were reversed within several weeks. While both species displayed full resilience to drought stress in water-related physiology, the recovery time was in several cases, e.g. u daily, ΨPD and g s, shorter for beech than for spruce. With future increases in the frequency of drought events under ongoing climate change, tree species that recover more quickly will be favored. [ABSTRACT FROM AUTHOR]

Soil color is a critical property, providing important information on soil properties. Soil color highly spatially varies on cultivated semi-arid sloping landscapes, indicating differences in soil properties that affect soil fertility. This study evaluated the relationships between color variables (L*: soil brightness, a*: redness, and b*: yellowness) and some basic soil properties on air dry and wet (around field capacity) soil samples, in a semi-arid sloping landscape having been under wheat cultivation for a long time. The values of color variables and soil properties were graphed and relationships between them were modeled using most proper regression models. The soil properties were poorly related to values of a* and b*, while CaCO3, sand, clay, and K contents and EC were highly significantly correlated with values of L*-wet (L*-values obtained on moist soil samples). Soil EC and CaCO3 content can be safely predicted by L*-wet in the study area. Also, the L*-wet should be preferred over L*-dry in predicting soil properties from soil color components in the study area and similar soils. [ABSTRACT FROM AUTHOR]

Clarifying the variations of sap flow rate of spring maize in the typical mollisol area and its main control factors is of great significance to explore water consumption from transpiration and regulate field water management. In this study, we installed the wrapped sap flow sensors and TDR probes to continuously monitor the sap flow rate of spring maize during filling-maturity stage and soil water and heat conditions of topsoil. In combination with meteorological data collecting from a nearby automatic weather station, we analyzed the correlation between the sap flow rate of spring maize and environmental factors at different time scales. The results showed that the sap flow rate of spring maize in typical mollisol area had an obvious fluctuation of high diurnal and low nighttime. The instantaneous sap flow rate peaked at daytime, with a value of 139.9 g ⋅ h-1, but being weak at nighttime. The starting time, closing time, and peak values of spring maize sap flow were significantly inhibited in cloudy and rainy days, compared with that in sunny days. On hourly scale, the sap flow rate was significantly correlated to solar radiation, saturated vapor pressure deficit (VPD), relative humidity, air temperature, and wind speed. On daily scale, only solar radiation, VPD, and relative humidity were significantly correlated with sap flow rate, with the absolute values of correlation coefficient being all above 0.7. Due to high soil water content during the observation period, the sap flow rate was not significantly correlated with soil water content and soil temperature of 0-20 cm layer, with the absolute values of correlation coefficient being less than 0. 1. Under the condition without water stress, solar radiation, VPD, and relative humidity were the top three influencing factors of sap flow rate in this region, on both hourly scale and daily scale. [ABSTRACT FROM AUTHOR]

Copyright of Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study evaluates the effects of shading nets with photoselective features, with an open-field control. A green-shade net with a shading intensity of 40% intensity and blue, pearl, and yellow-shade nets with shading intensity of 75% were used as netting materials and the total radiation and photosynthetically active radiation (PAR) transmittance of the shade nets were analysed. The environmental conditions such as air temperature, relative humidity, and canopy temperature were measured with the aid of appropriate sensors. Tomatoes were grown to determine the effects of shade nets on crops cultivated under the four shade nets, and an additional treatment (control) was used in which tomatoes were grown under full sun conditions. The vegetative growth parameters, fruit quality parameters and yields were assessed and the findings showed that shading resulted in a significant increase in the total yield and pearl-shade nets are the best choice for producing a high quality tomato crop based on PAR transmittance (between 44.8% and 52.8%). [ABSTRACT FROM AUTHOR]

Soil moisture (SM) and temperature (ST) are critical factors in forest eco-hydrological research. In this study, we investigated the inter- and intra-annual changes in SM and ST profiles in a mixed Mediterranean maquis forest stand together with soil and meteorological parameters. Hourly data from three field measurements points at four depths (−5, −20, −40 and −70 cm) for 6 years were interpolated using the kriging method to produce annual SM and ST profiles. The results indicate that air temperature highly affects the upper 5 cm of the mineral soil. In general, it increases with depth in winter at an average rate of 0.036 °C/cm and decreases in summer (0.035 °C/cm), presenting higher values compared to air temperature from April to August and lower ones during the rest of the period. Precipitation is the main factor driving SM variations up to a superficial soil depth of 40 cm. The upper soil layer (0–40 cm) infiltrates water faster and presents high SM variability, especially in monthly and seasonal (year to year) time steps. The maquis forest stands are likely to be strongly affected by climate change, therefore the results of this study could be useful in hydrological and climate change studies focused on maquis vegetation water management. [ABSTRACT FROM AUTHOR]

