【Objective】Taxus chinensis has important medicinal, ornamental and ecological value. Its seedling development is sensitive to soil water and nutrient availability. This study experimentally evaluated suitable wetted zone size under drip irrigation and fertilizer application rate for promoting seedling growth and improving water- and fertilizer-use efficiency.【Method】The experiment was conducted during the 2023 and 2024 growing seasons. It involved three irrigation treatments and three fertilization treatments. The irrigation treatments were defined by the ratio of wetted-zone area to total soil-profile area, which was set at 45%, 60%, and 75%. Each irrigation treatment had three fertilizer application rates: 0, 3.0, and 4.2 kg/m3. During the experiment, photosynthetic traits, chlorophyll content and leaf anatomical characteristics were measured in each treatment.【Result】Both the wetted-zone size and fertilizer application rate significantly affected photosynthesis, chlorophyll content, and leaf anatomical development. When fertilizer application was the same, photosynthetic and chlorophyll traits showed a unimodal response to increasing wetted-zone size, initially increasing and then decreasing. When wetted-zone size was the same, fertilization significantly increased photosynthetic and chlorophyll traits compared to the unfertilized control. A moderate increase in fertilizer application rate further enhanced these responses. A wetted-zone coverage of 60%, combined with a fertilizer application rate of 4.2 kg/m3, resulted in the highest net photosynthetic rate, stomatal conductance, transpiration rate, chlorophyll content, midrib development, and palisade tissue thickness among all treatments. These results suggest that optimizing the size of the wetted zone is important for maximizing fertilizer-use efficiency. TOPSIS-based comprehensive evaluation indicated that the combination of a 60% of wetted-zone coverage and 4.2 kg/m3 fertilizer application was optimal for Taxus chinensis seedling growth.【Conclusion】Under the experimental conditions, maintaining a 60% wetted-zone coverage combined with a fertilizer application rate of 4.2 kg/m3 was optimal for promoting photosynthetic performance and leaf structural development in Taxus chinensis seedlings, while improving water- and fertilizer-use efficiency.
【Objective】Climate change can alter water availability and drought risk in arid regions, where even small changes in temperature and precipitation can substantially influence regional water balance and ecological security. This study characterize the spatiotemporal variations in key climatic factors and drought risk in Bayingolin Mongol Autonomous Prefecture (Bazhou), Inner Mongolia, to support regional ecological security and water- resource management. 【Method】Meteorological data measured from eight stations in the region from 1960 to 2020 were used to characterize climatic variability and drought trends. Linear trend analysis and the Mann-Kendall test were used to identify temporal trends and abrupt changes, while the standardized precipitation evapotranspiration index (SPEI) was used to assess drought dynamics.【Result】①From 1960 to 2020, the region exhibited a significant warming-wetting trend, with temperature and precipitation increasing at an average rate of 0.2 ℃/10 a and 5.4 mm/10 a, respectively (p＜0.05). In contrast, sunshine duration decreased at an average rate of 2.9 h/10 a, and the SPEI-12 index declined at an average rate of 0.13-0.36/10 a, indicating increasing drought severity despite increasing precipitation, likely due to enhanced atmospheric evaporative demand. ②Climatic factors showed strong spatial heterogeneity, with temperature increasing from north to south, whereas precipitation showed an opposite spatial pattern, resulting in substantial spatial variation in water availability. ③Significant abrupt changes in precipitation and atmospheric pressure were detected around 1981 and 1966, respectively, indicating important shifts in regional climate conditions. Together, these results reveal that the apparent warming-wetting trend from 1960 to 2020 masked an increasing drought risk associated with enhanced atmospheric evaporative demand.【Conclusion】Bazhou became warmer and wetter from 1960 to 2020, but drought risk increased because the increase in precipitation was insufficient to offset the increase in atmospheric evaporative demand. Drought severity was greater in the south than in the north, while abrupt changes in atmospheric pressure and precipitation marked important transitions in the regional climate.
