Farmland ecosystems exchange heat, water, and carbon dioxide with the atmosphere continuously, consuming available water resources while producing the food necessary for human survival. Land surface models can quantitatively describe the energy, momentum, and water vapor exchange between soil, vegetation, and atmosphere, but their application is constrained by input parameter uncertainty. This study selected two typical agricultural ecosystems experimental stations, e.g., Yucheng Station and Luancheng Station in the North China Plain, and used Latin hypercube sampling (LHS) based on Sobol method to detect the global sensitivity of five output variables, e.g., latent heat flux (LE), sensible heat flux (H), net ecosystem carbon exchange (NEE), first-layer soil moisture (SM1), and second-layer soil moisture (SM2), to 42 input parameters of the Noah-MP model, and screened out highly sensitive parameters. The results showed that if the exact ranking of sensitivity indicators is not considered, Latin hypercube samples can be about five times the number of parameters to save computational costs. For these five model outputs, highly sensitive parameters were consistent between sites and under different stomatal resistance parameterization schemes, including five vegetation parameters (LTOVRC, QE25, MRP, VCMX25, SLA) and four soil parameters (BEXP, SMCMAX, SMCREF, SMCWLT). In arid areas, special attention should be paid to the calibration of BEXP.

The correlation of crop growth and its response to water stress are an important basis for establishing a material distribution model and simulating crop growth. Using the data of summer maize (4 years) at Huoquan Experiment Station in Shanxi Province and spring maize (2 years) at Wenyuhe Experiment Station, it was concluded that stem-leaf ratio, grain-stem ratio and root-shoot ratio of maize showed an S-shape, exponential function and power function curve with growth time, respectively. The correlation coefficients between measured and simulated values of stem-leaf ratio, grain-stem ratio in Huoquan and root-shoot ratio in Wenyuhe were all above 0.8, and the fitting accuracy was high. Both stations have been subjected to varying degrees of drought stress for 6 years, and most of the water stress occurred in the filling stage of male-pumping. The root-shoot ratio of spring maize was mostly affected by water stress (σ=0.166), stem-leaf ratio of summer maize (σ=3.7×10^-3) and spring maize (σ=1.5× 10^-4) were less affected by water stress, and the effect of water stress on grain-stem ratio of summer maize in Huoquan(σ=0.065) was greater than that of spring maize in Wenyuhe(σ=1.0×10^-8).

This study aimed to solve the problem of poor growth and yield of Xanthoceras sorbifolia in Hexi Corridor region due to water shortage and soil salinization. The distribution characteristics of soil water and salt under different soil matric potentials (SMP) of drip-irrigated Xanthoceras sorbifolia orchards were studied, providing a scientific basis for the drip irrigation scheduling for Xanthoceras sorbifolia in the Hexi Corridor region. The field experiment was conducted in Zhangye City, Gansu Province (central region of Hexi Corridor) from May to September of 2021. The young (1-year-old) and fruiting (5-year-old) Xanthoceras sorbifolia fruit trees were selected, and different SMP thresholds were set under drip irrigation conditions. The SMP values for young tree were -10, -20, -30, -40, -50 kPa, and those for the fruiting tree were -5, -10, -15, -20, -25 kPa. The results showed that: ①Under drip irrigation conditions, the soil volumetric water contents in the orchard decreased with the decrease of SMP thresholds. As the SMP thresholds gradually decreased, the soil volume moisture contents in the root zone at the end of the growing season were 0.14, 0.13, 0.13, 0.12, and 0.11 cm³/cm³, respectively for the young tree; while the corresponding values were 0.21, 0.20, 0.17, 0.16, and 0.12 cm³/cm³, respectively for the fruiting tree. ②After one season drip irrigation, the soil electrical conductivity of saturated paste extract (EC_e ) in each treatment significantly decreased. As the SMP thresholds gradually decreased, the soil EC_e at the end of the growing season decreased from 5.45 dS/m before irrigation to 3.69, 3.85, 4.23, 4.61 dS/m and 5.00 dS/m, respectively for the young tree; while the values decreased from 6.96 dS/m before irrigation to 4.47, 4.87, 4.83, 5.59 dS/m and 5.71 dS/m, respectively for the fruiting tree. ③Unlike traditional surface irrigation, drip irrigation could effectively reduce soil salt accumulation in the root zone of Xanthoceras sorbifolia, and was more conducive to forming a suitable water and salt environment in the root zone for crop growth. In a word, considering the salt tolerance and water use efficiency of Xanthoceras sorbifolia, it is recommended to control the SMP threshold at -30 kPa during the young tree stage and -20 kPa during the fruiting stage for drip irrigation in the Hexi Corridor area.