Purpose: Inconsistent controlling factors of soil water content (SWC) spatial variation across regions and spatial scales have been acknowledged in previous studies. However, universal principles explaining these inconsistencies are still needed to be explored. The main aim of this study was to conclude the universal principles across regions and scales. Materials and methods: In this study, based on the surface (< 10-cm soil depth) SWC dataset from Meng et al. (2021) (https://doi.org/10.5194/essd-13-3239-2021) and the relevant environmental variables (climate including temperature and precipitation, topography including elevation and slope, soil including sand and clay contents, and vegetation including normalized difference vegetation index or NDVI) in a 1500 km × 1500 km study region in China, we calculated the correlations between them, and identified the controlling factors of surface SWC in different subregions and at different spatial scales. Results and discussion: Local factors like temperature, precipitation, and clay content that controling the vertical soil water replenishment and removal dominated the surface SWC spatial variation in this dry study region (mean SWC ≤ 0.10 m3 m−3). Nonlocal factors like topography (e.g., elevation and slope) and soil porosity (sand content) determining the lateral soil water redistribution had outweighed effects in the representative wet subregion. In addition, topography also exerted considerable effects on SWC in this study region due to its great spatial variability, especially when spatial scale < 800 km. As NDVI was complicatedly controlled by other environmental variables, its effect on SWC performed dramatic regional differentiation. In contrast, effect of slope on SWC was more associated with its spatial variability as it was independent from other environmental variables. Conclusions: This study emphasized that the inconsistencies of controlling factors of SWC spatial variation can be comprehensively explained by different regimes in the dry and wet conditions, spatial variability of environmental variables and the interactions among different environmental variables. These findings can deepen our understanding of the controls on SWC spatial variation across regions and scales. [ABSTRACT FROM AUTHOR]

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Afforestation is an approach for ecological restoration. Soil total phosphorus is one of the important ecological and evolutionary elements for carbon cycles and plant growth following afforestation. However, studies on soil total phosphorus of afforestation on abandoned ponds with different slopes are still lacking. Soil total phosphorus and other soil properties from afforestation sites with different slopes were investigated. Soil total phosphorus, total nitrogen, bulk density, soil water contents and pH of poplar (Populus spp.) plantation sites (Slope 1) with a steep slope and pond cypress (Taxodium spp.) plantation sites (Slope 2) with a flat slope were determined. Soil total nitrogen stocks, soil total phosphorus stocks and the ratio of soil total nitrogen to total phosphorus (N:P) were calculated. Results showed that soil bulk density, soil water content, total phosphorus, total phosphorus stocks and total nitrogen stocks of three soil layers at Slope 1 were significantly lower than those of Slope 2. N:P of Slope 1 was significantly higher, but no significant difference of total nitrogen and pH were found between the two sampling sites. Soil bulk density, soil water content and total nitrogen had significant positive relationships with both total phosphorus and total phosphorus stocks. No obvious correlation was found between pH and total phosphorus or total phosphorus stocks. Redundancy analysis (RDA analysis) suggested that soil water content and bulk density had the most important individual effect on total phosphorus and total phosphorus stocks with values at 59.3% and 59.5%, respectively. It is recommended that afforestation on a flat or gentle slope rather than on a steep gradient could be helpful for accumulation of soil total phosphorus and phosphorus stocks and could decrease the risk of soil phosphorus loss, when afforestation is used for ecological restoration. [ABSTRACT FROM AUTHOR]