【Objective】In well-irrigated districts, accurately metering water pumped from individual boreholes is challenging because of their dispersed distribution and high costs of meter installation and maintenance. This paper proposes a low-cost and efficient method for estimating groundwater pumped for irrigation in areas without metering facilities.【Method】Measured electricity-to-water conversion coefficients and factors that affect the conversion coefficients were collected across multiple regions. These factors included well age and depth, groundwater table depth, pump model and age, and irrigation type. Missing data were imputed using an XGBoost-based chained imputation method. Random Forest and LightGBM were used as benchmark model for predicting the conversion coefficient, and an optimized XGBoost model was developed by integrating the Optuna automated hyperparameter optimization framework with stratified K-fold cross-validation. Statistical significance tests were conducted to compare model performance; permutation importance with error bars was used to quantitatively identify the key factors that influence the electricity- to-water conversion coefficient.【Result】①The XGBoost chained imputation method effectively captured nonlinear interactions among variables while maintaining high physical consistency of the imputed data. ②The XGBoost model achieved a Nash-Sutcliffe efficiency (NSE) of up to 0.987 on the test set, significantly outperforming the LightGBM and Random Forest models. ③Statistical tests showed that XGBoost significantly outperformed LightGBM and was more robust than Random Forest under extreme conditions, such as high pumping lift. ④Actual pumping lift, rated pump lift, and rated flow rate were the most influential factors affecting the electricity-to-water conversion coefficient.【Conclusion】The proposed imputation-optimization-prediction framework effectively addresses the challenges associated with missing data and demonstrates the ability of XGBoost to capture nonlinear relationships among irrigation-related variables. Our results show that the actual pumping lift is the most important factor for data collection; they provide a generalizable, low-cost approach for estimating agricultural groundwater use for irrigation in areas without metering facilities.
【Objective】Biochar can improve soil quality and crop productivity, but its environmental aging, including repeated dry-wet cycles, may alter its properties and efficacy. This study experimentally investigated how dry-wet cycle-induced biochar aging affects its ability to regulate paddy soil properties and rice growth.【Method】The experiment was conducted in pots from 2023 to 2024 using rice straw biochar. It consisted of four treatments: biochar not undergoing to dry-wet cycling (CK), biochar undergoing three dry-wet cycles (C3), six dry-wet cycles (C6), and ten dry-wet cycles (C10). Changes in soil pH, soil organic carbon (SOC), dissolved organic carbon (DOC), soil nitrogen forms, redox potential (Eh), rice yield, and irrigation water-use efficiency were measured under each treatment.【Result】①Biochar undergoing six dry-wet cycles (C6) produced the greatest increases in soil pH, SOC, and DOC contents and optimized soil redox conditions during key rice growth stages. ②C6 significantly increased soil ammonium nitrogen content at the tillering stage and promoted nitrate nitrogen accumulation at the jointing- booting stage, thereby improving soil nitrogen retention and supply. ③Compared with CK, C6 achieved the highest grain yield and irrigation water-use efficiency, increasing grain yield in 2023 and 2024 by 11.2% and 14.7%, respectively, while reducing irrigation water use by 4.9% and 3.9%, respectively.【Conclusion】Subjecting biochar to undergo six dry-wet cycles enhanced its capacity to improve paddy soil properties by optimizing soil pH, carbon and nitrogen balance, and redox condition, thereby creating a favorable condition for rice growth and simultaneously increasing grain yield and irrigation water-use efficiency.
【Objective】Ratooning rice can produce two harvests from a single planting, but its yield is strongly influenced by sowing date. This study investigated the effects of sowing date on annual yield and yield formation of a medium-duration ratoon rice.【Method】The field experiment was conducted in Changsha, central Hunan Province, from 2020 to 2021, using the ratooning rice variety Huiliangyou 898, a widely cultivar grown in the region. We compared six sowing dates: March 15 (B1), March 20 (B2), March 25 (B3), March 30 (B4), April 5 (B5), and April 10 (B6).【Result】Delayed sowing progressively shortened the annual growth duration, primarily because of the reduced vegetative growth period in the main crop, whereas the growth duration of the ratoon crop remained relatively stable. The growth duration of the main and ratoon crops was negatively correlated. Reproductive periods differed between years and were negatively correlated with mean temperature. For the main crop, the tillering rate increased with delayed sowing, resulting in earlier attainment of maximum tiller number. In the ratoon crop, seedling emergence was rapid within 5 days after main-crop harvest, subsequently slowing and stabilizing. Sowing on March 20 produced the greatest number of regenerated seedlings. Both main-crop and ratoon-crop yields showed unimodal responses to sowing date, with B2 producing the highest yields in both 2020 and 2021. Compared with other treatments, B2 increased main-crop yield by 6.31%-13.28% and ratoon-crop yield by 9.49%-69.55%. It also maintained slow post-heading decline in SPAD value, rapid ratoon regeneration, more regenerated seedlings, low sheath blight incidence, and significantly high harvest index and panicle number per unit area. In contrast, B6 had the lowest harvest index, panicle number per unit area, and seed-setting rate. Annual yield showed a unimodal response to sowing date, with B2 producing the highest yield in 2020 and B3 in 2021, representing an increase of 0.23%-8.70% and 9.49%-69.55%, respectively, compared with other treatments.【Conclusion】In central Hunan Province, the optimal sowing window for medium-duration ratoon rice is March 20–25, which maximizes annual yield. Both excessively early and late sowing reduced annual yield, with magnitude of the reduction depending on sowing date.
