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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 the hidden underground life of our planet – its soil microbiome (bacteria, fungi, and protozoa).
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 becomes “locked” in a distorted, unnatural state. Scientists warn that even if the drought ends and rains return, 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 don’t just get stressed during drought; they move, and the further they move, 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 down dramatically. This means the land loses its capacity to retain nutrients and support plant growth.
To counter the destructive impact of drought on underground life, it is proposed to restructure ecological policies and agricultural practices. The main message from scientists is that one cannot simply passively wait for the drought to end – soil must be actively managed, as its changes are difficult to reverse.
Scientists recommend including the state of soil microbes in national biodiversity conservation programs.
Active application of compost, mulch, and biochar (charcoal) will help create protective micropores in the soil (shelters for microbial survival) and retain residual moisture.
Artificial inoculation of affected soils with laboratory-grown “cocktails” of drought-tolerant bacteria (PGPB) and plant growth-promoting fungi that help plants retain moisture can also be an effective countermeasure strategy.
Abandoning monocultures is recommended. Sowing a mixture of deep-rooted perennial grasses and drought-resistant crops. The roots of different plants release 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.
All about crop nutrition
Olena Basanets, SuperAgronom.com
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