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 codes given below.
✓ Correct answer: c) 2 and 3 only
ExplanationWith excessive use of nitrogenous fertilizers in agricul- ture, the necessity for nitrogen-fixing bacteria decreases as soil nitrogen levels increase.The soil becomes more acidic and ni- trate leaches into the groundwater when nitrogenous fertilisers are used excessively or inappropriately.Fertilizers in agriculture increase inputs of nutrients to soils affecting their pH value.Statement 1 is incorrect: Nitrogen-fixing microorganisms, such as Rhizobium (in leguminous plants), Azotobacter, and Cyano- bacteria (blue-green algae) fix atmospheric nitrogen into the soil.But excessive nitrogen fertilizers reduce biological nitrogen fix- ation because plants get sufficient nitrogen from fertilizers and do not depend on these microbes.Thus instead of increasing, nitrogen-fixing bacteria decrease in population due to re- duced plant-microbe symbiosis.Statement 2 and 3 are correct: The conversion of Nitrogen from one form to the other involves the generation or consump- tion of acidity and the uptake of urea, ammonium or nitrate by plants will also affect the acidity of the soil.Due to
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