THE EFFECT OF VESICULAR-ARBUSCULAR MYCORRHIZAL INOCULATION ON NUTRIENT-UPTAKE AND YIELD OF ALLEY-CROPPED CASSAVA IN A DEGRADED ALFISOL OF SOUTHWESTERN NIGERIA
O. Osonubi et al., THE EFFECT OF VESICULAR-ARBUSCULAR MYCORRHIZAL INOCULATION ON NUTRIENT-UPTAKE AND YIELD OF ALLEY-CROPPED CASSAVA IN A DEGRADED ALFISOL OF SOUTHWESTERN NIGERIA, Biology and fertility of soils, 20(1), 1995, pp. 70-76
Leaf and root (tuber) nutrient uptake patterns of cassava (Manihot esc
ulenta Crantz) alley-cropped with gliricidia (Gliricidia sepium), leuc
aena (Leucaena leucocephala), and senna [(Senna (syn. Cassia) siamea]
as influenced by vesicular-arbuscular mycorrhizal (VAM) inoculation in
a degraded Alfisol were investigated in 3 consecutive years. The cass
ava plants were mulched with fresh prunings of each hedgerow tree spec
ies at 2-month intervals in the second and third years of alley croppi
ng. While VAM inoculation significantly influenced the root uptake of
nutrients, the leaf uptake was not affected except for the uptake of P
. In most cases, there was no difference in the nutrient concentration
between inoculated and uninoculated plants, either in the leaf or in
the root, indicating that the productivity of cassava was regulated by
the amount of nutrients the roots could absorb. In spite of similar t
otal soil N in all inoculated and uninoculated alley-cropped cassava p
lots and similar exchangeable soil K contents in inoculated and uninoc
ulated alley-cropped cassava plots with leucaena and senna, greater up
take of N, P, and K and greater concentrations of K were observed in r
oots of inoculated alley-cropped cassava with gliricidia and leucaena
than with senna. These results indicated that greater mineralization a
nd availability of nutrients to cassava roots from prunings of nodulat
ing gliricidia and leucaena than from non-nodulating senna may be impo
rtant, particularly with efficient VAM inoculation, in these alley-cro
pping systems. Also, for similar nutrients in the inoculated and unino
culated cassava soils alley-cropped with each hedgerow species, VAM in
oculation significantly enhanced cassava root dry weights, indicating
that an effective VAM fungus can be an agent of greater nutrient uptak
e in a competitive environment.