In order to understand the overall equilibrium of water environment in Shandong Province, this paper uses the grey water footprint method to quantitatively analyze the water pollution status, and evaluates the regional equilibrium of the grey water footprint in Shandong Province through the Gini coefficient and the matching distance in the imbalance index. The research result showed that: ①The grey water footprint of Shandong Province had shown a downward trend from 2005 to 2017. In the composition of the grey water footprint, agriculture accounts for the largest proportion, followed by life, and industry accounts for the smallest proportion. ②The regional difference in grey water footprint per capita is relatively small, while regional difference in grey water footprint intensity and water environmental pressure is more obvious. The balance of industrial grey water footprint is the worst, and that of the agricultural grey water footprint is the best. ③The regional grey water footprint of Heze City, Dezhou City and Liaocheng City is too large, Linyi City has the lowest water environment pressure, Qingdao City has the lowest grey water footprint intensity, and Heze City has the highest grey water footprint intensity. On this basis, some practical suggestions are put forward to improve the balance and matching of grey water footprint in Shandong Province.

The simulation of evapotranspiration and water-yield relationship based on crop model can provide a key scientific basis for improving crop water use efficiency and integrated management of agricultural water resources. In this study, the relationship between evapotranspiration composition and water yield of naked oats under rain-fed condition in the agro-pastoral ecotone of northern China was studied by using the observation data of large-scale lysimeter in 2018 and 2019 and the calibrated RZWQM2 model. The response characteristics of biomass, yield, water use efficiency and irrigation production efficiency of naked oat under total irrigation of 30 mm, 60 mm, 90 mm and 120 mm were quantified. The results showed that:①During the entire growth period of naked oats, crop transpiration mainly occurred at jointing stage (35.50%), booting stage (23.54%) and flowering stage (28.26%). The total monthly evapotranspiration was the lowest in June (10.40 mm) and the highest in August (164.10 mm).②Compared with rain-fed treatment, the average leaf area index (LAI) and biomass of naked oat were all increased by more than 10% and 20% under total irrigation amount of 60 mm, and the yield of naked oat increased by 7.49% and 9.50%, respectively. ③Water use efficiency under total irrigation of 60 mm in 2018 and 2019 reached 0.91 kg/m³ and 1.34 kg/m³, respectively, and the irrigation water production efficiency was 33.3%~50.0% higher than that under total irrigation amount of 30 mm, 90 mm and 120 mm. The results of the study provide a theoretical basis for high yield and efficient water use efficiency of naked oats in this area.

In order to reveal the differences of phreatic evaporation between undistributed soil and backfill soil, a comparative study of phreatic evaporation during the whole growth period in two soil lysimeters for mortar black soil in undistributed and backfill soils was conducted by using daily phreatic evaporation test data of winter wheat and summer maize from 2017 to 2019 at Wudaogou Experimental Station. The results showed that: there were differences in phreatic evaporation between undistributed and backfilled soils during development of winter wheat and summer maize. In 2017 to 2018 and 2018 to 2019, the average daily phreatic evaporation of winter wheat in the backfill soil was 0.53 mm/d more than that in the undistributed soil. In 2018 to 2019, the average daily phreatic evaporation of summer maize in the backfill soil was 0.84 mm/d more than that in the undistributed soil. Linear relationships between daily phreatic evaporation in backfill soil and in undistributed soil were established for winter wheat and summer maize development, respectively. For winter wheat the linear relationship was highly significant (P<0.01) with E_{g\mathrm{0}} = \mathrm{0.78} \text{?} E_{g\mathrm{1}} + \mathrm{0.041} and R ² of 0.987. For summer maize, the linear relationship was highly significant (P<0.01) with E_{g\mathrm{0}} = \mathrm{0.509} \text{?} E_{g\mathrm{1}} + \mathrm{0.010} \text{?} \mathrm{4} and R ² of 0.944. The relationship between phreatic evaporation in backfill soil and undistributed soil can be used to estimate the phreatic evaporation in undistributed soil. When using lysimeter method to carry out experimental research on factors such as phreatic evaporation and evapotranspiration, it was recommended to use undistributed soil lysimeter.

