In order to explore how to improve the water use efficiency of drip irrigated silage maize， field irrigation experiments were carried out for two consecutive years， and the effects of different soil moisture regulation（four irrigation levels， 70%θ_fc 、60%θ_fc 、50%θ_fc 、40%θ_fc ） on crop coefficient and water use efficiency of drip irrigated silage maize were studied. The results showed that the jointing-heading stage of silage maize were the critical period of water demand for silage maize， compared with the control treatment， the yield was reduced by 27 150 kg/hm²， and the yield reduction rate was 41.8%； water consumption (ET_a ) of silage maize showed a quadratic parabola relationship with yield， and the correlation was 0.911 8； the crop coefficients of silage maize were 0.81~0.97 in sowing-seedling stage， 0.97~1.32 in seedling-jointing stage， 0.98~1.63 in jointing-heading stage and 0.59~1.07 in heading harvest stage. The crop coefficient of the whole growth period was a quadratic parabola. Under different precipitation and water regulation conditions， irrigation amount had a more obvious effect on the water use efficiency of silage maize in the year with smaller precipitation. On the contrary， the irrigation amount had no significant effect on the water use efficiency of silage maize.

In order to investigate the effect of soil film residue on the seedling emergence and soil salinity at the emergence stage of cotton under brackish water irrigation, four factors and three levels of orthogonal tests were set for residual film quantity, lower limit of irrigation control, soil bulk density and irrigation water conductivity, respectively. The results showed that the effects on the emergence rate of cotton were in the order of residual film quantity＞irrigation water conductivity＞lower limit of irrigation control＞bulk density. Soil conductivity increased with the increase of film residue, lower limit of irrigation water control and conductivity of irrigation water, and decreased with the increase of soil bulk density. The content of Na⁺, K⁺ and Cl^- in soil increased with the increase of film residue and conductivity of irrigation water. The content of K⁺, Ca²⁺ and SO₄ ^2- in soil and the content of Mg²⁺ in soil increased with the increase of residual film amount and irrigation water amount. With the increase of residual film content, the content of HCO₃ ^- decreased. The increase of soil residual film and irrigation water conductivity would reduce the emergence rate of cotton and aggravate soil salinization. The upper limit of brackish water irrigation conductivity of cotton at seedling stage without residual film and with residual film was 3 800 μS/cm and 2 500 μS/cm, respectively.

In order to reduce the interference caused by the soil background， obtain the corn canopy temperature in the UAV thermal infrared image more accurately and efficiently， and then quickly retrieve the soil moisture content of the corn field， this paper used four kinds of water gradient processing jointing stage corn as the research object and used the UAV visible light and thermal infrared images to extract the corn canopy temperature information in the thermal infrared image by using three processing methods， including RGRI index method， Otsu threshold method and no soil background removal， and calculated the crop water stress index (Crop water stress) index， CWSI) to retrieve the soil moisture content at different depths of the corn field under different water gradient treatments. The CWSI obtained based on the three methods were recorded as CWSI_RGRI， CWSI _Otsu， and CWSI_sc . The results showed that： ①The corn canopy temperature obtained by the RGRI index method had the highest correlation with the measured canopy temperature (R ² was greater than 0.8， and the RMSE was less than 1 ℃)， followed by the Otsu method， and the method without soil background had the worst effect. ②In the whole jointing period， CWSI _RGRI had the best inversion effect of soil moisture content (R ² was greater than 0.5， P <0.01， the effect was significant)， CWSI _Otsu was the second， and CWSI _sc had the worst inversion effect. ③CWSI_RGRI was selected as the optimal CWSI index， and its R ² in the five soil depths of the corn jointing stage showed a trend of first rising and then falling， and all reached the maximum in the depth of 0 ~ 30 cm. Therefore， CWSI_RGRI established based on the RGRI index method could be used as an effective index for retrieving soil moisture content of corn fields.