An addition of straw interlayer in the 0.40 m soil depth could effectively reduce salt accumulation in the surface soils by regulating water fluxes, thus mitigating the salt stress to the crop growth and development. However, the positive effects of straw interlayer were weakened with straw decomposition, and whether we could use sand (an indecomposable substance) instead of straw for saline soil amelioration still needs further investigation. Therefore, a three-year field experiment was established with straw and sand interlayers, as well as with no interlayer as a control. Straw interlayer demonstrated an increase of 4.85~13.10% of water content, while the sand interlayer increased 12.41~16.48% of water content in the soil layer of 0–0.40 m depth comparing to the control. Salt contents were lowered by 10.69~17.01% in the same soil layer of the straw interlayer and lowered by 7.00~7.59% in the sand interlayer treatment after irrigation. Data also shows that irrigation significantly increased water content and lowered salt accumulation in the soil plough layer, thus increasing the sunflower emergence rate of 10.49~13.54% in the straw interlayer treatment and 12.53~14.78% in the sand interlayer treatment, respectively. Both the straw interlayer and sand interlayer treatments effectively reduced the evaporation of groundwater and established a beneficial plough layer with a lower salt accumulation throughout the sunflower growth period. At harvesting stage, the evaporation fluxes of salt in the straw interlayer and sand interlayer treatments were significantly lower than that in the control treatment. Lower salt accumulation conferred a beneficial promotion for the growth of sunflower, while the grain yields in the straw interlayer treatment were increased by 8.67% in 2018, 11.00% in 2019 and 17.37% in 2020 compared to the no-interlayer soil, respectively. However, the low water content in the soil layer of 0–0.40 m depth in the sand interlayer treatment inhibited the growth of sunflower, resulting in a significant decrease in the seed yields. It is worth noting that the precipitation effectively alleviated water stress on the sunflower at the middle and late growth stage in the sand interlayer treatment. This study suggests that a maize straw burial of 0.05 m thickness at a depth of 0.40 m soil layer could be used as an effective tillage practice that could improve the distribution of water and salt in saline soils. [ABSTRACT FROM AUTHOR]

Soil moisture content changes caused by rainfall and other factors can significantly affect slope stability and potentially lead to geological disasters, such as landslides and debris flows. However, conventional finite element methods for strength reduction do not consider the impact of water content on slope stability. This paper examines classical finite element methods for reducing the double strength coefficient and then introduces a novel approach using changes in moisture content. The new method is implemented through the use of an ABAQUS FE program's USDFLD user-defined subroutine. This paper concludes by contrasting the outcomes derived from the limit equilibrium technique and other techniques and verifying the accuracy of the suggested approach through theoretical and numerical simulations. The numerical calculations for the stability evaluation of the Azhuoluo slope in the Chinese province of Guizhou, Shuicheng county were performed utilizing the ABAQUS FE platform's USDFLD user-defined subroutine based on the double-strength discounting method, in response to the large landslide disaster in the region. The results show that the red clay, formed from the weathering of basalt in the area, experiences asynchronous decay in both friction angle and cohesion as the water content increases, with a significantly higher decay rate in the internal friction angle compared to cohesion. This indicates that traditional finite element methods that synchronously discount the internal friction angle and cohesion do not correspond to reality, whereas this proposed double-strength discounting method, based on water content changes, accurately reflects the essential characteristics of slope instability and has clear physical meaning and practical engineering applications. [ABSTRACT FROM AUTHOR]

Stable hydrogen and oxygen isotopes provide a powerful technique for quantifying the proportion of root water uptake (RWU) from different potential water sources. Although many models coupled with stable isotopes have been developed to estimate plant water source apportionment, inter-comparisons of different methods are still limited, especially their performance under different soil water content (SWC) conditions. In this study, three Bayesian tracer mixing models, which included MixSIAR, MixSIR and SIAR, were tested to evaluate their performances in determining the RWU of winter wheat under various SWC conditions (normal, dry and wet) in the North China Plain (NCP). The proportions of RWU in different soil layers showed significant differences (p < 0.05) among the three Bayesian models, for example, the proportion of 0–20 cm soil layer calculated by MixSIR, MixSIAR and SIAR was 69.7%, 50.1% and 48.3% for the third sampling under the dry condition (p < 0.05), respectively. Furthermore, the average proportion of the 0–20 cm layer under the dry condition was lower than that under normal and wet conditions, being 45.7%, 58.3% and 59.5%, respectively. No significant difference (p > 0.05) was found in the main RWU depth (i.e., 0–20 cm) among the three models, except for individual sampling periods. The performance of three models in determining plant water source allocation varied with SWC conditions: the performance indicators such as coefficient of determination (R2) and Nash-Sutcliffe efficiency coefficient (NS) in MixSIAR were higher than that in MixSIR and SIAR, showing that MixSIAR performed well under normal and wet conditions. The rank of performance under the dry condition was MixSIR, MixSIAR, and then SIAR. Overall, MixSIAR performed relatively better than other models in predicting RWU under the three different soil moisture conditions. [ABSTRACT FROM AUTHOR]

