One of Tampa Bay’s earliest industries was the mining of phosphates for fertilizer.
"Hidden History" is a diary series that explores forgotten and little-known areas of history.
In 1881, US Army Captain J Francis LeBaron of the Corps of Engineers was exploring an area along the Peace River just north of Tampa Bay, surveying a possible pathway for a canal. He never found a suitable route, but he did find a lot of fossils. These included marine animals, shark’s teeth, and a smattering of Ice Age mammals. Following standard US Government policy, LeBaron collected nine barrels full of fossils from the sand banks and sent them off to the recently-formed Smithsonian Institution in Washington DC.
The Smithsonian’s paleontologists were impressed by the finds, and dubbed the area where the fossils had been collected as “Bone Valley”. A message was sent to LeBaron asking him to collect more, but he had already moved on to a new project expanding a harbor near Jacksonville.
It wasn’t until December 1886 that LeBaron was able to return to Bone Valley and dig a few test pits. He found more fossil bones. But he also noticed that the sand deposits here contained significant amounts of phosphate rock, formed as a sediment at the bottom of an ancient sea that had once covered Florida. And that discovery was of far more than scientific interest.
Since time immemorial, ancient farmers had been fertilizing their fields with animal manure and with dried bird droppings (known as “guano”) to improve their yields. But it wasn’t until the mid-19th century that European scientists began to understand the biology of plants and the chemical basis of fertilizers, and this led to a breakthrough of immense significance—the industrial manufacture of artificial fertilizers. This was done by treating phosphate rock with sulphuric acid, extracting the resulting phosphoric acid and chemically converting it into fertilizer.
The first commercial phosphate mines, worked by men with picks and shovels, were found in England in 1847. But the deposits that LeBaron had discovered in Bone Valley were immense—many times the size of the British mines. Realizing the potential commercial value, he tried to persuade a number of New York and Philadelphia financiers into forming a partnership to mine the phosphate, but at the time this area of Florida was an isolated backwater with little infrastructure, and nobody was interested. LeBaron gave up and moved on to become involved in another project, which turned out to be the unsuccessful American effort to construct a seaway canal across Nicaragua.
Word of LeBaron’s phosphate discovery had gotten around, however—though not the exact location of the deposit. But within a few years, several people had stumbled upon Bone Valley. One of them was GW Scott, an industrialist from Atlanta. He quickly purchased tracts of land along the phosphate beds. Another was TS Moorhead, from Pennsylvania, and in 1886 they formed a partnership, with Scott’s Fertilizer Works in Atlanta contracting to buy all the phosphate mined by Moorhead’s Arcadia Phosphate Company. A year later, another player entered the field, when two men from Orlando found a phosphate deposit during a hunting trip and formed the Peace River Phosphate Company.
By this time, the Florida Southern Railway had reached the nearby town of Arcadia. Railroad magnate Henry Plant, realizing the potential, tried to buy it, but when the owner refused to sell, Plant made a deal to incorporate the Railway into his own network without owning it. Now it was possible to ship large quantities of phosphate rock to Savannah and Atlanta. Soon there were dozens of companies with interests in Bone Valley, and new rail lines connected the mines to the ports in Tampa and Punta Gorda. By the 1920s, Florida was providing about 75% of all the phosphates used for fertilizer in the US.
By the 1960s, big oil companies like Mobil and Occidental were looking to invest in phosphate mines as a way to diversify their interests, and many Florida companies were bought up and consolidated. The industry peaked in the 1980s, when about one-fourth of all the phosphate in the world came from Florida. Much of this was shipped through Tampa Bay.
All of this wealth came at a cost, however. As the environmentalist movement gained power in the 70s and 80s, the phosphate industry was the focus of attack. The mining process was destructive and dirty: huge steam shovels would strip-mine the surface, and a single mining operation could strip thousands of acres to a depth up to 60 feet. The deposits would then be mixed into a watery slurry and treated with a variety of toxic chemicals and allowed to settle in huge tanks or artificial ponds, and the waste clay and sand (much of it mildly radioactive) would then be piled up onsite into “stacks” several hundred feet high, sometimes to slowly seep chemicals into the underground freshwater aquifers. These holding ponds were toxic and highly acidic, and leaks, tropical storms, and mechanical failures caused a number of spectacular fish kills in the Peace River and in Tampa Bay. Florida responded by passing laws requiring “reclamation”—once an area was mined out, the companies had to then restore the land back to its original ecological wetland or upland pine-palmetto forest conditions.
The mines also use a huge amount of water during their operations, both to extract the phosphates and to dilute their toxic waste products. As Florida faces an increasingly more serious water-supply issue, that has become the focus of many concerns.
By the 1990s, therefore, although the estimated reserves that still remain were calculated at about 300 years’ worth of world consumption, the Florida phosphate industry was in decline. The owners griped that this was caused by the “burdensome regulations”, but it was really due to geoeconomics—China had emerged as the largest source of phosphates in the world, and American mines simply could not compete with the cheaper Asian operations. By 2020, only two major mining companies remained in Florida, the Potash Corporation of Saskatchewan (PCS) and Mosaic. (A third one, the Mulberry Corporation, went bankrupt in 2001.) They ship most of their raw phosphate to China for processing.
In a typical year, the Port of Tampa still ships out around 11-12 million tons of phosphate, making up almost 90% of all outbound cargo. Phosphate processing plants, with their associated piles of clay and sand, can still be seen along the shore at the Port.