What Processes Contribute Directly to Soil Nitrate Concentrations

Question

What processes contribute directly to soil nitrate concentrations?
A)Nitrification by bacteria and weathering of rock.
B)Nitrification by bacteria, but not weathering of rock.
C)Ammonification, but not nitrification by bacteria.
D)Ammonification and nitrogen fixation by bacteria.

Accepted Answer

Nitrification by bacteria is the process of converting ammonium to nitrate, which is a major source of nitrate in soil. Weathering of rock can also contribute to soil nitrate concentrations, as it releases nitrate from minerals in the rock.