【Objective】The capacity of soils to infiltrate and retain water is influenced by multiple abiotic and biotic factors. In this paper, we studied the effects of different organic amendments on water infiltration and storage in typical chernozem black soils in eastern Inner Mongolia.【Method】The experiment compared five amendments: straw alone, cattle manure alone, combined application of straw and humic acid, and combined application of cattle manure and humic acid, together with an unamended control. Changes in soil pore characteristics, soil water dynamics across the soil profile, and soil hydraulic properties were measured for each treatment.【Result】Compared to the control, organic amendments reduced soil bulk density in the 0-30 cm layer by 1.4%-6.5%, while increasing saturated hydraulic conductivity, field capacity, available water storage capacity, and mean infiltration rate by 23.8%-35.0%, 1.8%-17.8%, 14.1%-59.3%, and 87.8%-154.8%, respectively. Compared with amendment with straw or cattle manure only, their combined application with humic acid further increased saturated hydraulic conductivity by 6.5%, mean infiltration rate by 8.8%-11.9%, field capacity by 5.0%-14.8%, and available water storage capacity by 20.7%-36.2%. Structural equation modeling revealed that organic amendments significantly improved soil physical properties, particularly capillary porosity. By enhancing saturated hydraulic conductivity, capillary water capacity, and field capacity, organic amendments promoted water infiltration and increased soil water storage.【Conclusion】 Organic amendments improved soil hydraulic conductivity and water-retention capacity by modifying soil pore structure, with their effects further enhanced when straw or cattle manure was combined with humic acid. These combined organic amendments provide an effective approach to improve the hydraulic properties of chernozem black soil in Northeastern China.
【Objective】Optimizing fertilization under water-saving irrigation can improve rice yield and nitrogen- use efficiency while reducing nitrogen losses. This study investigated the effects of fertilizer application rate on soil nitrogen dynamics and rice yield under shallow-wetting-drying irrigation to find an optimal irrigation–fertilization strategy for simultaneously improving rice yield and nitrogen-use efficiency.【Method】The experiment was conducted in five paddy fields under shallow-wetting-drying irrigation. Fertilization treatments were as follows: slow-release fertilizer (ω(N)∶ω(P)∶ω(K)=24∶8∶10), urea (ω(N)＞46%), and compound fertilizer (ω(N)∶ω(P)∶ω(K)=26∶10∶15) were applied as basal fertilizer and topdressings at the jointing and booting stages, respectively. Fertilizer application rate in four fields was set at 100%, 90%, 85%, and 80% of the conventional fertilization rate, and one unfertilized field served as the control. The spatiotemporal distributions of NH4⁺-N and NO3--N in the 0-30 cm soil layer, as well as rice yield and nitrogen-use efficiency, were measured for each treatment.【Result】NH4⁺-N and NO3--N concentrations peaked following each fertilizer application. NO3--N concentrations were significantly lower than NH4⁺-N concentrations, and the peak in NO3--N concentration generally lagged behind that of NH4⁺-N, except under the conventional fertilization rate. Overall, reducing fertilization rate by 10% relative to the conventional fertilization rate resulted in the most stable spatiotemporal distributions of NH4⁺-N and NO3--N, and achieved the highest rice yield and nitrogen-use efficiency.【Conclusion】Under shallow-wetting-drying irrigation, reducing fertilizer application by 10% relative to the conventional fertilization rate was most effective, increasing both rice yield and nitrogen-use efficiency. This irrigation-fertilization strategy reduced nitrogen losses through gaseous emissions and leaching by regulating the spatiotemporal dynamics of soil nitrogen.