To explore the effects of biochar and straw returning to the field on winter wheat yield and water use efficiency in fluvo-aquic soil regions can provide theoretical basis for the efficient agricultural utilization of straw resources. In this study, a field plot experiment was conducted and a total of 9 treatments including control (CK, no straw and biochar returning to the field) were set up. Straw returning amount was set as 0.5 (S0.5), 1.0 (S1.0), 1.5 (S1.5), 2.0 (S2.0) times of the dry matter weight of corn straw. Biochar was set as the equivalent amount of corn stalks carbonized (450 ℃) and then returned to the field (B0.5, B1.0, B1.5, B2.0). The effects of different amounts of straw and biochar in the field on soil water content, plant height, dry matter accumulation and transportation, yield and water use efficiency during the growth period of winter wheat were analyzed. The results showed that the S2.0 treatment had the best promotion effect on the average soil water content of 0~100 cm in the winter wheat turning green, jointing and flowering stages, and the B2.0 treatment better promoted the increase of the average soil water content in the mature period. Compared with the control, the two methods of returning to the field both promoted the increase of plant height and above-ground dry matter quality of winter wheat at maturity stage, both improved dry matter accumulation of winter wheat after flowering, grain yield and water use efficiency, and B1.5 and B2.0 treatments significantly increased plant height, grain yield and water use efficiency of winter wheat at maturity stage. Therefore, compared with straw returning directly, returning corn straw to the field after 1.5~2.0 times carbonization is beneficial to the growth and development of winter wheat and improves the grain yield and water use efficiency of winter wheat in the fluvo-aquic soil area.

In daily use, the water source at the inlet of the sprinkler does not maintain a steady water supply, resulting in a certain random fluctuations in pressure and flow, which has an impact on the operational effectiveness of the sprinkler. In order to explore the influence of unsteady water supply on the pressure distribution of sprinkler, this paper mainly studies the distribution law of pressure and flow in the pipeline of sprinkler under different configurations through outdoor physical tests. Under the condition of stationary sprinkler, the pressure sensors were installed at various locations in the sprinkler to monitor pressure changes in real time, and the pressure data were processed and analyzed. The results showed that when the unsteady water supply spigot was used for water supply, the pressure at the inlet of the sprinkler fluctuated greatly. When the variable frequency pump was not in operation, the coefficient of variation was up to 10.72%. In the experiment, the average pressure at the inlet of the sprinkler decreased with the increase of nozzle size, and the average pressure loss from the inlet to the tail of the sprinkler was positively correlated with the operation frequency of the variable frequency pump. The average pressure amplitude at the inlet of sprinkler decreased first and then increased with the increase of variable frequency pump. Under this water source, the variation of instantaneous pressure in the sprinkler was very random, but there was still a certain rule in its average pressure and other parameters. In the practical application process, parameters with less fluctuation can be selected to configure irrigation to improve the irrigation effect.

In order to explore the impact of ecological factors on agricultural drought and improve the evaluation accuracy of agricultural drought vulnerability, based on the summary of previous research experience, this study considered three criteria levels of natural sensitivity, social sensitivity, and resilience. Taking Anyang City as an example, eight indexes including standardized precipitation index, crop water deficit index and ecological factor of Temperature Vegetation Dryness index (TVDI) were selected to construct the comprehensive evaluation system of agricultural drought vulnerability. The reliability of the evaluation model was verified by comparing the evaluation results with the actual annual yield reduction rate. The factor contribution analysis method was used to analyze the influence of temperature vegetation drought index on drought vulnerability. The results showed that: ①from 2003 to 2018, the city's drought was mainly affected by climate and environmental factors, with a high frequency of about 63%. The comprehensive evaluation model could better identify drought, and the evaluation accuracy with TVDI was 12.5% higher than that without TVDI. ② In terms of temporal and spatial distribution, the evaluation result was basically consistent with the change trend of the annual yield reduction rate, and the city's drought mainly occurred in the northern plain west of the Taihang Mountains.③Ecological factors have a high contribution degree to the vulnerability index system, and the proportion of temperature vegetation drought index in sensitivity factor and natural type factor can reach 10% and 23% respectively, so the impact of ecological factors on drought should be paid more attention in the future study of agricultural drought vulnerability.

In order to reduce the temperature in the greenhouse during the high temperature in summer, the spray cooling process of a single nozzle in a double-arch double-membrane greenhouse was studied through experiments so as to explore the indoor temperature and humidity change rule under different atomization indexes, spray duration and side window opening and closing conditions of single nozzle. The results showed that:①With fixed nozzle working time and nozzle diameter, increasing the water pressure increased the cooling and humidifying range; with fixed working time and water pressure of the nozzle, increasing the nozzle diameter increased the cooling and humidifying range. With fixed same atomization index, the range of cooling and humidification increased with the extension of spraying time.②When the initial temperature in the greenhouse was 40 ℃, under the condition of spraying for 5 minutes and closed the side window, through seting different water pressure and nozzle diameter, the temperature decreased by 2~4 ℃, and the relative humidity increased by 20%~30%; while when the side window was opened, the temperature decreased by 5~7 ℃, the relative humidity increased by 5%~10%. Opening the side windows and spraying at the same time could lower the temperature while reducing indoor humidification.③Water pressure of 0.25 MPa, nozzle diameter of 0.75 mm, spraying time of 10 min, and side window ventilation were the conditions with the best cooling effect and the lowest energy consumption, which could provide reference for rapid cooling of double arch and double membrane greenhouse in summer.

