What nitrogen fertilizer form is often considered the most efficient for lowering soil pH?

Ammonium sulfate is considered the most efficient nitrogen fertilizer for lowering soil pH primarily due to its contribution of sulfur and its ammonium nitrogen content. When ammonium sulfate is applied to the soil, the ammonium ion (NH4+) undergoes nitrification, a biological process where it is converted to nitrate (NO3-). This process releases hydrogen ions (H+) into the soil solution, thereby increasing the acidity of the soil and effectively lowering its pH.

Additionally, ammonium sulfate provides both the nitrogen needed for plant growth and the sulfate form of sulfur, which is important for various biological processes in plants and helps improve nutrient uptake. As a result, using ammonium sulfate not only aids in nutrient management but also contributes to the correction of soil pH when required.

In contrast, other nitrogen forms like urea, calcium nitrate, and ammonium nitrate either do not significantly contribute to soil acidity or may even lead to less acidity. Urea requires conversion to ammonium and nitrate through microbial activity before it can effectively influence pH, while calcium nitrate can actually raise soil pH due to the calcium content. Ammonium nitrate provides a quick release of nitrogen, but its influence on long-term pH reduction is not as pronounced as that