【Objective】Automatic irrigation improves irrigation efficiency and reduces labor costs, but its application is constrained in areas with limited access to electricity and communication networks. We developed a hydraulically actuated automatic irrigation system based on a hydraulically actuated irrigation control valve (HAICV) to overcome these limitations and investigated field pipe-network configurations suited to its operation.【Method】Based on the composition and operating principles of the hydraulically actuated automatic irrigation system, material requirements and network configurations among different irrigation plot layouts were compared. To address excessive flow rate and pressure during system operation, a hierarchical control-valve assembly structure was proposed, and its flow characteristics and irrigation cycles were compared and analyzed. The economic feasibility and operational reliability of the hydraulically actuated automatic irrigation system were evaluated.【Result】The HAICV was optimally positioned at the center of the irrigation plot, with an ‘X’-shaped connecting-pipe layout providing the optimal field pipe-network configuration. The field pipe network with a two-stage control-valve assembly showed the best overall performance. Compared with a traditional automatic irrigation system, the hydraulically actuated automatic irrigation system reduced initial investment by 35.67% and annual operating costs by 28.60%. Although the valve opening and closing processes were relatively slow, irrigation control accuracy was comparable to that of the traditional system.【Conclusion】The hydraulically actuated automatic irrigation system based on the optimized field pipe network and two-stage HAICV configuration can meet the requirements of automatic irrigation while substantially reducing initial investment and annual operating costs. It is particularly suitable for agricultural areas with limited electricity and communication network coverage.
【Background】Irrigation district modernization is essential for improving irrigation water-use efficiency and facilitating sustainable water-resource management. In this paper, we analyzed the long-term changes in modernization of irrigation districts in the lower reaches of the Yellow River Basin and identified the key constraints and drivers that have hindered or facilitated modernization.【Method】We used the Panzhuang Irrigation District as a case study and constructed an evaluation index system covering water-resource use efficiency, socioeconomic benefits and irrigation-infrastructure support capacity, based on data collected from 2001 to 2023. A game- theory-based combined weighting method, integrated with the analytic hierarchy process and entropy-weight method, was used to determine the weights of individual indicators. The TOPSIS model was used to dynamically evaluate the modernization level, and an obstacle-degree model was used to diagnose the key factors constraining the modernization.【Result】①The combined weighting results indicated that investment in water-saving renovation projects, per capita income, and water consumption per 10 000 yuan of industry-added value were the three most important factors influencing the modernization level. ②From 2001 to 2023, the modernization level of the irrigation district followed a trajectory of ‘fluctuating growth-rapid growth-plateauing’ with the comprehensive evaluation score increasing from 0.275 3 to 0.665 1; meanwhile, the water-resource carrying capacity improved from Grade II to Grade IV. ③Obstacle-degree analysis revealed that the factors constraining modernization shifted substantially during the study period.【Conclusion】Modernization of the Panzhuang Irrigation District has made substantial progress, with the dominant constraints shifting from low water-use efficiency and poor management in the early stage to unstable investment and increasing water-resource scarcity in the later stage. Future modernization efforts should focus on establishing stable, long-term investment mechanisms and improving coordination of water and land resource usage to support sustainable development in the basin.
【Objective】Potential evapotranspiration (PET) is an important indicator of atmospheric water demand, particularly in arid and water-limited regions. Understanding its spatiotemporal variability is essential for water resource management under, especially water conservation conditions. This study investigated the spatiotemporal patterns of PET in the Manas River Basin and identified the climatic and anthropogenic factors that drive its variation.【Method】Using meteorological and socioeconomic data measured from 1980 to 2023, the spatiotemporal variation of PET in the basin was analyzed using Theil-Sen median trend analysis and the Mann-Kendall (M-K) test. GeoDetector and Random Forest regression were combined to quantify the contributions of climatic and anthropogenic factors and identify the key drivers underlying PET variation.【Result】①Mean air temperature increased significantly, whereas mean wind speed and relative humidity decreased significantly across the basin from 1980 to 2023. ②PET showed a significant upward trend with pronounced spatial heterogeneity, with the highest rate of increase in desert areas, followed by oasis-plain areas, and the lowest rate of increase in mountainous areas. ③GeoDetector analysis indicated that temperature, precipitation, and wind speed had relatively high explanatory power (q-values) for PET variation, whereas Random Forest analysis identified temperature, sunshine duration, and relative humidity as the most important predictors. ④Population and GDP had relatively weak direct explanatory power but enhanced the effects of climatic factors, particularly temperature, through significant interactions.【Conclusion】PET in the Manas River Basin increased significantly from 1980 to 2023 and exhibited a spatial pattern of higher values in the north than in the south and in the west than in the east. Temperature was the dominant driver of PET variation. Anthropogenic factors had a relatively weak direct effect but could amplify PET variation through interactions with climatic factors. These findings provide a scientific basis for understanding changes in atmospheric water demand and supporting water resource management in the basin under water-conservation conditions.
