Effect of Different Fertilizer Sources on Accumulation of Heavy Metals (Pb, Cu, Zn & Se) in Biomass of Amaranth (Amaranthus Hybridus l.) Grown at Federal Polytechnic Wannune, Benue State

The contamination of agricultural soils by heavy metals through fertilizer application poses a significant threat
to food safety and human health, particularly in regions where leafy vegetables constitute a major dietary
component. This study investigates the influence of different fertilizer sources—NPK 15:15:15, poultry litter,
crystallizer, and compost plus—on the accumulation of cadmium (Cd), lead (Pb), zinc (Zn), and selenium (Se) in
the biomass of amaranth (Amaranthus hybridus L.) grown at the Teaching and Research Farm of Federal
Polytechnic Wannune, Benue State, Nigeria. A pot experiment was conducted using a randomized complete block
design (RCBD) with thirteen treatments replicated three times. Surface soil samples (0–20 cm) were collected,
air-dried, and sieved through a 2 mm mesh. Four kilograms of sieved soil were placed in each of thirty-nine
plastic pots. Three levels (0.5, 1.0, and 1.5 t/ha) of NPK 15:15:15, poultry litter, and crystallizer, and three levels
(0.6, 1.2, and 1.8 t/ha) of compost plus were applied and mixed thoroughly. A control treatment without fertilizer
application was included. Five amaranth seedlings were transplanted per pot and later thinned to three.
Destructive sampling was conducted at 2, 4, and 6 weeks after transplanting (WAT). Heavy metals were extracted
using the single acid solution, double acid mixture, and DTPA extraction procedures and quantified using atomic
absorption spectrophotometry. Data were subjected to analysis of variance (ANOVA), and means were separated
using Duncan's Multiple Range Test (DMRT) at P < 0.05. The study hypothesizes that fertilizer source and
application rate significantly influence heavy metal accumulation in amaranth biomass, with organic fertilizers
exhibiting different accumulation patterns compared to inorganic fertilizers. The findings are expected to provide
critical baseline data for fertilizer management recommendations in Benue State, contributing to food safety and
sustainable agricultural practices.

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