Maize yield and growth showed high inter-annual variability depending on the organic amendment.
Vermicompost improved maize growth and yield but its effect was rather small and was only significant when
water availability was limited (year 2). This suggests that vermicompost could be a promising substrate for improving
the resistance of agrosystems to water stress. When the vermicompost–biochar mixture was applied,
further growth and yield improvements were recorded in some cases. When applied alone, biochar had a positive
influence on maize yield and growth, thus confirming its interest for improving long-term soil productivity. All
organic amendments reduced water runoff, soil detachment and NH4
+ and NO3
− transfer to water. These effects
were more significant with vermicompost than with buffalo manure and compost, highlighting that the benefi-
cial influence of vermicompost is not limited to its influence on plant yield. In addition, this study showed for the
first time that the combination of vermicompost and biochar may not only improve plant productivity but also
reduce the negative impact of agriculture on water quality.