【Objective】To investigate the effects of different agronomic practices on the physiological characteristics, water and nitrogen utilization and drought resistance of maize, so as to identify a water-saving and high-yield cultivation patterns suitable for this region.【Method】A three-factor randomized block experiment was conducted, including two mulching treatments (M0, no mulching; M1, black plastic film mulching), three plant densities (D1, low density: 45 000 plants/hm2; D2, local conventional density: 60 000 plants/hm2; D3, high density: 75 000 plants/hm2), and three biochar application rates (B0, no biochar: 0 t/hm2; B15, low application rate: 15 t/hm2; B30, high application rate: 30 t/hm2). Maize growth and development, water and nitrogen use indices and drought resistance were systematically monitored.【Result】①The D3M1B30 treatment improved soil porosity more effectively than any single practice, with an increase of 7.68% compared with the D2M0B0. Plastic film mulching combined with biochar application significantly enhanced soil structural stability and water-holding capacity. The water use efficiency of maize under D3M1B30 was 59.78% higher than that under D2M0B0, accompanied by an increased in nitrogen use efficiency. ②In the two experimental years, the number of ears under D3 was averagely increased by 17.73%, and grain yield rosed by 2.04 % relative to D2. During 2023–2024, the grain yield of the D3M1B30 was averagely enhanced by 37.43% compared with the D2M0B0, and the harvest index reached 45.42% in 2024. ③The drought resistance index of the B30 was averagely 11.87% higher than that of the B0. The drought resistance index under D3B30 increased by 5.95% relative to D2B0, and the drought resistance index was significantly positively correlated with crop yield (R2=0.684).【Conclusion】In the dry-farming regions of Northwest China, the combination of plastic film mulching, biochar application at 30 t/hm2 and high-density planting (D3M1B30) represents a suitable cultivation pattern for simultaneously achieving high maize yield and resource-use efficiency while enhancing soil water retention and drought resistance, and shows good regional adaptability.
【Objective】Sandy soils have high hydraulic conductivity and low water-holding capacity, making irrigation management essential for achieving high and stable crop yields in such soils. Here, we experimentally investigated the effects of irrigation frequency under mulched drip irrigation on growth, water-use efficiency (WUE), and yield formation of densely planted spring maize in sandy soils of the Hetao Irrigation District.【Method】The experiment was conducted in a spring maize field with a total irrigation amount of 6 000 m3/hm2, applied at three irrigation frequencies: 20 events (W1), 15 events (W2), and 10 events (W3). Conventional irrigation practiced by local farmers, with an irrigation amount of 6 375 m3/hm2, was used as the control (CK). During the experiment, we measured plant height, leaf area index (LAI), dry matter accumulation, water consumption, WUE and grain yield.【Result】Under the moderate irrigation frequency (W2), plant height and LAI reached their highest values at the grain-filling stage, at 297.67 cm and 2.62, respectively. W2 showed the best overall performance in WUE, dry matter accumulation, and grain yield. Compared with CK, W2 increased WUE and promoted dry matter accumulation, resulting in a grain yield of 19 820.09 kg/hm2, the highest among all treatments.【Conclusion】Under densely planted spring maize in sandy soil, applying 6 000 m3/hm2 of irrigation water in 15 events improved soil water availability, promoted plant growth and canopy development, enhanced dry matter accumulation, and increased WUE and grain yield. Thus, W2 was the optimal irrigation strategy for densely planted spring maize under mulched drip irrigation in the sandy soils of the Hetao Irrigation District.
