In order to explore the impact of coupling effects of different water and carbon on the growth，yield and water use efficiency of rice，two-factors field experiments were conducted with 3 irrigation patterns and 3 biochar proportions． The results show that water carbon coupling has significant effects ( P＜ 0． 01) on rice seed setting rate，grain weight，theoretical yield; in contrast，the biochar application quantity has more significant effect on plant height，tillers，leaf area index，grain growth index，while the irrigation mode has more significant effect on seed setting rate，dry weight，the average grain number per spike and yield; the rice yield under conventional irrigation ( W1 ) is the highest，but the water use efficiency is low; compared with the severe water deficit model ( W3 ) ，the growth index and yield index of rice significantly increase with the increase of biochar application amount under the slightly water deficit model ( W2 ) ; the water use efficiency is the highest ( 0．958 kg /m3 ) when the irrigation model is slightly water deficit model and the biochar application amount is 2 g / kg( W2B2 ) ． 

Trace quantity irrigation ( TQI) is a new water-saving technology，including two lays of filter menbranes，one with large surface and tiny aperture，the other with small surface and big diameter． In the period of researching and developing the TQI products，the product parameters need to be modified． And then after the small amount trials，the shape can be defined，which results in the high cost and time wasting． In the great scale of field irrigation experiments，all geometry sizes of irrigation pipe and parameters of irrigation system need plentifully repeated tests，which results in high cost and time． To save the period and cost of trace quantity irrigation( TQI) experiments，the TQI products are simulated to prove and improve the model by laboratory tests for defining the shape of the TQI products． The research results show that the simulation models can match well with the experiments with the sum of squares of residuals of 0． 021，0． 12 and 0． 003， respectively．

In order to study the hydraulic performance and mixing process of venturi injector，through a combined method of experiment and numerical simulation，an unsteady numerical simulation based on the mixture model and the cavitation model and contrast experiments were carried out under different operating conditions by using Ansys-Fluent software． The results show that the numerical simulation considering cavitation model is basically consistent with the experimental results，which indicates that the calculation considering the cavitation model can better predict the hydraulic performance of the venturi injector． In addition，it is found that the mixing chamber and throat of the venturi injector are the main areas of energy loss． The mixing of fertilizer solution and working fluid occurs mainly in the diffusion section.

Drip fertigation technology can directly supply water and fertilizer to the soil near the crop roots，can achieve water and fertilizer saving，high yield，reduce environmental pollution． In this study，spring maize was used as the research object，drip fertilization way was used，four fertilization period ( the first fertilizer after the water，the first water and then fertilizer after the water，the first water after fertilizer，fertilizer and water synchronization) were set，the distribution of NO3 -N in the soil profile of the second and tenth day after irrigation was observed． The results showed that in the first fertilizer and fertilizer and water synchronization，the nitrate-N migration was active and the distribution range was relatively large; the distribution range of nitrate-N in the first water was relatively small，it mainly distributed in the sub-surface layer and above，and the radial distribution was also relatively narrow; after the absorption of maize，the first fertilizer after water irrigation way had the fewest nitrate nitrogen residue，corn absorption was more thorough，fertilizer utilization rate was slightly higher than other treatments．

With the dry farmland soil on the Loess Plateau as the research object，based on the annual tracking test，the variation and characteristics of cultivation layer bulk density within the year process are analyzed and the mechanism of soil bulk density in maize growth period is explored by combining with the datas of rainfall，temperature and soil moisture content，which were monitored simultaneously，of the test area． The results show that: as time goes by，surface soil bulk density is increasing in maize growth period; the process of density change in growth period can be divided into five stages: rapid growth stage after sowing，slow growth stage after sowing，sharply growth in rainy periods，fluctuation stage in rainy periods，gentle decline stage after harvest; the surface soil bulk density reaches the maximum after the rain drop and the process of collapsibility deformation has basically completed; soil bulk density of the 10 ～ 20 cm layer are the largest in the three stages in the deep range of cultivation layer; before the arrival of the main flood season，the soil bulk density of 0 ～ 2 cm layer is bigger than that of of 2 ～ 10 cm layer; while the soil bulk density of 0 ～ 2 cm layer is less than that of of 2 ～ 10 cm layer in the main flood season． The results can provide parameter support for the management of farming operations，the prediction of soil infiltration parameters and irrigation management．

