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Green and sustainable development of irrigated agriculture and protec tion of agricultural biodiversity are the inevitable require -ments for the construction of modern irrigated districts in China. However, in order to ensure the efficient utilization of irrigation water, the construction of irrigation channels has been dominated by hard engineering, which has caused the loss and fragmentation of amphibian habitat, and the damage for ecological environment of the irrigation districts. The construction of amphibian corridors in irrigation channels is an important way to improve the connectivity of agricultural landscape and the migration efficiency of frogs in farmland. This paper innovatively applies the hydraulic characteristics of curved channels to the research on ecological channels, builds the curved irrigation channel models, conducts numerical simulation experiment, analyzes the trajectory of frogs at the curved irrigation channels, proposes the design of engineered modifications to allow frogs to escape from field concrete ditches. To evaluate the effects of engineered modification on the effectiveness of frog-ways and the water transfer efficiency of irrigation channels, the paper compares the water flow pattern and calculates the head oss. By carrying out numerical simulation tests, the paper obtains the flow movement law of the concrete-lined irrigation channels with different bend angles, and the flow dynamic axis and velocity distribution are compared. As a result, the slow flow zone and the transverse circulation are found. The locations suitable for amphibian corridors to be built vary when the curvature of the curve changes. The numerical simulation and head loss calculation results show that the amphibian corridors in the bend has no obvious influence on flow pattern and water transfer efficiency, and the head loss in bend is about 3.83X10"4 m, which can ensure the safe and unobstructed water flow. This study is expected to provide a scientific reference and technical support for the ecological reconstruction of end irrigation channel systems. [ABSTRACT FROM AUTHOR]

[Objective] Intermittent irrigation has become an important water-saving irrigation method to conserve water and improve rice yield in southern China. This paper presents the results of an experimental study of the combined effect of intermittent irrigation and silicon fertilization at different stages on rice growth and yield, to find the optimal timing for silicon fertilization. [Method] The experiment was conducted in a field with the Jinyuan 85 variety used as the experimental plant. There were six silicon applications: no silicon fertilizer (CK), applying silicon fertilizer at tillering stage (F1), jointing stage (F2), booting stage (F3), heading stage (F4), or blooming and filling period (F5). Growth traits and yield of the rice in each treatment were measured. [Result] Silicon fertilizer application combined with intermittent irrigation not only promoted rice growth and development, but also improved its yield and water use efficiency. Compared with CK, silicon fertilization increased leaf area index, dry matter, yield, and irrigation water use efficiency of the rice by 1.15% to 11.36%, 9.17% to 24.24%, 2.05% to 8.63%, and 2.16% to 8.63%, respectively, depending on fertilization timing. The best effect was observed when the silicon fertilizer was applied at the tillering stage. [Conclusion] Combining intermittent irrigation with silicon fertilization can promote rice growth and development, thereby improving yield and irrigation water use efficiency of the rice. For the Jinyuan 85 variety studied in this paper, the optimal timing for silicon fertilization is at the tillering stage. [ABSTRACT FROM AUTHOR]

Background and Objective The decrease in available water resources for agriculture in the South of China has made developing water-saving irrigation essential for rice production. This paper investigates the impact of an improved irrigation method on growth and water use of conventional rice and hybrid rice. Method The experiments were conducted from 2018 to 2020 in plots within a paddy field in the Irrigation Experimental Station of Jiaxing Pinghu in Zhejiang province. The rice varieties Xiushui 134 (conventional) and Yongyou 9 (hybrid) were used as the model plants. They were irrigated by conventional flooding irrigation and thin-water film irrigation by keeping the topsoil just saturated. In each treatment, we measured the leaf area index, total dry matter, root growth, grain yield, and water demand and consumption of each rice variety. Result Water demand and consumption of both rice varieties under thin-water film irrigation were lower than that under flooding irrigation (P<0.01). Under flooding irrigation, water demand and consumption of both varieties during their whole growth period increased with the increase in precipitation, albeit the conventional rice consumed slightly less water than the hybrid variety (P>0.05). Compared with conventional flooding irrigation, thin-water film irrigation reduced average daily water consumption by 22.6%-59.5%, with the hybrid rice consuming 1.3%-3.0% more water than the conventional variety. Compared with flooding irrigation, thin-water film irrigation increased average rice yield by 1.7%, especially the hybrid variety whose yield was 31.9% higher than that of the conventional variety. Thin-water film irrigation reduced water consumption by 30.1%-35.0%, in addition to its significant increase in WUEI and WUEET. Due to the difference in yield between the two varieties, there was an interactive effect between the irrigation method and rice variety, with their WUEI, WUEP and WUEET differing significantly.Conclusion The thin water-film irrigation was effective to increase the development of leaf area and dry matter accumulation, especially for the hybrid variety. Water demand and consumption of both varieties were affected not only by annual precipitation and evaporation, but also by irrigation method, though no significant difference was found between the two varieties. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Objective] Qingtongxia irrigation district is one of the irrigation districts in northwestern China which rely on Yellow River water for irrigation. Using the water footprint concept, this paper proposes a system dynamic model to help improve agricultural water use efficiency in this district. [Method] Blue and green water footprints of major crops in the district were calculated from their evapotranspiration and transpiration. A system dynamics model for agricultural water use efficiency was then established, and the model was solved using the Vensim software. [Result] Irrigation water is the primary water source for agriculture in the district, forming a production water use pattern in which blue water is the main source and green water is a supplementary source. The blue and green water footprints vary oppositely in order to meet the demand of crops for water. On the premise to ensure constant blue water use for the crops, we selected the green water use coefficient and irrigation water use coefficient as parameters in the modelling. The model results show that increasing green water utilization coefficient from 0.7 to 0.8 can increase wheat production by 2.7x105 t, rice production by 2x105 t, and corn production by 5.5x105 t. We also found that increasing the irrigation water utilization efficiency by 10 can increase wheat production by 4.7x105 t, rice production by 3.5x105 t, and corn production by 7.7x105 t. Collectively, increasing green water utilization coefficient and irrigation water utilization coefficient simultaneously can increase wheat production by 7.5x105 t, rice production by 5.5x105 t, and maize production by 1.32x107 t. [Conclusion] Agricultural production in Qingtongxia irrigation area should consider increasing utilization of green water and improving agricultural water use efficiency by improving engineering and non-engineering facilities to increase crop yields. [ABSTRACT FROM AUTHOR]

