What can be the impact of excessive/inappropriate use of nitrogenous fertilizers in agriculture? 1. Proliferation of nitrogen-fixing microorganisms in soil can occur. 2. Increase in the acidity of soil can take place. 3. Leaching of nitrate to the groundwater can occur. Select the correct answer using the code given below.

Proliferation of nitrogen-fixing microorganisms in soil can occur: This is incorrect. Excessive application of nitrogenous fertilizers can actually suppress the activity of natural nitrogen-fixing microorganisms (like rhizobia in legumes) because the plants have an ample supply of readily available nitrogen, reducing their need to form symbiotic relationships for nitrogen fixation. Over-fertilization can reduce microbial diversity and activity.

Increase in the acidity of soil can take place: This is correct. Many nitrogenous fertilizers, particularly ammonium-based ones (e.g., urea, ammonium sulfate), undergo nitrification in the soil, a process where ammonium (NH4+) is converted to nitrate (NO3-). This process releases hydrogen ions (H+), which increases soil acidity. Prolonged use can lead to soil acidification, impacting nutrient availability and crop growth.

Leaching of nitrate to the groundwater can occur: This is correct. Nitrate (NO3-), a highly mobile form of nitrogen, is not readily bound by soil particles. When applied in excess or during heavy rainfall, nitrate can easily leach through the soil profile and enter groundwater, leading to contamination of drinking water sources and contributing to eutrophication in surface water bodies.