This study was about the water-nitrogen regulation model and its soil nutrient environment effect for increasing the yield and efficiency of Bromus inermis in the Hexi Corridor, Gansu Province, China. Bromus inermis was used as the research object in this study and four irrigation management types and four nitrogen application levels were set. The four irrigation management types (controlled by the percentage of field capacity (θf) at the jointing stage) were 75–85% (W0), 65–85% (W1), 55–85% (W2) and 45–85% (W3). The four nitrogen application levels were pure nitrogen 0 kg·ha−1 (N0), 60 kg·ha−1 (N1), 120 kg·ha−1 (N2) and 180 kg·ha−1 (N3). The effects of water-nitrogen regulation on the spatial and temporal distribution of soil moisture and nitrate nitrogen (NO3−–N), plant height, chlorophyll content, yield and water-nitrogen use efficiency of Bromus inermis were studied. Results demonstrated that (1) soil water content (SWC) was mainly affected by irrigation and W1 treatment helped maintain shallow soil (0–40 cm) water's stability and avoided water redundancy or deficit in the 60–80 cm soil layer. The distribution of soil NO3−–N was mainly affected by nitrogen application. The N2 treatment could effectively increase the NO3−–N content in shallow soil (0–40 cm) and prevent nitrate-nitrogen leaching in the 60–100 cm soil layer. (2) Irrigation and nitrogen application could significantly increase the plant height and chlorophyll content of each cut of Bromus inermis. The average plant height and chlorophyll content of the N2W1 treatment were 66.99% and 30.30% higher than N0W3. (3) At the same time, irrigation and nitrogen application could significantly increase the yield of each cut of Bromus inermis, and the interaction between the two had a significant effect on the total yield. The total yield of the N2W1 treatment was the highest (12,259.54 kg·ha−1), 157.95% higher than N0W3. Irrigation and nitrogen application could significantly improve the water-nitrogen use efficiency of Bromus inermis, and their interaction only significantly impacted the partial-factor productivity of the applied nitrogen (PFPN). Meanwhile, the N2W2 treatment had the highest water use efficiency (WUE) (23.12 kg·m−3), and the N1W1 treatment had the highest PFPN (170.87 kg·kg−1). In summary, the moderate nitrogen application rate (120 kg·ha−1) combined with mild water deficit (65–85% θf at the jointing stage) could not only promote the high yield of Bromus inermis, but also avoid the leaching of water and nitrogen in deep soil. It is a suitable water and nitrogen management mode for Bromus inermis in the Hexi Corridor of Gansu Province, China. [ABSTRACT FROM AUTHOR]

Leaf respiration drives plant energy use and greatly influences global carbon balance. It is inhibited by light. The climate-driven effects of changes in nitrogen deposition and soil moisture on leaf respiration in light (RL) are not well understood. To better understand the response of RL and its inhibition by light, we experimentally determined RL and light inhibition degree, an index of the inhibitory effect of light on leaf respiration with respect to dark leaf respiration, for potted specimens of an evergreen conifer species (Pinus koraiensis) and a deciduous broadleaved species (Tilia amurensis) in Changbai Mountains forests that were subjected to soil nitrogen and moisture treatments. RL increased as nitrogen deposition increased to a particular level (46 kg/ha/y N), when enzymes and mineral nutrients became imbalanced. RL decreased as soil moisture decreased to a drought level. Light inhibition degree behaved inversely to RL, and the average range for both species combined was 42.0%-78.4% for nitrogen treatments and 58.3%-87.0% for soil moisture treatments. The results are fundamental to accurate modeling of terrestrial carbon budgets and assessment of the carbon economy in forest ecosystems in a rapidly changing climate. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plant–soil water relations are important for understanding the development of plant communities, especially in arid and semiarid areas. However, the interactions between vegetation characteristics and soil water dynamics in the restored grasslands along succession chronosequence were limitedly understood. In this study, we measured the functional traits of dominant species, plant community characteristics and soil water dynamics in grasslands restored for 5, 15, and 30 years (RG5, RG15 and RG30, respectively), and investigated the linkage between plant traits and soil water at the community/plot scale. The results showed that soil water content was high at RG5, while soil water storage increment at RG5 was low. With soil water content highest at RG5 (16.25%), decreased at RG15 (14.81%), and then recovered in some degree at RG30 (15.2%), dominant plant species changed from pioneer species Artemisia capillaries to perennial legume Lespedesa davurica with high specific leaf area, and finally to perennial forb Stipa bungeana with low specific leaf area and low shoot/root ratio. Plant community characteristics including aboveground biomass, vegetation coverage, species diversity all increased with restoration and reached the highest value at RG15 or RG30. Aboveground biomass of perennial grass, as well as species richness showed a significantly positive relationship with soil water recharge and soil water storage increment at deeper layers (10–120 cm and 40–120 cm). Species diversity had positive correlations with soil water content in 0–10 cm layer, a negative correlation with soil water storage increment in 0–10 cm layer and no correlation in 10–20 cm layer. Our findings suggested that changes in soil water content might enhance perennial grass species in semiarid grasslands, and time lag also existed in the plant–soil water interactions. [ABSTRACT FROM AUTHOR]

