Abstract:
The overall objective of the study was to investigate the effect of farmyard manure (FYM)
and calcium ammonium nitrate (CAN) and cooking on micronutrient content (iron, zinc,
potassium, calcium, manganese) and seed yield in two African leafy vegetables (ALVs),
Solanum villosum and Cleome gynandra in Keiyo District of the Rift Valley Province. The
micronutrients were determined using the energy dispersive X-ray fluorescence (EDXRF)
analysis method. Results from the study indicated that addition of various levels of
fertilisers either had no effect, depressed or slightly increased the amounts of various
micronutrients in the two ALVs. Edible portions of Solanum villosumwere found to be richer
than their Cleome gynandra counterparts in iron, manganese and potassium content.
Cleome gynandra on the other hand contained more zinc and calcium than Solanum
villosum. Incorporation of either FYM or CAN decreased the iron accumulation in leafy
tissues of the two ALVs. Application of FYM or CAN had no significant or clear effect on the
levels of zinc and potassium in both ALVs, while moderately high levels of FYM increased
the levels of manganese in Cleome gynandra but showed no clear trend in Solanum villosum
edible tissues. The farmer’s crop was comparable in the measured attributes to the produce
grown on soil amended with low levels of either FYM or CAN. Boiling significantly decreased
the amount of micronutrients retained in edible portions of both vegetables, except for
manganese where it had no effect. The FYM and CAN fertilisers significantly increased seed
yields of both ALVs. In conclusion, Solanum villosum and Cleome gynandra are rich sources
of iron, zinc, calcium, potassium and manganese and incorporation of various levels of FYM
and CAN improved seed yields in the two ALVs, although showing no major influence on the
micronutrient densities. Traditional methods of prolonged boiling to reduce the bitter antinutrients
and make them palatable seriously eroded the levels of micronutrients in some
instances by up to 65%.