In order to explore the winter wheat high -yield and water -saving planting approach based on ridge and furrow rain -harvesting planting mode in semi-humid traditional irrigation area，in October 2015 to June 2016，the Xinong 979 was taken as study object to study the effects of different planting ways combined with limited irrigation in the growth period of winter wheat on soil water content and water use efficiency of winter wheat． The results showed that: when the irrigation amount was decreased by 50% of the traditional border irrigation amount ( F150) ，the wheat yield of F75 treatment was decreased by 18．86% and 10．07%，respectively，for the two years; comparing the Ｒ75 treatment ( rain-harvesting planting with 75mm irrigation amount ) with the F150 treatment，the wheat yield was decreased slightly，not reached the significant level( P＜0．05) ; the Ｒ75 treatment and Ｒ150 treatment had no significant difference; the IWUE of Ｒ75 treatment was significantly enhanced by 95．51% and 104．2%，respectively，and WUE was enhanced by 31．23% and 13．1%，respectively，for the two years． The results indicate that the rain-harvesting planting can efficiently use rainfall and irrigation water，meet the wheat growth and increase yield; rain-harvesting planting with limited irrigation in key growth period can save water by 40% to 70% without obvious yield decrease． 

In this study，rape is taken as the research object，the SAP ( Super Absorbent Polymers) is applied to the nursery substrate and the gully in the sand to study the effects of different concentrations of SAP on the seed germination of the matrix seedling，the seedling growth and the growth effects of rape in sand planting． The test results show that: ① SAP can improve the water holding capacity of nursery substrate，reduce irrigation times and had no significant effect on the germination rate and germination vigor of seeds． It also can promote the plant height，leaf number，leaf area and dry weight and fresh weight growth accumulation． The comprehensive analysis shows that when the concentration of SAP is 0．6%，the best effect can be achieved． ② SAP can effectively improve the water holding capacity of sand，reduce the average daily amount of irrigation of rape，promote the plant growth and is conducive to the accumulation of production． When the concentration of SAP is 90 kg / hm2 ，the effect is the most remarkable．

In order to effectively utilize the abundant salt water resources and reduce the environmental pollution caused by excessive fertilizer，this paper studies the coupling of water and fertilizer under the brackish water drip irrigation through field experiments． In the test， three irrigation levels ( W1: 2 325 m3 / hm2 ，W2: 2 850 m3 / hm2 ，W3: 3 375 m3 / hm2 ) and three nitrogen levels ( N1: 525 kg / hm2 ，N2: 750 kg / hm2 ，N3: 975 kg / hm2 ) are set，the effects of different water and nitrogen on the growth and yield of Lycium barbarum，irrigation water use efficiency and partial factor productivity of fertilizer are analyzed． The results show that increasing the amount of irrigation and the amount of nitrogen applied can promote the growth of Lycium barbarum plants． Compared with N1，under the same irrigation level，the 100 fresh fruit grain weight of N2 and N3 are increases by 7．3% ～ 11．4% and 1．9% ～ 4．0%，respectively，and the sequence from large to small is W2，W3，W1 under the same fertilization level． In each treatment，the yield of W2N2 is the highest，5 547．22 kg / hm2 ，and the yield of W2N2 Lycium barbarum is decreased by 1．94% ～ 33．27% compared with the other treatments; with the increase of irrigation and the decrease of fertilization，iWUE increases，while PFP decreases; otherwise，iWUE decreases，PFP increases; when water and nitrogen are treated as W2N2，both high yield and high iWUE and PFP can be ensured． Therefore，the suitable amount of water and nitrogen is 2 850 m3 / hm2 and 750 kg / hm2 ( W2N2) ．

