In its pure form, chromium is a steel-gray, lustrous hard metal that has a high polish. It has many compounds that are all colored. [See Periodic Table of the Elements] Of the compounds, the most important are the chromates of sodium and potassium; the dichromates; and potassium and ammonium chrome alums.
Raising pH The ideal pH range for soil is from 6.0 to 6.5 because most plant nutrients are in their most available state. Ifa soil test indicates a pH below 6.5, the usual recommendation is for the application of ground limestone. Inaddition to having the ability to raise pH, limestone contains calcium. Lowering pH Some soils are alkaline and have a pH above 6.5. Some fertilizers (ammonium sulfate, urea, and ammoniumnitrate) create an acid reaction in the soil, so they aid in lowering or maintaining a specific pH.
Treatment of High pH Soil. Fertilizers and chelates can be added to soil to increase concentrations of plant nutrients. It is important to note that addition of phosphate fertilizer alone will further reduce the availability of other nutrients. Lowering the pH of alkaline soils, or acidifying the soil, is an option.