In order to study the influence of sediment content on the fractal dimension and saturated hydraulic conductivity of the weight distribution of clayey saline soil， the relationship equation between the fractal dimension and saturated hydraulic conductivity was studied. The silt that needs to be treated urgently in the Yellow River Delta diversion channel was used as the modifier to improve the clay saline soil indoor and field. The wet sieve-pipe method was used to determine the soil particle gradation， and the saturated hydraulic conductivity was determined by the variable head method. The relationship equation between the amount of sand， the fractal dimension and the saturated hydraulic conductivity was analyzed and established， and the field experiments were conducted to verify the indoor test. The results showed that： ① The particle gradation of yellow-diluted sediment and clayey saline soil was obviously different. With the increase of the amount of sand， the particle gradation and texture of the soil changed significantly. ② As the amount of sand distribution increased， the fractal dimension decreased significantly. The fitting equation between the fractal dimension and the amount of sand distribution was D=-0.050 51 e^{0.018 51 x} +2.891. When the amount of sand distribution increased， the saturated hydraulic conductivity increased exponentially， and the fitting equation of saturated hydraulic conductivity K_s and sediment distribution amount x was K_s =0.025 61 e^{0.049 31 x} . ③ The saturated hydraulic conductivity of soil decreased with the increase of fractal dimension. The fitting equation of D-K_s was K_s =4.94×10⁸ e^{-7.246 D} -0.541 1. ④ In the field test from S0 to S7 treatment， the saturated hydraulic conductivity of the soil increased significantly， and the error between the cumulative value of saturated hydraulic conductivity and the measured value in the field test was small. Therefore， sand distribution can effectively improve the saturated hydraulic conductivity of clayey saline soil， and the accuracy of the saturated hydraulic conductivity estimated by the D-K_{s fitting equation is higher.}

In order to improve the yield, water and fertilizer use efficiency and economic benefit of Lycium barbarum in the central arid region of Ningxia, the effects of different water and fertilizer ratio on the yield and water and fertilizer use efficiency of Lycium barbarum were studied in this paper. Four years old Lycium barbarum “Ningqi No.7” was used as the research object to carry out experiments with “311-B” saturation D optimum design. The effects of different water and fertilizer treatments on water consumption, water and fertilizer utilization efficiency and economic benefits of Lycium barbarum were analyzed. A regression model with yield, water and fertilizer utilization efficiency and economic benefit as dependent variables and water and fertilizer as independent variables was established to calculate the amount of water and fertilizer corresponding to the maximum of each factor. Based on regression analysis and TOPSIS method, the optimal water and fertilizer application scheme of Lycium barbarum were determined under drip irrigation under film mulching. The results showed that the water consumption of Lycium barbarum was positively proportional to the irrigation water quantity, while the WUE decreased with the increase of water consumption. The maximum of WUE was 0.39 kg/m³ and 41% higher than the minimum value; the highest yield of fresh yield and dried yield of Lycium barbarum was 8 436 kg/hm² and 2 250.3 kg/hm², respectively, and the highest economic benefit was 24 212 yuan/hm² and 24.16% higher than the average; the maximum 100 grain weight of T3 treatment with medium water and high fertilizer was 3.0% higher than that of T11 treatment, and the minimum particle size was 12.18% lower than that of T11 treatment; the partial productivity of fertilizer was significantly influenced by irrigation amount and the interaction between water and nitrogen, which was inversely proportional to the amount of fertilizer. Comprehensively considering the effects of irrigation amount, nitrogen fertilizer and potassium fertilizer on yield, water and fertilizer utilization efficiency, economic benefit, water saving and fertilizer saving, the recommended irrigation quota was 2 324.25～2 464.05 m³/hm², and the fertilizer application rate (N-P₂O₅-K₂O) was 419.85-269.25-330 kg/hm²～486-294-330 kg/hm².

