Plants require nitrogen to grow, but they preferentially absorb nitrogen in the form of nitrates. Typically, soils with higher levels of nitrates have better plant growth and higher levels of productivity.

Question

A farmer finds that his soil has high levels of nitrites but low levels of nitrates. What could the farmer add to the soil to most directly increase its concentration of nitrates?
A.
nitrogen-fixing bacteria
B.
denitrifying bacteria
C.
nitrifying bacteria
D.
decomposers

Answer 1

C. nitrifying bacteria

Nitrifying bacteria convert ammonia (produced by the decomposition of organic matter) into nitrites and then into nitrates. By adding nitrifying bacteria to the soil, the farmer can increase the concentration of nitrates, which will promote better plant growth and productivity.