Short-term effects of a biochar–compost–clay amendment on physical properties of psamment and maize performance: A pot experiment

Psamment is a coarse-textured soil with low water and nutrient retention capacity, which limits its agricultural productivity. This study investigated the effects of a biochar–compost–clay amendment on the physical properties of Psamment and evaluated maize (Zea mays L.) growth as an indicator response in a short-term pot experiment. In contrast to most studies on sandy soils that evaluate biochar, compost, or clay individually, this work examines their combined short-term application within a single amendment system. Pot experiments were conducted using five amendment rates 0, 10, 20, 30, and 40 t ha⁻¹, equivalent to 0, 67, 135, 202, and 270 g pot⁻¹, respectively.. Initial soil properties were analysed before treatment application, and soil physical properties were assessed at the end of the growing period to capture treatment effects after one cropping cycle. The results showed that higher amendment rates induced statistically significant changes in selected soil physical properties. Bulk density decreased significantly, whereas total porosity increased significantly at the 30 and 40 t ha⁻¹ rates. Other physical parameters, including pore size distribution, available water, water retention, and soil aggregation showed numerical changes but were not statistically significant. Plant responses varied, and most growth and yield parameters did not differ significantly among treatments, with the highest biomass occurring in the 40 t ha⁻¹ treatment. These findings suggest that the combined application of biochar, compost, and clay initiates measurable short-term changes in selected physical properties of Psamment, while agronomic benefits may require longer-term soil–plant interactions.