Which nitrogen cycle process primarily converts organic nitrogen to ammonium, making it available for nitrification and plant uptake?

Which nitrogen cycle process primarily converts organic nitrogen to ammonium, making it available for nitrification and plant uptake?

• A. Nitrification
• B. Ammonification
• C. Immobilization
• D. Denitrification

Answer: (B)

The main concept here is how organic nitrogen becomes a form plants can use. Ammonification, also called mineralization, is the process by which microbes break down organic nitrogen in dead matter and waste (proteins, amino acids, etc.) and release ammonium (NH4+). This step makes nitrogen available for plant uptake and also provides substrate for the next stage of the nitrogen cycle, nitrification, where ammonium is oxidized to nitrite and then nitrate. Keeping that in mind, nitrification is the conversion of ammonium to nitrite and nitrate, not the release of ammonium from organic matter. Denitrification reduces nitrate back to gaseous nitrogen, removing usable nitrogen from the soil. Immobilization is when microbes take up inorganic nitrogen and convert it into organic microbial biomass, temporarily making nitrogen less available to plants.

The main concept here is how organic nitrogen becomes a form plants can use. Ammonification, also called mineralization, is the process by which microbes break down organic nitrogen in dead matter and waste (proteins, amino acids, etc.) and release ammonium (NH4+). This step makes nitrogen available for plant uptake and also provides substrate for the next stage of the nitrogen cycle, nitrification, where ammonium is oxidized to nitrite and then nitrate.

Keeping that in mind, nitrification is the conversion of ammonium to nitrite and nitrate, not the release of ammonium from organic matter. Denitrification reduces nitrate back to gaseous nitrogen, removing usable nitrogen from the soil. Immobilization is when microbes take up inorganic nitrogen and convert it into organic microbial biomass, temporarily making nitrogen less available to plants.