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【Objective】 Changes in water pressure in pipe networks can cause partial filling of pipes, leading to non-full flow. The objective of this paper is to investigate the impact of non-full flow on the hydraulic performance of canal-pipe water delivery systems. 【Method】 The study was based on experimental and theoretical analysis. We examined the distribution of water velocity in channels, changes in the water surface profile, flow rates in pipes, and the diversion ratio under different pipe-filling levels. 【Result】 The water velocity distribution along the main channel remained consistent at different filling levels in the pipes, with notable changes occurring within regions approximately twice the longitudinal and 1.5 times the transverse diameter of the pipe. Water velocity fluctuations were most pronounced near the channel walls at the water surface, following a pattern of initial decrease, subsequent increase, and final decrease along the flow path. Through dimensional analysis, a formula was derived for calculating the water velocity coefficient, with a maximum relative error of 8.81% compared to experimental data. For a constant water flow rate in the main channel, the velocity coefficient for the partially filled pipes increased with the Froude number of the main channel but decreased as the water depth ratio and the filling level increased. Additionally, the diversion ratio was found to increase with filling levels. At a constant filling level, increasing the flow rate in the main channel increased the velocity coefficient in the pipes and reduced the diversion ratio. 【Conclusion】 The impact of partially filled pipes on water flow in the main channel is minor. Installing gate valves and water measuring equipment should avoid areas that are likely to be impacted. The formula we derived for calculating velocity coefficient only needs the Froude number and water depth in the main channel, and it can quickly calculate water velocity in partially filled pipes. Under certain conditions, increasing water depth in the main channel can increase flow rate in the pipes.

【Objective】 Biochar and lime nitrogen have been increasingly utilized as conditioners to improve soil quality, yet their effects on soil microbial communities remain relatively unexplored. This study aims to investigate the impact of soil amendment with biochar and lime nitrogen on fungal community diversity and the correlation between fungi and Fusarium. 【Method】 The experiment was conducted in soil columns with biochar and lime nitrogen applied separately or in combination. Untreated soil served as the control. For each treatment, we measured physicochemical properties, fungal community structure, Fusarium abundance in the soil, as well as their interactions. 【Result】 In comparison to the control, application of biochar significantly increased soil pH and available potassium (P

【Objective】 Optimizing water allocation to channel networks in irrigation districts can reduce water waste and help improve water use efficiency. This paper presents the application of a modified beetle swarm optimization algorithm to achieve this goal. 【Method】 The analysis was based on irrigation in 2020 at Dagong irrigation district. Reducing water losses from seepage in the channel network was taken as the optimization objective, and operating duration of each channel and water discharge to the low-order branches were taken as the decision variables. We constructed water distribution in the channel network and solved the optimization using the beetle swarm optimization algorithm. The results were compared with those obtained from the beetle antennae search algorithm and the particle swarm algorithm. 【Result】 The total water distribution calculated from the beetle swarm optimization algorithm is 3 918 500 m3, the total loss from leakage is 228 700 m3, and the total water distribution time is 7.30 d. These are a great improvement compared with those obtained from the beetle antennae search algorithm, and close to the results calculated from the particle swarm algorithm. 【Conclusion】 The modified beetle swarm optimization algorithm is efficient and the results calculated by it meet the requirements for optimal allocation of water resources to channel network in irrigation district. It can be used to improve water management in irrigation districts and other areas.

【Objective】 Water and fertilizer use efficiency of crops depends on many factors, and the objective of this paper is to investigate experimentally how to achieve this through optimizing planting density, irrigation and nitrogen topdressing. 【Method】 The experiment was conducted in lysimeters with winter wheat used as the model plant. It compared two planting densities: 5×106 plant/hm2 (D1) and 3×106 plant/hm2 (D2). For each planting density, there were three irrigation treatments: irrigating at the turning-green stage and the grain-filling stage (W1), irrigating at the turning-green stage, jointing stage and grain-filling stage (W2), irrigating at the turning-green stage, jointing stage, heading stage and grain-filling stage (W3), and two nitrogen topdressing treatments: topdressing all nitrogen at the turning-green stage, topdressing a half at the turning-green stage and the other half at the jointing stage. In each treatment, we measured the changes in soil water contents. 【Result】 Irrigating scheduling W2 made soil water in 0~100 cm more suitable for the crop to grow and increased its water use efficiency. Increasing irrigation frequency enhanced photosynthetic and transpiration rates, but it reduced leaf water use efficiency and the content of amino acid and protein in the grain. Increasing planting density or nitrogen topdressing frequency can improve photosynthetic rate even when the total amount of nitrogen application was the same. Increasing planting density increased spike numbers, but reduced grain numbers per spike and kernel weight, all at significant level (p

