Oklahoma has an iconic red soil that can almost appear like red desert sand creating a vibrant, unique look to the area.
This soil is found right across the state through Oklahoma City and Tulsa.
To put a long story of geology short, Oklahoma soil is red as a result of red sediments deposited by rivers carried downstream from red rocks in the west of the USA.
This sediment is iron rich and was formed and moved around the earth to get where it is in Oklahoma quite a bit. Creating an interesting story of history and geology.
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What makes Oklahoma soil red?
The soil in Oklahoma is red because there is a reddish colour to the Port Silt Loam, the name of the soil native to the region.
Port Silt Loam is usually found along flood plains, and Oklahoma is for the most part on the flood plain of the Arkansas River and also the Red River which has flooded many times throughout recent history.
The red soil forms as a result of ferric oxide rich sedimentary rock being weathered away upstream towards the west of the USA and deposited in Oklahoma soil during times of flood.
Ferric oxides give sandstones, shale and siltstones their red look and create the old red sandstone most commonly found throughout the west of the USA and places in Europe.
In fact, this red sandstone found in the west of the USA, northern Europe and Greenland were all part of the same continent a very long time ago!
This continent was called Laurasia and collided with Gondwana 300 million years ago to create the most famous super continent that formed the world we know today called Pangea.
This video of the history of the continents outlines this very well.
Why is the Red River red in Oklahoma?
The red river is a river that flows along the southern border of Oklahoma, bordering Texas. It is sometimes therefore called “the red river of the south”.
It gains its colour for the same reason as the soil does. From picking up the red bedded rock sediments and carrying it downstream.
What grows well in Oklahoma soil?
Because of the Iron rich soil in Oklahoma, the soil becomes slightly acidic.
This means plants that prefer soils that are around 5.5PH (slightly acidic) will thrive in this environment given the weather is also preferable.
Planting in bare soil is a great alternative to potting soil. Especially if you find you don’t know if you potting soil is still able to be used.
Iron is also beneficial for plants but plants only require a small amount. Therefore it is not as if additional Iron in the soil like in Oklahoma will have any drastic positive effects.
Any type of deciduous tree will generally grow well in the slightly acidic soils of Oklahoma. These can include Beech trees, Oak trees or Magnolias.
Vegetables and beans that are able to be planted in the soil during early spring when the weather is cooler are also safe bets. Often coming in the form of leafy greens and tubers.
- Beetroot
- Broccoli
- Cabbage
- Onions
- Peas
- Potatoes
- Spinach
- Kale
- Collards