In order to study the effects of different fertilization treatments on agronomic characters, yield and quality of pepper under drip irrigation, taking the varieties of bright red pepper in Henan Province as experimental materials, four fertilization treatments were set: A (no fertilization), B (organic fertilizer + compound fertilizer), C (compound fertilizer) and D (organic fertilizer), with the same amount of nitrogen fertilizer applied to B, C and D. The results showed that different fertilization treatments had significant effects on the agronomic characters, yield and quality of pepper. Considering the agronomic characters, yield and quality of pepper, the order of fertilization treatments was B > D > C > A. That is, single application of compound fertilizer and no fertilization were not conducive to pepper growth and low yield. When organic fertilizer and compound fertilizer were applied together, the agronomic characters, yield and quality of pepper were comprehensively improved, and the content of vitamin C in pepper was the highest. The total yield and vitamin C content of pepper treated with single application of organic fertilizer were slightly lower than those treated with mixed application of organic fertilizer and compound fertilizer, but the formation of crude protein and spicy degree of pepper treated with single application of organic fertilizer was higher than that treated with mixed application of organic fertilizer and compound fertilizer.

In order to optimize the water and nitrogen management scheme for summer maize planting in the North China Plain, the data obtained from the 2019-2020 summer maize field experiment in Linqing city, downstream of the Weishan Yellow River Irrigation Area, were used to determine and verify the parameters of water, nutrient and growth modules in the RZWQM model. The results showed that root mean square error (RMSE) and mean relative error (MRE) of soil moisture content, NO₃ ^--N content and crop yield were within acceptable range after optimization of simulation parameters. Then the calibrated RZWQM model was used to simulate crop yield, water and nitrogen use efficiency and NO₃ ^--N leaching process under 24 different water and nitrogen conditions. Considering crop yield, water and nitrogen use and environmental effects, the recommended water and nitrogen management scheme was 166 mm irrigation amount and 180 kg/hm² nitrogen application amount. This study provides a theoretical basis for the optimization of farmland water and fertilizer management in the downstream of Weishan Yellow River Irrigation area.

Irrigation is an important measure to maintain crop production in semi-arid areas. Water saving irrigation technology will be different due to different national conditions, geography and climate conditions. The development of water-saving irrigation is the direction of future agricultural irrigation and the only way towards precision agriculture and intelligent agriculture. The growth and development of crops in arid and semi-arid areas are greatly affected by irrigation factors. Understanding the physiological response mechanism of crops to irrigation can improve the growth and development of crops under irrigation conditions, and lay the foundation for the formation of crop yield under irrigation conditions. Based on the current situation of agricultural irrigation at home and abroad, this paper summarized the effects of agricultural irrigation on crop yield formation characteristics, nutrient accumulation and transport characteristics and physiological characteristics in recent years, providing theoretical basis for agricultural irrigation and physiological response mechanism of crops under irrigation conditions.

In order to investigate the effects of different irrigation methods on soil physical and chemical properties of platycladus orientalis plantation in semi-arid of loess plateau, the changes of soil physical and chemical indexes under sprinkler irrigation, hole irrigation and flood irrigation were conducted through the combination of field experiment and laboratory analysis in Xiaoqingshan soil and water conservation science and technology demonstration in Lanzhou. The results showed that soil water content, porosity and water holding capacity decreased with the increase of soil depth, while soil bulk density showed an opposite trend. The soil bulk density and water content in sprinkler irrigation were lower than those in flood irrigation, while porosity and water holding capacity were higher than those in hole irrigation and flood irrigation. Soil nutrient indexes were also different under different irrigation methods, the soil organic carbon, total nitrogen, hydrolysable nitrogen and available potassium decreased with the increase of the soil depth with the order of sprinkler irrigation > hole irrigation > flood irrigation, while the soil pH and available phosphorus had no obvious change regularity. Among the three irrigation methods, sprinkler irrigation had the best effect on improving soil physical and chemical properties, and was a more suitable irrigation measure for platycladus orientalis plantations.

