This paper analyzes the spatial and temporal patterns of agricultural water use efficiency in the Tarim River basin over a six years period (2015-2020) using panel data from 46 counties (cities). The study employs the SBM-undesirable model, kernel density estimation and Tobit model to analyze the data. The results indicate that while the agroecological water use efficiency, considering water pollution, has shown annual improvement, it remains relatively low overall. The agroecological water use efficiency of the Corps cities and Kizilsu Kirgiz Autonomous Prefecture in the basin is relatively high, particularly Alar City and Ruoqiang County, which reached the optimal efficiency levels (efficiency value of 1) given the current technology. Conversely, the Aksu and Kashgar regions demonstrate lower agroecological water use efficiency. Counties and cities with higher efficiency values are primarily located at the eastern and western edges of the basin. The distribution of efficiency values during the study period shows an evolving trend from the central to the southwestern part of the basin. Further investigation reveals that factors such as agricultural water price, economic development level, and water-saving irrigation technology significantly influence agroecological water use efficiency in the basin. Results indicate that a closer alignment of water price with the cost of water supply contributes to higher agroecological water use efficiency. Additionally, the widespread adoption of water-saving irrigation technology and mulch leads to increased efficiency. Based on these findings, the study emphasizes the policy implications, suggesting the continued promotion of water-saving irrigation technology in the basin., and in addition to popularize drip irrigation facilities, ground film cover can be used to reduce evaporation in areas with suitable conditions; agricultural water price reform should be continuously promoted, agricultural water prices should be adjusted according to local conditions, ladder water prices should be reasonably set, and the water rights trading system should be actively explored.

In order to optimize the alternating water supply mode of reclaimed water and fresh water, this study analyzed the influence of alternating water supply mode on the infiltration characteristics of red soil and the distribution of water and salt, so as to determine the optimal alternating water supply mode. In this study, 5 g/L and 10 g/L sodium salt solution along with fresh water were selected as the test water, five water supply methods were set up with brackish water mixture (SF mix), salt-light alternation (SF), light-salty alternation (FS), salt-light and salt-light alternation (SFSF) and light-salt-light salt alternation (FSFS), and freshwater (CK) was used as the control to carry out one-dimensional vertical soil column infiltration test. The results showed that the cumulative infiltration rate of the two sodium salts increased with the increase of the number of alternating times, and the alternating treatment of 5 g/L and 10 g/L sodium salt solution increased by 28.85% and 18.98% compared with the alternating treatment of light and salty at 360 min. The Philip model is more suitable for describing the change of soil infiltration with infiltration time under CK and FS alternating water supply, and the Kostiakov model is more suitable for describing the infiltration characteristics of red soil under SF mixture, SF, SFSF, and FSFS treatment. The salt distribution of the soil profile was affected by the alternating water supply mode, the salt accumulation degree was affected by the sodium salt concentration, and the conductivity (EC) distribution of the two sodium salt concentrations was consistent under the same water supply mode, and the EC value increased with the increase of sodium salt concentration. The alternating water supply of light and brackish can enhance soil infiltration capacity and reduce soil salt accumulation under the treatment of 5 g/L sodium salt solution, which is the optimal alternating water supply method, and it is recommended that the alternating water supply of light and salty water supply be the irrigation method of red soil reclaimed water in the southern subtropical region.

A BAS-BP model was developed to improve the estimation of spatial-temporal continuity soil moisture across multiple soil layers from surface to deep zone. This model combined the BP neural network with the Beetle Antennae Search Algorithm and utilized limited meteorological observations from McClellanville Station and MAWORS Station. It is found that: ①The fusion-optimized BAS-BP model outperforms the BP model for the inversion of soil moisture at all layers. The evaluation metrics for the test set indicate that the BAS-BP model achieves better performance. The RMSE for the test set based on the BP model ranges from 0.016~0.191 m³/m³, MAE ranges from 0.012~0.177 m³/m³, and R ranges from 0.390~0.987. The RMSE for the test set based on BAS-BP ranges from 0.014~0.143 m³/m³, MAE ranges from 0.010~0.131 m³/m³, and R ranges from 0.504~0.994. ②Both BP and BAS-BP model perform best for the soil moisture inversion at 10 cm depth, where the RMSE and MAE are both less than 0.016 m³/m³, and R is greater than 0.879. With the soil depth increases, the inversion efficiency tends to decline. ③The performance of each model is significantly affected by the driving factors. Both models perform well and exhibit stability at McClellanville station but show slightly poorer performance at the MAWORS station. The difference of R between the training and testing set based on BP and BAS-BP model is 10.789%, and 5.061%, respectively, at McClellanville station. However, the difference increases to 38.531% and 14.624% at MAWORS station. ④Overall, the inversion based on BAS-BP model has higher quality and stability than BP model. BAS-BP model is more suitable for the soil moisture inversion at surface to deep layers.

