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A large-scale six-year ecological study, published in the journal Proceedings of the National Academy of Sciences (PNAS), examines how prolonged and severe drought alters our planet’s hidden underground life – its soil microbiome (bacteria, fungi, and microorganisms).
According to the study’s authors, soil under drought conditions doesn’t just dry out; the microbial community begins to change rapidly (“drift”). The longer the drought persists, the further the microbiome deviates from its normal state. Due to strong selection, only highly specialized microbial species survive. The community “locks” into a distorted, unnatural condition. Scientists warn that even if the drought ends and rains come, restoring the soil to its original healthy balance will be extremely difficult, if not impossible.
“We’ve known for a long time that aboveground plant communities respond to drought, but what happens underground has been much harder to observe. Now that we have six years of continuous data, we’re finding that soil communities aren’t just stressed during drought; they’re shifting, and the further they shift, the less likely recovery becomes,” said Jizhong Zhou, senior author of the study.
With the decline in soil biodiversity, ecosystem processes responsible for nutrient cycling (carbon, nitrogen, and sulfur) have slowed dramatically. This means the land is losing its capacity to retain nutrients and support plant growth.
To counteract the devastating impact of drought on underground life, it is proposed to reform ecological policies and agricultural practices. The key message from scientists is that one cannot passively wait for the drought to end; soil must be actively managed, as its changes are difficult to reverse.
Scientists recommend incorporating the state of soil microbes into national biodiversity conservation programs.
Actively adding compost, mulch, and biochar (wood charcoal) will help create protective micropores in the soil (refuges for microbial survival) and retain residual moisture.
Artificial inoculation of affected soils with laboratory-grown “cocktails” of drought-tolerant plant growth-promoting bacteria (PGPB) and fungi that stimulate plant growth and help them retain moisture can also be an effective counteraction strategy.
The abandonment of monocultures is recommended. Sowing a mixture of deep-rooted perennial grasses and drought-resistant crops. The roots of different plants excrete different sugars, feeding and supporting the diversity of underground bacteria even during severe water scarcity. Scientists also advise completely abandoning deep plowing in arid regions (no-till technology) to avoid destroying fragile soil capillaries and the protective biofilms formed by microbes.
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Olena Basanets, SuperAgronom.com
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