Results
Overall plant growth was increased by an average of 43.3% when
inoculated with microorganisms (p = 0.0001, CI = 29.69% - 58%, Figure
1A). Most studies reported positive effects of microbial inoculation on
plant growth (N = 158, 92%), with only 13 of the 172 observations (7.5
%) reporting negative effects of microbial inoculation and a single
record finding no statistically significant effect of inoculation on
plant growth.
Native microbial inoculants increased plant growth on average by 53%
(CI = 31% - 80%, replicates (N) = 78) while commercial inoculants
increased plant growth by 40% (CI = 9% - 78%, replicates (N) = 23).
However, we found no statistically significant difference between the
two types of inoculants (p = 0.57, CI = -0.18 – 0.37, Figure 1B).
Single microbial inoculants increased plant biomass by an average of
39% (CI = 24% - 55%, replicates (N) = 108) while multiple strain
inoculants (biodiverse microbes) increased plant biomass by 49% (CI =
32% - 68%, N = 64). This difference was not statistically significant
(p = 0.27, CI = -16.71% – 5.12%, Figure 1C).
Fungal inoculation increased plant biomass by 39% (CI = 28% - 61%, N
= 88) while bacteria inoculation increased plant biomass by 43% (CI =
23% - 58%, N = 77). We found no statistically significant difference
between the effect of bacteria and the effect of fungi on plant growth
(p = 0.69, CI = -15.6% - 11%, Figure 1D).