Experimental Investigation on the Impact of Drying–Wetting Cycles on the Shrink–Swell Behavior of Clay Loam in Farmland

Abstract

Soil shrink–swell behavior is a common phenomenon in farmland, which usually alters the process of water and solute migration in soil. In this paper, we report on a phenomenological investigation aimed at exploring the impact of drying–wetting cycles on the shrink–swell behavior of soil in farmland. Samples were prepared using clay loam collected from farmland and subjected to four drying–wetting cycles. The vertical deformation of soil was measured by a vernier caliper, and the horizontal deformation was captured by a digital camera and then calculated via an image processing technique. The results showed that the height, equivalent diameter, volume and shrinkage-swelling potential of the soil decreased with the repeated cycles. Irreversible deformation (shrinkage accumulation) was observed during cycles, suggesting that soil cracks might form owing to previous drying rather than current drying. The vertical shrinkage process consisted of two stages: a declining stage and a residual stage, while the horizontal shrinkage process had one more stage, a constant stage at the initial time of drying. The VG-Peng model fit the soil shrinkage curves very well, and all shrinkage curves had four complete shrinkage zones. Drying–wetting cycles had a substantial impact on the soil shrinkage curves, causing significant changes in the distribution of void ratio and moisture ratio in the four zones. However, the impact weakened as the number of cycles increased because the soil structure became more stable. Vertical shrinkage dominated soil deformation at the early stage of drying owing to the effect of gravity, while nearly isotropic shrinkage occurred after entering residual shrinkage. Our study revealed the irreversible deformation and deformation anisotropy of clay loam collected from farmland during drying–wetting cycles and analyzed the shrink–swell behavior during cycles from both macroscopic and microscopic points of view. The results are expected to improve the understanding of the shrink–swell behavior of clay loam and the development of soil desiccation cracks, which will be benefit research on water and solute migration in farmland.

Minimum tillage on vertisols lowland increases rice production and soil properties

“…In addition to soil management factors, the water supply system also plays a role in influencing plant growth and yield as well as the physical and chemical properties of vertisol. As stated by Qi et al (2022), the effects of wetting and drying resulted an increase and shrinkage of vertisols, which would improve the land management. Therefore, according to Hamoud et al (2019), it is critical to practice proper water management for rice cultivation on vertisol land in order to maintain soil water content and increase plant growth due to adequate air and nutrient requirements via the roots to the stems.…”

“…The pattern of rice cultivation in wetlands is always synonymous with silting of land (Sione et al, 2017), which often has an impact on soil degradation (Fang et al, 2019;Qi et al, 2022), without exception in paddy fields with vertisol soil type (Paul et al, 2021). Furthermore, it has been widely reported that the application of notillage and maximum tillage positively and negatively impacts the physical and chemical properties of soil.…”

Analysis of Feed Inlet and Optimal Feeding Amount of Waste Ground Film Impurity Removal Equipment

“…The average value was calculated, and a scatter plot was plotted as shown in Figure 14. A curve fit was performed [24][25][26][27][28].…”

“…The average value was calculated, and a scatter plot was plotte shown in Figure 14. A curve fit was performed [24][25][26][27][28]. The quadratic equation was solved when x = 202.45, y had the maximum valu 2.25, and the parameters were rounded.…”

Effect of Diatomaceous Earth on Desiccation Cracking of Expansive Soils

“…Shrinkage and swelling of expansive soil are commonly observed physical phenomena in civil engineering applications, primarily due to the dynamic change of soil pore structure at a micro level and macroscopically manifested in volume change response to moisture variation in the wet and dry season [1,2]. In the dry season, desiccation cracking develops arising from water loss.…”