Considering the low sweet potato yield and water use efficiency in Shandong province due to the inefficient irrigation and nitrogen (N) fertilization application, a two-year (2020 and 2021) field experiment of sweet potato (Pushu 32) cultivation under drip irrigation with film mulching was conducted at the Special Potato Experimental Station, China Agricultural University, Rizhao City, Shandong Province, China. Three irrigation levels (no irrigation, P0; soil wetted percentage 30%, P1; and soil wetted percentage 60%, P2) and three N-application rates (90 kg/hm², N1; 180 kg/hm², N2; and 270 kg/hm², N3) were involved, resulting in a total of 9 treatments. The soil moisture, physiological growth, yield and yield components, and water use efficiency of sweet potato under different irrigation and fertilization treatments were measured. The results showed that soil water content, soil water storage, soil water distribution, and sweet potato growth were affected by different irrigation amounts and N-application rates. Sweet potato grew vigorously and promoted the soil water consumption in 0~50 cm soil layer, resulting in soil water storage reduction in N2 treatment. In 2021, the soil water storage in N2 treatment was 17.8% and 17.7% lower than that of N1 and N3 treatments, respectively. The average sweet potato vine length under P2 treatment was 29.3% and 14.8% higher than that in P0 and P1 treatments in 2021, respectively. Under the same irrigation conditions, the number of tubers per plant and the yield of sweet potato decreased with the increase of nitrogen application. In 2020, the yield of sweet potato in N2P2 treatment increased by 19.9 % and 3 %, respectively, compared with N1P2 and N3P2 treatments. In 2021, the yield of sweet potato treated with N2P2 was 18.7 % and 24.5 % higher than that of N1P2 and N3P2 treatments, respectively. Under the same nitrogen application conditions, the yield of sweet potato increased with the increase of irrigation amount. In 2021, the yield of sweet potato treated with N2P2 increased by 14.4 % and 24.2 % compared with N2P0 and N2P1. Generally, the N2P2 treatment can improve sweet potato growth and increase yield and water use efficiency. The N2P2 treatment was suitable for sweet potato cultivation under drip irrigation with film mulching in Shandong province.

The aim of this study was to investigate the impact of different irrigation patterns on rice growth characteristics, yields, and water use efficiency under various cultivation methods. The hybrid rice variety cv. Yliangyou 1928 was used in this study, with two cultivation methods: transplanting (C1) and direct seeding (C2), and three irrigation modes: continuous flooding (W1), alternate wetting and drying (W2), and rain-gathering alternate wetting and drying irrigation(W3). The results demonstrated that C2 showed a higher number of stems and tillers throughout the whole growth stage compared to C1. Additionally, W2 and W3 were found to effectively inhibit the growth of ineffective tillers in the early stage of rice development while maintaining the number of effective tillers during the maturity. Moreover, the leaf area index of C2 was significantly higher than that of C1, and W2 and W3 helped slow down the decline of the leaf area index. The average yield of C2 was 1.92% higher than that of C1, while W2 and W3 resulted in average yield increases of 11.47% and 10.54% respectively, compared to W1. Furthermore, W2 and W3 average improved water use efficiency by 35.5% and 40.72% respectively, compared to W1. The irrigation water amount required for W3 throughout the whole growth period decreased by 66.06% and 19.80% compared to W2 and W1 respectively. Additionally, the rainfall utilization rate average increased by 30.66% and 26.28% compared to W2 and W1 respectively. In conclusion, combining direct seeding cultivation with rain storage irrigation can effectively enhance rice yield, reduce irrigation water requirements, improve water use efficiency, and optimize rainfall utilization, ultimately achieving high yields and efficient water use.

