Which material is primarily used to decrease soil pH through bacterial metabolism?

The material primarily used to decrease soil pH through bacterial metabolism is elemental sulfur. When elemental sulfur is applied to the soil, specific soil bacteria, such as Thiobacillus, convert it into sulfuric acid during the process of oxidation. This acidification of the soil effectively lowers the pH, making the soil more acidic. This is an important practice in agriculture, especially when dealing with soils that are too alkaline for certain crops.

In contrast, calcium carbonate and sodium bicarbonate are alkaline substances that would actually raise soil pH, while magnesium sulfate, often used for its magnesium content, does not play a significant role in lowering soil pH through bacterial activity. Thus, elemental sulfur is distinct in its capacity to actively lower soil pH by utilizing microbial processes.