Abstract: In order to evaluate the effect of different spacing of blind ditch treatment on the improvement of saline-alkali soil in Irrigation Districts of Yellow River in Ningxia, different blind ditch spacing (3 m, 6 m, 9 m, 15 m and control group CK) were set to measure pH, electrical conductivity（EC）and growth of weeping willow（Salix babylonica）. The results showed that 1) Compared with the control group, the pH value of soil treated with 3 m, 6 m, 9 m and 15 m blind ditch spacing decreased by 4.58%, 4.90%, 2.66% and 2.08%, respectively. 6 m blind ditch spacing had the best effect on the reduction of soil pH value. 2) Compared with the control group, EC treated with 3 m, 6 m, 9 m and 15 m blind ditch spacing decreased by 93.05%, 93.77%, 95.34% and 94.51%, respectively. 9 m blind ditch spacing had the best reduction effect on EC. 3) There were extremely significant differences in DBH, plant height and crown width of weeping willow treated with 9 m blind ditch spacing and CK in the control group (P<0.01), which were 80.52%, 58.11% and 50.00% higher than those in the control group, respectively. In conclusion, blind ditch drainage technology can effectively improve saline-alkali soil in Irrigation Districts of Yellow River in Ningxia. Considering the influence of culvert on soil physical and chemical properties and the growth and development of weeping willows, 9 m is the optimal spacing of culvert treatment.

In this paper, we studied citrus trees and loquat trees in Yichang, Hubei, and studied the transpiration rate of citrus trees and loquat trees by SF-DL2 sap flow. The transpiration rate of citrus trees and loquat trees were compared, and the relationship between transpiration rate of citrus trees and loquat trees and its meteorological factors was analyzed. The results showed that :(1) the transpiration rates of citrus trees and loquat trees were both multi-peak curves, and the difference of transpiration intensity between day and night was significant; The transpiration rate curve of citrus trees was gentle and the peak range was narrow, while the transpiration rate curve of loquat trees was steep and the peak range was wide; Under the same condition, the transpiration rate curve of loquat trees increased faster than that of citrus trees, and the average daily transpiration rate of loquat trees was also higher than that of citrus trees (44.33%, 376.95g). (2) the start time of transpiration of the two plants was basically the same, and the phenomenon of midday depression was more obvious in loquat trees than in citrus trees. (3) the transpiration rates of citrus trees and loquat trees were positively correlated with net solar radiation, ambient temperature and soil temperature, but negatively correlated with environmental humidity; For citrus trees, environmental humidity was the biggest factor, and the correlation coefficient was 0.79. Atmospheric temperature has the least influence on it, and the correlation coefficient is only 0.65. Compared with citrus trees, the solar radiation was the factor limiting the transpiration rate of loquat trees, and the correlation coefficient was 0.77. Comparatively, the soil temperature had the least influence, and the correlation coefficient between the solar radiation and transpiration rate was only 0.46.

In the practical application of small－scale sprinkler irrigation systems，there will be working pressure difference between adjacent sprinklers due to various terrain conditions and the hydraulic loss along the pipeline． In order to study the influence of pressure difference on the irrigation uniformity，two indicators including the irrigation uniformity coefficient Cu and the distribution uniformity coefficient Du are applied． The impact sprinkler typed 10PY is used，and the water distribution and irrigation uniformity are tested under the working pressures ( 0．22，0．25，0．28 MPa) and five groups of pressure differences ( 0，0．01，0．02，0．03，0．04 MPa) ． The results indicate that the influence of working pressure difference between adjacent sprinklers on the irrigation uniformity coefficient Cu and the distribution uniformity coefficient Du varies considering different working pressures． The irrigation uniformity under lower working pressures is more sensitive to the change of pressure difference between adjacent sprinklers; the irrigation uniformity at the working pressure 0．25 MPa is the most stable． Higher pressure difference between adjacent sprinklers will lead to the move of areas of higher irrigation depth to the downstream of the pipeline． The distribution uniformity coefficient Du is more suitable to indicate the effect of pressure difference between adjacent sprinklers on the areas with lower irrigation depth． The highest difference between the distribution uniformity coefficients under different working conditions is 8． 2%． These may provide a certain reference for the configuration optimization of small－scale sprinkler irrigation machines．