According to water and fertilizer coupling experiments of cherry tomato cultivated with substrate culture in the greenhouse，the inherent relationships between cherry tomato quality and irrigation quantity and fertilizer application rate were revealed． The experiment result indicates that the irrigation and fertilization have significant effects on cherry tomato quality，moreover，there has coupling effects; when the fertilizing amount is small，the vitamin C content will improve significantly with irrigation volume，whereas the nitrate content also increases; the higer the irrigation amount，the lower the titratable acid content and solubility sugar content of cherry tomato; when the fertilizing amount is on low level，the soluble solids content can be improved effectively by increasing irrigation，the soluble solids content will be obtained with modest water and fertilizer． Taking vitamin C content into consideration，the optimal fertilization for the period of one month before picking is heavy water and medium fertilization; taking soluble sugar content into consideration，the optimal fertilization is little water and heavy fertilization; taking soluble solid content into consideration，the optimal fertilization is medium water and medium fertilization; for reducing nitrate content，the optimal fertilization is little water and fertilization．

In order to study the influences of different drip pipes buried depth on water use efficiency and grassland coverage of alfalfa，the experiment was carried out in Sunan Yugu autonomous county of Gansu Province． The results show that the first hay yield of alfalfa accounts for about 40% of the total annual output under underground drip irrigation conditions． At the same time，the proportion will be reduced with the increase of drip irrigation pipe buried depth． The yield and water use efficiency can reach the highest level when the drip irrigation pipe buried depth is 0．20 m，which is the optimal depth for alfalfa under underground drip irrigation in this area． The influences on water use efficiency and grassland coverage will be different in distinct growth period of alfalfa under different drip irrigation pipe buried depth． It will be advantageous for the first and second alfalfa turning green when the drip irrigation pipe is buried within 0． 1 m depth，while the 0． 3m buried depth is not conducive to the first emergence of alfalfa．

In order to study the influence of urea concentration on sand soil water characteristic curve and field capacity，this paper uses the centrifuge to measure the water characteristic curves of soil containing urea concentration of 0%，1%，4% and 7%，respectively． The measurement results are fitted with the classical VG model and the influence of urea concentration on VG model parameters under the test condition is discussed based on the fitting result，then the influence of urea concentration on field capacity index is studied． The results show that with the increase of urea concentration，the water retaining ability gradually decreases，the value of parameter αgradually decreases and the effect of urea is relatively large，the value of parameter n gradually increases，the values of θs and θr gradually decrease，and the influence degree of urea is relatively small，the water capacity，field capacity，wilting coefficient，and total effective water range all decrease．

Water resources carrying capacity indicates the maximum scale of the social and economic system supported by the water resources system at a certain period in a region． In view of the uncertainty and fuzziness of the index attributes in the evaluation of water resources carrying capacity，in order to improve the reliability of evaluation results of water resources assessment model，a model of water resources carrying capacity evaluation based on variable fuzzy set is proposed． In this model，the evaluation indexes are divided into two levels，namely criterion layer and index layer，the weight of the two layers are determined by AHP and entropy method． Fuzzy sets theory is used for comprehensive evaluation of study area using the maximum nearness criterion． The model is used to calculate the carrying capacity of water resources in Yichang city for 2009 to 2014 years． The results showthat: ① the application of this model is simple，it overcomes the uncertainty and fuzziness of each index attribute in the evaluation of water resources carrying capacity and the results is more reliable; ② the carrying capacity of water resources in Yichang is at a high level and able to meet the demand of social and economic development in the current economic and technological level and development trend．

