Soil-Water Retention Curves and Pore-Size Distribution in a Clay Loam Under Different Tillage Systems

Tillage practices significantly impact soil structure, pore-size distribution (PSD), and soil-water retention curves (SWRC). The SWRC, which represents the relationship between soil water content and soil water potential, is important for various studies involving plants, soil, environment, irrigation, drainage, modeling, and hydrology. In this study, the HYPROP method was used to measure SWRCs and estimate soil physical and hydraulic properties under conventional tillage (CT), strip tillage (ST), and no-tillage (NT) systems in clay loam soil. Undisturbed soil cores were collected from 0–15 cm and 15–30 cm depths within sugarbeet rows, with sampling replicated five times following a randomized block design. Soil-water retention curves were modeled using the van Genuchten (vG) model for each depth under each tillage system. The results showed that none of the soil parameters from the vG equation, plant-available soil water content, or pore-size distribution were significantly influenced by tillage type. This lack of significant difference may be attributed to considerable soil disturbance from sugarbeet root harvesting, freeze and thaw cycles between tillage and sampling, or soil displacement caused by beet root growth. However, small differences in soil parameters among the three tillage systems were noted at both soil depths, due to minor variations in soil porosity and pore-size distribution. Regardless of the tillage system, understanding SWRC is essential for insights into soil and water processes such as water flow, soil water storage, and water availability for plants.