Magnesium is naturally found in some types of clay soils. Clay soils with high magnesium are composed of the type of clay that can be used for pottery because the magnesium binds the clay together. Magnesium is important for plant metabolic processes, especially in chlorophyll production and in the uptake of phosphorus. Too much magnesium can “bind up” your soil so that water and nutrients do not penetrate well, in addition to causing high pH. You can add magnesium either with or without calcium depending on the amendment you use.
Sulfur (S) is an important nutrient often forgotten as a needed element in the soil’s mineral bank. Though it exists as elemental sulfur in some places on earth, sulfur is usually found as a natural compound, such as gypsum. Like nitrogen, it is also an important ingredient for the fabrication of proteins. A soil very high in sulfur can be acidic, but it takes an extremely high amount to cause damage to plants. Soil sulfur can be added to lower the soil pH.