Farmer-participatory and researcher-managed trials were conducted at Ayepe,
in south-west Nigeria, between July, 1991 and October, 1992, to determine
the biophysical compatibility of soybean and cassava intercrop and the
optimum time for introducing cassava (Manihot esculenta Crantz) in
soybean-based intercropping systems. Soybean (Glycine max L.) was
planted in monoculture and also intercropped with cassava at varying stages
of soybean development. Results indicated that seed yield of soybean was
depressed by intercropping. Land equivalent ratio (LER) increased with
growth stage of soybean prior to introduction of the cassava intercrop.
Yield of soybean ranged from 327 kg ha-1 to 642 kg ha-1 in farmers'
fields, and from 723 kg ha-1 to 1201 kg -1 in the researcher managed
field. Intercropping caused slight etiolation during the early growth of
cassava but this disappeared after soybean harvest. Tuberous root yield of
cassava was improved by intercropping irrespective of the stage of
development of soybean. Relative total yield increased with growth stage
of soybean prior to introduction of cassava. Both crops were least
competitive with each other when intercropped at 6 weeks after sowing
soybean. Introducing cassava into soybean in a relay-intercropping system
is advantageous for this agroecological zone.