Improving Barley (Hordeum vulgare L.) Yield through Deeper Root Architecture Impacted by Nitrogen Management in a Reengineered Kurosol

Subsoil acidity and compaction are major constraints to crop production on Kurosols, duplex soils, in Western Australia, limiting root proliferation, nutrient uptake, and grain yield. This study evaluated how soil re-engineering practices, particularly deep liming, interact with nitrogen (N) fertiliser application to influence barley ( Hordeum vulgare L. ) root system development, crop performance, and soil properties in an acidic Kurosol. A semi-controlled experiment was conducted using 80 cm reconstructed soil profiles using soils from a field site. Treatments included soil loosening with or without lime incorporation, combined with varying N rates in split applications. Results showed that lime incorporation significantly enhanced total root length, volumetric root length density, and root surface area, shifting root distribution deeper into the profile and reducing reliance on surface soils. Grain yield and biomass increased markedly under limed treatments, with responses to N remaining linear, whereas unlimed soils showed yield plateaus at higher N rates. Root surface area was the strongest predictor of yield and biomass (R² >0.8), highlighting the importance of fine-root proliferation. Liming also increased subsoil pH, decreased extractable aluminium, and increased organic carbon. These findings show that effective management of acidic, compacted subsoils requires integrated amelioration and nutritional strategies, where liming enables sustained root development and efficient fertiliser use. While soil column studies provide mechanistic insights, validation under field conditions is needed to assess persistence, rainfall interactions, and the economic viability of deep liming combined with optimised N management for sustainable barley production in water-limited environments.