For thousands of years, South Florida’s landscapes have been shaped by rich organic soils known as Histosols. These unique soils play a crucial role in agriculture, water management, and environmental conservation. While they are essential for Florida’s economy and ecology, Histosols face increasing challenges due to changes in climate and land-use practices. The publication ”Histosols of South Florida: Past, Present, and Future” by UF/IFAS researchers and USDA/NRCS provides an in-depth look at the characteristics, distribution, and management.

Histosols, commonly referred to as peat or muck soils, are rich in organic material. They form in waterlogged environments where plants decompose slowly. Unlike mineral soils, they contain more than 20-30% organic matter by weight. They often reach depths greater than 40 centimeters (nearly 16 inches). These soils are highly productive but require careful management. This is due to their susceptibility to oxidation when drained, commonly referred to as soil “subsidence.”

Distribution

Histosols cover approximately 4.23 million km² worldwide–approximately 3% of the Earth’s soils. They are found in cold, wet regions like Canada, Russia, and Northern Europe. The United States contains about 7.7% of the world’s Histosols. Florida is home to approximately 16,000 km², representing 17% of the U.S. total. These soils are predominantly located in the Everglades, forming the largest contiguous organic soil area in the continental U.S. They provide critical ecosystem services, including carbon sequestration and water filtration, while also supporting Florida’s robust agricultural industry.

Histosols develop under anaerobic (water-saturated) conditions, preventing the rapid breakdown of organic material. Five key factors contribute to their formation:

1. Parent Material: Unlike mineral soils, Histosols form from accumulated organic plant debris in wetland environments.
2. Climate: Florida’s warm, humid conditions extend the growing season, ensuring a continuous supply of organic material.
3. Vegetation: Wetland plants like sawgrass contribute to organic matter accumulation and influence their properties.
4. Topography: These soils develop in low-lying areas like floodplains, marshes, and swamps.
5. Time: In Florida, they have been forming for more than 3,200 years, shaped by gradual sea-level changes and wetland dynamics.

Properties, Land Use & Management

Histosols exhibit unique physical, chemical, and biological properties that influence their use and management. These soils have low bulk density and high porosity, making them prone to subsidence when drained. They can hold large amounts of water, supporting wetland ecosystems and agriculture. They are naturally fertile and acidic. However, the Histosols of South Florida have high pH due to the influence of underlying calcareous bedrock.

The Everglades Agricultural Area (EAA) relies on Histosols for sugarcane, rice, sod, and vegetable production. However, prolonged drainage of these soils leads to oxidation and subsidence, threatening long-term agricultural viability. Beyond farming, the soils act as carbon sinks, filter water, and provide habitats for diverse wildlife. Changes in weather patterns and rising sea levels pose significant risks, potentially altering wetland hydrology and accelerating soil loss. Careful management is needed to address the challenges Florida’s Histosols face, including balancing agricultural needs with conservation efforts. Also, strategies such as controlled water table management, conservation tillage, cover crops and rotational rice farming can help slow soil loss.

You can read the full EDIS publication here: https://edis.ifas.ufl.edu/publication/SS741

Featured image: UF/IFAS Photo by David Stevens

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