For scientificly study the rainfall variation characteristics，stability and annual distribution characteristics of monthly scale rainfall were studied by analyzing the relative variability，PCD and PCP of the rainfall data，and then Linear trend analysis，Mann-Kendall，and MorletWavelet were applied to analyze the trend，mutation and period characteristics for the seasonal precipitation，finally the future characteristics was estimated by using the Correlation Function Method． The results show that the relative variability of rainfall is large，and the maximum value is 71． 34%，monthly rainfall is unstable，PCD is between 0． 17 ～ 0． 63，and the rainfall concentrates in June; rainfall decreases during spring and autumn，while in summer and winter it shows a rising trend，the mutation for the seasonal rainfall takes place in the 80 ～ 90＇s of 20th century，among them，the mutation time of winter precipitation sequence is relatively early，just around 1980，while the mutation time of winter precipitation sequence is relatively late，which is around 1990; season rainfall shows periodic characteristics of multi -scale nested，of which the main periods in summer and winter are shorter than those in spring and fall． It is estimated that the characteristics of future rainfall are similar to the present situation，that is to say，the characteristics of rainfall have durative characteristics． 

The development of reasonable water and nitrogen coupling scheme is an important approach to change traditional irrigation and fertilization management strategy，save water resources，improve yield and quality of flue-cured tobacco． Aiming at the inharmony between irrigation and N fertilization，the tobacco K326 is selected as test materials，different irrigation amounts ( 600，800 and 1 000 mm) and N application rate ( 0，90，120 kg / hm2 ) are designed，and the agronomic，photosynthetic characteristics and dry matter accumulation of fluecured tobacco under different water and nitrogen treatments are observed and analyzed． The results show that the 800 mm irrigation amount and 120 kg / hm2 N application amount obtain the greatest leaf area of single flue -cured tobacco，and both the whole plant dry matter accumulation and leaf dry matter accumulation amount are the highest，328．6 g / plant and 163．1 g / plant，respectively． The crop growth model can well simulate the dynamics of flue-cured tobacco leaf area index under water and nitrogen treatments，the correlation coefficient reaches 0．987 5 to 0．987 5． In addition，in this study，high water supply combined with high N application amount results in late-maturity of the flue -cured tobacco，which negatively affects the yellowing of tobacco leaves.

In order to explore the optimum fertilization scheme of winter potato with water and fertilizer integration，under the condition of mulched drip irrigation，based on the recommended fertilizer application amount，which is determined through early spring potato“3414” tests for several years in Luliang county，5 treatments are set to conduct a field experiment，in which the effects of different fertilization treatments on growth and yield of winter potato are studied． The results show that under the condition of mulched drip irrigation and the same fertilizer application amount，compared with conventional fertilization ( T1) ，the drip fertilization treatments of T2，T3，T4 and T5 have earlier potato growing period，higher germination rate，better growth，higher tuber number and tuber weight per plant，and better yield． Two fertilization ways show the best effect． One is that 70% fertilizer as base fertilizer with 30% drip fertilizer at seedling stage and budding stage; the other is that 50% fertilizer as base fertilizer with 50% drip fertilizer at seedling stage and budding stage ( water soluble fertilizer) ． Compared with conventional fertilization，the usage of this two new fertilization ways can enhance the germination rate by 1．5% to 4．7%，the number of tubers per plant is increased by more than 0．7，the tuber weight per plant is increased by 33．6 to 47．3g，the rate of marketable potato is increased by 0．2% to 0．5%，the yields under the two fertilization ways are increased by 10．7% and 9．3%，respectively，and the efficiency are increased by 15．6% and 9．7%，respectively． The two fertilization ways can be popularized in practical production of winter potato．

In view of the problems existing in communication mode of traditional orchard irrigation automatic control system，this paper proposes a method integrating the power lines and the signal lines to one，and studies the sprinkler intelligent control system based on low voltage power line carrier communication． The power line carrier communication module is designed with ST7540 chip as the core，the STM32F103 chip is used as the main controller of the total controller node，and the STM8S103 is used as the main control of the sensor node and the water pump control node． The problems of the repeat wiring of the power and control cables of solenoid valve and the stability of wireless irrigation control system were solved，the reliability of communication is improved，the cables are saved，and the complexity of maintenance is reduced． The test results on the twisted pair with 100 m length and 0．5 mm2 cross-sectional area show that the transmission rate can be up to 4．8 kbps，the bit error rate is less than 0．1%． In a test in litchi orchard in South China Agricultural University，the high reliability zoning rotation irrigation is achieved． So applying the power line carrier communication technology in agricultural automatic control system will have a broad application prospects．

