The purpose of this research is to solve the complex long-distance and high-lift water supply engineering accident water hammer protection problem. Taking the Zhaojinzhuang water supply project as an example, based on the method of characteristics (MOC), the water hammer of the pumping station under the combined action of a water hammer relief valve, hydraulic-control butterfly valve, air vessel, air valve, and other water hammer protection measures is numerically simulated and calculated, and the effectiveness of the range method is analyzed, to ensure a waterproof hammer in pump stop accidents. The results show that the main factors affecting the effect of water hammer protection under the two-stage valve-closing parameters of the hydraulic-control butterfly valve are the fast-closing angle and the slow-closing time. The arrangement of the air vessel behind the pump can effectively increase the minimum water hammer pressure in the climbing section, and with the increase of the volume of the air vessel, the pump reverse speed and the maximum positive pressure increase slightly, but the overall water hammer protection effect is better. With the increase of the moment of inertia of the motor, the maximum positive pressure and minimum negative pressure of the pipeline still do not meet the requirements of the specification, and the modification cost is relatively large. The combination of the one-stage hydraulic-control butterfly valve, the air valve, the air vessel, and the water hammer relief valve can effectively reduce the volume of the air vessel. Under the optimal method, the maximum positive pressure head is 236.61 m, and the minimum negative pressure head is −3.18 m. Compared with the original method, the maximum positive pressure head is increased by 1.18%, the minimum negative pressure head is reduced by 95.78%, the maximum reverse speed of the pump is reduced by 100%, and the maximum reverse flow of the pump is reduced by 70.27%, meeting the requirements of water hammer protection. This is a safe and economical protection method.

A reasonable fertilization rate and appropriate irrigation technology can lead to the green development of greenhouse tomatoes. The purpose of this study was to explore suitable irrigation technology for greenhouse tomatoes and the appropriate application rate of the soluble organic fertilizer and inorganic fertilizer combination. In 2021 and 2022, the effects of different irrigation techniques and fertilization treatments on tomato plant growth, fruit quality, yield, and efficiency were studied. The irrigation techniques in this study were drip and Moistube irrigation, and there were seven types of fertilization treatment, namely, no fertilization treatment (CK); low-volume (T1, 330 kg/hm²), medium-volume (T2, 660 kg/hm²), and high-volume inorganic fertilizer treatments (T3, 990 kg/hm²); and three inorganic fertilizer treatments of low-volume inorganic fertilizer (T1, 330 kg/hm²) combined with low-volume (F1, T1 + 75 kg/hm²), medium-volume (F2, T1 + 225 kg/hm²), and high-volume (F3, T1 + 375 kg/hm²) organic fertilizer. A total of 14 experimental treatments were implemented for irrigation and fertilization. The results of the two-year experiment show that the growth effect on the height, stem diameter, and leaf area index of tomato plants was the best using the treatment of low-concentration inorganic fertilizer combined with medium-concentration organic fertilizer with Moistube irrigation and drip irrigation. Using the two irrigation methods, the application of soluble organic fertilizer increased the yield and improved the fruit quality of the tomato. The maximum yield increased by 28.52%, the soluble sugar content increased by 14.49%, the vitamin C content increased by 45.04%, and the lycopene increased by 18.79%. The entropy-weight TOPSIS model was used to comprehensively evaluate 14 evaluation objects with different irrigation methods and fertilization treatments. The results of the two-year experiment show that the best fertilization treatment under Moistube irrigation and drip irrigation conditions was low-concentration inorganic fertilizer combined with medium-concentration soluble organic fertilizer, which was combined with the best fertilization treatment, and the most suitable irrigation method for greenhouse tomato cultivation in the Loess Plateau was Moistube irrigation. The results of this study also provide practical experience and theoretical support for adaptive irrigation and the integrated management of water and fertilizer.

To investigate the variation laws of various hydraulic parameters and internal fluid flow patterns of eccentric semi-ball valves under different boundary conditions, the DPM model was used to numerically simulate the eccentric semi-ball valve based on Fluent 2021 R1 software. The flow velocity, pressure distribution, and erosion wear rate on the valve wall were simulated under different combinations of opening, inlet flow velocity, and sediment concentration conditions, and hydraulic parameters such as drag coefficient, flow coefficient, and cavitation coefficient were calculated. The results show that as the opening of the eccentric semi-ball valve increases, the valve drag coefficient decreases, the flow coefficient increases, the cavitation coefficient increases, and the degree of cavitation decreases. The flow velocity in the high-velocity zone at both ends of the valve plate decreases, and the gradient of water flow velocity passing through the valve decreases. The area of the low-velocity zone at the rear of the valve plate decreases, and the vortex phenomenon gradually weakens; as the sediment content in the water increases, the valve drag coefficient increases, the flow coefficient decreases, and the cavitation coefficient first increases and then decreases. The maximum flow velocity of the pipeline decreases faster and faster, causing an increase in pressure gradient in the flow area and drastic changes. This results in higher pressure on the pipe wall near the valve plate, especially a significant increase in negative pressure; As the inlet flow rate increases, the valve drag coefficient decreases, the flow coefficient increases, and the cavitation coefficient gradually decreases. The flow velocity of the water passing through the valve increases, and the low-pressure area downstream of the valve plate increases. The pressure gradient at both ends of the valve port increases significantly from small to large, and the positive pressure upstream of the valve plate gradually increases. The force of the water flow on the valve plate is large, causing friction between the valve stem and the valve body, which is not conducive to long-term operation. With the increase in inlet flow rate, the maximum wear amount and wear range of the valve plate have significantly increased, and erosion wear is mainly distributed in point blocks at the edge of the valve plate. This study can provide certain references and solutions for the key technology research of eccentric semi-ball valves and assess the performance indicators of the operation being maintained.

