By 
The Last Drop
Tim Smedley
Picador, $29.99
A journalist and a farmer visit three fields with different styles of cultivation — conventional, organic and no-till — to bury cotton underwear in each. Though this sounds like the beginning of a bad joke, it’s actually a test of soil health. Healthy soil that produces robust crops holds plenty of water and teems with life that will feast on the undies. This scene is just one of many in U.K.-based journalist Tim Smedley’s book The Last Drop.
The book provides an exhaustively reported primer on the world’s water problems and dives into potential fixes, including agricultural remedies, policy changes, tech innovations and at-home solutions like rainwater harvesting.
“The world isn’t running out of water — people are,” Smedley writes. He travels to the Hoover Dam in the American Southwest to see the low water levels at Lake Mead (SN: 5/18/23). He visits the Middle East, stopping by Jordan’s Karameh Dam, where the impounded water has become too saline for irrigation. Closer to home, he tours Europe’s largest artificial lake, northern England’s Kielder Water, which was constructed during the late 1970s in anticipation of a water demand that petered out within about a decade of completion. It’s the southern half of the country that has become water-stressed.
Such megaprojects highlight how “water crises are usually caused by all-too-human mismanagement, not climate,” Smedley writes. But climate change is certainly making things worse, he adds: “As climate change bites, precipitation patterns change.” For instance, the warmer atmosphere holds more water vapor, a greenhouse gas that exacerbates warming and fuels massive storms that unleash devastating floods.
Flooding can make water pollution worse. Runoff from storms carries extra nitrogen and phosphorus from farms. A “poonami” of livestock-sourced manure, which contains those elements, contaminates freshwater supplies, as do fertilizers (SN: 9/14/21). Some agrochemicals, Smedley writes, have been tied to increases in pediatric cancer cases.
Changes to farming practices, just some of the solutions Smedley explores, could mitigate pollution, water scarcity and potentially flooding all at once. No-till agriculture results in root systems, webs of fungi and burrowing bugs that maintain a spongy soil that sucks up water. Because they hold more water, these fields can better weather dry spells. Their soil structure helps them resist erosion, minimizing runoff (SN: 4/12/22). They also need far less fertilizer because fungi and other microbes, in conjunction with cover crops planted between growing seasons, maintain and return nutrients to the soil. England’s water woes — shortages are an issue despite the reputation for heavy rainfall — could be solved through no-till farming alone, Smedley’s reporting reveals.
As for the interred underwear, after a couple months, Smedley and the farmer unearthed dusty, holey pants from the organic field, whereas the conventional farm produced dirty-yet-wearable ones. The no-till field, unplowed for decades, turned up a “bedraggled mess” of soil, fungal residue and purple patches, along with a millipede that leaped from the scraps and scurried away.
Smedley packs his book with sometimes funny, often serious insights that people can apply to their lives. Most of the “water footprint” of people in the Western world, for example, comes not from tap water used for bathing, cooking and cleaning, but from the water that goes into making the products we consume. Depending on where and how it’s grown, and the specifics of the calculations, tossing a browned avocado can waste 273 liters of water. A single steak can cost 2,000 liters. “If you’re wearing a T-shirt made from cotton grown in Egypt,” Smedley writes, “you are, in a sense, wearing water from Egypt.”
Given all the water we waste, Smedley notes, small changes can make a big difference. “The ‘last drop’ doesn’t mean waiting for the water to run out,” he explains. “It means valuing every last drop as precious.”
BuyThe Last Drop from Bookshop.org. Science News is a Bookshop.org affiliate and will earn a commission on purchases made from links in this article.
