Degraded ecosystems can be restored to health by inoculating them with healthy soil, reports a paper published in Nature Plants this week. The study also shows that inoculation with different kinds of soil steers recovery towards the donor system, meaning that intensively farmed land can be directed to become a healthy grassland or heathland. This finding could help to rewild landscapes that have deteriorated after decades of farming.
Restoring ex-farmland is difficult because years of intensive production promotes competitive weeds and disrupts the soil community. Previous studies have shown that transplanting healthy soil to the ex-farmland helps it recover. However, Jasper Wubs and colleagues are the first to show that injecting small amounts of healthy soil biota not only helps restore the land, but that recovery can be directed towards different kinds of ecosystems, depending on where the donated soil comes from.
They removed the top layer of soil from parts of a 160-hectare field that had been farmed for nearly 60 years, and then applied a thin (<1 cm) layer of soil inoculum from grassland or heathland to different areas. Six years later, they observed that the treated areas had responded differently, with the inoculated sites acquiring plants associated with grassland or heathland. Furthermore, they found that the plots had been colonized by the characteristic soil invertebrates, microbes and fungi of each kind of ecosystem.