The development of soil crust affects the nutrient loss in the soil leaching process. Different degrees of crust development formed at 0 min, 10 min, and 30 min under a rainfall intensity of 30 mm/h were selected. Soil tray and soil column experiments were conducted to analyze the loss of ammonium ions and phosphate ions. The results indicate that: ①The development of soil crust significantly affects the soil infiltration capacity, and the average permeability reduction effect of soil crust at 10 min and 30 min under two kinds of rain intensity is 39.99% and 61.93%, respectively. ②The significance analysis of leached water nutrients showed that under two rainfall intensities, the development of crust would have a significant difference in the loss of ammonium and phosphate ions. ③The physical properties of soil crust were correlated with the leaching volume of soil and nutrient loss. The loss rate of ammonium ions and phosphate ions showed a negative correlation with the shear strength and bulk density of the soil crust and a positive correlation with the porosity of the soil crust and the leaching volume of the soil.

In order to explore the potential of water-saving and emission reduction of rice under different water-saving irrigation methods in Heilongjiang Province, the study analyzed the irrigation water consumption and CH₄ emission of the traditional flooding irrigation (TI) method in Heilongjiang Province, collecting relevant experimental data on rice. The Chinese official provincial greenhouse gas inventory method of IPCC guidelines was used to calculate the CH₄ emissions generated under wet irrigation (MI), dry-wet alternate irrigation (AWD), intermittent irrigation (II), and controlled irrigation (CI), and then the water-saving potential and CH₄ emission reduction potential under different water-saving irrigation methods. The results showed that different water-saving irrigation methods had obvious effects on rice irrigation water consumption and CH₄ emission, and the water management mode was beneficial in reducing rice water consumption and CH₄ emission. The water-saving potential from large to small is MI, AWD, CI, and II, which are 25.03 %, 15.65 %, 10.80 %, and 5.05 % respectively. The emission reduction potential from large to small is AWD, MI, CI, and II, which are 50.77%, 46.30%, 45.25%, and 38.14% respectively. Dry-wet alternate irrigation (AWD) is an effective measure to reduce the comprehensive greenhouse effect of rice. The research results can provide a reference for water saving and emission reduction of rice in Heilongjiang Province.

In order to investigate the effect of soil moisture on the light effect of crops, this paper classifies, summarizes and concludes the research results on the light effect of soil moisture on the net photosynthetic rate, transpiration rate, intercellular CO₂ content, stomatal conductance, stomatal limitation value and leaf water use efficiency of crops. The results showed that the decrease in soil moisture led to a decrease in the single peak curve of light response, indicating that water stress affects light energy utilization efficiency; Severe water stress can lead to a decrease in net photosynthetic rate, dark respiration efficiency, and apparent quantum efficiency, thereby affecting crop sugar production; Under severe water stress and strong light, the crop photosynthesis system will be damaged, and the crop transpiration rate will increase with the increase of soil moisture, but it will decrease when the soil moisture exceeds a certain threshold; When water stress and light intensity increase within a certain range, the intercellular CO₂ concentration decreases and the stomatal limit value increases. Beyond this range, the opposite phenomenon occurs: A certain amount of water stress can maximize the water use efficiency of leaves; The total chlorophyll content of crops decreases with the decrease of soil moisture, and the decrease rate of chlorophyll b content is faster than chlorophyll a. With the goal of saving water resources and promoting efficient crop growth, more research on the potential association between soil moisture and light effects on crop growth is explored going forward, providing theoretical support for in-depth research on soil moisture and light complementarity, crop water-light balance and efficient use of agricultural resources in arid regions.

