Total sulfur in soil includes both organic and inorganic forms, such as sulfates and sulfur in organic matter. Sulfur is essential for protein synthesis and enzyme functions in plants. Deficiency leads to stunted growth and yellowing of leaves. Total sulfur provides insight into the soil's potential to release plant-available sulfur over time, critical for sustaining crop health. Source: Havlin, J.L., et al. (2014). Soil Fertility and Fertilizers.