The irrigation methods of large grain growers play an important role in improving the technical efficiency of grain production． Based on the survey data of 535 large grain growers，this paper uses nonparametric meta-frontier method and DEA model to measure the technical efficiency of metafrontier and group frontier，uses the technology gap ratio ( TGＲ) to analyze the differences in the production technology between large grain growers． The results show that the technical efficiency of large grain growers is not high; under the metafrontier，the technical efficiency levels of big grain farmers in different groups from high to low are: water saving irrigation，traditional irrigation and non irrigation; the technical efficiency values with respect to the group frontiers are higher than that to the meta-frontiers，so the group frontiers are overestimated; there are significant gaps in the production technology of large grain growers of three groups using different irrigation methods．

In order to calculate the effective utilization coefficient of farmland irrigation water in recent years in Xianyang City and provide theoretical and technical support for the planning and utilization of regional water resources and the development of efficient water saving, this paper calculates the effective utilization coefficient of farmland irrigation water in Xianyang City from 2015 to 2017 by the first and last measurement algorithm, and uses the sectional first and last method to review the calculation results, and analyses the influencing factors of the effective utilization coefficient of farmland irrigation water. The following conclusions are drawn: (1) 47 sample irrigation districts were selected in Xianyang City, including 3 large-scale irrigation districts, 11 medium-sized irrigation districts, 8 small-scale irrigation districts and 25 pure well irrigation districts. After calculation, the effective utilization coefficients of comprehensive farmland irrigation water in Xianyang City in 2015, 2016 and 2017 are 0.5768, 0.5770 and 0.5784, respectively. Compared with 2016 and 2015, 2017 increased by 0.24% and 0.27% respectively. The results show that after a series of water-saving measures have been implemented in Xianyang City for three years, the effective utilization coefficient of farmland irrigation water shows an overall upward trend year by year. (2) The relationship between the effective utilization coefficients of farmland irrigation water in different types of irrigation areas in Xianyang City is as follows: large-scale irrigation area < medium-sized irrigation area < small-scale irrigation area < pure well irrigation area, and water-raising irrigation area > self-drainage irrigation area. The effective utilization coefficient of farmland irrigation water calculated by the piecewise head-tail method is higher than that calculated by the head-tail method. The results calculated by the two methods are quite different in large irrigation area and medium irrigation area, and the results calculated by the two methods in small irrigation area are slightly different. (3) The influencing factors of the effective utilization coefficient of farmland irrigation water are as follows: the length of seepage-proof canal, the lining rate of canal, the area of water-saving irrigation project, the scale of irrigation area, the management level of irrigation area, irrigation system, soil moisture and rainfall, while the effective utilization coefficient of farmland irrigation water is affected by crop irrigation system, the length of seepage-proof canal, the lining rate of canal and the area of water-saving irrigation project. The relationship between the effective utilization coefficient of farmland irrigation water in different soils is loam > clayey soil > sandy soil, and there is a positive correlation between the effective utilization coefficient of farmland irrigation water and rainfall. Within a certain range, the greater the rainfall, the greater the effective utilization coefficient of farmland irrigation water. Through calculation, the effective utilization coefficient of field irrigation water under inadequate irrigation system is 0.941, which is significantly higher than the effective utilization coefficient of field irrigation water in Jinghuiqu irrigation area as a whole 4.19%, and also significantly higher than that of field irrigation water under pure well irrigation area in Xianyang City 1.94%. It can be seen that inadequate irrigation system not only saves water, but also achieves water saving and high yield. It is also helpful to improve the effective utilization coefficient of farmland irrigation water.