To investigate the impact of sudden alternations between drought and floods on rice yield and its underlying causes, we conducted a study on early rice (Xiangzaoxian six) in Dongting Lake area. We used bucket planting to create different levels of drought (D, 65±5% θ field, 50±5% θ field, 35±5% θ field, θ field is field water holding capacity), different drought exposure time (T, 5, 7, 9 d), different flood exposure level (H, 50% h plant height, 75% h plant height, 100% h plant height, h plant height is plant height), and different flooding time (L, 5, 7, 9 d). There were three levels of each factor, a total of nine drought and flooding treatments (T1~T9), with normal irrigation as the control (CK), to study the effect of different drought and flooding treatments on rice yield, dry matter accumulation, leaf physiological characteristics and soil redox potential (Eh). The results showed that ①the order of influence of the four factors on yield was: D>L>T>H, and the influence of all four factors on yield was highly significant (P<0.01); ②compared with CK, the yield reduction of each drought and flood treatment ranged from 67.32% to 98.71%, the aboveground dry weight decreased from 14.09% to 70.03%, the root dry weight decreased from 21.34% to 78.34% ( T1 treatment slightly increased), drought-floods abrupt alternation can lead to an increase in rice root-shoot ratio and a decrease in dry-fresh weight ratio; ③There was both superimposed loss effects and compensation effects of drought and flood stress on chlorophyll content and photosynthesis of rice, and soil Eh decreased in all treatments of flood stress compared with drought stress, with a decrease of 10.29%~67.81%, and the reduction of soil was enhanced; ④There was a highly significant positive correlation between yield and aboveground dry weight, and a significant positive correlation between root dry weight, net photosynthetic rate, and chlorophyll content. In this study, we analyzed the photosynthetic characteristics, soil Eh and dry matter accumulation of rice during and after the drought and flooding stress period, and explored the potential mechanism of yield reduction under the drought and flooding stress, which provided a theoretical reference for coping with the drought and flooding stress in Dongting Lake.

To investigate the effects of different irrigation amounts on eggplant yield, quality, and salt accumulation in the root zone, this study used “Jingjiaheibao” as the experimental material, and six daily irrigation treatments were set up: T1 (2.4 mm), T2 (3.6 mm), T3 (4.8 mm), T4 (6.0 mm), T5 (7.2 mm), and CK (8.4 mm). Indicators of ion concentration, photosynthetic characteristics, fruit quality, single fruit yield, and water utilization were determined in the root zone of eggplant. The results showed that the amount of nutrient solution irrigation had a significant effect on the physiology of eggplant plants and fruit quality and that too little irrigation caused ion accumulation, which was unfavorable to plant growth and fruit quality formation. With decreasing irrigation, soluble sugar content and soluble solids of eggplant showed a gradual increase, and root vigor, leaf photosynthetic parameters, and leaf chlorophyll fluorescence parameters showed a decreasing trend. When the nutrient solution was irrigated at T4 (6.0 mm), eggplant plant biomass accumulation was the highest, and fruit vitamin C content, soluble protein content, yield per plant, and water use efficiency were significantly higher than in all other treatments (P<0.05). In addition, as eggplant plants grow, ion accumulation occurs in the root zone of eggplant grown in inorganic substrate tanks, leading to a rise in the EC of the nutrient solution in the root zone.At 64 d of plant growth, the highest EC value of nutrient solution in the root zone of eggplant was shown: T1>T2>CK>T5>T3>T4, and at this time, the contribution of the mass concentration of each ion in the T1 (2.4 mm) treatment to the cumulative intensity of salts in the root zone was shown as K⁺> Ca²⁺> total phosphorus> Mg²⁺> total nitrogen. Finally, correlation analyses showed highly significant positive correlations (P<0.01) between net photosynthesis rate and transpiration rate, between net photosynthesis rate and root vigor, between vitamin C and yield per plant, between soluble sugars and soluble solids, and between total phosphorus and Ca²⁺. In this study, it was concluded that eggplant fruit quality, yield per plant and water utilization were optimal when the daily nutrient solution irrigation rate was T4 (6.0 mm), and that an appropriate reduction in the nutrient solution irrigation rate would help to reduce the accumulation of salts in the root zone, and at the same time would be conducive to the formation of eggplant fruit quality and the increase of yield per plant.