Researching accurate and rapid methods for detecting soil moisture content holds significant practical importance for agricultural irrigation, ecological restoration, and other applications. In this study, we conducted physical experiments to acquire ground-penetrating radar (GPR) signals at different soil moisture levels. The power spectrum of the radar signals was calculated using the AR power spectrum model, and power spectrum attribute parameters were extracted. Cross-correlation was employed to optimize the selection of power spectrum attribute parameters. These parameters were then used as input samples for training a backpropagation (BP) neural network to predict soil moisture states. The experimental results demonstrated that the combination of GPR power spectrum attribute parameters and the BP neural network yielded an accuracy of 96.3% for identifying soil moisture states. The average absolute error between the predicted and actual soil moisture content was 1.2%, with a root mean square error (RMSE) of 0.015. In field measurements, utilizing this method, only one error occurred in identifying the water-rich nature of 16 soil samples, and the absolute and relative errors in soil moisture content inversion were within 3% and 10%, respectively. This method exhibits high precision in soil moisture detection, with small prediction errors, thus providing valuable insights for rapid soil moisture assessment.

In order to explore the changes of physiological indexes and photosynthetic characteristics of winter wheat leaves under drought stress and rewatering, this study took "Jimai 22" as the research object, and conducted one-time irrigation at four levels of 80%, 50%, 25% and 0% of the normal water supplement at the beginning of jointing stage. After that, there was no water supplement, and rewatering was unified after entering the flowering stage. Taking winter wheat under normal irrigation management as the control, the activities of antioxidant enzymes, the content of malondialdehyde (MDA) and the photosynthetic parameters of winter wheat leaves were measured. The results showed that under drought stress, the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and malondialdehyde (MDA) in winter wheat leaves increased significantly, while the photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), intercellular CO₂ concentration (Ci) and leaf water use efficiency (WUE) decreased, The Ls value showed an upward trend, and the more severe the drought stress was, the greater the change range was. When the extreme drought conditions were reached, the SOD and CAT values slightly decreased compared to other treatments, the Ci value slightly increased, and the Ls value slightly decreased. After rewatering, winter wheat had a compensation effect. All indexes of the treatment with light drought stress could return to the normal level, while the treatment with heavy drought stress could not return to the normal level.

This paper uses game theory to analyze the behavior logic of the main actors in the construction of small-scale farmland water conservancy facilities in China, and to investigate the main causes of the current dilemma in the construction of small-scale farmland water conservancy facilities in China: first, the goals pursued by the main actors conflict with each other, and second, the cost of small-scale farmland water conservancy facilities construction by local governments and farmers outweighs the benefits. Based on this, we propose a new funding mechanism based on the incentive-behavior-goal paradigm of organizational behavior, and propose the incentive mechanisms of "capital-based allocation of use rights" and "water subsidies", so that the property rights incentive can be transferred from the organization to the individual, and give specific recommendations for implementation.

Taking the Yellow River Basin as the research object, based on geographical variable interrelationships, this study selected the geographical variables which strongly correlated with irrigation water use, using the Convolutional Neural Networks, the spatial distribution of irrigation water use in the Yellow River Basin from 2000 to 2013 was generated, the accuracy of the simulated irrigation water use was evaluated using three metrics: root mean square error, Nash-Sutcliffe efficiency, and relative error. The results showed that, in terms of spatial agglomeration, positive agglomeration was observed from 2000 to 2013, with a decreasing trend over time; in terms of temporal evolution, the annual growth rates in different regions varied, with the highest rate of 12.14% in Jincheng, Shanxi and the highest annual decrease rate of -5.49% in Gannan Tibetan Autonomous Prefecture, Gansu. In terms of accuracy, this model had high accuracy, and the error was within an acceptable range.