The precipitation (P) and reference crop evapotranspiration (ET₀ ) during crop growth period are the main factors that cause agricultural drought. It plays an important role to analyze the frequency of wet and dry during crop growth period in guiding agricultural drought control. Based on the precipitation and the reference crop evapotranspiration during the growth period of spring maize in Heilongjiang Province 1980-2017， this paper used the Copula function to construct a P-ET₀ joint distribution model to study the frequency of wet and dry. The research results showed that： P and ET₀ obey Gamma distribution. Among the 9 kinds of wet and dry combinations， the joint probability value of the P-ET₀ dry and wet type showed an increasing trend with the increase of P and the decrease of ET₀ . Under natural water conditions， the combined return period and co-occurrence return period， in which P was dry and ET_{0 was we， of the growth period of spring maize in Heilongjiang Province were 2.50 and 3.33 years， respectively. For the situation that water supply and demand are not coordinated， natural water supply cannot meet crop water demand， and the interval of recurrence period is short， the drought risk can be qualitatively described and quantitatively evaluated through different combinations of P-ET0， so as to provide irrigation planning and scientific deployment of water resources with some reference.}

Soil water is an important part of the natural water cycle. Considering the influence of heat in the study of soil water movement can improve the accuracy of simulation and reflect the real physical process. In this paper， a numerical simulation model of soil moisture content and temperature was established based on the soil moisture-vapor-heat coupled transport equation， and the empirical fitting parameters n and α， soil residual moisture content θr， and saturated moisture content θs of the VG model were calibrated to optimize the simulation results； the modified parameters were used as the basic parameters of the model， together with meteorological data and boundary conditions， were input into the model to simulate the change process of soil moisture and temperature. The results showed that the simulation effect of moisture content and temperature in the rainfall stage was better than that in the evaporation stage， and the simulation accuracy of moisture content and temperature in the rainfall stage was ‘good’ or ‘very good’， and only the simulation accuracy of surface soil moisture content at 3 cm is ‘fair’ (The relative root mean square error RRMSE was 21.99%)， which was due to the uneven texture of the top soil. The simulation accuracy of moisture content and temperature in the evaporation stage was ‘very good’ at most depths， only the temperature simulation accuracy of the deep layer (28 and 48 cm) was ‘fair’(RRMSE was 21.18% and 22.92%)， the reason should be that the lower part of the soil column will be significantly affected by the ambient temperature. This research can be applied to the simulation of hydrological cycle and can improve the simulation accuracy of infiltration process.

Based on the daily meteorological data of 17 meteorological stations in Henan Province from 1960 to 2019， the spatial and temporal variation characteristics of reference crop evapotranspiration (ET ₀) and its influencing factors were analyzed by using Penman-Monteith model， M-K test method and Morlet wavelet analysis. The results showed that： from 1960 to 2019， the multi-year average ET ₀ in Henan was 1 050.11 mm， and showed a downward trend with a rate of -14.81 mm/10a. In 1971， the ET ₀ in Henan mutated and decreased by 80.73 mm after the mutation. In the past 60 years， the ET ₀ in Henan had a main cycle change of about 28 year. Spatially， the ET ₀ in Henan increased from southeast to northwest. In the past 60 years， the ET ₀ of four seasons in Henan accounted for 29.79%， 39.34%， 20.17% and 10.69% of the whole year， respectively. In terms of change trend， the ET ₀ in spring showed a slight upward trend， while ET ₀ in summer， autumn and winter showed a downward trend. The spatial distribution of ET ₀ in spring and summer were close to that of the average ET ₀ in the whole province， which played a decisive role in the spatial distribution of ET ₀. The ET ₀ in Henan was most sensitive to relative humidity (-0.645)， followed by sunshine hours (0.444)， maximum temperature (0.323)， average wind speed (0.171) and minimum temperature (0.090). The contribution rates of sunshine hours， average wind speed， relative humidity， maximum temperature and minimum temperature to ET ₀ were -12.841%， -7.426%， 3.045%， 1.321% and 1.800%， respectively. The decrease of sunshine hours and average wind speed were the leading factors of ET ₀ decrease in Henan in the past 60 years.

In order to study the spatiotemporal characteristics of soil moisture under restricted infiltration area condition, the indoor soil box simulation experiment method is chosen to establish mathematical relationship between wetting front migration and time under different drip irrigation flow rates, and then variational process of wetted soil is analyzed. The results show that restricted infiltration area condition has significant effect on the shape of wetted soil. The restricted infiltration area condition can effectively reduce the infiltration rate of soil water, prevent ineffective diffusion and reduce the deep leakage of irrigation water. Compared with the normal condition, the restricted infiltration area condition can reduce the water infiltration rate by 2.30% to 40.38%. With the same irrigation amount and different irrigation rates, 3 L/h flow rate not only reduces the evaporation of soil surface water, but also makes wetting front reach the deep layer of soil at the later stage of irrigation. While compared with 3 L/h flow rate, 4 L/h flow rate reduces the deep leakage of irrigation water. This study further verifies the rationality of water-saving with cultivation technology of restricted root volume. The results can provide some references for the selection of drip irrigation flow rate of crops cultivation technology of restricted root volume.

