Infiltrability characteristics were measured on field runoff plots established in March 1982 at the research farm of the International Institute of Tropical Agriculture (IITA). IITA is situated at latitude 7°30'N and longitude 3 ° 54' E at Ibadan, in a region underlain by metamorphic rocks belonging to the Pre-Cambrian Basement Complex. The major rock type is banded
gneiss, a grey quartz-biotite plagioclase-hornblende paragneiss.