Maury Soil Series

Maury soil covers the gently rolling ridges and slopes of the Nashville Basin, sitting wherever the limestone bedrock has weathered deeply enough to build a full residual profile. The terrain is smooth enough for row crops and pasture on most slopes — a contrast to the rocky, dissected Highland Rim plateau that rings the basin on all sides and is far harder to farm.

Maury is an Alfisol, defined by an argillic horizon — a clay-enriched subsoil that formed as particles leached downward and accumulated. The surface is brown silt loam. The subsoil turns yellowish red within a foot, then deepens to brick red clay by two feet. The red color comes from iron oxides, and the subsoil can extend six feet or more before reaching the weathered limestone residuum at the base.

The soil is deep, well drained, and nearly neutral to slightly acidic in the surface layers — a consequence of the calcium carbonate in the parent limestone buffering acidity over time. That near-neutral pH, combined with the phosphate parent material, gives Maury its exceptional natural fertility without heavy amendment.

The Maury series is named after Maury County, Tennessee, in the heart of the Nashville Basin south of Nashville. Maury County has been one of the most productive agricultural counties in the state since the early 1800s, when planters recognized the unusual depth and fertility of its red clay limestone soils. USDA soil scientists formally described and named the series there during early-twentieth-century federal soil surveys.

The Soil Science Society of America recognizes Maury as Tennessee's state soil because it represents the Nashville Basin — the physiographic and agricultural center of the state that drew the heaviest settlement, produced the most valuable crops, and gave middle Tennessee its identity as some of the finest farm country in the South.

Maury was chosen over the thin, rocky soils of the eastern mountains and the loessial soils of west Tennessee because the Nashville Basin's phosphatic limestone soils are the most distinctive geological feature of Tennessee's agricultural landscape — the reason the Nashville Basin was farmed intensively a century before the surrounding Highland Rim.

Digging into Maury soil shows a dramatic color change within the first foot. The brown, workable surface transitions within ten inches to yellowish red as the argillic clay horizon begins. By two feet it is deep brick red — dense, slick clay that holds water and smears between the fingers. Below the subsoil, reddish clay loam transitions gradually toward the weathered limestone residuum.

Maury soil covers the Nashville Basin, an oval lowland of roughly 5,500 square miles in middle Tennessee, surrounded by the Highland Rim plateau. The basin sits where the ancient Ordovician limestone bedrock is exposed at the surface, and Maury soil forms wherever that phosphatic limestone has weathered into deep residual clay. The terrain is gently rolling to rolling, with good natural drainage on the upland slopes.

The soil is most extensive in Maury, Davidson, Williamson, Rutherford, Wilson, Sumner, Robertson, and Cheatham counties — the ring of counties that form the core of the Nashville Basin — and extends into Bedford, Marshall, Smith, Cannon, and Trousdale counties on the basin margins.

Burley tobacco was the defining cash crop of Maury soil for most of Tennessee's history. Middle Tennessee's Nashville Basin counties — anchored on Maury soil — were among the top burley tobacco producers in the country through the twentieth century. The deep, fertile, nearly neutral soil suited tobacco's demand for phosphate and calcium in ways that the thinner, more acidic soils of the surrounding Highland Rim could not match.

Corn and soybeans now dominate the row-crop acres on Maury soil. Tennessee consistently ranks in the top tier of southeastern states for soybean production, with the Nashville Basin counties contributing disproportionately to that output. Winter wheat and grain sorghum are also grown in rotation across the basin.

Tall fescue and orchard grass pastures cover a large share of Maury soil farmland. The near-neutral pH and high natural phosphate make Maury land exceptionally productive for cool-season grasses without heavy fertilization. This is Tennessee Walking Horse country — the Maury County seat of Columbia is the home of the Tennessee Walking Horse National Celebration held annually in nearby Shelbyville, and the same phosphate-rich pastures that built thoroughbred racing in Kentucky's Bluegrass extend into the Nashville Basin.

Where Maury soil is forested, the canopy is eastern red cedar, white oak, chinquapin oak, and blue ash — species adapted to the near-neutral, calcium-rich conditions of a limestone-derived soil. Eastern red cedar colonizes abandoned Maury soil fields aggressively, making it the first woody species to reclaim cleared land across the Nashville Basin.