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the recommended pH range by Day & Shaw (2001) and Sullivan & Miller (2001), respectively 7.5 - 8.5 and 6.0 - 8.0. Overall,
it can be concluded that the final pH value of the compost usually depends on several factors such as the organic material
used, method of composting, as well as the addition of other materials for pH correction such as calcium oxide and ferric
chloride (Sullivan & Miller, 2001). Thus, Sample 3 is better than another based on the pH value of the resulting compost.

Table 4.3(c): pH value

DAYS pH
SAMPLE 1 SAMPLE 2 SAMPLE 3 SAMPLE 4
1 7.7 7.2 7.4 6.9
3 7.5 7 7.3 6.7
5 7.2 7 7.2 6.6
7 7.5 7.2 7.4 6.7
9 7.8 7.6 7.5 6.9
11 7.9 7.8 7.6 7
13 8.1 7.9 7.2 7
15 8.1 7.8 7.2 7
17 8 7.7 7.1 6.9
19 7.9 7.9 7.2 7
21 8 7.6 7.3 7.1
23 8.3 7.9 7.4 6.9
25 8.3 8 7.3 6.9
27 8.2 8.2 7.2 6.8
29 8.1 7.6 7.2 6.9
31 7.9 7.3 7.1 6.8
33 7.9 7.4 7.1 6.7
35 7.9 7.4 7 6.7
40 7.5 7.3 7 6.7
45 7.4 7.2 7 6.6
50 7.4 7.2 7 6.6

9
8
7
6
pH 5 pH SAMPLE 1
4
pH SAMPLE 2
3
pH SAMPLE 3
2 pH SAMPLE 4
1
0
0 10 20 30 40 50 60
COMPOST DURATION (DAYS)

Figure 3: Comparison between pH value and Composting Duration (days)

4.1 (d) C / N Ratio

The ratio of C: N are among the factors that will affect the quality of the compost produced. Previous studies indicated
that the ratio of C: N optimal for the survival of the composting process is between 20-25: 1, 25-30 (Huang et.al, 2004) and
26-31 (Latifah, 2001). Figure 4 shows the average ratio of C: N in all samples.
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