[Objective] Bisphenol compounds of different origins have been found in many terrestrial ecosystems in across China. Their accurate detection is a key to mitigating their impact on the environment. In this paper, we present an improved method to reliably detect BPs in water and sediment in irrigation districts. [Method] A high-performance liquid chromatography-fluorescence (HPLC-FLD) method was established for simultaneously measuring three types of bisphenol compounds. Suitable pre-treatment method for detecting these compounds was selected from the filtration method and centrifugation method by comparing their efficiency. The tested method was then used to analyze main bisphenol compounds in water and sediment samples taken from vegetable and paddy fields. [Result] The HPLC-FLD can detect BPS when its concentration is not lower than 0.2 µg/L, while for BPF and BPA, the method can detect them when their concentrations are as low as 0.2 µg/L. The centrifugation method can recover 76.69% to 99.03% of the water from the samples, and the detection rate for BPF in ditch water and sediment is 100% and 88.89%, respectively. The greatest BPs concentration the method can detect is 1.45 µg/L for water samples and 587.4 µg/kg for sediment samples. The contents of BPF, BPA and BPS in the sediment samples are 962.95 times, 871.82 times and 72.81 times those in the water samples, respectively. [Conclusion] The centrifugation method works better for pretreating the samples. BPF is the main BPs detected in water and sediment samples taken from the vegetable and paddy fields. BPs in sediments are substantially higher than in water. [ABSTRACT FROM AUTHOR]

[Objective] Agriculture is responsible for 8.5% of greenhouse gasses emitted to the atmosphere. Improving agricultural management and reducing gas emissions from soils is hence important in the fight against global warming. In this paper, we investigate the effect of different irrigation and fertigation on reducing nitrogen losses from rice fields in Poyang Lake Basin in southern China. [Method] The field experiment was conducted at the Ganfu Plain Irrigation Area located at the Irrigation Experiment Center Station of Jiangxi Province. It consisted of an intermittent irrigation (W1) and a flooding irrigation (W0), each irrigation treatment had three nitrogen fertilizations: no fertilization (N0), fertilizing 135 kg/hm² (N1), and 180 kg/hm² of nitrogen (N2). Rice growth, its associated water use efficiency, and nitrogen emissions from each treatment were measured during the experiment. [Result] Irrigation impacted water consumption and leakage. Compared with W0, W1 reduced irrigation water usage by 18.12%~28.37%, water leakage by 13.68% to 22.85%, and saved water by 28.77%. Depending on nitrogen application, W1 treatments increased the average yield by 16.57% to 29.94% and reduced average nitrogen emissions by16.42%, compared to the W0 treatments. Increasing nitrogen fertilization led to an increase in nitrogen emission when the irrigation was the same; fertilization had a significant effect on ammonia volatilization. Irrigation-fertilization did not show a significant interactive impact on ammonia volatilization. [Conclusion] The optimal irrigation and fertilization for rice production in Poyang Lake Basin was intermittent irrigation coupled with fertilizing 135 kg/hm² of N. Compared to W0+N2 - flooding irrigation with 180 kg/hm² of nitrogen fertilization, the optimal irrigation and fertigation can increase rice yield by 9.82%, reduce irrigation amount, nitrogen pollution and nitrogen emissions by 27.54%, 25.67% and 11.90%, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective Agricultural production in most regions in northern China relies on irrigation. Understanding spatiotemporal variation of the demand of different crops for water is critical to improving agricultural management. Taking the northwest Shandong province as an example, this paper studies the change in its demand for irrigation. Method We took winter wheat as the model plant, and calculated its water demand based on the Penman-Monteith formula. Spatiotemporal variation in the water demand was analyzed using the Mann-Kendall mutation test, the inverse distance weighting and the interpolation method. The factors that affect the water demand was calculated using the Pearson correlation analysis method. Result Annual average irrigation water demand of the winter wheat is 339 mm, but has been increasing. Spatially, distribution of irrigation water demand is ring-shaped across the studied region, with the shape of the rings varying with growth season. The relative humidity and sunshine duration are the factors that affect the irrigation water most, with the former negatively correlated while the latter positively correlated with the irrigation water demand, both at significant level. Conclusion The irrigation water demand of winter wheat in northwest Shandong province has been increasing. Spatially, it increases from the northeast to the southwest. Precipitation cannot meet the demand of the wheat during its seeding, returning green and elongation stages. Topping up the soil water by irrigation is hence required. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)