Conducted a field experiment to control the irrigation and fertilization amount for winter wheat under the straw returning field for examining the effect on the stomatal characteristics of the leaves． The results show that: ① Increasing the irrigation amount during the same irrigation period can increase the area of the paraxial pores of winter wheat at jointing stage，while the width of the abaxial surface pores and the shape of the pores increase，but the circumference of the abaxial surface pores is decreasing． However，the amount of irrigation is reduced，and the paraxial pore density of winter wheat at jointing stage is increased，and the shape of the abaxial pore shape is also increased． ② In the early growth stage ( jointing stage + heading stage) of winter wheat，reducing the amount of fertilization resulted in an increase in the density and area of the paraxial pores at the jointing stage． However，increasing the amount of fertilization increases the area and width of the abaxial surface pores in the late growth stage of winter wheat ( filling stage + maturity stage) ． ③ The stomatal distribution is more regular under the treatment of fertilization during wintering and less fertilization during jointing． The results of the study will help to further explore the optimal irrigation system and fertilization system for winter wheat under straw returning，and provide a theoretical basis for increasing yield，thus promoting the sustainable development of agriculture．

The effects of different drip fertilization schemes on the physiological growth and yield of dwarf apple trees were studied，which provided a theoretical basis for the scientific fertigation management of orchard． The test set five drip fertilization levels: low phosphorus medium potassium ( P1K2) ，medium phosphorus medium potassium ( P2K2) ，high phosphorus medium potassium ( P3K2) ，low potassium medium phosphorus ( K1P2) and high potassium medium phosphorus ( K3P2) ． The fertilization level of ground irrigation ( CK) in the control group was medium phosphorus medium potassium ( CK－P2K2) ． The results show that: different irrigation methods and fertilization levels have different effects on new shoots，trunk diameter，leaf water potential and yield of dwarf apple trees; the P2K2 fertilization level of drip irrigation can effectively promote the growth of the trunk diameter and shoot of the dwarf anvil tree，which can significantly increase the cumulative growth of trunk diameter and new shoots compared with other schemes; the K3P2 and P2K2 fertilization levels of drip irrigation can significantly increase the yield of dwarf apple trees; compared with ground irrigation，drip fertilization can effectively promote the growth and development of dwarf apple trees and increase production．

In order to further determine the reasonable fertilizer application and guide fertilizer management under drip irrigation，a field experiment comparing the effects of five different fertigation levels on soil nutrient accumulation and potato ( Shepody) yield was carried out． The five fertigation levels include 10% ( F1) ，30% ( F2) ，50% ( F3) ，70% ( F4) and 90% ( F5) of the recommended fertilizer quantity ( N，P2O5，K2O content is respectively 420，105，495 kg / hm2 ) ，which was estimated based on the nutrient balance method． The results show that: after drip fertigation during the whole growth period，the nitrate nitrogen concentration in the 0 ～ 60 cm soil layer increases with the increase of fertilizer amount，and the movement to the lower layer of soil increases; the concentration of ammonium nitrogen in the 0 ～ 40 cm soil layer and the concentration of available phosphorus in the 0 ～ 30 cm soil layer first increase and then decrease; the available potassium concentration in 0 ～ 60 cm soil decreases in the vertical distribution，but increases in the horizontal distribution; when the proportion of fertilizer application is about 70% ( F4) ，soil nutrients mainly accumulate in the 0 ～ 40 cm soil layer，and less leach to the lower soil layer; the potato yield increases first and then decreases with the increase of fertilizer application，and the highest value is 25．3 t / hm2 under F3 treatment，which wis not significantly different from other treatments except F1 treatment． Therefore，when the proportion of fertilizer applied in drip irrigation is about 70% of the recommended amount，soil nutrients in potato fields mainly accumulate in the soil layer of 0 ～ 40 cm， which reduces the amount of fertilizer applied and the loss of nutrients from the root zone，and the yield is relatively high．

