Stratified soil profiles and arbuscular mycorrhizal fungi reshape plant water use strategy and enhance root development in arid mine waste dump restoration

Abstract

Soil moisture is a pivotal constraint on vegetation establishment in spoil heaps of coal mining regions, particularly within arid and semi-arid landscapes. Optimizing the retention and utilization of soil water in these disturbed ecosystems is an urgent challenge with direct implications for ecological restoration. In a field-based factorial experiment conducted in a coal mine reclamation zone, we investigated two key variables: soil reconstruction strategy and microbial inoculation. The soil treatments included a homogeneous soil profile and a stratified profile. The microbial factor involved inoculation with the arbuscular mycorrhizal fungus (AMF) Funneliformis mosseae, compared against a non-inoculated control. Our findings revealed that stratified soil reconstruction significantly enhanced alfalfa (Medicago sativa) performance, root biomass increased by over 12.9 %, and average fine root length density by more than 22.5 % relative to homogeneous soil. The stratified configuration markedly improved soil water retention, creating a more favorable environment for root development and plant growth. AMF inoculation further amplified root water uptake and stimulated root proliferation. Notably, the combined treatment of stratified soil and AMF inoculation reshaped the plant's water acquisition strategy, reducing reliance on shallow (0–20 cm) soil moisture while enhancing uptake from deeper layers (20–40 cm and 40–100 cm). This synergistic approach, integrating engineered soil profiles with microbial symbiosis, proved most effective in promoting biomass accumulation and improving water-use efficiency. Collectively, these results offered actionable insights and a scientific basis for advancing vegetation recovery strategies in water-limited, post-mining environments.