To investigate the effects of nitrogen fertilization times under wheat-maize rotation system on population characteristics and carbon assimilation ability of flag leaves in wheat. The base topdressing ratio of nitrogen fertilizer in wheat was 3:7, and five treatments were set according to the topdressing times, namely, topdressing twice (F37-2), three times (F37-3), four times (F37-4), and five times (F37-5) by drip irrigation. The traditional irrigation and fertilization methods were used as the control (flood irrigation, topdressing once, CK). At the jointing, booting, flowering, and harvesting stages, the total stem number of F37-3, F37-4 and F37-5 and were significantly higher than that of CK under drip irrigation. The relationship of leaf area index after flowering was F37-4>F37-5>F37-3>F37-2>CK, while the relationship of light transmittance between middle and bottom canopy populations at 18 days after flowering was CK>F37-4>F37-5>F37-3>F37-2. The correlations of chlorophyll SPAD value was F37-4 > F37-5 > F37-2≥F37-3 > CK from 0 to 36 days after flowering (measured every 6 days), and the values of chlorophyll SPAD under drip irrigation were significantly higher than CK. From 24 to 30 days after flowering, the chlorophyll SPAD value of CK, F37-2, F37-3, F37-4 and F37-5 decreased by 13.89%, 11.36%, 11.90%, 8.33% and 10.87%, respectively. The transpiration rate, stomatal conductance, yield and yield components of drip irrigation treatment (F37-2, F37-3, F37-4 and F37-5) were significantly higher than CK, the yield of F37-4 treatment was up to 10 381.1 kg/hm², while the intercellular CO₂ concentration, especially at 30 and 36 days after flowering, was lower than CK. Therefore, nitrogen fertilization by drip-irrigation had a significant effect on the establishment of rational population and light energy utilization of wheat, and the best effect was achieved when fertilizer was applied four times (F37-4) at regreening stage, jointing stage, booting stage and flowering stage, respectively.

Realizing the optimization of autumn irrigation mode in the Hetao Irrigation District (HID) based on multi-objectives at the regional scale is of great significance to ensure the food security, water security and ecological security. In this study, we utilized distributed SWAP-WOFOST model which has been calibrated and validated. Through AHP-CRITIC-Entropy method and TOPSIS subjective and objective comprehensive evaluation method, we evaluated the results of 12 autumn irrigation modes under three main crops(spring wheat, spring maize and sunflower) planting conditions simulated by the model from 2000 to 2017 using crop yield, water productivity(WP), groundwater depth(GWD), soil water content(SWC) and soil salt content(SSC) as evaluation indexes. The planting structures of the three main crops under the suitable autumn irrigation modes were preliminarily zoned. The results show that the average annual yields of the three crops under suitable autumn irrigation modes are 4 945、8 331 and 3 496 kg/hm², respectively. The average annual WP of the three crops are 1.12、1.82 and 1.04 kg/m³, respectively. The amount of water diverted from the Yellow River for autumn irrigation can be saved by about 14.8%~30.7%. Under the suitable autumn irrigation modes based on TOPSIS evaluation method for zoning, the spring wheat, spring maize and sunflower planting areas accounted for 21.1%, 37.8% and 41.1% of the total area respectively, and the amount of water diverted from the Yellow River for autumn irrigation could be saved about 304 million m³ under this planting structure.

This study took a field experiment in Wuwei, Gansu Province in 2022 and 2023, studied the changes in leaf area, leaf water potential, photosynthetic characteristics, and yield of spring wheat under different water and nitrogen conditions, as well as the physiological mechanisms of yield formation. Using two wheat varieties“Yongliang 4”（YL4）and “Longchun 41”（LC41）as plant materials, set 4 treatments for each variety, including two water irrigation treatments, one is full irrigation（W1）during all growth stage, the other is deficit irrigation (irrigated 65% of the water demand for irrigation crops in jointing -booting stage and grain filling stage, irrigation at other growth stages is 100% of the predicted crop water requirement of adequate irrigation treatment), two nitrogen treatments were N1 (local conventional nitrogen application, 220 kg/hm²) and N2 (reduced nitrogen application, 110 kg/hm²). The changes of flag leaf area (LA), leaf water potential (Ψ _pd), relative chlorophyll content (SPAD) and gas exchange parameters (P _n, G _s) and yield of spring wheat under different water and nitrogen treatments were analyzed. The results showed that the leaf area, leaf water potential, relative chlorophyll content, net photosynthetic rate, stomatal conductance and yield of LC41 were higher than those of YL4, the water and nitrogen stress could reduce leaf area, leaf water potential, relative chlorophyll content, net photosynthetic rate, stomatal conductance and yield of wheat; leaf water potential and leaf area affected crop yield by regulating photosynthetic performance, the single and combined effects of leaf morphology, leaf water potential and photosynthetic performance explain 83% of wheat yield variation, water and nitrogen stress decreased G _s through the hydraulic characteristics of plants, which affected the yield, higher Ψ _pd and G _s were key factors in ensuring yield formation of wheat; under the condition of high nitrogen, under the condition of high nitrogen, the yield of certain water deficit was less, therefore, reducing the irrigation amount in non-critical growth stages could help maintain the yield of spring wheat.

