Jejak Pedogenesis Awal pada Inceptisol Berkembang Material Vulkanik Pulau Makian Maluku Utara

Abstract

Volcanic island soils provide a strategic setting for examining how early pedogenic signatures emerge before diagnostic horizons are fully expressed. This study evaluates the relationship between chemical development and morphological differentiation in Inceptisols developed from volcanic parent materials on Makian Island, North Maluku, Indonesia. Two representative profiles were selected within relatively homogeneous volcanic land units but different topographic positions. Morphological properties were described using standard soil survey procedures, while texture, bulk density, porosity, infiltration rate, C-organic, C/N ratio, and cation exchange capacity (CEC) were analyzed by horizon. Linear regression and principal component analysis were applied as exploratory tools to assess intervariable patterns. The results show weak horizon differentiation (A-B-C), limited structural development, coarse texture, moderate bulk density (1.25-1.40 g cm⁻³), high porosity (47-51%), and moderate to rapid infiltration (20-40 mm h⁻¹), indicating strong parent-material control over physical properties. Chemical properties showed clearer vertical gradients, with higher C-organic content (up to 2.44%) and CEC (up to 21.95 cmol(+) kg⁻¹) in surface horizons. C-organic and CEC had moderate linear relationships in Profile I (R² = 0.56) and Profile II (R² = 0.55), whereas other relationships were weak or inconsistent. These findings indicate pedogenic decoupling, where chemical functions develop earlier than clear morphological differentiation. The study strengthens the concept that early pedogenesis in humid tropical volcanic islands may proceed through asynchronous organo-mineral and biological processes.