Indicate the cause of each soil colours 1. Black 2. Red 3. Gray ?

1. Black soil color is caused by the presence of organic matter, such as decomposed plant material.
2. Red soil color is caused by the presence of iron oxide, also known as rust.
3. Gray soil color is caused by poor drainage and waterlogging, which leads to a lack of oxygen in the soil and the formation of gray-colored minerals.

1. Black: Organic matter (humus) content
2. Red: Iron oxides (hematite)
3. Gray: Poor drainage and lack of oxygen