Abstract
SummaryThirty‐three samples of Ando soils were extracted by sodium pyrophosphate (O.IM; pH 10) and by dithionite‐citrate. The Al, Fe, and C contents of these two extracts offer a means of differentiating the status of humus in relation to Al and Fe in the different horizons. The humus that forms at first in the Al horizon has a very low complexing ability for Al and Fe and little is dissolved by pyrophosphate. The humus evolves with time or pedogenesis into forms that complex Al and Fe released from volcanic ash by weathering, and which are dissolved by pyrophosphate. In the old horizons, the humus further reacts with additional Al and Fe, some of which may be present as hydrous oxides or allophane‐like constituents, allophane and imogolite. This reaction probably makes the humus less soluble in pyrophosphate.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