【Background and Objective】 The dwindling water resources in north China over the past decades has called for improving irrigation water use efficiency and reducing groundwater extraction, especially for winter wheat whose production largely relies on irrigation. While various water-saving irrigation technologies have been developed and tested, how agronomic management can help improve water use efficiency remains absurd. The purpose of this paper is to investigate the efficacy of biochar amendment coupled with different irrigations to improve soil structure and boost winter wheat yield. 【Method】 The experiment was conducted from October 2018 to June 2019 in a field in central China. It consisted of four irrigations: flooding, drip, sprinkler and micro-sprinkler irrigations. Added to each irrigation were three biochar amendments at rates of 0, 10 t/hm2 and 20 t/hm2 respectively. All treatments were randomly arranged in the field. In each treatment, we measured the yield and yield traits, irrigation water use efficiency and apparent nitrogen fertilizer use efficiency of the wheat. 【Result】 Neither irrigation method nor biochar amendment showed noticeable effects on stem height and root length. Using 50% of the water used in flooding irrigation, drip irrigation, sprinkler irrigation and micro-sprinkler irrigation all reduced grain yield though not at significant level (p>0.05). Drip irrigation reduced straw yield but increased harvest index of the wheat. In contrast, sprinkler irrigation reduced grain numbers per ear and increased the ratio of defect grains, resulting in yield reduction. Biochar amendment did not show significant effect on irrigation water use efficiency and apparent nitrogen fertilizer use efficiency (p>0.05). Compared with flooding irrigation, drip, sprinkler and micro-sprinkler irrigations reduced the apparent nitrogen fertilizer use efficiency although the difference between them was not significant (p>0.05). Compared with flooding irrigation, drip irrigation, sprinkler irrigation and micro-sprinkler irrigation increased irrigation water use efficiency by 42.79%, 39.09% and 47.71% respectively (p0.05), probably due to the low amending rate. 【Conclusion】 Using 50% of the water used in flooding irrigation, drip, sprinkler and micro-sprinkler irrigations did not comprise grain yield. Considering plant growth, grain yield and irrigation water use efficiency, drip irrigation coupled with biochar amendment is a more suitable agronomic practice for winter wheat in north China.

【Objective】 One challenge facing developing sustainable irrigation districts is to alleviate water deterioration. This paper is to present the results of a preliminary study on water quality and nitrogen and phosphorus contents in the main canal of Guangli irrigation district in Henan province, and propose strategy to prevent water from deterioration. 【Method】 We selected six sections along the canal from June to December 2019, and measured monthly changes in total nitrogen (TN), total phosphorus (TP), CODCr and BOD5. We then evaluated water quality and eutrophication in the canal using the comprehensive water quality identification index - suitable for comprehensive evaluation of river water quality in China - and the exponential universal formula of power function in logarithmic form. 【Result】 ①The comprehensive water quality identification index showed that 86% of the water in the irrigation district meets the Grade V standard for agricultural water usage. It was also found that the comprehensive water quality index varied spatiotemporally at significant level. In July, 66.7% of water in the canal deteriorated below Grade 5 standard, with black and odorous water (eutrophication) found at Gate 3 and the entry point to the canal. ②Eutrophication was widespread. The maximum eutrophication evaluation index was 80.5 and appeared in July at the entry point to the canal; approximately 41.6% of water in the district was seriously eutrophic. ③The average mass concentration of TN was 5.30 mg/L, 2.65 times the Grade V standard for surface water. The average mass concentration of TP was 0.156 mg/L and the ratio of total nitrogen to total phosphorus was 33.97∶1, an ideal environment for algae bloom. 【Conclusion】 Overall, the water quality in the irrigation district meets the requirements for irrigation, but it is highly eutrophic with high nitrogen content. The original earth canals with aquatic plants are able to purify the water and keep the district ecologically function. Keeping water from deterioration therefore should tighten control of pollutants from entering the irrigation district, and monitor the changes in nitrogen and phosphorus. Channel lining should consider its consequence for ecological functions. Alternating lining and earth canal bed, combining with aquatic plants to take up the pollutants such as nitrogen and phosphorus, can improve water quality in the irrigation district.