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