Tillage effects on estimated parameters of soil-water retention curves and pore-size distribution in a clay loam.

Authors: Jabro, Jalal - Jay; Stevens, William - Bart; Iversen, William - Bill; Sainju, Upendra; Allen, Brett; Rana Dangi, Sadikshya; CHEN, CHENGCI - Montana State University

Submitted to: Land
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2024
Publication Date: 11/22/2024
Citation: Jabro, J.D., Stevens, W.B., Iversen, W.M., Sainju, U.M., Allen, B.L., Rana Dangi, S., Chen, C. 2024. Tillage effects on estimated parameters of soil-water retention curves and pore-size distribution in a clay loam.. Land. 13, 1987. https://doi.org/10.3390/land13121987.
DOI: https://doi.org/10.3390/land13121987

Interpretive Summary: Tillage has significant effects on soil physical and hydraulic properties, including soil-water retention curve, pore-size distribution, large and small pore spaces, and total porosity. ARS scientists at the Northern Plains Agriculture Research Laboratory in Sidney Montana and Montana State University conducted a study to assess the effect of no-tillage, minimum tillage and intensive tillage practices on soil-water retention curve and pore-size distribution properties in a clay loam soil. The curve describes the inverse relationship between changes in volumetric water content and how strongly water is held by the soil. When soil in the field is holding maximum water against gravity, a point referred to as field capacity. Eventually soil water is depleted over time to the point that plants are no longer able to pull it away from the soil and the plants wilt and die. The point where this happens is referred to as the permanent wilting point. The amount of water content between these two levels is known as plant-available water capacity, it is easy for plants to uptake this type of water from the soil. Knowledge of these values as determined from a soil-water retention curve is essential for many agronomic, soil, irrigation, and environmental studies. Regardless of type of tillage, these relationships between soil-water content and soil suction forces can empower producers and researchers to accurately estimate field capacity, permanent wilting point and available water capacity for plants, allowing them to effectively plan irrigation events. The curve provides good information about pore-size distribution in the soil that governs water infiltration into the soil surface, internal drainage through the soil and water storage in the soil profile. Long-term effects of no-tillage or reduced tillage practices conversion could improve soil pore-size distribution, soil structure and other properties compared to tilled soils due to an increase in plant residues and organic matter levels in the topsoil layer over time. This work provides a base for better understanding how sustainable farming management practices such as reduced tillage and organic residues can enhance soil water storage and availability and improve soil quality.

Technical Abstract: length) were sampled at 0-15 and 15-30 cm depths in sugarbeet rows. Sampling was replicated five times in a randomized block design. Soil cores were saturated prior to measurement by a capillarity method and SWRCs were developed using the evaporation method. Soil-water retention curves and hydraulic properties data were modeled using the van Genuchten (vG) model for each depth under each tillage system. Our results indicated that all soil parameters of the vG equation, plant available soil water content, and pore-size distribution were not significantly affected by type of tillage. The lack of difference may be due to considerable soil disturbance by the harvest action of sugrabeet roots, the freeze and thaw cycles that occurred between tillage and sampling, or displacing soil by the growth of beet roots. However, small differences existed in soil hydraulic properties among three tillage practices at both soil depths due to minor variations in soil porosity and pore-size distribution; however, the water content at saturation ('s) varied with depth. The 's was greater at 0-15 cm depth for all three tillage systems due possibly to an increase of small soil pores at this depth.