Su et al. (2025) Integrated effects of rainwater harvesting and organic fertilization on soil structure and aggregates in a rainfed orchards on the Loess Plateau

Identification

• Journal: Agricultural Water Management
• Year: 2025
• Date: 2025-12-16
• Authors: Wenjing Su, Bin Li, Xiaofeng Ouyang, Shufang Wu, Hao Feng, Kadambot H.M. Siddique
• DOI: 10.1016/j.agwat.2025.110088

Research Groups

• Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas of Ministry of Education, Northwest A&F University, Yangling, China
• College Of Water Resources and Architectural Engineering, Northwest A&F University, Yangling, China
• State Key Laboratory of Soil and Water Conservation and Desertification Control, Northwest A&F University, Yangling, China
• The UWA Institute of Agriculture, The University of Western Australia, Perth, Australia

Short Summary

This study investigated the integrated effects of a novel Water Harvesting, Irrigation, and Organic Fertilization (WHIOF) system on soil structure and aggregates in a rainfed apple orchard on the Loess Plateau. The WHIOF system significantly improved soil physical properties and aggregate stability by enhancing soil organic matter, surface electrochemical properties, and interparticle attractive forces at both macroscopic and microscopic scales.

Objective

• To investigate the macroscopic soil structural improvement effects of Water Harvesting, Irrigation, and Organic Fertilization (WHIOF) practices.
• To determine the effect of WHIOF on soil surface electrochemical properties, intergranular pressure, and aggregate stability at the microscale.
• To elucidate the coupling relationship between soil aggregates, surface electrochemical properties, and inter-particle pressure indices.

Study Configuration

• Spatial Scale: Field experiment conducted in a rainfed apple orchard (795 m²) on loessial soil in Wanzhuang Village, Yan’an City, Shaanxi Province, China. Soil samples were collected from 0–100 cm depth, with detailed analysis at 0–20 cm, 20–40 cm, 40–60 cm, 60–80 cm, and 80–100 cm layers.
• Temporal Scale: Rainfall patterns monitored from July 2022 to November 2023. Soil sampling and measurements were conducted after apple maturation in October 2023.

Methodology and Data

• Models used:
  • Calculations for Mean Weight Diameter (MWD), Geometric Mean Diameter (GMD), and Particle Aggregate Destruction (PAD) using standard formulas.
  • Determination of soil surface electrochemical properties (surface potential, surface charge density, electrostatic field strength, specific surface area, surface charge number) using a combined method.
  • Calculation of soil internal pressure (electrostatic repulsion, hydration repulsion, van der Waals attraction, net pressure) based on soil surface chemistry parameters and the Hamaker constant.
  • Conceptual model based on extended DLVO theory framework.
• Data sources:
  • Field experiment with five treatments: conventional management (CK), rainwater harvesting only (WH), WH with irrigation (WHI), WHI + low organic fertilizer (WHIOF1), and WHI + high organic fertilizer (WHIOF2), each with three replicates.
  • Soil physical properties: Bulk density (cutting-ring method), porosity, saturated hydraulic conductivity (constant-head permeability test).
  • Soil organic matter content: Dichromate oxidation method with external heating.
  • Soil aggregate size distribution and stability: Dry and wet sieving.
  • Soil surface electrochemical properties: Combined method for material surface properties.
  • Soil water potential: Dew-point potentiometer.
  • Ion concentrations (Na⁺, Ca²⁺): Atomic absorption spectrophotometry.
  • pH: Precision pH meter.
  • Hamaker constant: Method of Markus and Dani (2005).

Main Results

• The WHIOF system significantly improved soil physical properties in the 20–40 cm layer, reducing bulk density by 8.51–8.78%, increasing porosity by 14.65–19.24%, and enhancing saturated hydraulic conductivity by 42.80–84.36% compared to CK and WH treatments.
• Organic fertilization elevated soil organic matter content, with WHIOF1 and WHIOF2 increasing SOM by 10.45% and 10.84% respectively in the 40–60 cm layer compared to CK and WH. It also substantially increased the proportion of macroaggregates (e.g., ≥5 mm aggregates increased by 66.64–92.91% in the 20–40 cm layer for WHIOF1/WHIOF2 vs CK).
• WHIOF amplified soil surface charge density (e.g., WHIOF2 at 0.754 C⋅m⁻² vs CK at 0.253 C⋅m⁻²), specific surface area (e.g., WHIOF2 at 20.524 m²⋅g⁻¹ vs CK at 8.438 m²⋅g⁻¹, a 143.23% increase), and interparticle attraction, leading to a reduction in aggregate disruption (PAD) by 7.01–10.57% for WHIOF1/WHIOF2 compared to CK/WH.
• Water-stable aggregate stability (WGMD) showed a strong positive correlation with soil organic matter (r = 0.96, p < 0.01) and specific surface area (SSA) (r = 0.90, p ≤ 0.05).
• The net interparticle pressure (Pnet) under WHIOF treatment exhibited a net attractive force at particle separations less than 2 nanometers (nm), indicating enhanced interparticle attraction.

Contributions

• Provides a mechanistic understanding of how integrated rainwater harvesting, supplementary irrigation, and organic fertilization (WHIOF) improve soil structure and aggregate stability in rainfed orchards.
• Elucidates the role of soil electrochemical properties and interparticle forces at the microscale in regulating macroscopic soil structural resilience, addressing a gap in existing literature.
• Offers a theoretical basis and innovative technological pathways for enhancing soil fertility and promoting sustainable soil management in arid and semi-arid rainfed agricultural systems, particularly on the Loess Plateau.
• Proposes a "water-fertilizer-electrochemistry" conceptual model to explain the multi-scale interactions driving soil improvement.

Funding

• National Key R&D Program of China (2023YFD1900300)

Citation

@article{Su2025Integrated,
  author = {Su, Wenjing and Li, Bin and Ouyang, Xiaofeng and Wu, Shufang and Feng, Hao and Siddique, Kadambot H.M.},
  title = {Integrated effects of rainwater harvesting and organic fertilization on soil structure and aggregates in a rainfed orchards on the Loess Plateau},
  journal = {Agricultural Water Management},
  year = {2025},
  doi = {10.1016/j.agwat.2025.110088},
  url = {https://doi.org/10.1016/j.agwat.2025.110088}
}