To solve the problems that plastic film mulching pollutes the environment and soil, an experiment was carried out to compare the new environment-friendly mulching material with the conventional one, aiming to provide reference for the sustainable development of surface mulching. Four treatments included biodegradable film (M3), liquid mulch (M4), black ground cloth (M2), and the conventional plastic mulch (M1) as control. The results showed that the warming effects of different mulching materials vary greatly at different time of the day. With the growth period of the maize, the range in warming effects of different mulching materials decreased gradually, with biodegradable mulches increasing temperatures significantly at the seedling stage. When treated with biodegradable film covering, the soil moisture had little difference with that under plastic film covering before tasseling stage, and the water-saving effect under degradable plastic film mulching was the best. Film mulch had varying effects on soil physicochemical properties, with the effects on fast-acting potassium most significant in all layers, the effects on fast-acting phosphorus mainly in the 0~10 cm depth, and little effects on total phosphorus. The seed yields covered by degradable film were 14 294.56 kg·hm^-2 and showed no significant difference compared with those covered by plastic film.The seed yield covered by liquid mulch (M4) was the lowest, only 10 535.64 kg·hm^-2, and showed significant difference compared with those covered by degradable film and plastic film. The treatment with biodegradable film mulching was the best in improving soil nutrient environment and maize yield. In conclusion, ridge-furrow planting with biodegradable film mulching over ridges would be the most effective way for maize cultivation in the central region of Gansu province.

Timely and accurate monitoring of soil water content is crucial for regional precision irrigation and water resource management. Image recognition technology has become an effective means to obtain soil water content information with its simple and fast advantages. In this research, we collected images of coarse sand, fine sand, chalky loam, loamy clay and chalky clay soils with different water contents by using a cell phone camera in a controlled indoor experiment. We also analyzed the relationship between seven color parameters such as red (R), green (G), blue (B), hue (H), saturation (S), value (V), and full-color gray value (DN) and soil water content. A support vector machine soil water content inversion model was constructed selecting R in RGB color space, V in HSV color space, and DN as input items. The results showed that there were different nonlinear relationships between each color characteristic parameter and soil water content, among which only S shows a positive correlation with soil water content, while the rest of the feature parameters show a negative correlation with soil water content. In RGB color space, the correlation is shown as R>G>B, and in HSV color space, the correlation is shown as V>H>S. The correlation between the feature parameters DN and water content of the panchromatic image is only smaller than R and V. Compared with the multivariate linear models proposed in the same type of studies (with R ² ranging of 0.600~0.990, RMSE ranging of 1.100%~8.000%), the soil water content inversion by support vector machine model developed in this study demonstrated higher prediction accuracy and stability, with R ² ranging of 0.986~0.997, RMSE ranging of 0.402%~0.911%, and MAE ranging of 0.339%~0.831%. This study provides a new method for obtaining soil water content, which can provide technical support for soil water content monitoring in fields such as agricultural irrigation management and hydrological cycles.

In order to improve the water, fertilizer utilization efficiency of tomato planting, growth, yield and quality, three irrigation water quantities (50%, 75% and 100% of crop evapotranspiration (E _p), denoted by W50, W75, and W100) and three silicon fertilizer application amounts (0, 1, 2 mmol/L, represented by Si0, Si1, and Si2) were set up for 9 groups of treatment. The effects of silicon fertilizer on tomato growth and quality under deficit irrigation were analyzed, and the growth, yield and quality of tomato were evaluated by membership function method. The results showed that W75Si1, W100Si2 and W75Si2 had the highest plant height, stem diameter and leaf dry matter mass, the best growth and development, and the highest yield. The plant height, stem diameter, leaf dry matter mass, yield increased with the increase of irrigation water and silicon application amount. Irrigation water amount and silicon application amount and their interaction had significant effects on plant height, stem diameter, leaf dry matter mass, WUE and yield (P<0.05). WUE increased with the increase of silicon fertilizer and the decrease of irrigation water amount. Lycopene, soluble sugar and soluble solid increased with the increase of irrigation water, while vitamin C increased first and then decreased with the increase of silicon fertilizer. Silicon application promoted the growth, yield and synthesis of lycopene, but also inhibited the formation of vitamin C, soluble sugar and soluble solid content. Membership function method showed that W75Si2 treatment was the best irrigation method under experimental conditions, which could improve WUE, growth, yield and quality.

In order to reveal the effects of water-saving irrigation and reduced nitrogen fertilizer combined with biochar on the total effective rate and loss rate of base fertilizer, tiller fertilizer, panicle fertilizer, and nitrogen fertilizer, four nitrogen application levels (110, 99, 88, and 77 kg/hm²) and four biochar application levels (0, 2.5, 12.5, and 25 t/hm²) were set. Using ¹⁵N tracer technology, taking the treatment of no biochar plus 110 kg/hm² nitrogen fertilizer as the control, the total effective rate and loss rate of water-saving irrigation and reduced nitrogen fertilizer combined with basal fertilizer, tiller fertilizer, panicle fertilizer, and nitrogen fertilizer under biochar were studied, and the profit and loss value of soil nitrogen was calculated. The results showed that the application of biochar could increase the total residue and residue rate of base fertilizer-¹⁵N, tiller fertilizer-¹⁵N, panicle fertilizer-¹⁵N, and fertilizer-¹⁵N in the soil layer with a depth of 0~20 cm. Reasonable reduction of nitrogen fertilizer combined with biochar increased the total effective efficiency of base fertilizer, tiller fertilizer, panicle fertilizer, and nitrogen fertilizer and rice yield, reduced the total loss rate of base fertilizer, tiller fertilizer, panicle fertilizer, and nitrogen fertilizer, while excessive reduction of nitrogen fertilizer or biochar reduced the total effective efficiency of base fertilizer, tiller fertilizer, panicle fertilizer, nitrogen fertilizer, and rice yield, and increased the corresponding loss rate. Generally speaking, the biochar treatment with 12.5 t/hm² in combination with 20% nitrogen reduction was the best.

