A field trial on alley-cropping was conducted at the University
of Ibadan research farm in the 1990/91
cropping season to assess the contributions of arbuscular mycorrhizal (AM)
fungi and hedgerow
woody legumes to the yield and nutrient uptake of cassava (Manihot
esculenta Crantz) as an intercrop
in an infertile soil. The trial also investigated the influence of
AM fungi on the interplanting of a non-nodulating woody legume
Senna siamea (syn. Cassia siamea) with a nodulating woody
legume
(Leucaena leucocephala).
AM contributions to cassava were greater than the hedgerow contributions,
which demonstrated
that AM associations are an essential component in the nutrition of
cassava. In contrast to cassava,
AM inoculation only influenced the leaf dry weight and uptake of nutrients
of non-interplanted
woody legumes but not the above-ground biomass and P uptake of interplanted
woody legumes.
However, non-inoculated interplanted Leucaena benefited more
from indigenous AM fungi than the
competing Senna. The negative contributions to the nutrient
uptake (K, Ca and Mg) of cassava by
hedgerows and the lack of response to AM inoculation in interplanted hedgerow
woody legumes
could be attributed to root competition among the different plant species
growing in close proximity
to each other. The present results show that cassava benefits more from
AM association than
Leucaena which in turn benefits more than Senna in an
alley-cropping system.