Correct option is A
The correct answer is (a) Industrial production of fertilizers.
The industrial production of fertilizers, primarily through the Haber-Bosch process, is the largest contributor of nitrogen to the global nitrogen cycle. This process fixes atmospheric nitrogen (N₂) into ammonia (NH₃), which is used in synthetic fertilizers. These fertilizers significantly enhance agricultural productivity but also contribute to nitrogen imbalances in ecosystems, leading to eutrophication, groundwater contamination, and greenhouse gas emissions.
While other sources like fossil fuel combustion and biological nitrogen fixation also contribute nitrogen, their impact is smaller compared to industrial fertilizer production.
Information Booster:
- Haber-Bosch Process: Converts atmospheric nitrogen into ammonia, enabling large-scale fertilizer production.
- Global Impact: Industrial fertilizers have increased global nitrogen inputs by more than 50%, primarily in agriculture.
- Environmental Consequences: Excess nitrogen runoff causes eutrophication in water bodies, leading to dead zones and biodiversity loss.
- Other Sources: Biological nitrogen fixation by legumes and fossil fuel combustion also contribute but on a smaller scale.
- Mitigation Efforts: Strategies like precision farming, crop rotation, and reduced fertilizer use aim to address nitrogen pollution.
Additional Knowledge:
(a) Industrial production of fertilizers:
This is the correct answer. The Haber-Bosch process fixes over 120 million metric tons of nitrogen annually. This nitrogen is added to agricultural systems, significantly increasing crop yields but causing ecological challenges due to overuse and runoff.
(b) NOₓ production due to combustion of fossil fuels:
This is incorrect. While fossil fuel combustion contributes nitrogen oxides (NOₓ) to the atmosphere, its contribution is smaller compared to industrial fertilizer production. NOₓ also contributes to air pollution and acid rain but is less impactful in the global nitrogen cycle.
(c) Nitrogen fixation by soybean farming:
This is incorrect. Soybeans are a significant source of biologically fixed nitrogen due to their symbiotic relationship with nitrogen-fixing bacteria, but their contribution is less than industrial fertilizers.
(d) Nitrogen fixation by cultivation of legumes (excluding soybean):
This is incorrect. While other legumes like alfalfa and clover also fix nitrogen biologically, their global contribution is smaller than that of industrial nitrogen fixation.