Infiltration irrigation is a subsurface water-saving irrigation technology which continuously inflates irrigation water into the soil of crop root zone through a porous medium. In this study, a microporous ceramic infiltration pipe was prepared using clay and slag as raw materials by growting method, resulting in excellent material properties and environmental friendliness. The soil water infiltration characteristics of microporous ceramic infiltration pipe were studied emphatically, and the working head optimization algorithm for microporous ceramic infiltration pipe was proposed with the goal of optimal root water matching. The results show that the flow rate of the microporous ceramic infiltration pipe decreases rapidly within 1 h, then stabilizes and reaches a constant flow state after 48 h. When the working head increases from 0.25 m to 0.75 m, the stable flow rate of the microporous ceramic infiltration pipe increases from 0.157 L/(h·m) to 0.270 L/(h·m). There is a significant linear positive correlation between the stable flow rate and the working head. The wetting body is a cylinder that is parallel to the soil surface. The soil water content on the wetting body profile gradually decreases along the wetting front migration direction. The wetting fronts in the vertical upward, vertical downward, and horizontal directions diffuse at a rate of 0.05 cm/h, 0.08 cm/h, and 0.04 cm/h, respectively. The average soil water content in the wet body increased with the increase of the working head. The average soil water content in the wet body under the working head of 0.25 m, 0.50 m, and 0.75 m was 0.243 cm³/cm³, 0.348 cm³/cm³ and 0.406 cm³/cm³, respectively. Using the constructed optimization algorithm of the working head of the microporous ceramic infiltration pipe, the working head of the microporous ceramic infiltration pipe for three typical dense planting crops of winter wheat, summer maize, and tomato were optimized. The recommended working heads are 0.423 m, 0.529 m, and 0.642 m, respectively. The research results can provide a scientific basis for the popularization and application of microporous ceramic infiltration pipes.

Studying the long-term variation characteristics of meteorological elements in irrigated areas and their influence on irrigation water consumption has significant guiding and practical value for understanding the patterns of irrigation water in irrigated areas so as to carry out more scientific and efficient irrigation practices. Based on the measured meteorological data of three meteorological stations in Fenxi Irrigation District, Shanxi Province spanning the period from 1975 to 2018, this paper analyzes the temporal variation characteristics of precipitation and temperature by linear tendency estimation and M-K test, calculates crop water demand and irrigation water consumption in irrigated area by crop coefficient method, comprehensively analyzes the impact of climate change on irrigation water consumption, and establishes the relationship between typical annual precipitation, crop water demand and irrigation water consumption in different hydrological typical years. The results show that the precipitation in Fenxi irrigation area decreased at a rate of 2.7 mm/10a and the first mutation occurred in 1977, the average temperature increased significantly at a rate of 0.471 °C/10a, and abruptly changed in 1997, in the past 44 years. The climate of the irrigation area is developing in the direction of warm and dry, and the irrigation water consumption increases at a rate of 25.4 mm/10a. The sudden change in temperature was accompanied by a sharp drop in precipitation to the lowest value in many years, and the irrigation water consumption increased by 396.8 mm compared with the multi-year average, which was much greater than the year when precipitation suddenly changed. The irrigation water consumption increases by 1.92 mm for every 1 mm increase in crop water demand. The increase in precipitation will reduce its impact on irrigation water, and the unit precipitation can cause changes in the irrigation water consumption of 1.29, 1.74, and 2.72 units in abundant, flat, and dry years, respectively. The irrigation quota in dry years is 20% more than that in abundant and flat years.

