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 ground-water can occur. Select the correct answer using the code given below.

1. Excessive use of nitrogenous fertilizers can inhibit the activity of nitrogen-fixing microorganisms in the soil because plants have readily available nitrogen and the symbiotic relationship becomes less necessary. Hence, statement 1 is incorrect. 2. Many nitrogenous fertilizers, particularly those containing ammonium (like ammonium sulfate or urea after conversion), lead to soil acidification through the process of nitrification, where ammonium ions are converted to nitrate, releasing hydrogen ions (H+) which increase acidity. Hence, statement 2 is correct. 3. Nitrate (NO3-), the form of nitrogen most readily absorbed by plants, is highly soluble in water and not well retained by soil particles. Excessive application leads to leaching of nitrate down through the soil profile into the ground-water, causing water pollution. Hence, statement 3 is correct. 4. Therefore, the correct statements are 2 and 3.