Soil acidity is a significant constraint to wheat production in the Western Australian (WA) wheat belt, affecting over 70% of topsoils and 50% of subsurface soils. This study investigates the complex relationships between soil acidity, nutrient cycling, and soil fauna dynamics, with a specific focus on implications for wheat cultivation. Through a combination of field sampling across the WA wheat belt and controlled glasshouse experiments, we examined how varying soil pH levels influence soil fauna communities, nutrient availability, and wheat growth parameters.

Our research revealed critical pH thresholds for optimal soil fauna activity and nutrient cycling processes essential for wheat production. The study demonstrated significant correlations between soil pH, fauna diversity, and nutrient availability, with direct implications for wheat root development, nutrient uptake, and overall crop performance.

Results showed that in WA dryland agricultural soils, approximately 0.6 million DNA copies/g soil of free-living nematodes were measured, indicating their potentially significant role in nutrient transformations. Lime application (4 t/ha) effectively managed soil acidity, leading to reduced metal toxicity and increased nutrient availability.

Notably, nematode population and diversity increased with lime application. Wheat productivity improved by 0.3 t/ha and 0.6 t/ha in the 2023 season (1 decile) under surface application and incorporation of lime, respectively. Long-term monitoring suggests these yield improvements are sustained over at least three growing seasons.

These findings provide valuable insights for developing targeted soil management strategies in WA wheat production systems and potentially other acidic agricultural regions globally. Our results suggest that optimizing soil pH through appropriate liming practices could significantly enhance wheat productivity by fostering beneficial soil faunal communities and improving nutrient cycling efficiency.

This research contributes to the development of sustainable agricultural practices that balance wheat yield optimization with long-term soil health maintenance in acidic agricultural landscapes, potentially increasing regional wheat production while promoting soil biodiversity.

Keywords: Soil acidity management, wheat production, soil fauna, nutrient cycling efficiency, lime application, free-living nematodes