In order to provide a theory basis for mulch － drip irrigation regime in Aeolian sandy soil area，through a field experiment， according to canopy evaporation and crop coefficients，four treatments with different irrigation amount ( IＲ1: 0．6KcE，IＲ2: 0．8KcE，IＲ3: 1． 0KcE，IＲ4: 1．2KcE) were set to study the effect of different irrigation amount of mulch－drip irrigation on maize growth and yield in Aeolian Sandy Soil． The results show that: the larger the irrigation amount，the better the growth of maize，the taller and stronger the plant，the greater the leaf area index ( LAI) and the ground matter weight per plant，the higher the chlorophyll value of the leaf． Yield and yield composition traits，such as panicle weight，panicle length，panicle width，panicle row number，row grain number，hundred grain weight and panicle grain weight，all increase first and then decrease with the increase of irrigation water，and each index reaches the maximum value when the irrigation amount is 1．0KcE． The order of production from large to small is: IＲ3＞IＲ2＞IＲ4＞IＲ1，which is 13．2，12．6，12．5 and 9．5 t / hm2 ，respectively． Water use efficiency ( WUE) decreases with the increase of irrigation water amount and the order from large to small is IＲ2＞IＲ3＞IＲ1＞IＲ4，which is 2．35，2．17，2．05 and 1．84 kg /m3 ，respectively． Therefore，considering the economic efficiency of agricultural production and rational utilization of water resources，the irrigation amount of drip irrigation under maize film should be controlled at 0．8KcE ～ 1．0KcE in the Aeolian sandy soil area of northwest Liaoning．

The reference crop evapotranspiration ( ET0 ) is an important basis for accurately estimating crop water demand and improving farmland water use efficiency． Based on field experiment data of 2013－2017 and related meteorological observation data，five kinds of ET0 calculation method were used to calculate the average ET0 and annual average ET0 in Guanzhong region，the Origin software was adopted to conduct related analysis of ET0 and environmental factors，the standard error estimate ( SSE) and determination coefficient r 2 were used to compare FAO－56 PM with four other simple alternatives． The results show that: the analysis of standard scores of ET0 and meteorological factors shows that the ET measurements and the estimates of the five methods are highly dependent on solar radiation and temperature，but have little relationship with relative humidity and wind speed． Five ET0 estimation methods，namely，FAO－56 Penman－Monteith ( FAO－56 PM) ，Penman－Monteith ( PM) ，Priestly－Taylor ( PT) ，Mankink ( MK) and Hargreaves ( HG) ，were evaluated． Statistical analysis shows that PM can replace FAO－56 PM to predict ET0 value in this region． This is directly related to accurate estimates of crop evapotranspiration ( ETC ) ，which also depends on crop physiological characteristics and developmental stages，weather parameters，environmental conditions and management practices．

In order to explore the impacts of different tillage and cover measures on soil water and heat environment and soybean yield under dry－farmed conditions，four treatments of traditional tillage ( T) ，no － tillage ( NT) ，traditional tillage with straw mulching ( TS) ，and traditional tillage and plastic mulching ( TP) were set to carried out experimental study． The results show that: during the whole growth period，compared with T treatment，TP treatment has the effect of increasing soil temperature，while NT and TS treatment show different degrees of soil cooling effect，and NT treatment has no significant effect on soil moisture conservation; TP treatment can increase temperature and retain moisture in the early stage and decrease temperature and inhibit evaporation in the later stage，which is conducive to improving soil hydrothermal environment and meeting the environmental requirements of soybean growth and development; under different measures，the order of soybean yield from high to low was TP＞TS＞NT＞T; the yield of TP，TS and NT treatment is 249．9，548．85 and 760．5 kg / hm2 higher than that of T treatment，respectively; TP treatment has the highest yield increase，and the yield increase rate of each treatment rangs from 9．02% to 27．45%; the correlation between soil temperature and yield is shown as TP ＞ TS ＞NT ＞ T，and there is a significant correlation between soil temperature and yield under TP treatment，indicating that soil temperature will have an impact on yield，and TP treatment has the largest impact．