Drought is a major limiting factor seriously influencing soybean production and its impact on yield, the impact of drought on root traits varies with the timing of its occurrence. Only limited research has however been conducted on soil drought affecting soybean yield and root characters in different periods. In order to reveal the response mechanism of drought resistant genotype soybean root system to drought stress, a pot experiment was conducted in Shenyang, Liaoning Province in 2020 to study the effects of water stress on root length, root surface area, root to shoot ratio, and yield of drought resistant genotype and drought sensitive genotype. The results showed that the total root length and root surface area of "Liaodou14" were higher in "Liaodou14" than in "Liaodou21" under drought (W1) and mild drought (W2) stress conditions when water was controlled at the same period. In general, the root length ratio of "Liaodou21" with an average root diameter of 0~0.5 mm was greater for "Liaodou21" than for "Liaodou14", while the root length ratio of "Liaodou14" with an average root diameter of 0.5~1.0 mm is higher than that of "Liaodou21".In addition, the fresh shoot weight, fresh root weight, dry shoot weight and dry root weight gradually accumulated with the growth and development of plants, reaching their maximum value after water controlled at pod filling stage. In general, the fresh shoot weight, fresh root weight, dry shoot weight and dry root weight gradually increased as soil moisture increased when water was controlled at the same growth stage. The fresh shoot weight, fresh root weight, dry shoot weight and dry root weight of "Liaodou14" were higher than that of "Liaodou21" on the same water conditions when water was controlled at the same period. The fresh weight root to shoot ratio and the dry weight root to shoot ratio gradually decreased with the growth and development of plants. Variety and water significantly affect yield per plant of soybean water controlled at each stage. However, the interaction between variety and water treatment only reached significance at the flowering and pod filling stages. Both drought (W1) and mild drought (W2) reduced the yield per plant of two varieties water controlled at the same period, with "Liaodou14" showing a less pronounced reduction in yield. Therefore, the drought resistant genotype soybean showed advantages over drought sensitive variety in terms of total root length, root surface area, aboveground dry weight, root dry weight, yield, and the proportion of root length with an average root diameter of 0.5~1.0 mm under drought stress conditions.

Agriculture is the foundation of the national economy and social development, and water conservancy is the lifeline of agriculture. Under the conditions of water shortage and uneven spatial and temporal distributions of water resources in China, strengthening the construction of water conservancy infrastructure and improving the agricultural water use efficiency are important support for the development of an agricultural power. Through literature review, the experience and lessons of water conservancy development in world agricultural powers have been summarized. On this basis, we propose suggestions for water conservancy support in the development of China’s agricultural power by considering characteristics of agricultural development and water use: actively promoting the water right system with Chinese characteristics, improving the national and regional water networks to achieve spatial balance of water resources, improving the level of water supply guarantee through comprehensive utilization and joint scheduling of surface water, groundwater, and unconventional water resources, and vigorously developing water-adaptive agriculture through efficient water-saving irrigation and efficient dryland agriculture.

In order to evaluate the effectiveness of NPP(Net Primary Production) as an assimilation variable to improve the accuracy of regional maize yield estimation and its potential application to regional maize yield estimation, the study selected the maize growing area of Youyi Farm, located in Shuangyashan, Heilongjiang, as the research area, and used WOFOST as a dynamic model of crop growth, and the Leaf Area Index (LAI) and the Net Primary Production (NPP) as the assimilation variables, respectively. MODIS LAI and NPP products were used as remote sensing observation data. This study focused on comparing the accuracy of regional maize yield estimation results using leaf area index (LAI) and net primary production (NPP) as assimilation variables. The results showed that compared with the statistical results of regional maize yield estimation using leaf area index LAI as the assimilation variable (mean value = 7 755 kg/hm², standard deviation = 1 303 kg/hm²), the statistical results of regional maize yield estimation using NPP as the assimilation variable (mean value = 9 214 kg/hm², standard deviation = 190 kg/hm²) were more accurate. They were closer to observations of the study area (mean value = 8 970 kg/hm²), but were slightly less effective in showing the spatial heterogeneity of maize yield. This study concludes that using NPP as an assimilation variable for regional crop yield estimation is a feasible data assimilation strategy with greater potential for application.