The Qinghai-Tibet Plateau (QTP) possesses the largest areas of permafrost in the mid-and low latitude regions on the earth and many large lakes in the permafrost area. Based on a comprehensive investigation around certain typical lakes, this study found that although the presence of lakes formed different ranges of unfrozen zones in permafrost, the heating effect of lake water on surrounding permafrost is limited to a small extent. The temperature of permafrost around the lake is closely related to the distance to the lake and the ice content of the permafrost. Around lakes are ice-rich permafrost zones and permafrost temperature in this area is significantly lower than that far away from the lake, which indicates that the existence of lakes in the QTP has special effect on the permafrost distribution. Based on the monitoring results, this study presents the typical distribution pattern of the permafrost around large lakes and discusses the reasons for the distribution pattern. Due to the huge area of lakes and the significant impact of lakes on permafrost distribution, it is suggested to re-estimate the total permafrost area and underground ice storage in the QTP. [ABSTRACT FROM AUTHOR]

The current climate emergency and its associated impacts on forest ecosystems are leading forest owners and managers to consider a broader diversity of species to enhance forest resilience. In this context, there is a growing interest in lesser-used timber species, such as silver birch, a promising candidate for forest diversification in Western Europe. Estimates of site productivity are essential to guide forest management decisions, but have not yet been accurately determined for silver birch in northwestern Europe. This study pursuits two main goals: (a) providing dominant height growth curves for birch in southern Belgium; (b) identifying the key biophysical factors affecting the productivity of silver birch within the study area. In this study, we tested and compared 16 growth models on a stem analysis dataset gathering the past height growth of 68 birch trees from 40 stands. The Duplat and Tran-Ha I model best predicted the dominant height growth. Using this model, the site index (SI) was estimated for 103 stands distributed throughout the study area and its variation was modeled in response to biophysical variables (climatic, edaphic and topographic). The best selected model (R² adj=0.50) revealed a positive effect of mean annual temperature on the SI, although limited when maximal soil water content was low. This model was ultimately used to map the spatial variation in birch yield potential in the study area, highlighting the ecological conditions under which birch silviculture could be promoted. • We modeled top-height growth of silver birch with stem analysis dataset. • Site index was modeled in response to biophysical variables. • Birch productivity is promoted by temperature and soil water content. • The positive effect of temperature is limited by soil water content. • Maps illustrating birch productivity have been produced for southern Belgium. [ABSTRACT FROM AUTHOR]

The profile of crop water uptake from the soil depends on rainfall regime (amount, seasonality, frequency distribution of rainfall event size), soil, crop, and management. This study, with a focus on winter wheat in a wheat-fallow system, combines measurements of hydrogen (δD) and oxygen (δ18O) isotopes with a Bayesian mixing model (MixSIAR), and measurements of root length density to (i) quantify crop water uptake from soil down to 3 m depth, (ii) to assess the influence of soil water at sowing, soil mulching, seasonal conditions and their interaction on the profiles of soil water uptake, and (iii) to probe for relations between yield and the profiles of soil water uptake. Across treatments and seasons, water uptake at jointing featured a ratio 2.1: 1.0: 1.8: 2.2 in four soil layers, top 0.2 m, 0.2 0.4 m, 0.4 1.2 m, and 1.2–3.0 m. At anthesis, the ratios shifted to 5.2: 1.0: 1.7: 2.0. Water uptake at jointing was higher from top-soil in dry (∼60 %) than in wet condition (∼30 %), and the opposite was true in deeper layers; water supply had a smaller effect on the profiles of water uptake at anthesis. Compared to bare ground, mulch favored root proliferation and water uptake in 0.4 2.0 m soil layer. For a given soil layer, soil moisture correlated negatively with root length density. Yield correlated positively and linearly with water uptake from 0.4 3.0 m soil at jointing, indicating that faster root development at early stages favors water uptake from deep soil in the critical period of grain yield formation. We discuss the implications of our findings for agronomic management and breeding. [Display omitted] • Soil water content correlated negatively with root length density at anthesis. • Mulch increased root length density and water uptake at 0.4−2.0 m soil • Yield associated with more water uptake from deeper soil layers. [ABSTRACT FROM AUTHOR]