The analysis of the characteristics of regional temperature, precipitation and other climate resources changes can provide a scientific basis for the planning and layout of agricultural production and meteorological disaster prevention under climate change. In this study, we used the climatic tendency rate, Mann-Kendal (MK) test and Morlet wavelet method to analyze the daily meteorological data from 7 stations in Hainan Island from 1960 to 2020, which could yield the temporal and spatial variation trend of temperature, precipitation and reference crop evapotranspiration (ET ₀). The results show that, in terms of time, the annual average temperature of Hainan Island increased significantly at the rate of 0.22 ℃/(10 a), the annual average precipitation increase mildly at the rate of 33.66 mm/(10 a), and the ET ₀ decreased slightly at the rate of -0.30 mm/(10 a). MK test shows that there is no mutation in temperature series, but there is mutation in precipitation and ET ₀ series. The wavelet analysis shows that there is a main cycle of 55 years for temperature change, and a main cycle of 56 years for precipitation and ET ₀. In different seasons, the temperature rises significantly, but the change trend of precipitation and ET ₀ is not significant. In terms of spatial distribution, the temperature in Hainan Island increases from the central Qiongzhong as the centre of low values to the surrounding coastal areas, with the temperature in the southeast overall is higher than that in the northeast; precipitation decreases from the central Qiongzhong to the surrounding coastal areas, with ET ₀ showing an increasing trend from northeast to southwest. The results indicate that the climate of Hainan Island has shown a warming and humidification trend in the last 61 a, responding significantly to global warming. It is predicted that the temperature, precipitation and ET ₀ will fall in the next few years, which will have an impact on the agricultural production and ecosystem in this area.

In order to understand the impact of different irrigation amounts of sprinkler irrigation on the biomass and quality of triticale in the Lhasa Valley, the triticale in Lhasa City was taken as the research object, and six irrigation treatments were set. Under the water deficit of triticale, the significance of growth, biomass and quality indicators of different treatments was comprehensively evaluated and analyzed. Moreover, based on the grey correlation theory of entropy weighting method, comprehensive analysis is conducted on each indicator. From the comparative analysis of various treatments and sufficient irrigation after cutting, the root length, SPAD, and overwintering rate of water deficient triticale significantly decreased by 10.5%, 12.9%, and 5.5% during the seedling to overwintering stages, respectively. The SPAD and crude protein of water deficient triticale significantly decreased by 14.9% and 13.8% during the turning green to jointing stage. The plant height, LAI, SPAD, and biomass of water deficient triticale significantly decreased by 23.5%, 44.0%, 13.2%, and 22.4% during the jointing and heading stages, respectively. The LAI, SPAD, and biomass of water deficient triticale significantly decreased by 24.0%, 4.5%, and 23.8% during the heading to cutting period, respectively. The jointing to heading stage is the critical period for water requirement of triticale, during which water shortage has the greatest impact on biomass and quality. Adequate water irrigation should be carried out. The lack of water before the jointing stage has a relatively small impact on its biomass and quality. Although the heading cutting period is during the rainy season in the Lhasa Valley, proper supplementary irrigation is beneficial to ensure high and stable yield of triticale. Adequate water irrigation can lead to waste of water resources and lower water use efficiency, while moderate water irrigation has the highest cost-effectiveness. Through comprehensive analysis of various irrigation treatments, the grey correlation degree is ranked from high to low as follows: moderate water > sufficient water > water shortage during heading to cutting > water shortage during seedling to overwintering > water shortage during turning green to jointing > water shortage during jointing to heading. With 75% field capacity as the lower limit and 100% field capacity as the upper limit, the triticale in Lhasa Valley was irrigated for 15 times, with the irrigation amount of 352 mm and the highest biomass. With 65% field capacity as the lower limit and 100% field capacity as the upper limit, 10 times of irrigation and irrigation were carried out, with the irrigation amount of 319 mm, and the overall quality was the highest.