To predict the impact of integrated waterlogging stress on agricultural production, we conducted a study focusing on a typical crop, summer soybean, in the Northern Plain of Anhui Province. Our research specifically examined the waterlogging stress process involving waterlogging followed by submergence. We perform a waterlogging stress test of summer soybean performed at the crop-water relationship test site of Wudaogou Hydrological Experimental Station from June to October 2021 and describe the relationship between waterlogging stress and crop yield. Through experiments with different forms and degrees of waterlogging stress, the theoretical yield reduction effects of surface waterlogging and underground waterlogging were analyzed, and the surface waterlogging index SFW and the underground waterlogging index SEW₃₀ in the process of comprehensive waterlogging stress were unified. We have improved water production function and finished the calibration, verification and evaluation of the function parameters. Results showed that in the identification of waterlogging stress-sensitive factors, the crop sensitivity to waterlogging stress obtained by the improved Blank model, Singh model and Hiler model was more reliable. In terms of yield prediction under waterlogging stress, the Blank model was used to predict the yield of soybean under comprehensive waterlogging stress at different growth stages with the highest accuracy. The comprehensive mean absolute error (MAE) was 0.116, the Nash-Sutcliffe efficiency coefficient (NSE) was closest to 1, indicating that the quality of the proposed model was the best, followed by that of the Jensen model, Hiler model and Singh model. The Stewart model has the worst quality, the predicted MAE of soybean yield under waterlogging stress reaches 0.294, and RMSE reaches 0.323, which is not suitable for use as a water production model under waterlogging stress. The research content of this paper provides a reference for expanding the calculation method of the crop water production function under waterlogging stress conditions and provides a theoretical basis for the prediction of crop relative yield under waterlogging comprehensive stress.

To improve the construction of water rights trading platforms under blockchain technology, establish a unified water rights trading market, stimulate the activity of water rights trading. Subsequently, we combined blockchain technology to reconstruct the water rights trading mechanism. We analyzed the compatibility between blockchain technology and the current demand for water rights trading, and combined it with microservices technology to build a water rights trading technology framework. We initially designed a blockchain based water rights trading process and reward and punishment mechanism, and simulated the credit reward and punishment mechanism using Python. The results indicate that the characteristics of blockchain technology are highly compatible with the needs of water rights trading, and the reward and punishment mechanism can ensure effective rewards for participating nodes in different trading scenarios, as well as credit and financial penalties for defaulting nodes, thereby motivating trading entities to actively fulfill contracts and improving overall trading willingness. The application of blockchain technology in the entire water rights trading process can achieve complete storage, distributed sharing, and traceability of water rights trading information. The research results can provide reference for optimizing water rights trading mechanisms and improving water rights trading activity.

In order to study the evolution path and application status of DNDC (Denitrification-Decomposition) model, CiteSpace software was used to analyze the research literature on DNDC model in the core collection database of Web of Science from 1996 to 2022. This study explains the distribution of the number of papers, keywords, research hotspot evolution, and research strength, and draws the relevant maps. The results show that the research and application of DNDC model show a trend of steady increase in popularity and wavy decrease in research topics. By keyword co-occurrence analysis, the core keywords such as management, rainfall events, soil organic carbon, denitrification, greenhouse gas and process oriented model were found. Keywords cluster analysis, Identify Crop model, Soil organic carbon, Denitrification, Life cycle assessment, Ipcc, Agricultural soils, Carbon dynamic and Blue carbon, Greenhouse gases emission, Nitrous oxide and other 11 clusters; China, the United States and Canada are the main research forces, accounting for 41.68%, 41.20% and 16.16% of the total number of publications, respectively. China's scientific research influence in international cooperation still has room for improvement. Current research on DNDC models focuses on crop yield prediction, water-saving agriculture, soil carbon sequestration, nitrogen leaching and greenhouse gases. Research on the DNDC model shows a trend of steadily increasing interest and a wavy decrease in research themes. In the future, the DNDC model can be improved to improve the accuracy of parameter input, reduce the uncertainty of regional scale simulation, and expand the application area of the model.

