Want to make your barren yard lush again? Just add a bit of soil from your local meadow. A new study reveals that the addition of foreign soil—and more importantly, the organisms it contains—can shape which plants will grow in the future. Such “inoculations” could even help bring back fallow farmlands and turn deserts green.”This is a really cool and remarkable study,” says Harsh Bais, a root biologist at the University of Delaware, Newark, who was not involved in the work. “Dirt matters.”Soil isn’t as simple as it seems. It contains microscopic bacteria and fungi, as well as tiny worms called nematodes and other invertebrates. Ecologists have long known that these underground communities build critical partnerships with the plants growing nearby. But many of these partnerships remain a mystery. Small-scale studies in greenhouses have shown that adding the right soil can promote the growth of a particular plant community, and some researchers have even tried soil transplantation—replacing one soil with another—to get certain endangered plants to grow.Such need is great across the globe, where many once-fertile lands are turning into desert, and a significant amount of agricultural land is lost every year. What’s more, when governments and nonprofit organizations try to bring back grasslands, forests, and other ecosystems destroyed by agriculture and other human uses, they are often disappointed: Restoration can take decades. It sometimes fails altogether.E. R. Jasper Wubs, an ecologist at the Netherlands Institute of Ecology in Wageningen, hoped to find a better way. But instead of doing wholesale transplantation of soil—which can be expensive—he wanted to see what would happen with a booster shot.He and colleagues set up a series of 2- to 5-hectare plots on abandoned, degraded farmland in the Netherlands. They removed about 60 centimeters of top soil from part of each plot and spread a 1-centimeter-thick layer of soil in others. The soil was taken from either a heathland—rolling hills dominated by heather and small shrubs—or a grassland. They then added seeds from 30 plant species from a variety of habitats and waited—for 6 years.When their waiting was up, they compared the seeded areas with and without the added soil layers, looking at which species were thriving and which were not. The source of the added soil greatly influenced what grew where, they report today in Nature Plants. Plots with heathland soil were covered with heather and gorse, whereas plots with grasslands soil were overflowing with a variety of grasses. The added soil made the existing land richer—as the researchers found more nematode worms, more bacteria, and more fungi in those sections of the plots. Those with heathland soil also had a greater diversity of springtails and mites.