The Tabu River Basin is not only the largest inland river in the western Inner Mongolia Plateau, but also the core area of the northern ecological barrier in China. It is of great significance that study the water supply service in the Tabu River basin, which makes a contribution to the development of local agriculture and animal husbandry and the protection of the ecological environment. In this study, based on the water quantity module of the InVEST model and the scenario analysis method, the response principle of water yield and water depth, which include spatiotemporal pattern of the precipitation variation and land utilization change, were revealed from 2000 to 2020 in the Tabu river basin. After that, under the implementation of returning farmland to forest and grassland, the effects of land use or cover change on water conservation were evaluated quantificationally in the study area. The results showed that: from 2000 to 2020, the land use in the Tabu River Basin changed from cultivated land to grassland, and the conversion of farmland to grassland significantly promoted the increase of water yield. The annual water yield in the Tabu River Basin showed a fluctuating decreasing trend with an average annual water yield of 7 752 × 10⁴ m³ and an average annual water depth of 8.63 mm. In space, the overall water yield is more in the south than in the north, the water yield in the hilly area is significantly greater than that in the intermountain basin plain area and the general plain area, and the type of significant increase in water yield is grassland. The water yield of the basin is greatly affected by precipitation change and less affected by land use change, and there is a significant relationship with temperature and potential evapotranspiration at the monthly and seasonal scales.

This paper establishes a 0-1 linear programming model for optimal water distribution in branch and lateral canals in irrigation districts, and analyzes the advantages and disadvantages of using discrete binary particle swarm algorithm (BPSO) and genetic algorithm (GA) to optimize water distribution in irrigation districts. The hybrid binary particle swarm algorithm (GA-BPSO) is proposed based on the analysis of the advantages and disadvantages of discrete binary particle swarm algorithm (BPSO) and genetic algorithm (GA). MATLAB is applied to solve the BPSO algorithm and GA-BPSO algorithm, and the application cases is used to examine and analyze the above method. The results show that GA-BPSO algorithm is more efficiently than BPSO algorithm is searching the optimal solution. For the study case, the GA-BPSO algorithm can obtain the optimal solution in about 12 iterations while the BPSO algorithm obtains the optimal solution in about 21 iterations. The GA-BPSO algorithm has fast convergence in optimizing the branch and lateral two-stage canal system water distribution, and the method still has room for further improvement.

Reducing operating pressure has been widely acknowledged as one of the most effective approaches to minimize the maintenance and operation costs of drip irrigation systems. However, the use of low-quality water, such as high-sand water, reclaimed water, and brackish water increases the risk of emitters clogging, so we explored the possibility of low-pressure irrigation. In this study, the effect of four pressure levels (50, 80, 100, and 130 kPa) on the anti-clogging performance of the labyrinth channel emitters was analyzed using high-sand content water as the drip irrigation water source, and the particle size distribution of retained and discharged silted sediment in the emitter was measured. The results show that the operating pressure has a significant effect on the anti-clogging performance of the labyrinth channel emitter. When the operating pressure is lower than 80 kPa, the sludge accumulation in the drip irrigation head is faster (the final cumulative amount reached 52.31 mg), the clogging process of the emitter is accelerated, the anti-clogging performance is significantly reduced, and the emitter shows overall clogging after 10.92~12.78 d of operation. In contrast, the anti-clogging ability of the drip head gradually decreases when the operating pressure is greater than 80 kPa, and the system shows sudden clogging of the emitter after 17.87~27.96 d of operation. At the end of irrigation, the content of silted sediment V10 (6.61~8.29 μm) and V25 (13.54~20.93 μm) in the emitter showed a decreasing trend with an increase in the average particle size by 12.41%~23.77%, and was less affected by the operating pressure; while increasing the operating pressure was beneficial to reduce the percentage of V50 (31.64 ~ 56.31 μm) in the irrigator. The proportion of sediment (down about 13.12%), coarse particles of sediment V75 (51.82~78.25 μm), V90 (80.76 ~ 118.13 μm) in the four operating pressures are not easy to discharge the flow channel, and in the smaller operating pressure is easy to bond into larger particles increase the risk of emitter clogging. The operating pressure has a greater impact on the emitter discharge of coarse particles of sediment and less impact on the discharge of tiny sediment. Therefore, in drip irrigation systems with high-sand content, the operating pressure for low-pressure irrigation in labyrinth channel emitter should be higher than 80 kPa.