Maize yields followed the same trend with higher values measured
when organic amendments were used (e.g., 5, 3 and 4 t ha−1 for the
control treatment after the first, second and third years of the experiment,
compared to 6.6, 4.3 and 6.0 t ha−1 on average for the other treatments,
for the first, second and third years of the experiment
respectively, Fig. 4). As mentioned above, differences between organic
amendments were low and in most cases not significant (P N 0.05),
except in the second year of the experiment when the maize yield
was highest for the vermicompost treatment (e.g., 4.7 t ha−1 for
vermicompost, against 4.1 t ha−1 on average for buffalo manure and
compost, and 3.2 t ha−1 for the control treatment). In the last year,
the trend was similar without any significant difference between compost
and vermicompost treatments. Biochar addition to vermicompost
increased maize yield significantly compared to the control treatment.
However this effect was only significant in the first year for both the