Yuliana et al. (2025) The influence of root-crack dynamics on soil water infiltration across seasonal variations

Identification

• Journal: Smart Agricultural Technology
• Year: 2025
• Date: 2025-11-17
• Authors: Yuliana Yuliana, Arwan Apriyono, Reza Pahlevi Munirwan, Song Feng, Viroon Kamchoom‬
• DOI: 10.1016/j.atech.2025.101636

Research Groups

• Excellent centre for green and sustainable infrastructure, School of Engineering, King Mongkut’s Institute of Technology Ladkrabang (KMITL), Bangkok, Thailand
• Department of Civil Engineering, Jenderal Soedirman University, Indonesia
• Department of Civil Engineering, Faculty of Engineering, Universitas Syiah Kuala, Banda Aceh, Indonesia
• College of Civil Engineering, Fuzhou University, Fuzhou City, Fujian Province, China

Short Summary

This study investigated the combined influence of root growth and soil desiccation cracks on soil water infiltration rates across seasonal wetting-drying cycles in bare and vegetated (vetiver grass) zones. It found that both root dynamics (growth and decay) and crack formation significantly regulate infiltration, with vegetated zones showing higher rates due to macropore creation and drying-wetting cycles enhancing overall infiltration capacity.

Objective

• To investigate the interaction between plant roots and desiccation cracks and to evaluate their combined effect on infiltration rates across different seasons.

Study Configuration

• Spatial Scale: Field site in Khlong Sam Wa, Bangkok, Thailand (13.8601°N, 100.7040°E). Three experimental zones (two vegetated with vetiver grass, one bare control), each 1.5 m x 1.5 m. Double-ring infiltrometer with an inner ring of 15 cm diameter (embedded 10 cm deep) and an outer ring of 30 cm diameter (embedded 20 cm deep). Root and crack observations were made at a depth of 5 cm in 10 cm x 10 cm holes.
• Temporal Scale: An 18-month observation period, encompassing two full cycles of rainy, dry winter, and dry summer seasons. Each infiltration test lasted 120 minutes.

Methodology and Data

• Models used:
  • Root Area Ratio (RAR) calculation: RAR = (∑ Ar / A) × 100%
  • Crack Intensity Factor (CIF) calculation: CIF = (∑ ac / A) × 100%
  • Infiltration rate calculation: I(t) = (1/A) * (dV/dt)
  • Cumulative infiltration depth calculation: F(t) = h1 - ht
  • Elrick’s formula for early-time cumulative infiltration: F(t) = S * t^0.5 (where S is sorptivity in m/s^0.5)
  • Approximate analytical relationship for sorptivity (S), saturated hydraulic conductivity (Ksat), and matrix potential (ϕm): S = {2(Δθ)KsatH + [(Δθ)ϕm / b]}
• Data sources:
  • Field measurements using the double-ring infiltrometer (falling-head standard test, ASTM D 3385).
  • Real-time water level changes monitored by HC-SR04 ultrasonic sensors with 1-second temporal resolution.
  • Minirhizotron camera for image-based observation of root growth (quantified as RAR) and crack formation (quantified as CIF).
  • Soil samples collected for laboratory tests: Atterberg limits (liquid limit 53.61 %, plastic limit 14.5 %), specific gravity (2.57), field dry density (1356 kg/m³), maximum dry density (1504 kg/m³) at optimum moisture content (23.8 %). Soil classified as high plasticity clay (Unified Soil Classification System).
  • Vetiver grass (Vetiveria zizanioides sp) used as vegetative cover.

Main Results

• Root growth peaked at a Root Area Ratio (RAR) of 6.3 % during the second rainy season, subsequently declining to 4.5 % in the second dry period due to water stress and root decay.
• Bare zones consistently exhibited higher Crack Intensity Factor (CIF) values compared to vegetated zones across all seasonal conditions.
• Both bare and vegetated zones showed an increase in CIF and infiltration rates during dry periods, with a subsequent decrease during wet periods.
• Vegetated zones generally experienced higher infiltration rates than bare zones.
• Infiltration rates in vegetated zones peaked at 4.37 × 10⁻⁶ m/s in the first dry season and demonstrated an 8-fold increase in the second cycle's dry summer, reaching 4.97 × 10⁻⁵ m/s, attributed to macropore creation by roots and the effects of drying-wetting cycles.
• In the bare zone, the final infiltration rate reached 1.63 × 10⁻⁶ m/s during the first dry summer.
• During the root growth phase, cumulative infiltration depth increased with RAR. However, in later stages, root decay led to a significant increase in cumulative infiltration depth (e.g., up to 70 mm in the second dry summer despite RAR dropping to 4.6 %), by creating preferential flow pathways (macropores).
• CIF-driven cracks significantly boosted cumulative infiltration depth in the bare zone during dry periods (e.g., a CIF of 5.2 % resulted in 50 mm cumulative infiltration depth), while CIF and infiltration rates were reduced during the wet season due to soil swelling and crack closure.
• Drying-wetting cycles were found to alter soil structure from non-aggregated to aggregated, leading to the formation of larger inter-aggregate pores that accelerate water infiltration.

Contributions

• This study provides a comprehensive investigation into the combined influence of plant roots and desiccation cracks on soil water infiltration rates, specifically examining how their interaction changes across seasonal variations over an extended 18-month period.
• It quantifies the temporal evolution of root dynamics (growth and decay) and crack formation (CIF) and correlates these with observed infiltration rates under natural field conditions.
• The research highlights the dual role of roots in soil hydrology: initially reducing crack formation and later enhancing infiltration through the creation of macropores as roots decay.
• It underscores the critical impact of drying-wetting cycles on soil structure and its capacity to significantly boost water infiltration over time, providing valuable insights for agricultural soil management and irrigation strategies.

Funding

• King Mongkut’s Institute of Technology Ladkrabang (KMITL) (Grant No RE-KRIS/FF69/36)
• National Science, Research and Innovation Fund (NSRF)

Citation

@article{Yuliana2025influence,
  author = {Yuliana, Yuliana and Apriyono, Arwan and Munirwan, Reza Pahlevi and Feng, Song and Kamchoom‬, Viroon},
  title = {The influence of root-crack dynamics on soil water infiltration across seasonal variations},
  journal = {Smart Agricultural Technology},
  year = {2025},
  doi = {10.1016/j.atech.2025.101636},
  url = {https://doi.org/10.1016/j.atech.2025.101636}
}