Author Dan Egan talks with The Texas Tribune about phosphorus overuse and toxic algae blooms

Recommended Videos



Watch more video.

Having trouble viewing? Watch this video on texastribune.org.

Sign up for The Brief, The Texas Tribune’s daily newsletter that keeps readers up to speed on the most essential Texas news.


Author Dan Egan spoke with The Texas Tribune to discuss his new book, “The Devil’s Element: Phosphorus and a World Out of Balance.” The book takes readers on a deep dive into how phosphorus, a key component in fertilizer that helps support worldwide food production, also causes toxic algae blooms that have contaminated lakes, rivers and other waterways across the United States.

Discovered in the 1600s by a German alchemist in Hamburg, phosphorus’ full potential to fertilize crops wouldn’t be fully realized until the 1800s. Egan’s book details how people have built businesses around extracting phosphorus from materials like the bones of soldiers slain in wars, bird poop off the Guano Islands in South America and phosphate rock found largely in Florida.

“This is what the story is about. It’s our constant chase for the next fertilizing substance,” Egan told Tribune environmental reporter Alejandra Martinez. “People thought at the time that this was going to be an endless supply, we would never run out.”

Egan said humans have become overly dependent on phosphorus and are burning through the world’s supply at an “unsustainable pace.”

“There is no substitute for phosphorus, it is life’s bottleneck,” Egan said.

Egan’s book says overuse of phosphorus has led to toxic algae blooms in the Mississippi River basin, Lake Erie and both the Atlantic and Gulf coasts. For the first time since 2018, Texas saw toxic algae blooms this year, near Galveston Bay and the Rio Grande Valley.

The algae that blooms when fed by phosphorus — known as cyanobacteria or blue-green algae — causes water to turn into a thick, green poisonous gloop that can “kill dogs and make a swimmer vomit in a matter of seconds after an accidental gulp,” Egan wrote in his book. Climate change is an additional factor in algae growth, with intense spring rains washing chemical fertilizers from farmland into nearby rivers and lakes, Egan wrote.

“Right now what we’re doing is we’re putting too much chemical fertilizer and manure on the crop lands,” Egan said in the conversation. “The philosophy was that a little is good, a lot is better, just in case. And so, more would go on the landscape than was needed.”

He said that has caused a lot of phosphorus to build up in soils that’s going to leach out over time. “We can’t just flip a switch and it’s going to be problem solved,” Egan said.

Farmers can help prevent future algae blooms from contaminating water by consolidating manure into a small area and then processing it using anaerobic digesters to strip out the phosphorus, something he said is “every bit as pure as what’s coming out of a chemical fertilizer factory,” allowing farmers to control the movement and amount of phosphorus used.

“It's here and it's not going anywhere until we better control what's coming off the land,” Egan said. “Too many people too often just kind of throw up their hands and think, ‘Well, this is just natural.’ It’s not.”