The problem of emitter clogging has become the main obstacle restricting the application and promotion of drip irrigation technology. Studying the process of emitter clogging helps improve irrigation efficiency and save water resources. A large number of researchers have tried to solve the problem of emitter clogging from many perspectives. However, the influence of micro-nano bubbles as well as generated blockage on the clogging process of drip irrigation systems is less studied. Here, the influence of aeration on emitter clogging was studied by adding micro-nano bubbles to groundwater. Four different emitters were selected. Two treatments, micro-nano aeration and non-aeration, were set up, with a total of eight sets of experiments, running for 1500 h. The degree of emitter clogging was quantitatively characterized using the discharge ratio variation (Dra). The Christiansen uniformity coefficient (Cu) and statistical uniformity coefficient (Us) were used to evaluate the influence of emitter clogging on the performance of the drip irrigation system. Compared with the non-aeration treatment group, the Dra of aerated E1–E4 decreased by 64.74%, 54.22%, 64.20%, and 94.69% in 800 h, respectively. At the same time, the Us of the aerated E1–E4 decreased by 100%, 60.05%, 92.32%, and 100%, while the Cu of aerated E1–E4 decreased by 76.64%, 53.79%, 74.11%, and 100% compared with the unaerated group. The Cu and Us of all emitters under the aeration treatment were smaller than those comparison group. As for the blockage, the main components were typical physical blockage SiO₂ and chemical blockage CaCO₃. Most of the blockages in the non-aeration treatment group are 5–10 μm in length, while those in the aerated treatment group were generally less than 5 μm. Aeration treatment made the blockage more broken and dense and more likely to accumulate in the flow channel, obstructing the flow of water and thus intensifying the clogging process. As a result, micro-nano aeration treatment increased the risk of emitter clogging, accelerated the development of blockage in the emitter, and disturbed the uniformity of the entire drip irrigation system. This study provides a reference idea for solving the problem of blockage in drip irrigation systems.

The matching relationship between the spatial structure of cotton cluster root systems and soil-wetting patterns under mulched drip irrigation forms the theoretical basis for the technical design of mulched drip irrigation. A 2-year field experiment was conducted, in which different soil-wetting patterns were produced by setting different emitter discharge rates. The envelopes of cotton cluster root length densities were derived using the topological methodology and used to examine the effects of different soil-wetting patterns on the spatial structure of root systems and water uptake capacity within row spaces. The results showed that the root systems in rows of cotton grown under narrower and deeper soil-wetting patterns exhibited a single-peak distribution, while those under wider and shallower soil-wetting patterns exhibited a two-peak distribution. Furthermore, cotton rows grown near mulch edges experienced lower moisture stress, and wider and shallower soil-wetting patterns contributed to greater root growth rates in the vertical direction and resulted in more even potential water uptake capacities. The findings of this study revealed that wider and shallower soil-wetting patterns were more desirable for mulched drip irrigation of cotton and should be considered in the technical design of drip irrigation systems. Keywords: mulched drip irrigation, soil-wetting pattern, envelopes of cotton cluster root length densities, soil matrix suction, potential root water uptake capacity DOI: 10.25165/j.ijabe.20201305.5790 Citation: Li D W, Li M S, Shen X J, Zhou X G, Sun H, Zhao Y L, et al. Response of spatial structure of cotton root to soil-wetting patterns under mulched drip irrigation. Int J Agric & Biol Eng, 2020; 13(5): 153–162.

Developing efficient water-saving irrigation technologies that utilize high sand-laden water is an important approach to alleviating agricultural water scarcity in the Yellow River Basin. This study aims to investigate sedimentation patterns and fluid movement characteristics in drip irrigation emitters under such challenging water conditions. The dynamic changes in Dra and Cu were determined through short-period intermittent clogging tests to evaluate the anti-clogging performance of four different emitter types. The distribution and particle size composition of the deposited sediments inside the emitters were analyzed using a high-resolution electron microscope and a laser particle size analyzer. Additionally, the RNG k-ε turbulence model was used to simulate the fluid movement inside the emitters. The results showed that the B drip irrigation belt had better sediment tolerance and operational stability. The anti-clogging capacity of drip irrigation can be improved by optimizing the combination of emitter channel structure and sediment content. The fluid in the channel was divided into mainstream zone and vortex zone. Sediment particles increased in the backing-water zone and vortex center, where particles of 0.05–0.1 mm were more prone to settling due to reduced transport capacity. Energy dissipation primarily took place at the curvature of the emitter channel, and within each channel unit, gradually decreasing along the vortex flow direction, with the lowest dissipation aligning with sediment deposition zones. These findings provide a theoretical basis for mitigating clogging in high sand-laden water drip irrigation systems, offering valuable insights for improving the effective utilization of water resources in the Yellow River Basin.

Brassica chinensis L. is often grown using ‘excessive water and fertilizer’, which has a negative impact on the inter-root soil environment and the yield and quality of the plant. As the concept of green and sustainable development takes root in people’s minds, it is important to determine the right amount of water and fertilizer. Based on this, the effects of different irrigation rates and microbial fertilizers on the inter-root soil environment and yield and quality of B. chinensis were investigated. A pot experiment was carried out with two irrigation levels (W1: 80–90% of field water capacity; W2: 70–80% of field water capacity) and three fertilizer treatments (F0: no fertilizer; F1: CPS Powder Drill microbial fertilizers; F2: Maya 85 microbial fertilizers). The results showed that microbial fertilizer and irrigation amount, as well as their interaction, all had significant effects on yield, polyphenol content, soluble protein content, nitrate content, and the activities of soil enzymes, such as urease, sucrase, and catalase (p < 0.05). Increases in irrigation amount and the application of microbial fertilizer can increase the yield of B. chinensis, effectively improve the activities of sucrase, urease, and catalase in soil, increase the contents of vitamin C, chlorophyll, soluble protein, and total phenol in leaves, and reduce the content of nitrate. In addition, the findings of the principal component analysis indicated that the F2W2 treatment was the optimal treatment. The results of this study demonstrate that an 80–90% field water capacity, in conjunction with Maya 85 microbial fertilizers, yields an optimal outcome, with a score of 1.86. This outcome suggests that this combination of water and fertilizer can be used as a recommended protocol for the cultivation of Brassica chinensis L.