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What is potash?
Potash is used primarily as an agricultural fertilizer (plant nutrient) because it is a source of soluble potassium, one of the three primary plant nutrients; the others are fixed nitrogen and soluble phosphorus.
Potassium is an essential nutrient for the growth and development of all plant and animals which is absorbed by the plant roots as cation (K+), a form in which it freely moves within growing plants.
Removal of K by crops increased considerably and mining of the K capital continued without supplementation of K from external sources and as such the soils K reserves of soil gets depleted, making K application essential to achieve high yield, high quality and high profit particularly in intensive agriculture in most soils and crops.
Potash and phosphorus are mined products, and fixed nitrogen is produced from the atmosphere by using industrial processes.
Potash in trade and extension literature:
K is often stated as K2O (its oxide form) and also referred to as potash while in research literature it is referred as in its elemental form (1kg K =1.2kg K2O).
Higher the crop yield, higher is the K requirement of crop.
About 70 -75 %of the K absorbed is retained by leaves, straw and the rest are found in grains ,fruits,nuts etc.,
As a contrast to phosphate deposits most potassium deposits are water soluble and need no further chemical processing. The Saskatchewan (Canada)deposit is the world's largest known high grade potash deposit.
K is less toxic serves as acidity neutralizing element and counters the acidic action of H in plants and animals.
Potassium is found in the largest amount in the xylem and phloem saps of most plants.
POTASH IN PLANTS:
Since the introduction of HYVs of food grains in the 1960s, tremendous progress has been made both in fertilizer use in agricultural production. However, higher production of food, fiber and other crops results in much higher removal of nutrients from the soils.
Expansion in fertilizer application continues to fall short of nutrient removals, resulting in depletion of soil fertility and negative nutrient balance sheet. Indian soils are already deficient in several nutrient with the result that medium to high yields are possible only if soil fertility is supplemented with nutrient additions through external sources.
Potassium plays an important role and is essential for controlling water status of the plants. It controls the opening and closing of stomata and therefore the photosynthesis, is involved in meristematic growth, regulates translocation of photosynthates and action of several enzymes.
Potassium activates more than 60 enzymes and is directly or indirectly involved in all major plant growth processes.
Promotes the transport of photosynthate s to storage organs of crops (seeds,roots,fruits ,tuber).
Essential for the formation and translocation of sugars in plants, potassium is of utmost importance for crops like sugarcane, Sugarbeet potato and other tuber crops.
Enhances the production of protein and thus improves the efficiency of fertilizer nitrogen.
Making plants more resistant to lodging.
Development of a healthy root -system and makes plants more resistant to poor soil aeration or conditions of poor drainage.
Improves the quality of crops and prolongs their shelf-life.
Favours the production of oil in crops such as oil palm, rapeseed, peanut and soyabean.
Develops the absorption of water by the roots and leads to water economy of the plant.
Adequate supply of K+ is indispensable for maintaining adequate turgor in young cells.
Using electron probe analysis technique Humble and Raschke (1971) showed a higher concentration of K in guard cells of open stomata.
Koch (1979) reported that stomatal resistance increased, and CO2 fixation decreased with the severity of K deficiency.
K+ plays a fundamental role in the synthesis of ATP during photosynthesis (photophosphorylation) by functioning as a counter ion for H+ influx into thylakoid membranes (Tester and Blatt.,1989).
Maintenance of high pH in the sieve -tube cells, establishment of a high osmotic potential in the phloem sap.
Partitioning of K carbohydrates between shoots and roots may also be influenced by K supply.
The release of H+ from the cytoplasm is balanced by K+ uptake, which forces the continuance of the release of H+.
Adequate K supply decreases the incidence of rust (Puccinia), powdery mildew, corn stalk rot and Stewart's wilt in cereals, leaf spot, wilt and scab in potato and pot rot in soybean.
BY KHAS.
REFERRENCE:
CROP NUTRITION -Rajendra Prasad.
TEXTBOOK OF PLANT NUTRIENT MANAGEMENT -Rajendra prasad, Dinesh Kumar, D.S. RANA, Y.S SHIVAY, R.K Tewatia.