Alternate moistube-irrigation is a new type of water-saving irrigation, and research on water infiltration with alternate moistube-irrigation is important for the design of irrigation schemes and helpful to understand and apply this technology. The effects of the pressure head (1.0 m and 1.5 m) and tube spacing (10 cm, 20 cm, and 30 cm between two moistubes respectively) on soil water infiltration in alternate moistube-irrigation were studied in laboratory experiments, and the cumulative infiltration, discharge of the moistube, and shape and water distribution of the cross-section of the wetting front were determined. The cumulative infiltration increased quickly and linearly with the infiltration time at 0-96 h (R2>0.99), and changed smoothly at 96-192 h with a basically steady infiltration rate. The discharge of the moistube increased rapidly at the beginning of irrigation, then decreased before stabilizing. The cumulative infiltrations and discharges of moistube under the 1.5 m pressure head were more than those under the 1.0 m pressure head. The shape of the cross-section of the wetting front for a single moistube was similar to a concentric circle. With the increase of tube spacing, the interaction between water infiltrations of two moistubes decreased. The soil water distributions around two moistubes were similar to each other under the 1.0 m pressure head and large tube spacing. When the tube spacing was 20 cm, the soil water distribution was more uniform around two moistubes. Keywords: alternate irrigation, moistube-irrigation, soil water infiltration, water use efficiency, water-saving irrigation DOI: 10.25165/j.ijabe.20201304.5297 Citation: Shen L X, Zhang Y M, Yang M, Liu R H. Effects of alternate moistube-irrigation on soil water infiltration. Int J Agric & Biol Eng, 2020; 13(4): 151–158.

Changes in crop types and long-term monoculture substantially impact soil microbial communities. Exploring these changes and their influencing factors is of great significance for addressing the challenges posed by continuous cropping. Soil surface layer samples from greenhouse tomatoes fields cultivated for 5 (Y5), 9 (Y9), 13 years (Y13), and a surrounding corn field (CK) as a control were analyzed. The Y13 sample showed a significant increase in the relative abundance of Pseudomonadota (43.1%) and a decrease in Actinobacteria (50.3%) compared to the CK sample. Soil bacterial alpha diversity generally declined from the CK to Y13 (0.1–22.2%) sample, with a small peak in Y9 for Chao1 and Observed_species. Significant differences in Chao1 and Observed_ species were observed between the CK and Y13 samples. Beta diversity analysis revealed a pronounced variation in soil bacterial community structure across planting years, with the divergence from the CK sample intensifying over time. In comparison to the Y5 vs. CK samples, Y9 and Y13 exhibited marked differences from the CK across the same and broader metabolic pathways, suggesting a potential convergence of microbial activities over time. The Y9 and Y13 samples showed significantly higher biosynthesis abundance (7.50% and 6.36%, respectively) than the CK. In terms of soil physicochemical indices, the carbon–nitrogen ratio was the primary factor influencing soil bacterial composition. In conclusion, we found that crop alteration and continued planting changed the soil’s bacterial composition and increasing planting years suppressed the soil’s bacterial diversity, leading to a stable bacterial ecology after nine years. Implementing appropriate measures during this critical period is vital for optimal soil utilization.

Soil erosion is a critical issue on the Loess Plateau due to weak soil and intense summer rainfall. Plant roots provide essential soil stabilization. A split-plot field experiment was conducted in Liulin County, Shanxi Province, to evaluate the effects of biodegradable mulch and organic amendments on maize root development and soil stabilization. The main plots included no mulch (N) and biodegradable mulch (M). The subplots comprised five treatments: control (CK, no amendment), peat (PT), biochar (BC), fermented pig manure (PM), and corn stover (CS). Correlation and principal component analyses were used to elucidate the underlying mechanisms. The results showed that organic amendments were the primary factor influencing the root and soil properties. Peat and biochar significantly raised the root surface area density (RSAD, p < 0.05) and root–soil composite cohesion (with increases of 122.56% and 109.06% for NPT and NBC compared to NCK, respectively). Biodegradable mulch, and its interaction with the organic amendments, had no statistically significant effect on either the root–soil composite cohesion or root system parameters. The strong positive correlations of cohesion with the root length density (RLD, r = 0.80) and root volume density (RVD, r = 0.81) highlight that root occupancy is the key mechanism for enhanced shear resistance. Therefore, biochar is recommended for its effectiveness in enhancing soil retention and its potential co-benefits for carbon sequestration. This study provides a technical reference for sustainable agriculture on the Loess Plateau, while also acknowledging the need for further research on long-term carbon dynamics.