What is the primary substance used to lower pH levels in soil?

The primary substance used to lower pH levels in soil is sulfur. When applied to the soil, sulfur undergoes a biochemical process whereby it is oxidized to form sulfuric acid. This acidification lowers the soil pH, making the environment more acidic. This is particularly useful in soils that are too alkaline, allowing for better nutrient availability for certain crops and improving overall soil health.

Other substances like lime are often used to raise pH levels rather than lower them, while salt and carbon do not directly serve the purpose of adjusting soil pH significantly. Understanding the role of sulfur in soil management is key for horticulturists and agronomists looking to optimize growing conditions for various plants.