BOTANY

Detailed explanation-1: -The topsoil is usually darker than lower layers (or horizons) because this is where organic matter accumulates. Soil colour is usually due to 3 main pigments: black-from organic matter. red-from iron and aluminium oxides.

Detailed explanation-2: -Topsoil is the upper layer of soil. It has the highest concentration of organic matter and microorganisms and is where most of the Earth’s biological soil activity occurs.

Detailed explanation-3: -Organic matter tends to make the soil color darker. Humus, the final stage of organic matter breakdown, is black. Throughout the stages of organic matter breakdown, the colour imparted to the soil varies from browns to black. Sodium content influences the depth of colour of organic matter and therefore the soil.

Detailed explanation-4: -This layer is also called the humus layer, which consists of rich decomposed material and organic matter. That’s why the topsoil has a dark brown colour. The humus makes the topsoil soft and porous to hold enough air and water. This is the layer where seeds germinate and roots of the plants grow.

Detailed explanation-5: -The topsoil is usually the darkest layer of the soil. It is the layer with the most organic material. Humus forms from all the plant and animal debris that falls to or grows on the ground. The topsoil is also the region with the most biological activity.