What is the impact of excessive nitrogen on crops?

Excessive nitrogen in crop production can lead to luxury consumption and environmental pollution, which is why this answer is correct. Luxury consumption occurs when plants absorb more nutrients, including nitrogen, than they actually need for optimal growth. This can lead to an imbalance in nutrient uptake and negatively affect crop health.

Moreover, an oversupply of nitrogen can contribute to environmental issues such as water quality degradation. Nitrogen can leach from the soil into nearby water bodies, leading to eutrophication—excessive nutrient loading that causes algal blooms and oxygen depletion in aquatic ecosystems.

Considering the other choices, while nitrogen is essential for plant growth and might initially seem beneficial, it does not enhance drought resistance, improve soil structure, or necessarily contribute positively to soil quality in the long term when applied excessively. In fact, poor soil quality can result from improper management of nitrogen levels, but this is a secondary concern compared to the immediate issues of luxury consumption and the potential for environmental pollution.