Materials and Methods
2.1 Characterization of Materials
2.1.1 Chemical Analysis of Raw Materials, Composts and Pellets
Total organic carbon, nitrogen, phosphorus and potassium concentrations in the samples were determined using
the procedure followed by Adamtey (2010). Determination of the concentrations of heavy metals (iron,
manganese, zinc, copper and lead), ammonium (NH4
+) and nitrate (NO3
-) nitrogen is also described in Adamtey
(2010). In determining the pH of the samples, 10 g of the ground material and 50 ml of distilled water were
combined to form a suspension. The suspension was stirred with a glass rod for 25 minutes and allowed to stand
for 30 minutes. A pH meter was then used to read the pH value of the supernatant. The electrical conductivity
(EC) of each sample (2 g of the ground material to 10 ml of distilled water) was measured using the EC meter
(Jenway PCM3). Each measurement was replicated three times.