The nexus of clay mineralogy and soil fertility under diverse parent materials in two distinct geomorphological settings

Clay minerals are essential components of the soil colloids accounting for a significant proportion of the soil matrix and are responsible for altering the physical and chemical properties of soils. Our study aimed to investigate the distribution of clay minerals in soils developed from basement complex (BC), sandstone (SS), mudstone (MS), shale stone (SH), and limestone (LS) parent materials (PM) in both upland and inland soils. Representative soil samples in each horizon across the five parent materials in both upland and inland soils were collected and analyzed for physicochemical properties, and clay mineralogy via X-ray diffraction method. The interrelated impact of parent materials on soil properties were assessed using principal component analysis (PCA). The results showed that in the inland valley soil, the values of ECEC, Ca, Mg, pH, and K were mostly influenced by SH and LS. In contrast, the values of silt, TN, OC, AP, and Al were influenced by MS and SS, whereas, in upland soil, higher values of silt, Mg, OC, TN, AP, Ca⁺ and pH were observed in SH soil at a depth of 0–12 cm, higher values of Na⁺, K⁺, and BS were observed in BC at a depth of 0–16 cm, while higher value of sand was obtained in SS soil at a depth of 0–22 cm. Soils of the upland province had 25%, 23.5%, 19.1%, and 22.7% kaolinite in BC, LS, MS, and SS, respectively, whereas in inland soils kaolinite contents were 36.9%, 30.8%, and 52.6% in BC, MS, and SS, respectively. The contents of montmorillonite were 23.5%, 35.56%, and 3.41% in LS, SH, and SS under upland soil and 20.7%, 17.3%, 33.3%, and 23.7% in BC, MS, SH, and SS under inland soil. Furthermore, vermiculite contents were 19.1%, 20%, and 12.8% in MS, SH, and SS under upland soil and 17.3% in MS under inland soil. Knowledge of soil mineralogy can aid in the understanding of nutrient availability and management of the soils.