Liu et al. (2026) Root zone adaptive irrigation technology: A novel subsurface irrigation method using for drought-resistant afforestation in water shortage regions

Identification

• Journal: Agricultural Water Management
• Year: 2026
• Date: 2026-04-02
• Authors: Xufei Liu, Shoujun Wu, Pute Wu, Lin Zhang, Ergashev Iftixor Sultonovich, Maosheng Ge, Sen Zhai, Lijie Liu, Mengxue Han
• DOI: 10.1016/j.agwat.2026.110326

Research Groups

• Northwest A&F University (Institute of Water-saving Agriculture in Arid Areas, Institute of Soil and Water Conservation, National Engineering Laboratory for Arid-Region Crop High-Efficiency Water Use, College of Water Resources and Architecture Engineering)
• Tashkent State Agrarian University
• China Railway 23Th Construction Bureau. Ltd
• Xinjiang Academy of Agricultural Sciences

Short Summary

This study developed and evaluated a novel root zone adaptive irrigation (RZAI) technology, demonstrating its superior efficacy in improving soil water-heat conditions and promoting seedling growth for drought-resistant afforestation across diverse arid, semi-arid, and semi-humid regions.

Objective

• To evaluate the efficacy of a novel root zone adaptive irrigation (RZAI) technology for drought-resistant afforestation under diverse climatic features of arid, semi-arid, and semi-humid drought-prone areas.

Study Configuration

• Spatial Scale: Three field experimental sites representing different climatic conditions: Tashkent, Uzbekistan (arid); North Mountain of Lhasa, Xizang, China (semi-arid); and Longquan Mountain of Chengdu, Sichuan, China (semi-humid drought-prone). Experiments were conducted at the individual seedling scale.
• Temporal Scale:
  • Tashkent: July to September 2025 (3 months)
  • Lhasa: May 2023 to October 2023 (6 months)
  • Chengdu: April 2025 to August 2025 (5 months)

Methodology and Data

• Models used: HYDRUS-2D (for simulating two-dimensional soil water distribution), Mualem (for estimating unsaturated soil hydraulic conductivity), Rosetta software package (for predicting soil hydraulic parameters).
• Data sources:
  • Field measurements: Soil water content (Time-Domain Reflectometer, capacitance probes), soil temperature (TDR, capacitance probes), actual evapotranspiration (ETa), preferential infiltration (PI), leaf water content, stem flow rate (thermal diffusion probe), new shoot length, ground diameter, seedling height, crown width, water level in RZAI storage tank, and meteorological conditions (rain gauge).
  • Laboratory analysis: Soil chemical and physical properties (e.g., available nitrogen, nitrous oxide, total potassium, total phosphorus, particle size composition, dry bulk density, field water capacity).

Main Results

• Soil Water Storage: RZAI significantly increased root zone soil water storage in arid and semi-arid regions. In Tashkent, average soil water storage under RZAI was 126.9 mm, 1.9 times that of the bare soil pit control (CK). In Lhasa, RZAI doubled average soil water storage to 18.2 mm compared to CK (9.1 mm). In Chengdu, RZAI and CK had comparable average soil water storage (66.5 mm vs 63.1 mm).
• Soil Water Distribution: At Longquan Mountain, RZAI maintained stable soil water content (0.216 cm³/cm³ to 0.240 cm³/cm³) around the ceramic emitter, confining the wetted zone to less than 30 cm horizontally and 40 cm vertically, minimizing deep percolation. CK showed a decline in soil water content (from 0.24 cm³/cm³ to 0.17 cm³/cm³) and a larger, deeper wetting area.
• Water Level in Storage Tank: The RZAI storage tank maintained a remarkably stable water level (5.6 cm to 10.7 cm) despite variable rainfall, demonstrating efficient rainwater collection and consistent water supply.
• Soil Temperature:
  • In Tashkent, no significant difference in mean soil temperature was observed between RZAI (26.0℃) and CK (26.5℃).
  • In Lhasa, RZAI consistently maintained higher soil temperatures, with a mean of 18.2℃ compared to 13.5℃ for CK, significantly mitigating low-temperature stress.
  • In Chengdu, RZAI buffered temperature fluctuations, leading to lower temperatures during warming periods and higher temperatures during cooling periods compared to CK.
• Actual Evapotranspiration (ETa) and Preferential Infiltration (PI):
  • In Tashkent, mean daily ETa was comparable between RZAI (118.9 mm) and CK (120.8 mm). RZAI exhibited predominantly negative PI (net upward water flux), while CK showed positive PI (net water loss below root zone).
  • In Chengdu, mean daily ETa under RZAI (22.3 mm) was significantly higher than CK (18.9 mm). PI values were negative for both, but consistently lower under RZAI, indicating stronger root water uptake.
• Leaf Water Content and Stem Flow:
  • In Tashkent, RZAI significantly enhanced leaf water content, reaching 64.8% by day 45 compared to 57.0% for CK.
  • In Chengdu, maximum stem flow under RZAI was 23.93 g/h, 16.7% higher than CK (20.5 g/h), with consistently greater rates under RZAI.
• Seedling Growth Performance: RZAI consistently and significantly promoted seedling growth across all three sites.
  • Average new shoot length under RZAI was 14.4 cm, a 35.5% increase over CK (10.6 cm).
  • Average ground diameter under RZAI was 1.3 cm, 56.3% higher than CK (0.8 cm).
  • Average seedling height under RZAI reached 90.0 cm, a 21.6% improvement over CK (74.0 cm).

Contributions

• Introduces a novel root zone adaptive irrigation (RZAI) technology that integrates in-situ rainwater harvesting, water storage, and adaptive irrigation via a ceramic emitter for drought-resistant afforestation.
• Systematically verifies the adaptive capability and multi-site applicability of RZAI across diverse arid, semi-arid, and semi-humid drought-prone regions, addressing a critical research gap in field-scale efficacy.
• Demonstrates that RZAI's self-adaptive flow rate, targeted water infiltration (confining water to the root zone), and synergistic rainwater utilization significantly enhance water productivity and mitigate the spatiotemporal mismatch between water availability and seedling demand.
• Provides evidence of RZAI's ecological and hydrological benefits, including reduced irrigation water demand, lower disturbance to local hydrological regimes, reduced weed germination, enhanced rainfall infiltration, and potential for mitigating surface runoff and soil erosion.
• Offers a new technical approach for promoting seedling growth in afforestation projects, particularly in water-scarce regions, by improving soil water and thermal environments and enhancing seedling physiological performance.

Funding

• Open Project of Shaanxi Agricultural Laboratory in Arid Areas (2024ZY-JCYJ-02–02)
• China Postdoctoral Science Foundation (2025M782476)

Citation

@article{Liu2026Root,
  author = {Liu, Xufei and Wu, Shoujun and Wu, Pute and Zhang, Lin and Sultonovich, Ergashev Iftixor and Ge, Maosheng and Zhai, Sen and Liu, Lijie and Han, Mengxue},
  title = {Root zone adaptive irrigation technology: A novel subsurface irrigation method using for drought-resistant afforestation in water shortage regions},
  journal = {Agricultural Water Management},
  year = {2026},
  doi = {10.1016/j.agwat.2026.110326},
  url = {https://doi.org/10.1016/j.agwat.2026.110326}
}