4. Discussion
Our results clearly show that the type of inoculum can greatly
influence the effect of inoculation on plant performance and the
observed soil effect. In our study negative soil effects were lower in
soil suspensions than in inocula with natural soil, and biomass was
highest in sterile soil inoculated with a soil suspension that was
sieved through a mesh of 20 mm. These results suggest that negative
soil effects can be partly sieved away. This effect is robust, as it was
found in two soils and in two growth phases. Hence, our results
show that choices made on what soil inoculation method to use in