Work

Stability of oxygen diffusivity and aeration indicators in soilless growth media under wetting–drying cycles

Year: 2025

Type: article

Abstract: In soilless cultivation systems, the growing medium plays a crucial role in supplying water, oxygen, and physical support for roots. Its properties may change with repeated wetting and drying (W/D) cycles. This study aimed to evaluate the stability of aeration indicators and oxygen diffusion parameters in fourteen growing media, focusing on changes in the relative oxygen diffusion coefficient (Dp/D0) after ten W/D cycles. Mixtures of mineral substrates, biochars, and agricultural residues were assessed for bulk density, mass loss, organic matter change, physical stability, and Dp/D0. The Dp was measured on samples equilibrated at matric suctions of 5, 10, 20, 40, 60, and 80 hPa using the one-chamber method. Dp/D0 vs. air-filled porosity (AFP) data were modeled using Millington–Quirk and Troeh equations. Results showed that W/D cycles reduced structural stability, increased pore tortuosity, and decreased Dp/D0 in most media. However, mixtures with perlite, rockwool, and stable biochars preserved favorable aeration. The Troeh model showed better fit to the Dp/D0–AFP data and is recommended. AFP alone proved insufficient to assess aeration; pore tortuosity and continuity must also be considered. Among the substrates tested, rockwool (0.1)-perlite [RW(0.1)-Perlite], rockwool (0.2)-perlite [RW(0.2)-Perlite], wheat straw–vermiculite (WS-V), and sawdust–sugarcane bagasse biochar produced at 300°C –vermiculite–zeolite (Sd-SCB300-V-Z) are recommended as stable growing media with high Dp/D0 and reuse potential. These findings emphasize the importance of carefully selecting raw materials and intelligently designing the growing medium to simultaneously achieve physical stability, oxygen supply efficiency, and economic feasibility in sustainable greenhouse production.

Source: Agricultural Water Management

DOI: 10.1016/j.agwat.2025.109953

Authors: Shahrokh Shahmansouri, Mohammad Reza Mosaddeghi, Hossein Shariatmadari

Institution: Isfahan University of Technology

Language: English

Topic: Soil and Unsaturated Flow

Subfield: Civil and Structural Engineering

Field: Engineering

Domain: Physical Sciences

SDG: Zero hunger

Open Access status: gold

Estimated APC paid: $3,070