Repeated use of which one of the following fertilizers would increase the acidity of the soil

Options

(a) Ammonium sulphate
(b) Superphosphate of lime
(c) Urea
(d) Potassium nitrate

Correct Answer:

Ammonium sulphate

Explanation:

Ammonia sulphate is a strong acid (H₂SO₄) and weak base (NH₄OH). Therefore repeated use of ammonium sulphate would increase the conc. of sulphuric acid, while ammonia from NH₄OH is used up by the plant. Hence the acidity of soil will increase.