Poor soil physical properties related to the least limiting water range (LLWR) limit the productivity of clayey red soil (Ultisol) under a subtropical monsoon climate in southern China. This study evaluated the effects of bio-tillage on LLWR and identified the key factors influencing LLWR through a field experiment. The treatments included no plant, two cultivars of oilseed rape (Brassica napus L. cv. Huashuang 4 and Brassica napus L. cv. Xinan 28), one-year-old and perennial lucerne (Medicago sativa L. cv. Ladino), and one-year-old and perennial vetiver (Vetiveria zizanioides L. cv. Wild), used as cover crops prior to summer maize. Key parameters measured included plant root morphological traits, and soil bulk density, field capacity (FC), wilting point (PWP), available water content (AWC), penetration resistance (PR) and air-filled porosity (AFP) were determined. The two rape cultivars exhibited the shallowest root distribution (limited to 20 cm depth) and the lowest root surface density (RSD, ∼16.61 cm²·cm⁻³) and root volume density (RVD, ∼0.58 cm³·cm⁻³). In contrast, lucerne and vetiver demonstrated greater root development, with deeper root penetration (>60 cm), and higher RSD and RVD, with vetiver showing the highest values (RSD ∼24.01 cm²·cm⁻³, RVD ∼0.96 cm³·cm⁻³). Lucerne and vetiver treatments increased AWC and AFP but reduced PR. Soil planted with vetiver had lower FC (0.35–0.48 cm3·cm−3) and PR (1362–3297 kPa) than soil planted with lucerne, while soil planted with lucerne had a lower PWP (0.25–0.35 cm3·cm−3) than soil planted with vetiver. All crops improved LLWR at 0–20 cm depth, but vetiver increased LLWR below the depth of 20 cm due to its higher root length density (RLD) and RSD. Path analysis revealed that PR had the strongest direct negative effect on LLWR (coefficients from −1.0528 to −1.7642), while redundancy analysis showed a strong correlation between LLWR and the RSD (12.00 %) and RLD (11.33 %) of perennial vetiver, with weaker correlation to root diameter (7.00 %). Bio-tillage reduced PR through root growth, enhancing LLWR particularly at depth of 20–40 cm, with perennial vetiver showing the most significant improvement due to its deeper rooting depth and denser root distribution. • The root performances of bio-tillage were compared in clayey red soil. • Fibrous-root vetiver with large RLD and RSD showed a deeper and denser root distribution. • RLD and RSD were beneficial for FC , PWP , PR and AFP. • The dominant factor of LLWR was PR and AFP but not field capacity and wilting point. • The perennial vetiver reduced PR by root growth, thereby improving LLWR. [ABSTRACT FROM AUTHOR]

