‘Booster Shots’ of Healthy Dirt Can Bring Barren Landscapes Back to Life

Soil may be one of our planet's most underrated heroes. Without it, we miss out on verdant lawns and shady forests and have nowhere to grow fruit, vegetables, nuts, or grains. And without it, our food chain could fall apart. And this is not some theoretical, dystopian future; soil degradation is already a real problem for farmers all over the globe. So you can imagine that researchers were pleased to learn that a tiny transplant of healthy soil might be enough to invigorate depleted land. They published their findings in the journal Nature Plants.

Earlier studies had already shown that infusing barren land with healthy soil can help restore its fertility, but large-scale soil transplants are expensive, and scientists weren’t totally sure how it worked. So four Dutch researchers decided to try a large-scale experiment to look at very specific aspects of the process.

They found a depleted field that had, for many years, been farmland, and marked off large plots (five to 12 acres). Next, they dug away the topsoil in the test areas, peeling back that layer to reveal the vulnerable earth underneath. Upon some plots, they then spread a very thin (just one centimeter) layer of healthy soil from either nearby grasslands or shrublands. They left other plots untouched to act as controls. Then they stepped back and let nature do its thing for six years.

They returned to find quite dramatic results. Plots that had gotten the micro-dose of new soil had made a tremendous recovery.

Untreated vs. treated plots of land. Image credit: E.R.J. Wubs

The areas inoculated with grassland soil had produced lots of grassland plants, and the same was true for the heathlands. This might seem obvious—of course grassland soil would include the seeds of grassland plants—but further tests in a greenhouse showed that even when a plot was strewn with both kinds of seeds, the soil itself determined which seeds succeeded.

This study opens up a lot of possibilities for soil treatment. Once again, that may not sound like much, but try imagining your life without food.

Root biologist Harsh Bais of the University of Delaware, Newark, was not affiliated with the study, but he’s excited about the results. "This is a really cool and remarkable study," he told Science. "Dirt matters."

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