Soil salinity and sodicity caused by saline water irrigation are widely observed globally. Clay dispersion and swelling are influenced by sodium (Na⁺) concentration and electrical conductivity (EC) of soil solution. Specifically, soil potassium (K⁺) also significantly affects soil structural stability, but for which concern was rarely addressed in previous studies or irrigation practices. A soil column experiment was carried out to examine the effects of saline water with different relative concentrations of K⁺ to Na⁺ (K⁺ $/$ Na⁺), including K⁺ $/$ Na⁺ of 0:1 (K0Na1), 1:1 (K1Na1) and 1:0 (K1Na0) at a constant EC (4 dS m⁻¹), and deionized water as the control (CK), on soil physicochemical properties. The results indicated that at the constant EC of 4 dS m⁻¹, the infiltration rate and water content were significantly (P<0.05) affected by K⁺ $/$ Na⁺ values, and K0Na1, K1Na1 and K1Na0 significantly (P<0.05) reduced saturated hydraulic conductivity by 43.62 %, 29.04 % and 18.06 %, respectively, compared with CK. The volumetric water content was significantly (P<0.05) higher in K0Na1 than CK at both 15 and 30 cm soil depths. K1Na1 and K1Na0 significantly (P<0.05) reduced the desalination time and required leaching volume. K0Na1 and K1Na1 reached the desalination standard after the fifth and second infiltration, respectively, as K1Na0 did not exceed the bulk electrical conductivity required for the desalination prerequisite throughout the whole infiltration cycle at 15 cm soil layer. Furthermore, due to the transformation of macropores into micropores spurred by clay dispersion, soil total porosity in K0Na1 dramatically decreased compared with CK, and K1Na0 even increased the proportion of soil macropores. The higher relative concentration of K⁺ to Na⁺ in saline water was more conducive to soil aggregate stability, alleviating the risk of macropores reduction caused by sodicity.

Soil pore is an important part of soil structure. According to the causes of formation, soil pores can be divided into biological pores formed by animal movement and plant root development and non-biological pores formed by dry-wet and freeze-thaw alternation or artificial tillage. The soil pore structure affects the migration of water, gas, nutrients and so on in the soil, especially the macropores can also produce water or solute preferential migration. Studying soil pores is of great significance for predicting soil hydraulic properties, reducing groundwater pollution and soil nutrient loss. Based on previous studies on soil pore structure, this paper systematically summarized the role of soil pores, influencing factors and the advantages and disadvantages of various research methods. This paper not only introduces traditional methods (including direct and indirect methods), but also summarizes the new research on soil pores combined with computed tomography (CT) technology and other science and technology in recent years. Finally, the prospect and development trend of soil pore research in the future were predicted, so as to provide reference for further research on soil pore structure.

Soil hydrothermal condition is one of the most important factors affecting crop growth in arid regions. This study aimed to investigate the effect of mulching and tillage on moisture and temperature variations in soil under drip irrigation in the arid Hetao Irrigation District, northwest China. Four treatments were included: (1) alternating ridges (40 cm wide and 20 cm high) and furrows (40 cm wide) with plots fully mulched with plastic film (RFM); (2) alternating ridges (40 cm wide and 20 cm high) and furrows (40 cm wide) with partial film mulch (only the plant rows mulched) (RPM); (3) flat tillage with plots fully mulched with plastic film (FFM); and (4) flat tillage with partial film mulch (only the plant rows mulched) (FPM). The ridge tillage and plastic film increased soil temperature and significantly conserved soil water, and thus increased the maize yield and water use efficiency (WUE). The RFM treatment had a greater effect than the RPM, FFM, and FPM treatments on the soil moisture and water storage over 0–70 cm in depth during the entire growing period in 2014 and 2015, indicating that full transparent plastic film mulch increased soil water status and promoted deep water percolation, and ridge tillage further enhanced water redistribution to deep soils. Furthermore, RFM proportionally increased soil temperature by 0.36 °C, 1.49 °C, and 1.27 °C above the temperatures under RPM, FPM, and FFM, respectively, in 2014 and by 1.19 °C, 1.62 °C, and 0.35 °C, respectively, in 2015. During the drought year of 2014, tillage influenced temperature more than mulching; however, mulching played a more important role in preserving thermal conditions than tillage during the humid year of 2015. Consequently, RFM increased the maize yield and WUE significantly. We conclude that a combined system of full plastic film mulch and ridge tillage creates beneficial soil hydrothermal conditions under drip irrigation and thus promotes the growth and performance of field crops.

Sediment deposition significantly impacts soil erosion processes, consequently influencing the geographical morphology and surrounding environments of reservoirs and estuaries. Given the intricate nature of sediment deposition, it is imperative to consolidate and analyze existing research findings. Presently, studies on sediment settling velocity primarily employ theoretical, laboratory, and field experimentation methods. Theoretical approaches, rooted in mechanics, examine the various forces acting on sediment particles in water to derive settling velocity equations. However, they often overlook external factors like temperature, salinity, organic matter, and pH. Although laboratory experiments scrutinize the influence of these external factors on sedimentation velocity, sediment settling is not solely influenced by individual factors but rather by their collective interplay. Field observations offer the most accurate depiction of sediment deposition rates. However, the equipment used in such experiments may disrupt the natural sedimentation process and damage flocs. Moreover, measurements of sediment particle size from different instruments yield varied results. Additionally, this paper synthesizes the impact of suspended sediment concentration, particle size, shape, temperature, salinity, and organic matter on sediment settling velocity. Future research should focus on innovating new laboratory observation methods for sediment settling velocity and utilizing advanced scientific and technological tools for on-site measurements to provide valuable insights for further investigation into sediment settling velocity.