Abstract

The objective of this study is to evaluate the effect of different types organic fertilizers on

growth performance, nutrient and toxicological composition of two varieties of amaranth

(Amaranthus caudatus (Samaru local variety) and Amaranthus cruentus (NH84/452)).The

study consists of seven treatments which includes control (no fertilizer), poultry manure of 5

tons/ha and 10 tons/ha, sewage sludge of 5 tons/ha and 10 tons/ha, NPK compound fertilizer

of 35 kg/ha and 70 kg/ha; with two varieties of amaranth (Amaranthus caudatus (Samaru

local variety) and Amaranthus cruentus (NH84/452)) in factorial arrangement fitted into a

randomized complete block design (RCBD) and replicated three times. Growth performance

data were collected on plant height, number of leaves, leaf length, leaf width, leaf area and

leaf area index from 2 weeks after transplanting (WAT) to 6 weeks after transplanting (WAT)

using measuring tape and ruler. At 6WAT, poultry manure of 10 tons/ha recorded the highest

value for all the growth parameters for both varieties except for leaf length, leaf width and

leaf area of Amaranthus caudatus (Samaru local variety), where 10 tons/ha sewage sludge

and 70kg/ha NPK compound fertilizer were highest. All the treatments showed increased

effect on proximate composition (ash, moisture, fat, crude protein, crude fibre, available

carbohydrate and energy) for the two varieties but there was no significant (p<0.05)

difference except for protein which was significantly (p<0.05) highest at 9.67 ± 0.16% for the

70kg/ha NPK compound fertilizer in Amaranthus caudatus (Samaru local variety), proximate

composition was determined according to A.O.A.C. (1999). Water soluble vitamins were

analyzed using High Performance Liquid Chromatography (HPLC) while the metals were

analyzed using Atomic Absorption Spectroscopy (AAS) For Amaranthus caudatus (Samaru

local variety). β-carotene, zinc, riboflavin, iron, niacin and vitamin C levels were highest for

10 tons/ha sewage sludge, poultry manure of 10 tons/ha, NPK compound fertilizer of 70

kg/ha, poultry manure of 10 tons/ha, NPK compound fertilizer of 70 kg/ha, and 10 tons

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poultry manure respectively while for Amaranthus cruentus (NH84/452), β-carotene, zinc,

niacin, iron, vitamin C and riboflavin were highest for 10 tons/ha sewage sludge, poultry

manure of 10 tons/ha, 70kg/ha NPK compound fertilizer, sewage sludge of 10 tons/ha, NPK

compound fertilizer of 70kg/ha and 10 tons/ha sewage sludge respectively. The 10 tons/ha

poultry manure gave the highest value of tannins for both varieties but there was no

significant (p<0.05) difference among the treatments. The 70 kg/ha NPK compound fertilizer

recorded the highest level of phytate while the 10 tons/ha sewage sludge had the highest level

of saponins, oxalate, and lead for both varieties of amaranth. Total aflatoxins and cadmium

were not detected in any of the treatments including the control. The experimental results of

this study have shown that poultry manure had higher growth performance and nutrients on

the two varieties of Amaranth when compared with sewage sludge and NPK compound

fertilizer, while sewage sludge resulted in the plants having higher anti-nutrients and heavy

metals. The application of poultry manures at 10 tons/ha is therefore recommended for

farmers to use to obtain higher yields of Amaranth.

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CHAPTER ONE