A global analysis of nitrogen use efficiency a measure of the amount of nitrogen a plant takes in to grow versus what is left behind as pollution says that using too much fertilizers will lead to increased pollution of waterways and the air. Currently, the global average for nitrogen use efficiency is approximately 0.4, meaning 40 per cent of the total nitrogen added cropland goes into the to the environment, says as study. More than half of the world's population is nourished by food grown with fertilizers containing synthetic nitrogen, which is needed to produce high crop yields. Plants take the nitrogen they need to grow, and the excess is left in the ground, water and air. This results in significant emissions of nitrous oxide, a potent greenhouse and ozone depleting gas, and other forms of nitrogen pollution, including eutrophication of lakes and rivers and contamination of river water.

Correct Option (A)

The passage highlights a critical global issue: low nitrogen use efficiency (NUE) in agriculture. It states that while synthetic nitrogen fertilizers are essential for high crop yields and global food security, a significant portion (approximately 60%) is not utilized by plants, leading to severe environmental pollution. This pollution manifests as nitrous oxide emissions (a potent greenhouse gas), eutrophication of waterways, and contamination of river water. Therefore, the most logical and crucial message is that enhancing nitrogen use efficiency is imperative to simultaneously ensure sustained food production and mitigate environmental degradation.

Incorrect Options:

• Option (B) is incorrect because while the passage acknowledges the current necessity of synthetic nitrogen fertilizers for food security, its central message is not about the impossibility of stopping their production or the absence of alternatives. Instead, it emphasizes the need to improve the efficiency of their application to reduce adverse impacts.
• Option (C) is incorrect because the passage does not advocate for identifying and cultivating alternative crops that require less nitrogen. Its focus is on optimizing the management and utilization of nitrogen within existing agricultural practices to minimize waste and pollution, irrespective of the crop type.
• Option (D) is incorrect because the passage does not propose a complete replacement of conventional agriculture with agroforestry, agroecosystems, or organic farming. While these are alternative agricultural systems, the passage's core message pertains to improving nitrogen management and efficiency within the context of current fertilizer use, rather than advocating for a fundamental shift in farming methods.