What is the primary function of soil bacteria?

The primary function of soil bacteria is to help decompose organic matter and fix nitrogen. These microorganisms play a crucial role in nutrient cycling within the soil ecosystem. When bacteria break down organic material, they release essential nutrients such as nitrogen, phosphorus, and potassium back into the soil. This process not only enriches the soil but also helps in the formation of humus, improving soil structure and fertility.

Furthermore, certain types of bacteria, such as nitrogen-fixing bacteria, have the ability to convert atmospheric nitrogen into a form that plants can utilize. This process is vital for plant growth, as nitrogen is a key component of amino acids, proteins, and nucleic acids. Without the action of these bacteria, plants would struggle to obtain enough nitrogen, adversely affecting their growth and the overall productivity of the ecosystem.

Thus, the role of bacteria in decomposition and nitrogen fixation is foundational to maintaining healthy soil and supporting plant life, making it clear why this option is the correct answer.