In this study，the suitable groundwater depth and the best groundwater depth of three main crops in two cultivated soils in Fu-yang are obtained based on the experiment of the influence of different groundwater depths on crop yield． In Loam distribution area，with no interference of rainfall，drought，irrigation and fertilization，the suitable groundwater depth of wheat，soybean and maize are 0．6 ～ 1．5，0．4 ～ 1．0，0．4 ～ 1． 0 m，while the best groundwater depth are 0． 8，1，1． 5 m，respectively． In sandy loam with same conditions，the suitable groundwater depth of wheat，soybean and maize are 0．4 ～ 1．5，0．6 ～ 1．5，1．5 ～ 2 m，respectively，while the best groundwater depth are 1， 1．5，1．8 m，respectively． With the basement of these results，the data of groundwater depth in Fuyang is obtained by field survey and measurement which are used to study the groundwater depth distribution and its influence on irrigation in Fuyang． Besides，the irrigation division of different crops in natural condition are proposed，which will provide scientific basis for groundwater resource saving，scientific irrigation，and the promotion of national high standards，high yield and high efficiency of farmland in the study area．

The experimental clay loam in Yangling area is taken as the object of study. The spectral information of the six bands of the soil is collected by using a unmanned aerial vehicle(UAV) equipped with a multispectral camera, so as to explore a rapid method for monitoring soil moisture content. The sensitive bands of soil moisture at different depths were screened by correlation coefficient method. Then, a single regression model was constructed using the spectral data at a single sensitive band, and the quantitative relationship was analyzed. The experimental results show that the one element quadratic regression model has the best fitting effect, and the one element logistic regression models is second. For the inversion of surface soil moisture content (about 1cm), the model fitting degree is above 0.81, the prediction correlation coefficients is above 0.92 and the root mean square error of prediction is within 0.10. Therefore, it is feasible to calculate soil moisture content by collecting clay loam reflectance. But as the depth increases, the model fitting effect decreases sharply. Thus, this study provides a new approach for rapid and accurate monitoring of surface soil moisture content using multispectral remote sensing of UAVs.

The tradable agriculture water right transfer price is determined by the relationship between supply and demand of agriculture water on the basis of agricultural water saving investment and agricultural water right price． Agricultural efficient water saving is an important way to save agricultural irrigation water． The price of agricultural irrigation water use is the key for the transfer of agricultural water to the industry with high water use efficiency． The water price has a leverage in the process of agricultural tradable water right transfer． Ｒeasonable price leverage can get more effective allocation of water resources to enhance the efficiency of the industry water and efficiency． Based on the study of domestic and foreign scholars ＇ research on the composition of water right transfer price，this paper establishes the price model of agricultural transactionable water right transfer，discusses the conditions of price levers，analyzes the incentives and the promotion of agricultural water rights transfer price for the transfer of agricultural water use rights to other water use industry．

In order to explore the new method of obtaining soil moisture characteristic curve model，the soil moisture characteristic curve test was carried out with the soil of the Loess Plateau of Shanxi Province as the experimental material． The Gardner model parameters a and b and the soil basic physical and chemical parameters were obtained，a data sample consisting of Gardner model parameters a，b and soil basic physical and chemical parameters was established． The relationship between soil physical and chemical parameters and Gardner model parameters was analyzed by Grey Ｒelational Analysis． Based on the theory of support vector machine ( SVM) ，a prediction model with soil bulk density，clay content，silt content，organic matter content and total salt content as input factors and Gardner model parameter a and b as output factors was established． The results show that it is feasible to predict the parameters of the Gardner model a and b with the soil bulk density，clay content，powder content，organic matter content and total salt content as the input factors; the average relative error between the measured values and the predicted values of parameters a and b is 3．96% and 4．68%，respectively，and the coincidence is high． The results of this study can provide technical means for obtaining parameters of soil moisture characteristic curve model，and promote the development of soil transfer function theory．