The promotion of water-saving irrigation technology is of great significance for alleviating the shortage of water resources and realizing the sustainable development of the Yellow River Basin. There is an inherent logical relationship between agricultural industrial organization and water-saving irrigation technology, and it is of great significance to explore the relationship between farmers joining agricultural industrial organizations and water-saving irrigation technology. Based on 839 survey data from Shaanxi, Gansu, and Ningxia provinces in the Yellow River Basin, this paper analyzed the influence of farmers joining agricultural industrial organizations on the adoption of water-saving irrigation technology and further discussed its internal transmission mechanism and effect difference under the situation of farmer characteristics differentiation. The results show that: ①The dual logit model proves that joining the agricultural industry organization promotes the adoption of water-saving irrigation technology by farmers, and verifies the reliability of this conclusion. ②The scale threshold for the adoption of water-saving irrigation technology is estimated to be about 0.8 hm² through the survey data, and 0.8 hm² is used as the threshold value of land scale for mechanism analysis. The intermediary model shows that joining agricultural industrial organizations promotes land scale and thus encourages farmers to adopt water-saving irrigation technology more actively. ③A multidimensional heterogeneity analysis was conducted on the adoption behavior of water-saving irrigation technology by farmers from the perspectives of intergenerational differences and household management status differences, and it was found that joining agricultural industrial organizations could better promote the adoption of water-saving irrigation technology by older farmers and farmers with poor family management status. Therefore, the government should encourage the development of agricultural industrial organizations, give play to their exemplary role, encourage more farmers to adopt water-saving irrigation technology, further improve the land system, promote land circulation and land scale, increase technical publicity and training, and promote the adoption of water-saving irrigation technology.

For agricultural production and water management, accurate knowledge of the amount and spatial distribution of irrigated land is essential. In complicated and fragmented agricultural areas, mono-temporal satellite imagery often fails to achieve the required accuracy, as traditional pixel-based remote sensing extraction techniques for irrigation can destroy the basic shape of plots. To address this problem, this study proposes a plot-scale irrigated cropland extraction method based on Sentinel-2 time-series imagery and designs various feature-combining schemes. Finally, a method for identifying irrigation areas based on the XGBoost classification model was developed and the generalization ability of the model was evaluated to achieve regional plot-scale irrigation area extraction. The method has been validated in a concentrated area of irrigation agriculture in the South Platte basin, Colorado, USA. The results show that: ①even in complicated and fragmented agricultural areas, the method can achieve accurate extraction of irrigated land by preserving the basic shape of the parcels, with an overall accuracy of 85.03%; ②the combination of mean, standard deviation, and median features performs best in terms of accuracy, with a Kappa coefficient of 0.69, where the classification accuracy of irrigated land is 86.76% and that of non-irrigated land is 82.30%; ③the effect of different time series lengths on the extraction of irrigated land was investigated and it was found that the sensitive time period for distinguishing irrigated land from non-irrigated land is mainly in the later part of the agricultural growing season, and the classification accuracy improves as the time series length increases. As the structured feature information contained in the time series facilitates model performance and optimal mapping accuracy, these findings provide insights for future research. This study provides ideas for further research in this area by combining machine learning and time series remote sensing, which can be used to survey and monitor irrigated land.

Experiment conducted to investigate soil water and salt movement and redistribution under different fertigation strategies for tobacco liquid fertilizer is of great significance for the rational regulation of water and fertilizer in integrated water and fertilizer management. The experiment compared five different treatments: CK(only drip fertilizer for 40 min)、W1(early dripping water 20 min, mid-term dripping fertilizer 40 min, late dripping water 10 min)、W2(early dripping water 30 min, mid-term dripping fertilizer 40 min, late dripping water 10 min)、W3(early dripping water 40 min, mid-term dripping fertilizer 40 min, late dripping water 10 min) and W4(early dripping water 30 min, mid-term dripping fertilizer 40 min, late dripping water 30 min). The study analyzed the changes in the wet front, soil moisture at characteristic points, and the variation in EC to understand the movement of water and salt in the soil. Results showed that the distribution of water and salt in the soil is obviously affected by fertigation strategies. Firstly, the radial movement of the wetting front was greater than the vertical movement. With the increase of irrigation time and irrigation volume, the wetting front, water moisture, and EC value tend to balance out in both horizontal and vertical directions. The duration of dripping in the early stage of fertigation has a greater impact on the migration of salt in the horizontal direction, while the dripping in the later period has a greater impact on the migration of salt in the vertical direction. Based on the long-term water and fertilizer requirements of flue-cured tobacco, a suitable fertigation strategy during the growth period would be to drip water for 30 minutes in the early stage, drip fertilizer for 40 minutes in the middle stage, and drip water for 30 minutes in the late stage.