Oxygenated irrigation is a new irrigation technology which is proposed and gradually developed at the beginning of the 21st century. It has obvious effects on water saving and emission reduction， fertilizer saving and production increase， resulting in producing significant economic and social ecological benefits. However， the existing oxygenated irrigation technology generally adopts mechanical aerobic method， which requires special oxygenated equipment， energy and power equipment. Hence， it is mostly used in the field of dry land efficient water-saving irrigation， such as facility agriculture， greenhouse fruit and vegetable planting. Due to the limitation of equipment and application conditions， the oxygenated irrigation technology has not been applied in the rice planting area under field conditions. In this paper， a drainage pipe of self-pressurized inspiratory oxygenated irrigation is developed to solve the key problems of oxygenated irrigation for rice under the condition of no energy and power in the field by using the self-pressure of water flow in the irrigation water supply pipe of the low-pressure pipe irrigation area. According to the field test， the oxygen content in irrigation water could be increased by 14% and the duration of high oxygen content in irrigation water could be lasted more than 20 hours.

In order to explore the impact of sediment concentration and inlet pressure on the clogging of the micro-spraying hose， this paper adopted the test method of short-period continuous irrigation with sand-containing water， and configured the sediment with a particle size of less than 1 mm into muddy water with three sediment concentrations. Under four inlet pressures， the flow changes of the single-circulation hole group of the micro-sprinkling hose were observed， and the blockage law of the micro-sprinkling hose was analyzed based on the relative flow of the hole group. The results showed that： under the conditions of the sediment particle size in this experiment， under the same inlet pressure， the clogging degree of the micro-sprinkling hose group did not completely increase with the increase of the muddy water content； at the same sediment concentration， when the inlet pressure is lower than the rated working pressure， it is easy to cause the nozzle to be blocked. Both the sediment concentration and the inlet pressure had significant effects on the anti-clogging performance of the micro-sprinkling hose. When the sandy-containing water with sediment particle size and gradation similar to that in this experiment is used for irrigation， the sediment concentration of 1.0 g/L should be avoided as far as possible， and high head pressure should be used， or the micro-sprinkling hose should be washed with the head pressure higher than the working pressure (not higher than the burst pressure) at the end of irrigation.

In order to explore the nitrogen concentration suitable for pakchoi in greenhouses under the condition of moistube-irrigation with fertilization， the experiments were set under the pressure head of 1.5m with four nitrogen levels， including 0 (CK)， 200 mg/L (T1)， 400 mg/L (T2)， and 600 mg/L (T3)， each treatment was repeated three times. In order to select the nitrogen concentration suitable for the growth of pakchoi， the soil moisture content， plant height， leaf area， fresh weight and contribution rate of fertilizer on yield increase under different treatments were measured and analyzed. The results showed that under the condition of the buried depth of the micro-moistening tube 15 cm and the laying spacing 30 cm and the pressure head 1.5 m， nitrogen fertilizer could promote the growth of pakchoi， and nitrogen fertilizer with the concentration of 400 mg/L was the best. At low nitrogen application level， the growth index of pakchoi increased with the increase of nitrogen application. However， high concentration of nitrogen fertilizer had an inhibitory effect on plant growth. As a new irrigation model， micro-irrigation still needs to be explored and tested in the field.

