Basalt rock dust as a soil remineralizer in upland rice grown in tropical soils: residual effects on soil fertility, Si availability, and leaf anatomy

Silicate agrominerals (SA) applied as soil remineralizers have garnered interest due to their capacity to supply plant–available nutrients while decreasing reliance on conventional mineral fertilizers (CMF). This research evaluated the residual effects of basalt rock dust (BRD), examining its role as a soil remineralizer and silicon (Si) source for upland rice cultivation. A greenhouse–based pot experiment was executed using a randomized complete block design. Treatments were factorially arranged (5 × 2 + 2), juxtaposing varying BRD application rates (0, 7.5, 15, 30, and 60 Mg ha–1) with two soil types, alongside control treatments receiving lime and CMF. Assessments included soil fertility parameters, soil–available Si levels, rice biomass production, nutrient accumulation in rice tissues, leaf anatomical traits, and stomatal density. We found that enhanced silicon availability, driven by improved soil fertility, positively impacted leaf anatomical features of upland rice, notably strengthening epidermal structures, and influencing nutrient accumulation. Additionally, BRD applications reduced soil acidity and increased base saturation. Silicon availability peaked at BRD application rates of 46 Mg ha−1 and 29 Mg ha−1 for the two soil types. We conclude that BRD application is a promising means of enhancing agricultural productivity in low–fertility soils, particularly within tropical regions heavily reliant on CMF. With BRD, the potential exists to address environmental and socioeconomic challenges while supporting the utilization of mining by–products and bolstering agricultural output and food security.