Question

Why do human modifications to the nitrogen cycle decrease soil fertility?

Answer 1

The nitrogen cycle is a biogeochemical cycle in which nitrogen is transformed into numerous chemical forms as it moves through the atmospheric, land, and sea ecosystems. Nitrogen conversion can take place through both biological and physical processes. Fixation, ammonification, nitrification, and denitrification are all important processes in the nitrogen cycle.

Complete answer:
As ammonium builds up in the soil, bacteria convert it to nitrate, which releases hydrogen ions and contributes to the acidification of the soil. In addition to increasing the stripping of highly water-soluble nitrate into groundwater or streams, nitrate buildup encourages the emission of nitrous oxides from the soil. Because the nitrates are negatively charged, they carry positively charged alkaline minerals like magnesium, calcium, and potassium with them. As a result, human changes to the nitrogen cycle can diminish soil fertility by hastening the loss of calcium and other essential elements for plant growth.

Nitrogen compounds make up between 40% and 50% of the dry matter in protoplasm, the live material of plant cells. As a result, growing plants necessitate enormous amounts of N, which is the key to soil fertility. Plants that aren't $N_2$-fixers, such as cereals, get all of their nitrogen from the soil.

According to a new study, humans are overloading ecosystems with nitrogen due to the burning of fossil fuels and an increase in nitrogen-producing industrial and agricultural activities. While nitrogen is necessary for life, excessive amounts can be harmful to the environment.

The nitrogen cycle is a series of events in which nitrogen passes through both living and nonliving organisms, including the atmosphere, soil, water, plants, animals, and microbes. Nitrogen must change forms in order to proceed through the various stages of the cycle.

Note:
Denitrification. By turning nitrate ($NO_3^-$) back to gaseous nitrogen, denitrification completes the nitrogen cycle ($N_2$). The agents of this process are denitrifying bacteria. These bacteria derive energy from nitrate rather than oxygen, releasing nitrogen gas into the atmosphere.