Hidden Half Network Model: A Prototype for Simulating Soil Pore Space, Root Architecture, and Water Movement.

Plenty models have been developed to study soils, roots, water, and their possible interactions. However, it is still a challenge to include feedback loops among these three features. This study attempts to develop a network-based model, called the Hidden Half Network (HHNet), to investigate the dynamics and feedbacks among soils, roots, and water in realistic soil profiles. The HHNet model consists of: 1) Soil structure module – Soil aggregates are simulated by a cracking-based method through adjusting the spatial distribution and force of cracking to consider different type of soil aggregates.; 2) Water movement module – Water flow is simulated according to soil pore space networks that separate preferential flow from matrix flow; 3) Root architecture module – Branching root architecture is simulated using scale-free network theory, with root growth dynamically influencing soil structure and water distribution. The three modules are then functionly linked to reveal real feedback loops among soils, roots, and water. The HHNet model provides a platform to study complex network systems in the hidden subsurface.