Potash Fertilizer

What You Should Know (But Don't) About Potash Fertilizers

Potash fertilizer refers to the type of soil fertilizer that contains potassium salts and/or minerals. While the main source of this fertilizer is the potash mineral located deep inside the Earth's crust, organic fertilizer can be extracted from wood ash.
Gardenerdy Staff
Last Updated: Apr 22, 2018
The prime requirements for growth of plants are sunlight, air, water, nutrients, and other environmental factors. And the three essential plant nutrients are nitrogen (N), phosphorus (P) and potassium (K), referred to as NPK. They are already present in varying amounts in garden soil. At times, external supply of these major nutrients is necessary to meet the demands of growing plants. This is where application of potash, nitrogen, and phosphorus fertilizers, or a mixed fertilizer, comes in the picture.

What is Potash Fertilizer?

Potash fertilizer, or simply potash, is a nutrient formulation used for enriching garden soil. As the name suggests, it contains potassium as a major element. The term is derived from the Dutch word for wood ash (Potaschen). It encompasses any type of soil fertilizer that contains potassium as one of its active ingredients. Examples are potassium chloride (KCl), potassium carbonate (K2CO3) or a combination of them. Amongst these, the most popularly used type is potassium chloride, commonly called muriate of potash.

The main role of potassium in plant growth is improving the growth of roots. In addition, it helps in the photosynthesis process, activates enzymes, increases protein synthesis, and maintains turgor pressure by reducing loss of water. Another of its benefits is increasing the resistance of plants to pest infestations and drought. As compared to other potassium salts or minerals, muriate of potassium is more soluble in water. It comes in a white or reddish crystalline form.

Potassium is a highly reactive element and occurs as a dissolved form in seawater. The mines that we explore today were formed in ancient times. As water from inland oceans evaporates, potassium salt crystallizes and gets deposited as potash beds. Thus, most of the mines are located some thousands of feet from the Earth's surface. Out of the total extracted KCl salt, approximately 93 to 95 percent is utilized by fertilizer industries for use in agriculture. Another method for producing potash is by evaporating brine solution in large amounts.

Organic potash fertilizer is extracted from wood ash. On an average, it contains about 6 percent of potash by weight. Nevertheless, the amount varies in accordance to the source of material used in production. Before, corn cobs were burned down to make fertilizer. The resulting ash was found to have approximately 35% potash. Likewise, organic fertilizer made from high fibrous plants contains higher potash levels than those based on non-fibrous organic materials.

Most of the fertilizers that we purchase from the market contain nitrogen, phosphorus, and potassium in specific amounts, along with some trace nutrients (iron, magnesium, manganese, etc). The concentration of these primary nutrients can be predicted from the product label. For example, a fertilizer with 10-10-10 indicates presence of 10 percent each of N, P, and K. Thus, the last number indicates amount of potassium. If you happen to buy muriate of potash, check the label. Most likely, you will find either 0-0-60 or 0-0-63. This crystalline fertilizer contains 50 to 52% K (in potassium oxide form) and about 46% chlorine (as chloride ion).

If you are a novice gardener and don't have much knowledge about fertilization of plants, always refer to the label while applying potash fertilizer to the soil. Remember that adding an excess dose will only cause harm to the plants, rather than improving their growth. For instance, adding nitrogen-rich fertilizer to lawn grass in higher percentages will promote shoot growth and at the same time, increase production of seed heads. Overall, it decreases the aesthetic value of lawn. Similarly, excess use will stimulate more root growth and lesser shoot development.

Whether you are using the fertilizer for lawns or gardens, the thumb rule is to add in appropriate amounts. The best way to find required concentration of fertilizer is by conducting a soil test. In response to increasing potash fertilizer prices, most hobbyists now prefer using natural potassium sources as a substitute for mineral-based fertilizers. In addition to wood ash, organic seaweed fertilizers serve as good sources of potassium.