In order to explore the applicability of deep learning models in the estimation of regional reference crop evapotranspiration (ET ₀), this paper took Shandong Province as the research area and selected 3 deep learning models (including deep neural network (DNN), time convolutional neural network (TCN) and long short-term memory neural network (LSTM) , 3 traditional machine learning models (including extreme learning machine model (ELM), generalized regression Neural network model (GRNN) and random forest model (RF), and 6 empirical models (including Hargreaves-Samani model (HS), Droogrs-Allen model (DA), Priestley-Tayor model (PT), Marrink model (MK), WMO model (WMO), Trabert model (TRA). Taking Root mean square error (RMSE), coefficient of determination (R ²), average absolute error (MAE) and efficiency coefficient (E_ns ) as the accuracy evaluation system, the optimal model for ET ₀ estimation in Shandong province was found. The results showed that the accuracy of the machine learning model was generally better than that of the empirical model under the same meteorological parameter input conditions, while the three deep learning models had the best accuracy, and the TCN model had the highest accuracy among all models. The accuracy of the model with radiation data input was generally higher than that of the temperature model and the mass transfer model. The GPI of the TCN2 model was 1.036, ranking first among all models. So the TCN model can be used as a recommended model for ET ₀ estimation in Shandong Province.

In order to study the adaptability of root growth of summer maize under different drought conditions and the recovery ability of root under rehydration after drought, taking 'Denghai 618' as the experimental material, four treatment groups under the same rehydration conditions after light drought, medium drought, heavy drought and extreme drought and one normal water supply control group were set under the ventilation shed. The changes of soil water content and its effects on root morphology and root biomass of summer maize were analyzed. The results showed that: ①under the four kinds of drought treatments, the soil water content at the depth of 10 cm, 30 cm, 50 cm and 70 cm decreased slowly five days before rehydration. After rehydration, the soil water content at the 10cm layer increased sharply within one day and then decreased again, increasing by 3.91%, 6.55%, 8.68% and 10.48%, respectively; From the vertical direction, the overall trend of soil water content in arid soil above moderate drought increased with the increase of soil depth.②Different degrees of drought in heading filling stage had different effects on summer maize roots. Moderate drought was beneficial to root growth and elongation. The occurrence of other degrees of drought was unfavorable to the whole root system, resulting in lower root tip number and root volume than the control group. Under drought, the root system became thinner and the proportion of fine roots increased. Under light drought, medium drought, heavy drought and extreme drought, the root length of 0~0.5 mm diameter was 2.98%, 12.35%, 18.62% and 7.12% higher than that of the control group; After drought and rehydration, the water absorption of summer maize root diameter becomes thicker, which affects the proportion of root volume with diameter of 0~0.5 mm, which is less than that in drought.③Different degrees of drought are not conducive to the accumulation of root biomass. The root dry weight of mild drought group, moderate drought group, severe drought group and extreme drought group was 39.49%, 59.62%, 53.98% and 9.37% less than that of the control group, respectively. The higher the degree of drought, the smaller the increase of root dry weight after rehydration. Adequate moisture is the key to summer maize growth.

Accurate calculation of reference crop evapotranspiration (ET ₀) is the basic basis for establishing irrigation schedule and planning regional irrigation water consumption. In order to improve the calculation precision of reference crop evapotranspiration (ET ₀) in different climatic regions of China, considering the ET ₀ values calculated by the FAO-56 Penman-Monteith (PM) method as the standard, this paper evaluated the applicability of 28 empirical ET ₀ methods based on the temperature and radiation in temperate monsoon zone (TMZ), temperate continental zone (TCZ), mountain plateau zone (MPZ) and subtropical monsoon zone (SMZ) of China. The results showed that the accuracy of radiation methods was higher than that of the temperature method nationwide, and the temperature methods had the highest accuracy in TCZ and the radiation methods had the highest accuracy in SMZ. The FAO24 radiation method was recommended in TMZ and TCZ (RMSE of 0.245, 0.237 mm/d, MAE of 0.210, 0.199 mm/d, ENS of 0.975, 0.986, respectively). The PT method was recommended in MPZ and SMZ (RMSE of 0.179, 0.159 mm/d, MAE of 0.133, 0.125 mm/d, ENS of0.978, 0.978, respectively). The B-R method of temperature methods performed well in TMZ and MPZ (RMSE of 0.245, 0.71 mm/d, MAE of 0.337, 0.208 mm/d, ENS of 0.923, 0.950, respectively). The MB (2005) method was recommended in TCZ (RMSE of 0.354 mm/d, MAE of 0.249 mm/d, ENS of 0.968). The HScor method had the highest accuracy in SMZ (RMSE of 0.255 mm/d, MAE of 0.195 mm/d, ENS of 0.944). Therefore, when the data was sufficient, the ET0 methods were recommended in different climatic regions, i.e., FAO24 radiation, FAO24 radiation, PT, PT (radiation method); when the data was insufficient, the best choice was B-R, MB (2005), B-R, HScor method (temperature method).