Aluminium is one of the primary factors that reduce the growth of plants on acidic soils. In acid soils the concentration of toxic Al cations increases and disturbs the growth and function of the root. It is generally harmless to plant growth in pH-neutral soils. Wheat has developed a tolerance to aluminium. It releases organic compounds that bind to harmful aluminium cations. Sorghum is thought to have the same method of tolerating aluminium.