【Objective】Maize production in semi-arid sandy regions is constrained by limited water and nutrient availability, making it challenging to simultaneously achieve high yield and efficient resource use. To address this challenge, we investigated the combined effects of dense planting and shallow-buried drip fertigation on maize growth, grain yield and quality, and resource-use efficiency in these regions.【Methods】A field experiment was conducted in 2024 and 2025 in Horqin District, Tongliao City, Inner Mongolia. Two contrasting cultivation systems were compared: dense planting (90 000 plants/hm2) combined with shallow-buried drip fertigation (DP), and conventional planting (60 000 plants/hm2) combined with surface irrigation and one-time basal fertilizer application (TP). Maize growth, grain yield and quality, yield component, water-use efficiency (WUE), and partial factor productivity of fertilizer (PFP) were measured and evaluated under each cultivation system.【Result】Dense planting combined with shallow drip fertigation significantly altered plant architecture and increased leaf area index and stomatal conductance. Compared with TP, DP reduced irrigation and fertilizer inputs by 33.3% and 32.8%, respectively, while increasing grain yield by 104.0% and 86.8% in 2024 and 2025, respectively, WUE by 115.3%- 140.4%, and PFP by 177.4%-202.4%. However, DP reduced grain protein content and test weight by 4.0%-4.3% and 7.1%-12.2%, respectively, and increased starch content by 3.8%-9.0% compared with TP. These results indicate a trade-off in grain quality, characterized by high starch content and low protein content and test weight in DP.【Conclusion】Dense planting combined with shallow subsurface drip fertigation substantially improved maize yield and resource-use efficiency in semi-arid sandy regions, but may compromise grain quality by reducing protein content and test weight while increasing starch content.
【Background and Objective】Soil salinity and alkalization are the main abiotic factors constraining agricultural production in the Yellow River Delta. Understanding its characteristics and the underlying mechanisms is essential for rational exploitation of this soil resource. This paper investigates the spatial distribution of soil salinization and alkalization and the impact of land use on it in this region.【Method】The study area was located in the north of the Yellow River Delta, in which 27 sampling points were established. For soil samples taken from each sampling point, we measured their electrical conductivity, pH, exchangeable cations and soil particle composition.【Result】Soil electrical conductivity increased with decreasing distance from the coastline, while soil pH showed strong spatial variability driven by land usage. The contents of exchangeable potassium and magnesium increased toward the coastline, and exchangeable sodium and calcium showed strong spatial heterogeneity. The electrical conductivity of cultivated land varied from 0.21 to 12.47 mS/cm, lower than that of wasteland (0.32 to 17.26 mS/cm). Soil pH in cultivated land varied from 7.43 to 9.35, higher than that in the wasteland (7.55 to 8.71). Silt accounted for 45.16% to 84.68% of soil composition in the area, followed by sand (7.17% to 48.94%) and clay (2.59% to 10.54%). Land use had a great impact on soil texture. Both clay and silt contents decreased from the inland toward the coastline, while sand content increased in the opposite direction.【Conclusion】Soil salinity in the Yellow River Delta is significantly influenced by location relative to the coastline and the Yellow River. Land use also affects soil salinization. Exchangeable K+ and Mg2+ contents increased toward the coastline, whereas Na+ and Ca2+ are largely controlled by land use. Soil texture showed strong spatial variation, with clay and silt contents decreasing from the inland to the coastline, while the sand content increased in the opposite direction.
【Objective】Acidic red soil is widely distributed in southern China. It is characterized by high acidity, poor structure and low organic matter and nutrient availability. This study investigated the combined effects of biochar, lime and humic acid on improving physicochemical properties of such soils.【Method】The study was based on laboratory incubation experiments and compared sixteen combinations of the three amendments applied at different ratios into the soil. At the end of the experiment, we measured the physical and biochemical properties of the soil in each treatment. Comprehensive soil improvement effects were evaluated using grey correlation analysis, and economic efficiency was calculated via input-output ratio analysis.【Result】Combined application of biochar, lime and humic acid not only effectively reduced soil bulk density and acidity, and increased field water-holding capacity, but also elevated the contents of soil organic matter, ammonium-nitrogen, nitrate-nitrogen, available potassium and total phosphorus; it also improved soil aggregate stability. Among all treatments, applying 2.60 g/kg of biochar, 1.20 g/kg of lime and 2.00 g/kg of humic acid yielded the optimal soil environment for crop growth. Compared with the untreated soil, this optimal treatment increased soil pH from 5.80 to 7.18, and raised soil porosity and field water-holding capacity by 54.55% and 34.27%, respectively. It also increased the content of ＞0.25 mm water-stable aggregates, aggregate mean weight diameter and geometric mean diameter by 17.56%, 26.03% and 39.58%, respectively, while reducing the aggregate fractal dimension by 0.17. In addition, this treatment increased soil organic matter content by 39.18%, and raised ammonium-nitrogen, nitrate-nitrogen, available potassium and total phosphorus contents by 23.89、33.10、63.08 mg/kg and 0.60 g/kg, respectively, relative to the control.【Conclusion】Combined application of biochar, lime and humic acid can effectively improve physicochemical properties of the degraded acidic red soil. Among all examined treatments, the combined application of 2.60 g/kg biochar, 1.20 g/kg lime and 2.00 g/kg humic acid showed the best comprehensive improvement effect on soil physicochemical properties.
