BayCEER Workshop 2026

Zeolite Amendment Effects on Soil Hydraulic Properties of a Coarse Sand

P 8 in Posters

Introduction: Climate change is increasing pressure on agricultural water resources, particularly in coarse sandy soils characterized by low water-holding capacity and rapid drainage. Zeolite amendment has been proposed as a strategy to improve the water retention properties of such soils. This study investigated the effects of zeolite amendment on the soil hydraulic properties, namely the water retention and hydraulic conductivity curves, of a coarse sand.

Methods: Soil columns were packed using coarse sand amended with fine (1-2.5 mm) or coarse (0-5 mm) zeolite at rates of 7.5 and 15 Vol%. Pure sand and pure zeolite were included as reference materials. Water retention and hydraulic conductivity were determined using KSAT, Hyprop and WP4C devices and the resulting curves were fitted using the Fredlund-Xing PDI model. Contact angle measurements were conducted using goniometer and dynamic Washburn methods.

Results: Zeolite addition increased water retention compared to pure coarse sand. Plant-available water content increased by 79 – 258 %, with greater increases at 15 Vol% and fine zeolite compared with coarse zeolite. Saturated and unsaturated hydraulic conductivity showed only limited changes after zeolite addition. Saturated hydraulic conductivity was highest for pure coarse zeolite, being only 4.6 % higher than for pure coarse sand. Both sand and fine zeolite exhibited strong hydrophilic behavior, with dynamic contact angles of approximately 0°.

Conclusions: Zeolite amendment improved the soil hydraulic properties of the investigated coarse sand, most notably increasing the plant-available water content. The effect was more pronounced for fine zeolite and at a higher amendment rate, indicating that particle size and application rate are important factors for optimizing water retention. However, as these effects were observed under controlled laboratory conditions, further research investigating zeolite application under field conditions is needed.

Keywords: zeolite, soil hydraulic properties, water retention, hydraulic conductivity, plant-available water