A soil amendment is any additive that provides nutrients the soil would otherwise lack. Gardeners and farmers add soil amendments before plants are placed in the ground to "prepare" the soil, or they add them to the soil around a plant as it grows. Potash is a common soil amendment that supplements potassium-deficient soils and fosters healthy plant growth.
Potash is a rather vague, loosely defined term describing any source of concentrated potassium used as a soil amendment. The name originates from the ancient practice of leaving wood ash in pots and allowing bacteria to decompose them into a potassium-rich fertilizer-like substance used for gardening and farming. The United States Geological Survey (USGS) estimates that in 2008, 2.5 million tons of potash were harvested for use as fertilizer.
The Potash Development Association claims that potash is the seventh most common element in the earth's crust and one of the most abundant naturally occurring chemicals in nature. Potash is abundant in clay soils and sea water; small amounts also naturally occur in rainwater. Most of the potash harvested for fertilizer, however, is mined from rock deposits, the remnants of dried-up ancient sea beds. Manufacturers separate salt and other minerals from the rock and are left with a form of potassium that can be used in fertilizers.
Potash and Plant Nutrition
Potassium plays a vital role in plant physiology. Without it, plants would be unable to absorb water into their cells, regulate the flow of nutrients and water inside their cells or complete the process of photosynthesis. In one sense, potassium is the most important of the three essential plant nutrients (potassium, nitrogen and phosphorus), since plants take up five times more potassium than either of the other two elements. Plants that are unable to absorb enough potassium will suffer from poor root structures and stunted growth and will be more prone to drought stress and insect pests.
Any potash fertilizer can be used to supplement potassium-deficient soils, thereby avoiding the deleterious effects of potassium deficiency. Be sure to have your soil tested by a local university extension service prior to using any soil amendments and to make sure that you need to amend your soil, since overfertilizing can cause just as harmful effects to your plants as can underfertilizing.