In order to analyze the influence of vortex on the flow pattern of labyrinth emitter， with the help of FLUENT software， the inner flow field of four types of emitters， namely rectangular， toothed， triangular and trapezoidal， were simulated， and the streamline boundary of the main flow area in the channel were reserved to the maximum extent. Meanwhile， four kinds of vortex free channel structure models with good anti blocking performance were determined. The velocity field and pressure field of the above-mentioned non vortex channel and corresponding vortex channel model were studied and analyzed. The results showed that the flow pattern in the non vortex labyrinth channel was between the laminar flow and the turbulent flow， and the head loss was proportional to the 1.49~1.60 power of the velocity； the flow pattern in the vortex free labyrinth channel was turbulent， and the head loss was proportional to the 1.75~2.00 power of the velocity. The flow pattern indexes of the four models were all close to 0.5， and the hydraulic performance was superior. For the same type of channel model， the flow coefficient became smaller， the flow pattern index became larger， and the hydraulic performance of emitter became worse after the vortex was removed. The simulation results showed that the presence of vortices could enhance the turbulence intensity of the flow channel and improve the hydraulic performance of the maze emitter.

In recent years， nanomaterials have been widely used in the field of environment due to their new properties， which have great potential in soil modification and waste utilization. In this paper， the application history of nanomaterials (including nanometer clay， nanometer oxide， nanometer carbon， etc.) in soil was reviewed， and the important achievements in improving soil mechanical properties of nanoparticles in the past 30 years were summarized. Based on different types of soil， the effects of nanomaterials on soil structure， strength and hydraulic properties were analyzed. Based on the structure of nanoparticles and the structure of modified soil， the mechanism of improving soil mechanical properties by nanomaterials was summarized. This paper enriched the research results in the field of modified soil by nanomaterials， and provided a reference and theoretical basis for the selection of modified soil materials and the determination of the content of modified soil materials.

In order to study the hydraulic performance of rectangular side weir under free flow condition， and to explore the calculation formula for discharge， the Control Variate Method was adopted to conduct experiment， setting different weir heights and weir widths to study the relationship between the discharge and various hydraulic performance parameters. The result showed that：① under ideal conditions， the total flow energy loss of the rectangular side weir was within 10%， and the energy loss was mainly at the weir mouth； ② the water surface line near the upstream end of the weir mouth was lower than that far away from the upstream end；③ The side weir flow was proportional to the weir width and the head above the weir. The flow coefficient m_d had a significant relationship with the Froude number Fr₁， the ratio of upstream water depth to weir height h/P， the ratio of upstream water depth to weir width h/b， and was positively correlated with the Froude number， and negatively correlated with h/P， h/b. When the formula of Q = F {r_{\mathrm{1}}}^{\mathrm{0.162}} {\left(\frac{h}{P}\right)}^{-\mathrm{0.113}} {(\frac{h}{b})}^{-\mathrm{0.045}} b \sqrt[]{\mathrm{2}} H^{\frac{\mathrm{3}}{\mathrm{2}}} was used to calculate discharge in the range of 0~30 L/s， the error range between the measured flow and the calculated flow was between -0.01%~6.86%， which was within the designated flow error range. The study results can provide theoretical basis for lateral weir flow measurement， which is of great significance to the development and improvement of water measuring equipment and methods in irrigation areas.

Water resources shortage has become an important factor restricting regional economic development. With the deepening of comprehensive agricultural water price reform， the analysis of farmers' affordability of water price is an important part of water price reform. Based on the national and local goals of water price reform， this paper took Shihezi irrigation area of the 8th Division of the Xinjiang Construction Corps as an example to analyzes the water consumption capacity of farmers in the irrigation area and the water-saving benefits after the implementation of irrigation water price on the basis of the water price calculated at full cost by using the intention investigation method and the water price-water quantity model. According to the calculation and analysis， the total cost water price and the farmers' bearing water price is 0.391 yuan /m³ and 0.439 yuan /m³， respectively. Compared with the current water price of 0.25 yuan /m³， the water price of the irrigation area has a great room for improvement. Under the full cost water price， the average irrigation amount can be saved 1 078.35 m³/hm²， about 15%， compared with the actual irrigation amount in the field， which shows great water-saving potential. When other conditions are unchanged， the average water consumption under full cost water price tends to be consistent with the irrigation amount under quota control. So irrigation areas should combine with the actual situation of water price reform of agricultural water rights and continuously deepen and improve the agricultural water price and water rights so as to provide a strong guarantee for the construction of water rights market.