Barley Root and Shoot Responses to Soil Re-engineering and Fertiliser Strategies in an Acidic Duplex Soil in Western Austraia

<title>Abstract</title> <p> <bold>Purpose</bold> Soil acidity, compaction, and low nutrition constrain crop productivity in texture-contrast soils of southern Australia. This study evaluated the effects of soil re-engineering (RE) and fertiliser strategy on root development and early growth of barley ( <italic>Hordeum vulgare</italic> L.) grown in a strongly acidic Kurosol. <bold>Methods</bold> Four RE treatments: no amendments, clay incorporation, lime incorporation, and lime and clay incorporation were combined with three fertiliser strategies: low-rate banded (F1), moderate-rate banded (F2), and high-rate incorporated at 0–80 cm (F3). Barley was grown for 22 weeks in reconstructed soil columns under semi-controlled conditions. <bold>Results</bold> Lime incorporation substantially increased pH _Ca from 4.3 to 5.4 and decreased aluminium concentrations to near zero. These changes promoted deeper and denser root systems, resulting in 258% greater volumetric root length density and 195% higher shoot biomass than unlimed treatments. Fertiliser strategy influenced crop performance, with F3 producing the greatest shoot biomass, tiller number, root growth and nutrient uptake. Across RE treatments, the F3 strategy generally produced greater shoot growth and nutrient uptake than the lower-rate banded strategies; however, because F3 differed in both nutrient rate and placement, these responses cannot be attributed independently to either factor. Root growth was positively correlated with soil pH _Ca (r = 0.53) and negatively correlated with aluminium concentration (r = -0.69). <bold>Conclusions</bold> These findings demonstrate that lime incorporation into acidic soil profiles is critical for improving root-zone conditions and barley root development in Kurosols, while highlighting the need to optimise fertiliser rate and placement for re-engineered soil profiles. </p>