In order to study the relationship between the changes of leaf photosynthetic parameters and soil moisture in jujube young fruit stage during the gradual aggravation process of soil drought to find the allowable soil water deficit threshold of jujube trees in the arid area of Northwest China，in this study，the photosynthetic parameters，including the net photosynthetic rate ( Pn) ，transpiration rate ( Tr) ，stomatal conductance ( Gs) ，intercellular CO2 concentration ( Ci) ，stomatal limitation ( Ls) and water use efficiency ( WUE) ，of seven different soil moisture gradient gray jujube trees under different photosynthetically active radiation ( PAＲ) were determined and analyzed by using the water control experiment of barrel jujube trees． The results show that Pn increases first and then decreases with the increase of PAＲ，and Tr，WUE and Ls show similar response with Pn; when the relative soil water content ( ＲWC) is 60．34% and 80．97%，the daily variations of Pn and Tr show a“bimodal”trend with a significant“siesta”phenomenon; when the ＲWC is 41．22%，the phenomenon of“double peak”and“siesta” disappears; when ＲWC is within the range of 48．89% ～ 68．58%，the main reason for the decrease of Pn is the limitation of stomatal factors; when ＲWC is less than 48．89%，the main reason for the decrease of Pn is the limitation of non－stomatal factors． The allowable maximum soil moisture deficit ＲWC of jujube at the young fruit stage is 48．89%，and ＲWC within the range of 53．36% ～ 60．34% can maintain high WUE and Pn in the young fruit stage of jujube．

In order to realize the recycling of cotton stalk resources，the effects of carbonization time on the physical properties of sandy soils in south Xinjiang were studied with cotton stalk as raw material，including the effects of biochar on soil bulk density，total porosity，capillary porosity，non－capillary porosity，water absorption and water retention． The results showed that biochar reduced soil bulk density and water evaporation rate，increased total porosity，capillary porosity and water absorption，and improved soil water retention performance． Compared with the control group，the soil bulk density was decreased by 8．06% to 10．95%，the total porosity and capillary porosity was increased by 2． 87% to 7．73% and 13．48% to 31．95%，respectively． The variation trend of water absorption and water retention with carbonization time was not consistent，but both reached the strongest at 3．5 h and the weakest at 1．5 h． This study provides theoretical data for improving the sandy soil and cotton planting by cotton stalk based biochar in southern Xinjiang．

By setting 6 different levels of water supplement，this experiment studied the influence of different water supplement on the growth and development of Ningshu 16，a new potato staple food variety，under the condition of drip irrigation under film． The results show that plant height increases with the increase of water supplementation in all growth stages except seedling stage，indicating that water supplementation promotes the rapid growth of Ningshu 16 plant before flowering stage，and delays plant atrophy after flowering stage; SPAD value gradually increases with the increase of water supplementation in bud and flowering stage，and shows a single peak curve change trend of increasing and then decreasing with the increase of water supplementation in starch accumulation stage and mature stage，indicating that different water supplementation has different effects on chlorophyll in Ningshu 16 potato leaves at different water demand periods． With the increase of supplementary water amount in each growth period，LAI first increases and then decreases，and when the supplementary water amount is 2 250 m3 / hm2 ，LAI reaches its maximum value，and LAI decreases gradually when the supplementary water amount further increases． The dry matter accumulation amount of Ningshu 16 increases gradually with the growth process and shows an“S”curve of slow to fast to slow． Adequate water supplementation can significantly promote the growth of stem，tuber and leaf，but has a certain inhibiting effect on the root growth． According to comprehensive analysis，under drip irrigation under membrane，the water supplement most conducive to the growth and development of Ningshu 6 is 2 250 m3 / hm2 ．

