Sulfur Application Calculator

About this calculator

Garden soil that is too alkaline for acid-loving plants like blueberries, azaleas and rhododendrons can be acidified by working in elemental sulfur, which soil bacteria (mainly Thiobacillus species) slowly oxidize into sulfuric acid over weeks to months, gradually lowering pH rather than shocking the soil the way a fast-acting acidifier would. How much sulfur is needed depends heavily on soil texture: clay soils have far more buffering capacity (cation exchange capacity) than sandy soils, so the same pH drop can take two to three times more sulfur in clay than in sand.

This calculator combines your current and target pH, soil texture, and treatment area to estimate the pounds of elemental sulfur required, following the same rate tables extension services publish for home gardeners and small-scale growers. Because the reaction is bacterially driven, applications are typically split and worked into the topsoil weeks before planting rather than applied all at once.