Pedology is the scientific study of soil, its formation, properties, and classification. This field of study focuses on understanding the physical, chemical, and biological characteristics of soil, as well as the processes that shape and modify it over time.

Option 1 - Light: Light refers to the electromagnetic radiation that is visible to the human eye. While light is important for various biological processes, it is not the subject of study in pedology.

Option 2 - Soil: This is the correct answer. Pedology is specifically concerned with the study of soil and all its aspects, including its composition, structure, and fertility. This field helps scientists understand how soils are formed and how they function in supporting plant growth and sustaining ecosystems.

Option 3 - Temperature: Temperature refers to the degree of hotness or coldness of a substance. While temperature can have an impact on soil properties, it is not the main focus of pedology.

Option 4 - Water: Water plays a crucial role in soil formation and its availability affects various soil processes. However, pedology includes the study of water within the context of soil, rather than being solely focused on water itself.

Therefore, the correct answer is option 2: soil.