What are the sources of nutrients in soil?

Nutrients in soil come from various sources such as decomposing organic matter (humus), weathering of rocks and minerals, fertilizers, and atmospheric deposition. These sources provide essential elements like nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur which are crucial for plant growth and development. Microorganisms also play a vital role in breaking down organic matter and releasing nutrients for plants to absorb.