Question

Brief why human modifications to the nitrogen cycle decrease soil fertility?

Answer 1

Nitrogen cycle:

1. Nitrogen cycle refers to a biogeochemical process in which atmospheric nitrogen is converted into multiple forms that can be utilised by living organisms.
2. The various steps of the nitrogen cycle are fixation, nitrification, assimilation, ammonification, and denitrification.

Human modifications decreasing soil fertility:

1. Ammonium is added to the soil by agricultural activities such as fertiliser application.
2. Ammonium accumulated in the soil is converted to nitrate by bacteria. This process releases hydrogen ions which causes soil acidification.
3. Nitrate buildup in the soil results in the emission of nitrous oxides from the soil.
4. Since nitrates are negatively charged, they carry alkaline (positively charged) minerals like calcium, potassium, and magnesium with them.
5. Hence, human modifications to the nitrogen cycle decrease soil fertility due to the loss of essential minerals.