Each treatment was repeated five times. Data were tested
for homogeneity of variance using the Levene’s test and logtransformed
(log10) when required. Plant biomass and yield,
chlorophyll content and earthworm abundance were evaluated
using two-way ANOVA with repeated measures. Time was the
repeated measure and treatments were within-subject factors. Soil
chemical properties and the abundance of earthworm casts at
the end of the one-year experiment were tested with a two-way
ANOVA. Comparisons between means were tested with an LSD test.
A principal component analysis (PCA) was also carried out on the
soil chemical properties. All statistical calculations were carried out
using R software (R Development Core Team, 2008). Differences
among treatments were declared significant at the