Figure 3

Cumulative CO2 emission at the Lusaka (left) and Kabwe (right) sites. The levels of significance at the top of the panels were determined using one-way ANOVA, followed by Tukey’s test. Different letters on bars represent significant differences among the treatment means within the same site. Error bars represent the standard deviation of the mean (n = 3). CF: chemical fertilizer treatment, CM: cattle manure treatment, PM: poultry manure treatment, MR: maize residue treatment, and NF: no fertilizer treatment.