In order to investigate the response pattern of summer maize to different forms and durations of waterlogging stress at different fertility periods, surface waterlogging(1, 3, 5 d), subsurface waterlogging(3, 5, 7 d) and combination of surface waterlogging followed by subsurface waterlogging stress experiments were conducted at the jointing stage, the tasseling stage and the grain filling stage of summer maize, and to analyze the effects of the various waterlogging stresses on the yield of summer maize and its composition, spike traits, and the loss and distribution of dry matter. The results showed that ①Waterlogging stress during the jointing stage resulted in the greatest reduction in summer maize yield, followed by the grain filling stage, and the least at the tasseling stage. Among the three kinds of waterlogging stresses, surface waterlogging followed by subsurface waterlogging stress had the most severe impact in terms of yield reduction. The yield reduction of summer maize exposed to the same waterlogging stress at each fertility stage increased with the increase of stress durations. The waterlogging stress durations of more than 3d in the jointing stage may make the maize harvest zero; the yield reduction in the tasseling stage and the grain filling stage was the most for 5 days of surface flooding followed by 5 days of subsurface waterlogging, and the yields were significantly reduced by 49.1% and 82.4%. ② 100-grain weight and the number of grains per spike jointly affect the summer maize yield, different fertility stages of waterlogging stress on the two different magnitudes of effect. Surface waterlogging stress or surface waterlogging followed by subsurface waterlogging stress in the jointing stage primarily affected the 100-grain weight; subsurface waterlogging stress at the jointing stage or grain filling stage and surface waterlogging followed by subsurface waterlogging stress at the tasseling stage or grain filling stage mainly reduced the number of grains per spike; subsurface waterlogging stress affected the number of grains per spike and 100-grain weight together at the tasseling stage; in the tasseling stage or the grain filling stage, surface waterlogging 1 d and 3d mainly affected the 100-grain weight, and surface waterlogging 5 d mainly affected the number of grains per spike. ③Waterlogging stress affected summer maize spike trait indicators. Waterlogging stress occurring in the jointing stage to make the spike length and spike thickness become shorter, occurs in the tasseling stage mainly affected the spike length, occurs in the grain filling stage mainly affected the spike thickness. Waterlogging stress increased the bald tip length and bald tip ratio in summer maize, which in turn led to yield loss. Waterlogging stress during the grain filling stage had the most obvious effect on bald tip length and bald tip ratio. ④Waterlogging stress led to loss and changes in allocation ratios of dry matter in summer maize. Waterlogging duration of more than 3d at jointing stage zeroed out the proportion of kernels and reduced the proportion of rachis. Waterlogging stress at the tasseling stage mainly affected the distribution of dry matter between stems, leaves and kernels, and there was no significant change in the proportion of the rachis. During the grain filling stage, waterlogging stress affected the distribution of dry matter among stems and leaves, kernels and rachis.

In order to reveal the effect of alternate irrigation mode of brackish water and fresh water on soil CO₂ emission flux, three irrigation water quality (salinity of 2, 3, 5 g/L, respectively) and three different ratios of brackish and fresh water were studied in extreme arid areas [brackish water: light =1∶1 (W1); brackish water: fresh water =1∶4 (W2); Effects of brackish water vs. fresh water =1∶0 (W3)] irrigation on soil CO₂ emission flux. The results showed that: ①Taking 2 g/L as the control, the cumulative CO₂ emission flux of 3 g/L brackish water combined with fresh water was reduced by 6.03%~7.19%. The cumulative CO₂ emission flux of 5 g/L brackish water and fresh water was reduced by 9.83%~10.15%. ②Under the same salinity condition, the cumulative CO₂ emission flux of soil was W2 treatment >W1 treatment >W3 treatment, and the CO₂ emission flux of the treatment with more fresh water irrigation was larger. ③Compared with 2 g/L, the yield of 3 g/L and 5 g/L treatments increased by 1.25% and 3.64% on average, and the yield of W1 treatment increased by 24.02% and 14.12% on average compared with 2 and W3 treatments. As salinity of irrigation water increased, soil CO₂ emission flux decreased, and the CO₂ emissions of all treatments with salinity of 5 g/L were lower than those of 2 and 3 g/L under different ratios. Among the alternating irrigation conditions, utilizing brackish water with a salinity of 3 g/L and a brackish water: fresh water ratio of 1∶1 resulted in reduced soil CO₂ emission flux and the highest cotton yield. This could provide a theoretical basis for the rational utilization of brackish water and the protection of farmland ecological environment in arid irrigation areas.