Efficient water management is critical to sustainable crop production in arid and semi-arid southwestern United States. A study was designed to evaluate the variations in soil water content (SWC) and nitrogen (N) dynamics within the 0–100 cm soil profile and forage maize (Zea mays L.) and sorghum (Sorghum bicolor) yields in winter cover crop integrated crop rotations in a semi-arid environment using a Root Zone Water Quality Model (RZQWM2). The cover cropping treatments were no cover crop (NCC), a mixture of grasses, brassicas, and legumes (GBL), a mixture of grasses and brassicas (GB), and a mixture of grasses and legumes (GL) under maize and sorghum silage production. The root mean square error (RMSE), index of agreement (d), and Nash-Sutcliffe model efficiency coefficient (NSE) were used to evaluate the effectiveness and efficiency of the model. The observations and simulations showed that the soil water content was greater and soil temperature was lower under cover crops than under NCC. Simulated N mineralization in maize and sorghum with cover cropping was 41.1–44.2 % and 41.9–42.3 % greater than NCC. Also, the model simulated that cover crops improved the plant N uptake by 15.4–17.3 % in maize and 13.6–14.7 % in sorghum compared to NCC. Simulated aboveground biomass yields of maize and sorghum were 8.11–24.2 % and 5.68–21.3 % greater with cover crops than with NCC. Integrating cover crops in maize and sorghum silage production systems can conserve soil water and improve N uptake, increasing silage yield under semi-arid irrigated conditions in the southwestern United States. • The RZWQM2 effectively predicted soil water, temperature, nitrogen (N), and crop yields. • N mineralization was 41.1 – 44.2 % greater under cover crops than under no-cover crops. • Cover crops increased N uptake by 13.6–17.3 % and forage biomass yield by 5.68–24.2 %. • Cover crops effectively manage water and nitrogen in semi-arid irrigated systems. [ABSTRACT FROM AUTHOR]

This study addresses the critical issues of water scarcity and soil salinization impacting cotton production in South Xinjiang, China. It introduces an innovative framework for assessing regional cotton crop suitability by integrating ground-measured soil water and salt data with UAV multispectral and Sentinel-2A satellite imagery from the 2022 cotton growing season. An optimized set of vegetation indices was identified through multicollinearity analysis and full subset selection. Six advanced machine learning methods, including Random Forest (RF), were used alongside the ratio mean method to effectively upscale soil water and salt content models from the field to the regional level. A newly developed cotton suitability index was created to categorize soil water and salt conditions, resulting in detailed suitability maps for 2022 and 2023. Key findings include: (1) Model Performance : The RF model outperformed others in predicting soil water and salt content, with R² values ranging from 0.763 to 0.846 for soil moisture and 0.703–0.843 for soil salinity. It showed greater accuracy at 0–10 cm depth than 10–20 cm depth. (2) Imagery Correlation : A significant correlation was observed between UAV and Sentinel-2A imagery (R² = 0.498–0.745). Reflectivity corrections in Sentinel-2A data notably improved RF model inversion accuracy (R² gains of 0.114–0.384). (3) Suitability Analysis : The cotton suitability index maps for 2022 and 2023 indicated that most fields in Tumushuke (TMSK) were moderately suitable for cotton growth, although some areas were unsuitable. This highlights the need for additional irrigation and targeted soil water and salt management to meet cotton requirements and reduce salinity risks. Overall, this study enhances precision agriculture techniques for arid environments and provides valuable insights for managing soil salinity, supporting sustainable cotton production in challenging climates. • The optimal combination of vegetation index and reflectivity was selected. • The RF model had the highest simulation accuracy. • An up-scaling quantitative and mapping method for soil water/salt was established. • The crop suitability index was introduced to evaluate the suitability of cotton. [ABSTRACT FROM AUTHOR]

In dense urban areas, trees are often planted in small root spaces. This results in an insufficient water supply in droughts, affecting the trees' vitality and evapotranspiration performance. However, water availability can be improved by irrigation. The study investigated whether weekly manual or daily irrigation through a rainwater harvesting system (RHS) fed by connected impermeable surfaces is sufficient to avoid drought stress. Using a 12 m³ root volume of the German minimum planting standard, we implemented a daily urban tree water balance model in a moderate climate, considering the future and current climate. We analyzed the site conditions for a 60-year-old tree in five cities in southern Germany. The results showed that weekly irrigation, as carried out in practice, does not prevent drought stress or significantly reduce drought duration compared to a tree without irrigation in all investigated locations. However, the application of daily irrigation with stormwater from an RHS reduces the duration of droughts, as shown for the species Platanus x acerifolia, which has a comparably high water demand. We optimized the required RHS storage volume depending on the tree species and location, as climate significantly influences water demand and supply. According to our results, future climate conditions must be considered in planning, as larger RHS storage volumes may be required. • The daily water balance of urban tree sites with limited root space was modeled. • Weekly irrigation fails to avoid drought stress for trees with limited root space. • Daily irrigation reduces sensitivity to drought stress and lower evapotranspiration. • Rainwater harvesting can provide enough water for the irrigation of urban trees. • Crucial for planning: Larger stormwater storage may be needed in future climate. [ABSTRACT FROM AUTHOR]