【Objective】Groundwater is a main water resource in the Yinchuan Plain, and its dynamics is controlled by complex interactions of various natural and anthropogenic activities. This paper proposes a method to predict groundwater level changes in the plain.【Method】The model was developed based on 33 years of field-monitored data, including groundwater level, air temperature, precipitation, and evapotranspiration across the plain. The optimal lag order of groundwater level was determined using the partial autocorrelation function and time-series mutual information method. Five machine learning models, including support vector machine regression (SVR), random forest (RF), artificial neural network (ANN), gradient boosting decision tree (GBDT), and extreme gradient boosting (XGBoost), were constructed to predict groundwater level dynamics. Based on the prediction results of each of the five models, a stacking ensemble model was established using the Ridge regression as the meta-learner to integrate outputs of the five single models for simulating groundwater level variation in the plain.【Result】The optimal groundwater level lag order for the monitored datasets ranged from 6 to 8. The proposed ensemble model was significantly superior to the five individual standalone models, achieving an average coefficient of determination of 0.933, mean absolute error of 0.357 m, and root mean square error of 0.500 m; the average residual distribution range and average residual mean were 1.393 m and 0.006 m, respectively.【Conclusion】The model we developed based on the multi-time-lag characteristics of groundwater levels and the Stacking ensemble strategy effectively improved the accuracy and stability of groundwater level prediction in the Yinchuan Plain.
【Objective】Rainstorms are prominent meteorological risks. Understanding their spatiotemporal variation and driving factors in a region is critical to developing mitigation strategies. This study analyses the spatiotemporal variation of regional rainstorms in Shandong Province and their determinants.【Method】The study was based on daily precipitation data measured from 109 meteorological stations from 1978 to 2020 across the province. The province was divided into five meteorological-geographical subregions. Empirical orthogonal function (EOF) decomposition, North significance test and climatic statistical analysis, combined with the self-established comprehensive rainstorm intensity index and percentile classification method, were used to analyse the spatiotemporal variation of its key driving factors.【Result】①EOF decomposition identified three significant spatial patterns of annual rainstorm days in the province, with a cumulative variance contribution rate of 39.34%. These three patterns are: provincially consistent pattern, southeast-northwest reverse pattern, and central-sides reverse pattern. The five subregions showed distinct spatiotemporal variation in each pattern. The south and centre of the province were highly rainstorm-sensitive areas, while rainstorms in the northwest and north showed dramatic fluctuations, jointly controlled by monsoon circulation and regional topography. ②A total of 386 regional rainstorm events were recorded from 1978 to 2020 across the province, with an average of 8.9 events per year. The overall rainstorm frequency showed a slight decreasing trend from 1978 to 2020, though not at significant level, accompanied by noticeable interannual and interdecadal fluctuations. In total, 65.8% of rainstorm events occurred in July and August. ③Most regional rainstorms were short event, with an average duration of 1.5 days; 94% of rainstorm events lasted 1-2 days. On average, each rainstorm event affected 23 meteorological stations. ④Analysis using the comprehensive intensity index constructed from the rainstorm duration, their affected area, and rainfall intensity showed that regional rainstorm events can be divided into four grades.【Conclusion】Three dominant spatial patterns of rainstorms were identified in Shandong Province, which were affected by atmospheric circulation and topography. The findings unveil the spatiotemporal heterogeneity of regional rainstorms and can help develop strategies to mitigate the adverse impacts of regional rainstorms in Shandong Province.