To explore the anti-clogging performance of different types of irrigation emitters in biogas drip irrigation, the irrigation emitters suitable for this purpose were developed. The clogging types of irrigation emitters under the conditions of biogas drip irrigation were identified. In this paper, three types of irrigation emitters are selected: internally inserted patch irrigation emitters (1.38 L/h, 2 L/h, 3 L/h), internally inserted cylindrical irrigation emitters (2 L/h, 3 L/h), and pressure compensation irrigation emitters (2 L/h, 4 L/h, 6 L/h). Periodic intermittent irrigation tests were conducted at an irrigation pressure of 0.08MPa and ratio of biogas slurry 4:1(volume ratio), and blockage conditions of different irrigation emitters were compared. Scanning electron microscopy was used to analyze the particle size and proportion of each particle size of the blockage. At the same time, the composition of the blockage was analyzed by Fourier infrared spectroscopy. The results showed that the time required for 8 types of irrigation emitters (E1~E8) to reach the plugging standard was 108 h, 126 h, 141 h, 111 h, 132 h, 84 h, 102 h and 117 h, respectively. The blockage of the irrigation emitter were observed at the water outlet, the water inlet and the water passage. The yellow sediment is deposited at the water inlet, and the black flocculent is at the corner of the water outlet and the water passage. The blockages consist of inorganic compounds such as sand, carbonate, sulfate, phosphate and organic compounds such as hydrocarbons, proteins and lipids. 88.42% of the particles were concentrated in the particle size range of 0.2~1.4 μm, and the remaining 11.58% were large flocculent. To sum up, in the same type of irrigation emitters, the greater the rated flow rate of the irrigation emitter to reach the plugging standard, the longer the time required, the better the anti-plugging performance. With the same rated flow rate, the internal patch type irrigation emitter has the best anti-plugging performance. The rated flow rate of 3 L/h has the best anti-clogging performance. The type of blockage in the irrigation emitter is compound blockage caused by the synergistic action of physical-chemical-biological.

The management of canal systems involves new objectives of periphyton removal and water quality preservation. To explore the optimal hydraulic mode that meets both demands, we build a periphyton management model and design a series of flushing plans, which are based on the methodology of orthogonal experiments and extreme variance analysis. By comparing the effects of various flushing plans on algae removal and water quality deterioration, we conclude that increasing the discharge by maximum extent with medium duration in the late stage of an algal bloom can greatly reduce both periphyton biomass and damage to water quality. The application of the optimal hydraulic mode depends on the periphyton bloom time and flow scheduling ability.

To clarify the practical effect of rainfall-collecting infiltration irrigation technology in solving the water shortage problem in red plum apricot planting in the Ningnan mountainous area, this study took five-year old red plum apricot fruit trees as the research object. Two treatments of natural conditions (NAT) and membrane-covered installation of soakaway (RCII) wrer set up. The root system was excavated by using the method of hierarchical section digging, and the distribution of the density of the root length was comparatively analyzed. The results showed that the water collected by rainfall-collecting infiltration technique could promote better growth of red plum almond root system and solve the water shortage problem. Under RCII conditions, root length density decreased with increasing depth within 0~100 cm below the surface. In addition, the comparison of root length density along the direction of row spacing and 45-degree direction under RCII conditions proved the effectiveness of water replenishment to the root system by percolator catchment. Through partial correlation analysis and non-parametric test of multiple independent samples for row spacing, plant spacing, depth, and root length density, we have found that the direction of row spacing (installing percolator) and plant spacing (without installing percolator) did not demonstrate a significant difference in the distribution of root length density in the horizontal direction (significance P>0.05). The depth of the subsurface, 60~80 cm, was the key interval that affected the distribution of root length density. In conclusion, rainfall-collecting seepage irrigation technology has a positive effect on solving the water shortage problem during the dryland planting of Hongmei apricot in Ningnan mountainous area, and it has a better promotion prospect.