Mixing soil inocula as a restoration measure: are there synergies?
Summary
The composition of soil communities can strongly affect the growth rate and the composition of grassland plant communities, as the soil community changes during succession. However, more research is needed on the most suitable soil (mixture) for soil transplantation as a restoration measure for species-rich grasslands. In this study, the effect of soil communities from different successional stages on the growth of target plants for nature restoration and non-target plants (weeds) was tested by using inoculation. Soil was collected at arable lands, grasslands, and heathlands. Two soil types were mixed (e.g. grassland soil and heathland soil), after which the effect of the mixture on the plant community was determined. Possible synergistic effects between soil communities could then be observed by comparing mixed inocula to pure inocula. This has received little experimental testing. Introducing soil mixtures with a synergistic effect on the plant community could then be a helpful tool for increasing succession from an arable land to grasslands.
It was observed that pots inoculated with 25 percent of grassland soil mixed with 75 percent of heathland soil created a surprising synergistic effect, where the target biomass was higher than expected based on the pure inocula. Furthermore, it was found that pots inoculated with 100 percent heathland soil contained a higher percentage of target biomass at the end of the experiment than pots with other inocula. It can therefore be concluded that soil mixtures containing a high percentage of heathland soils and little grassland soil can enhance the nature restoration of grasslands, where a mixture with 25 percent of grassland soil and 75 percent of heathland soil was most effective due to its synergistic effect on the target biomass.