[Objective]Spring maize production in arid northwest China relies heavily on irrigation.Irrigation amount and scheduling thus exert considerable impacts on crop growth and yield.Using a crop model,this paper models the effects of drip irrigation scheduling on growth and yield of spring maize in plastic-mulched fields in the region.[Method]The modelling was based on field data collected during the 2020-2021 growing seasons.These data were used to calibrate and validate the AquaCrop model first,and the validated model was then used to simulate the responses of maize growth and yield(Y)to different irrigation scenarios.We set 10 irrigation quotas ranging from 300 to 740 mm(W1-W10),and three irrigation modes that prioritized water supply at the jointing stage(I1),tasseling stage(I2),or grain-filling stage(I3).The simulations covered three precipitation year types:wet year(N1),normal year(N2)and dry year(N3).[Result]The AquaCrop model satisfactorily reproduced the crop growth and yield dynamics;its normalized root mean square error(NRMSE)for canopy cover(CC)and aboveground biomass(B)was≤9.33%,while the index of agreement(d)and coefficient of determination(R2)were both≥0.98.The relative errors between simulated and measured maize yield ranged from 3.76%to 7.08%.Simulation results showed that irrigation quota,irrigation allocation prioritization,and precipitation year type all significantly affected maize yield and irrigation water productivity.Under the same irrigation quota,prioritizing irrigation at the tasseling stage produced significantly higher yield than at the jointing stage(I1)and grain-filling stage(I3).With increasing irrigation quota,maize yield varied quadratically:rising first and then declining,while irrigation water productivity decreased monotonically.[Conclusion]Considering both maize yield and irrigation water productivity,the optimal irrigation quota was 400、440 mm and 480 mm for wet,normal and dry year,respectively,with irrigation water preferentially applied during the tasselling stage.This irrigation scheduling can be used for drip-irrigated spring maize production in plastic-mulched fields in arid regions in Northwestern China.
【Background】The growth in installed capacity of green energy has exerted growing operational pressure on the national power grid. Hydropower stations play a vital role in grid regulation. However, long-term operation under suboptimal conditions triggers pressure pulsation and other faults in hydropower units, causing component damage and deteriorating operational performance. 【Objective】This paper analyzes the effects of pressure pulsation on operating unit under variable water head and load conditions. 【Method】We collected on-site operational parameters to obtain pressure pulsation data, as well as spindle swing and vibration measurements of the operating unit across different water head and load scenarios. 【Result】The results show that intense pressure pulsation occurs in the medium-load region. As the water head rises, the range of severe pressure fluctuation shifts toward higher load levels. Spindle swing amplitude is positively correlated with pressure pulsation. Furthermore, pressure pulsation in the unit’s tail water area is more pronounced and highly susceptible to load variation. 【Conclusion】Therefore, the unit should preferably operate at loads above 80% rated load. When operating far from the optimal working point, pressure pulsation and spindle swing intensify, raising the risk of component failure and lowering unit efficiency.
【Objective】Soil texture is an important factor affecting soil pore structure and water retention capacity, which control plant-available soil water. This paper investigates the spatial variation in soil texture in tea plantations and its regulatory effects on soil pore structure and soil water content. 【Method】We studied 72 typical tea plantations across seven major tea-producing regions in Jiangxi Province. We measured soil particle composition, bulk density, total porosity, three-phase composition, saturated water-holding capacity, field capacity and relative water content of soil samples collected from these plantations.【Result】Soil texture in the study area was diverse, dominated by loamy clay (37.50%) and silty clay (20.83%). Sand content showed the highest spatial variability, with a coefficient of variation of 52.25%. Soil texture significantly affected soil physical structure. Clay loam had a significantly high bulk density than silty clay, sandy loam and loamy clay, while loamy clay featured favorable soil pore structure and high total porosity compared with sandy loam and clay loam. Soil texture is a key factor regulating soil water retention. Loamy clay had the highest saturated water-holding capacity (415.02 mg/kg), while clay soil exhibited the strongest available water retention capacity, with a relative water content of 54.07%. Correlation analysis revealed that sand particle content increased significantly with elevation and slope, but decreased significantly with longitude, latitude and plantation age. Silt particle content was significantly positively correlated with longitude, latitude and plantation age, and negatively correlated with elevation, slope and aspect. Clay particle content was significantly positively correlated with relative soil water content, longitude and latitude, and negatively correlated with elevation.【Conclusion】Soil texture in the tea plantations of Jiangxi Province is spatially heterogeneous, mainly controlled by topographic and geographical factors. Loamy clay exhibited the optimal soil pore structure and saturated water-holding capacity, whereas clay soil performed best in retaining available soil water.