To study the optimal irrigation system for high-quality, high-yield, and high-efficiency facility tomatoes, a comprehensive evaluation model was developed using evaporation pans, meteorological stations, and soil moisture sensors as irrigation decision-making criteria. Five irrigation treatments were designed, and several evaluation indicators were selected, including tomato single fruit weight, yield, irrigation amount, sugar acid ratio, Vc content, and soluble sugar content. The TOPSIS based on entropy weight was used to analyze and evaluate the irrigation system, and high-quality facility tomatoes were established, which is a comprehensive evaluation model for high yield and efficiency to determine the optimal irrigation schedule. The results showed that the recommended optimal irrigation system for greenhouse tomatoes was as follows: 37 mm for seedling stage irrigation, 44 mm for flowering and fruit setting stage irrigation, and 17 mm for fruit ripening stage irrigation. The model evaluation results were consistent with experimental study. This method considers the sensitivity of water deficit at different growth stages when selecting evaluation indicators, avoiding errors caused by subjective factors. The evaluation results are objective and accurate, and the method is simple, providing a new way to optimize and evaluate irrigation systems for greenhouse tomatoes.

When using the Priestley-Taylor model to estimate evapotranspiration, the calculation accuracy mainly depends on the localization degree of coefficients. This study takes summer corn fields in northern Henan as the research object, using the eddy covariance technology and meteorological data from June to September, to analyze the characteristics of water and heat flux of corn fields at different time scales, to determine the various characteristics of P-T model coefficients and modify the coefficient, and to recommend the reference values for corn fields in northern Henan. The results indicated that the variation of water and heat flux during the growth period of summer maize presented an inverted U-shaped single peak curve on a daily scale. The difference between sensible heat flux and latent heat flux was relatively small in late June and September, and the latent heat flux (average of 33.57 W/m² in June and 19.88 W/m² September) was slightly greater than the sensible heat flux (average of: 27.75 W/m² in June and 16.62 W/m² in September). The latent heat flux (average of 42.30 W/m² in July and 51.52 W/m² in August) gradually increased in the middle growth stage, while the sensible heat flux (average of 18.05 W/m² in July and 9.59 W/m² in August) decreased, showing a significant difference between them. The soil heat flux varied with the fluctuation of total radiation and had a certain lag. At the monthly scale, there was a significant change in total radiation with seasonal changes, and the overall latent heat flux varied accordingly with the fluctuation of total radiation. The simulation accuracy of the P-T model was significantly improved after coefficient correction, α (June 1.12, July 1.12, August 1.32, September 1.24) can be used as a suitable parameter for localization of the P-T model.

To make a scientific and rigorous assessment of the construction of modern ecological irrigation districts, this paper based on fuzzy analytic hierarchy process to address the issues of randomness, repeatability, and incompleteness in indicator selection. Focusing on objectives of large-scale irrigation district modernization in China, a comprehensive evaluation system for the health of the modern ecological irrigation district in Ningxia was developed. The evaluation system comprised six aspects, including modernization of safety assurance and service capacity, modernization of engineering facilities, modernization of innovation capabilities, modernization of management systems, water-saving efficiency and production efficiency, and optimization of the ecological environment. By applying an index optimization model, the number of evaluation indicators was reduced from 44 to 27, capturing approximately 90.37% of the overall system’s essence. This optimization achieved the desired outcome of fewer indicators while maintaining a high level of comprehensiveness. Taking the pilot counties of Ningxia modern ecological irrigation district as the evaluation object, an empirical study of the evaluation system was conducted. The results showed that 57.85% of Litong District was at a healthy level, which was consistent with the actual situation of the irrigation district. The evaluation system could effectively reflect the main achievements, existing challenges, and deficiencies of the pilot counties’ efforts to promote the construction of a modern ecological irrigation district. The study also illustrates the feasibility and soundness of the evaluation index system and evaluation method to modern irrigation districts.