Thousands of years ago, beasts of burden helped make humanity what it is today. When farmers first started putting down roots, they’d plant and tend their crops by hand. With the power of oxen, they could drag plows across their fields before sowing, which boosted soil fertility and eliminated weeds. Today, that job has been made even easier by giant machines that rake the landscape.

Millennia of tilling, though, have come at a cost. While plowing releases nutrients in the short term, it degrades soil fertility in the long term, requiring farmers to load their fields with synthetic fertilizers. (The burst of microbial activity after roiling the ground also chews through accumulated carbon, returning it to the atmosphere as planet-warming greenhouse gas.) In addition, all this cultivation destroys the natural subterranean structures that hold onto water, meaning less is delivered to crops.

Fiber optic cables, of all things, have now exposed just how badly tilling messes with a farm’s ability to retain moisture. Using a technology known as distributed acoustic sensing (DAS), scientists analyzed how seismic waves disturbed the cable as they rippled through harrowed fields, compared to adjacent undisturbed plots. This created subtly distinct signals, showing that plowing obliterates the “capillaries” that carry water like tiny interconnected reservoirs.

The findings point to a serious problem with modern agriculture, to be sure, but also to solutions. “Regenerative farming practices based on principles of no-till—combined with cover crops and a diversity of crops—can basically lead to less agrochemical reliance, better soil organic matter contents, comparable yields, [and] lower diesel use,” said David Montgomery, a geomorphologist at the University of Washington and coauthor of a new paper describing the research.

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