In order to solve the increasingly serious shortage of water resources and ecological environment in traditional irrigation districts，an ecological irrigation district based on the concept of“resource conservation，high yield and high efficiency，good ecological environment”was constructed to study the optimal allocation of water resources in irrigation districts． Taking jinhui canal irrigation area in shaanxi province as an example，this paper constructed a coupling model of System Dynamics－ multi－objective Programming ( SD－MOP) based on multiple goals of water－saving－economy－ecology，simulated the causal feedback relationship among subsystems of eco－irrigated areas，and carried out research on optimal allocation of water resources in eco－irrigated areas of“P = 50%”horizontal year． The results show that by 2030，when the irrigation water demand，industrial water demand，living water demand and ecological water demand is 323，58，37 and 116 million m3 ， respectively，the eco－type irrigation district festival water benefit，economic benefit and ecological benefit will be the best，that is，the total water demand in the Jinghuiqu irrigation district decreases by 7．93%，and the economic and ecological benefits increases by 67． 78% and 9．09%，respectively． Compared with the simulation results of single－objective SD model，the industrial water demand increased by 3．57% and 2．78% respectively，the agricultural water demand decreased by 14．10% and 9．38% respectively，the total water demand of irrigated areas decreased by 10．40%，and the economic and ecological benefits increased by 27．28% and 10．20% respectively． The study shows that the optimal water resource allocation scheme based on SD－MOP model is more conducive to the realization of ecological irrigated areas，and the achievement can provide scientific basis for the sustainable utilization of water resources and the benign development of ecological environment in ecological irrigated areas．

In this paper，the water consumption population，total fixed asset investment and annual water supply of 8 counties and cities in Xiangxi Autonomous Prefecture of Hunan province from 2006 to 2016 are used as input indicators，the gross regional product is used as output indicators，the static efficiency evaluation of water resource utilization efficiency of 8 counties and cities is carried out by DEA number envelopment analysis method，and then the Malmquist index method is used to analyze the dynamic efficiency． The results show that in terms of static efficiency analysis，only Jishou city and Huayuan county realize DEA efficiency，and most areas have high scale efficiency，which is close to the optimal scale． The utilization efficiency of water resources is mainly improved through improving the technical efficiency． From the dynamic efficiency analysis，the annual increasing rate of total factor productivity of water resources in this region is 2%，the annual increasing rate of technical progress index is 2．3%．Technological progress is the main driving force to promote the increase of water resources total factor productivity in Xiangxi Autonomous Prefecture． In terms of different regions，except Guzhang county，the total factor productivity of water resources in all counties and cities is greater than 1，which indicates that the water resource utilization efficiency in Xiangxi region is improving continuously．

Abstract In order to evaluate the groundwater quality of drinking water sources in the urban area of Guoyang County, Anhui Province, it provides support for the division and post-management work of urban groundwater source protection areas. Based on the groundwater quality data of 35 sampling points in the dry season of Boyang County in October 2018, 21 water quality assessment factors including iron, manganese and fluoride were selected, and the comprehensive index evaluation method and improved Nemero pollution index evaluation were adopted. The method and the projection pursuit evaluation method based on accelerated genetic algorithm are used to evaluate the water quality of groundwater source. The results show that there are some differences in the evaluation results of the above methods. By comparing and analyzing the differences between the methods, the groundwater quality of the groundwater quality evaluation method based on the accelerated genetic algorithm is considered to be in the drinking water source area of the urban area of Guoyang County. The evaluation has better applicability and can reflect the water quality status of the drinking water source in the current urban area more objectively and accurately.

