Answer to Question #124000 in Chemistry for Jesty

Question

Continuous application of nitrogenous fertilizers leads to soil acidification. Explain

Answer 1

There are three common nitrogen fertilizers: NH₄NO₃, urea, and anhydrous NH₃. Although these fertilizers are not acidic, they may be converted into acidic compounds in the soil. In particular, microbial oxidation of nitrogen fertilizers leads to the production and release of free protons H⁺ into the soil. The of conversion of ammonium to nitrate is called nitrification. As a result, long-term application of nitrogen fertilizers lowers the soil pH. The bacterial reactions of the fertilizers nitrification are:

NH₄⁺ + 2O₂ = 2H+ + NO^- + H₂O (nitrification of ammonium)

NH₄NO₃ + 2O₂ = 2H⁺ + 2NO₃^- + H₂O (nitrification of ammonium nitrate)

CO(NH₂)₂ + 4O₂ = 2H⁺ + 2NO₃^- + H₂O + CO₂ (hydrolysis of urea and nitrification of products)