|Reddish brown, iron containing, light colored soil|
|Yellow, iron containing, light colored soil|
|Dark, humus rich soil|
Light colored soils: Any light colored soil no mater what shade indicates the soil has a low humus content. These are often rain forest or desert soils. Rain forests are too hot and wet for humus to accumulate in the soil, it simply breaks down too much. Deserts are also often too hot for humus to accumulate and don't have much plant material to produce it. Light color often indicates the soil is leached, or nutrients have been washed out of it. This all makes light colored soils nutrient poor. For the gardener with light colored soil you can simply add compost to it, making your soil more productive. The yellow and reddish brown soil pictures above are examples of light colored, humus poor soil.
|Soil with high amounts of calcium carbonate.|
|Gray colored soil.|
There are a few other soil colors that are a lot less common. One of the more rarely seen and interesting is purple soil. Purple soil has a strong sulfur smell and results from sulfur bacteria that grow when a soil is waterlogged for a long period of time. Which brings up another interesting point, soil smell. As odd as it might sound a lot of soils have different smells to them. Anaerobic, soils without oxygen, have a sulfur smell to them. While aerobic soils, soils with oxygen, have a different smell. Soils with and without certain nutrients or humus also have different smells. These smells are a result of different soil microbes like bacteria and fungi, which also contribute to soil color. I have kind of learned some of these smells with experience and occasionally they can be useful. Yes, soil covers all the senses; sight, smell, touch, sound in some cases, and some people tell me taste (though I haven't tried it)!