The location of oilfield drilling must minimize its impact on groundwater and the surrounding environment. Taking the drilling site selection of Yitong County oilfield as an example, this paper uses the Principal Component Analysis (PCA)and Weight of Evidence (WOE) to evaluate the groundwater vulnerability of the study area. Based on the inherent vulnerability assessment model, land-use, distance from river and river density are added. The results evaluated and verified by using nitrate concentration. The efficacy of the two methods was evaluated quantitatively using the Area Under the Receiver Operating Characteristic Curve that resulted with AUC values of 0.73, and 0.80. Then the evaluation performance of WOE is superior. The WOE results show that the low vulnerability area accounts for 25.57% of the total study area, and the medium and high vulnerability area accounts for 69.85% .The drilling site selection of the oilfield should avoid the floodplain, the first terrace, the rivers and the reservoir. This study has reference value for the application of Weight of Evidence to groundwater vulnerability assessment, and provides a basis for oilfield drilling site selection.

In order to understand the relationship between ecological flow and water quality, and to analyze the spatial and temporal trends of ecological water pollution in the river basin, this paper used the Lyon method to quantify river ecological flow. By analyzing the priority degrees between the three main pollutants and ecological flow, the typical pollutant most closely related to river ecological flow was screened out. Then the nine-point quadratic smoothing trend method was used to evaluate the spatial and temporal trend of typical pollutants and to analyze the effect rate between them and ecological flow. Taking the Xiaohong River Basin as an example, the results show that due to the vigorous development of the industrial and aquaculture industry in the counties, the typical pollutant in the Xiaohong River Basin is ammonia nitrogen. This pollutant has the greatest impact on the ecological flow of the river basin, and is the most important factor in the deterioration of the water ecological environment in the river basin. With the continuous development of river basin ecological water pollution control, the concentration of ammonia nitrogen has decreased, and the ecological flow of the river basin has been improved, but the water ecological status is still not optimistic. The research results can provide reference for water environment pollution control and ecological civilization construction in Xiaohong River Basin.

According to the development demand of integrated irrigation of water and fertilizer in China，a set of integrated circular irrigation system of water and fertilizer is designed． The system adopts coconut chaff substrate culture，mainly composes of three parts，fertilizer distribution system，irrigation system and nutrient liquid circulation system． The system realizes automatic fertilization and irrigation by controlling EC and pH value of fertilizer and water and the amount of fertilizer and water entering the irrigation pipe，and has the function of nutrient solution recycling． It can carry out more accurate fertilization process，prevent waste of fertilizer solution，and improve the utilization efficiency of water and fertilizer． The practical application has proved that the system is stable and easy to operate，EC value control accuracy is ±0．2 mS/cm and PH value control accuracy is ±0．2．The water consumption of integrated cycle irrigation system of water and fertilizer is 66．7% of that of traditional soil cultivation，the cucumber yield is 1．16 times of that of traditional soil cultivation，and the labor consumption is 63．2% of that of traditional soil cultivation． The system can save water，increase output and save labor.

The technology of CFD numerical simulation has been widely applied in the design of emitter. Dental flow channel is the core part in the design of emitter with dental flow channel, but the upstream palisade area and downstream storage tank are often neglected in numerical modeling. It is certain to influence the prediction precision of numerical model, thus this paper studies its exact influence on prediction. Aiming at one kind of emitter with dental flow channel, set up three models with different computational zones for numerical simulation in Fluent 14.5. After analyzing the pressure and velocity cloud pictures of a emitter model closest to the prototype, the law of pressure loss across different zones can be found. After comparing the difference of flow rate of the three models, the different effects of palisade area and storage tank can also be obtained. Based on the research results, optimize the computational geometric zone, and set up a new model. The calculation result shows that optimized geometric model can not only reduce the computation greatly, but also keep high precision of prediction .