Background and aims: Understory plants are important determinants of plant diversity in most forest ecosystems, which also play a key role in maintaining forest structure and function. Understory vegetation responds to local environmental gradients, so understanding the main drivers of plant diversity and composition in the understory is important for the conservation of forest diversity and ecosystem functions under current global change scenarios.We quantified plant species richness and composition for four groups (woody species, grasses, forbs, and a group of shade tolerant species), and examine their relationship to local environmental factors in the understory of the Hoyocasero forest, an isolated Mediterranean Scots pine (Pinus sylvestris) forest that harbors several singular understory plant taxa.Our results indicate that soil water content, light conditions in the understory, and overstory composition were important factors determining species richness and floristic composition within the forest. Soil characteristics explained some spatial variation in species richness for all understory plants and the group of shade species, and modulated the response of individual species.The conservation and management of this singular forest should promote its natural regeneration and the restoration of degraded areas, and forestry activities should be compatible with the maintenance of the moisture and shade conditions that allowed the preservation of a rich and diverse flora in this pine dominated forest surrounded by more human impacted oak forests and deforested areas.Methods: Understory plants are important determinants of plant diversity in most forest ecosystems, which also play a key role in maintaining forest structure and function. Understory vegetation responds to local environmental gradients, so understanding the main drivers of plant diversity and composition in the understory is important for the conservation of forest diversity and ecosystem functions under current global change scenarios.We quantified plant species richness and composition for four groups (woody species, grasses, forbs, and a group of shade tolerant species), and examine their relationship to local environmental factors in the understory of the Hoyocasero forest, an isolated Mediterranean Scots pine (Pinus sylvestris) forest that harbors several singular understory plant taxa.Our results indicate that soil water content, light conditions in the understory, and overstory composition were important factors determining species richness and floristic composition within the forest. Soil characteristics explained some spatial variation in species richness for all understory plants and the group of shade species, and modulated the response of individual species.The conservation and management of this singular forest should promote its natural regeneration and the restoration of degraded areas, and forestry activities should be compatible with the maintenance of the moisture and shade conditions that allowed the preservation of a rich and diverse flora in this pine dominated forest surrounded by more human impacted oak forests and deforested areas.Results: Understory plants are important determinants of plant diversity in most forest ecosystems, which also play a key role in maintaining forest structure and function. Understory vegetation responds to local environmental gradients, so understanding the main drivers of plant diversity and composition in the understory is important for the conservation of forest diversity and ecosystem functions under current global change scenarios.We quantified plant species richness and composition for four groups (woody species, grasses, forbs, and a group of shade tolerant species), and examine their relationship to local environmental factors in the understory of the Hoyocasero forest, an isolated Mediterranean Scots pine (Pinus sylvestris) forest that harbors several singular understory plant taxa.Our results indicate that soil water content, light conditions in the understory, and overstory composition were important factors determining species richness and floristic composition within the forest. Soil characteristics explained some spatial variation in species richness for all understory plants and the group of shade species, and modulated the response of individual species.The conservation and management of this singular forest should promote its natural regeneration and the restoration of degraded areas, and forestry activities should be compatible with the maintenance of the moisture and shade conditions that allowed the preservation of a rich and diverse flora in this pine dominated forest surrounded by more human impacted oak forests and deforested areas.Conclusion: Understory plants are important determinants of plant diversity in most forest ecosystems, which also play a key role in maintaining forest structure and function. Understory vegetation responds to local environmental gradients, so understanding the main drivers of plant diversity and composition in the understory is important for the conservation of forest diversity and ecosystem functions under current global change scenarios.We quantified plant species richness and composition for four groups (woody species, grasses, forbs, and a group of shade tolerant species), and examine their relationship to local environmental factors in the understory of the Hoyocasero forest, an isolated Mediterranean Scots pine (Pinus sylvestris) forest that harbors several singular understory plant taxa.Our results indicate that soil water content, light conditions in the understory, and overstory composition were important factors determining species richness and floristic composition within the forest. Soil characteristics explained some spatial variation in species richness for all understory plants and the group of shade species, and modulated the response of individual species.The conservation and management of this singular forest should promote its natural regeneration and the restoration of degraded areas, and forestry activities should be compatible with the maintenance of the moisture and shade conditions that allowed the preservation of a rich and diverse flora in this pine dominated forest surrounded by more human impacted oak forests and deforested areas. [ABSTRACT FROM AUTHOR]