Disentangling the pedogenic factors controlling active Al and Fe concentrations in soils of the Cameroon volcanic line

Active Al, Fe and Si (i.e., oxalate extractable fraction: Alo, Feo, Sio) strongly affect soil physical, chemical biological properties. This study examined the pedogenic factors affecting Feo Sio contents across a weathering sequence in Cameroon volcanic line. We investigated B horizon (∼50-cm depth) from 26 soils formed basaltic materials at different elevations (110–2570 m) incorporating wide range of temperature (14–27 °C) precipitation (1520–3130 mm). The ranged weakly weathered Andisols southwest region grading to Oxisols on central highlands. assumed pyrophosphate Al/Fe (Alp/Fep) as organo-Al/Fe complexes, Sio, (Alo − Alp) (Feo Fep) short-range-order (SRO) minerals. Factor analysis climatic (e.g., precipitation/leaching metrics) geochemical properties indices) identified three independent representing temperature/dry season intensity, degree primary determinants concentrations. Organo-metal complexes (Alp were negatively correlated with intensity factor, whereas SRO mineral phases (Sio, Alo Alp degree. factor positively Sio. Our infers that low promotes formation preservation is more critical for Further, increased drier climate enhance crystalline clay minerals expense Allophanic (Sio) evident (Sio: 9–43 g kg−1) only soils. However, allophanic found highly 2–7 accompanied by high Fep, suggesting importance parent direct source Al via organo-metal complexes. In sum, we clarified discriminatory effects regulating composition active fractions along