The hydrothermal state of shallow soil is the key factor affecting physical，biological and chemical processes in the region． According to the characteristics of low moisture content and large temperature variation of shallow soil on the surface，a theoretical model of one－dimensional coupled water－vapor－heat migration in unsaturated soil under the action of heat source is constructed by using Hydrus－1D software． The numerical simulation of vapor migration in sand with different initial moisture content was carried out． The results show that compared with only considering liquid water migration，the whole moisture migration quantity of sand increases and the temperature rises faster after considering vapor migration; the smaller the initial moisture content of sand is，the greater the effect of vapor migration on the whole moisture migration and temperature change is; with the increase of water content，the effect of vapor migration on water content and temperature decreases gradually until disappearing． Therefore，in the study of hydrothermal migration of sand with low moisture content，the vapor migration factor should be considered to improve the simulation accuracy，and in the sand with high moisture content，this factor can be neglected to simplify the calculation．

The current irrigation water quota standard of Hubei Province was promulgated in 2003，which is difficult to meet the current and future water resource management needs． Early rice is the main irrigation crop in Hubei Province，so revising its irrigation quota is of great significance for achieving total amount control，quota management and implementing the most stringent water resources management system． In this paper，the calculation parameters of early rice crop coefficient，paddy field leakage，water surface evaporation，saturated water demand，growth period and water layer control standard in different zones of Hubei Province are analyzed． Based on the main influencing factors of early rice irrigation quota，the early rice irrigation quota with different zones and frequencies under different combination of tillage methods and irrigation modes is put forward，which can reflect the irrigation water level of early rice in Hubei more comprehensively and truly，and has important guiding and reference significance for the revision of rice irrigation quota in other areas．

Climate change has affected the regional hydrological cycle process and water resource management． Studying the characteristics and causes of changes in reference evapotranspiration ( ET0 ) is of great significance for water resources allocation in the irrigated agriculture areas． In this paper，based on daily meteorological data of 8 stations from 1974 to 2016 in Guanzhong region，Penman－Monteith equation was used to calculate reference crop evapotranspiration ( ET0 ) ，Mann －Kendall test and Sen＇s slope estimator were used to test the variation features of reference crop evapotranspiration and climatic variables． Sensitivity analysis method was used to explore the main meteorological factors affecting the change of ET0 ． The results showed that air temperature and saturation vapor pressure difference showed a significant increasing trend，whereas relative humidity and average wind speed decreased dramatically，and precipitation，sunshine duration，radiation decreased slowly for the past 43 years in Guanzhong region． These changes resulted in a slight increase in ET0 ． The sensitivity of ET0 to climatic variables in the Guanzhong area varied from time and region． In general，wind speed was the most sensitive factor in summer， autumn，winter and wheat growing season，while air temperature had most impact to ET0 in spring and year time scale． The main meteorological factors affecting the ET0 change in the northwest of the research area are air temperature and relative humidity，while the ET0 at other locations is most sensitive to the wind speed．

Agricultural water－saving irrigation service industry is a new form of business derived from agricultural production activities，and it is the key to solve the problem of“who should manage，what to manage and how to manage”in the current agricultural water－saving irrigation system． Agricultural water－saving irrigation service cost is the basis of agricultural water－saving irrigation service pricing． Service price is the result of game and cooperation between supply and demand． Cost and price jointly affect the development process of agricultural water－saving irrigation service industry． Combining with typical cases in Changji city of Xinjiang，this paper analyzes of the agricultural water －saving irrigation service pricing and production cost under different situations，thus find the economic law of agricultural water － saving irrigation service cost and price under different situations and its influence on the development of the marketization of agricultural water－ saving irrigation service to provide policy suggestions for the promotion of agricultural water－saving irrigation services．

In this paper, the estimation theory of agricultural water-saving potential in irrigation district scale is applied to the main grain producing areas in China. Based on the existing water-saving irrigation engineering measures, the agricultural irrigation water-saving potential of each province in the main grain producing areas is estimated. The water-saving potential of each province is in line with the actual situation in the local area. After increasing the water-saving irrigation rate, The utilization efficiency of agricultural irrigation water has increased in all provinces.However, the water saving potential of the northern provinces in the main grain producing areas is stronger than that of the south, and the water-saving potential is mainly the gross water-saving.While developing water-saving irrigation, the actual conditions of each region should be contacted to combine project water-saving measures with non-engineering water-saving measures to ensure food security and improve the regional ecological environment.