Potassium and its role in sustainable agriculture

Abstract

Apart from two major components nitrogen and phosphorous, potassium is the third essential macronutrient required for the growth and metabolism of plant, and its deficiency in plants causes poorly developed roots, slow growth, low resistance to disease, delayed maturity, small seed production and lower yields. The concentration of soluble K in soil is very small as maximum part of K exists in insoluble form. Silt, clay and sand are important components of soil in earth and biggest reservoir of potassium. Most common deposits of potassium are feldspar and mica. The available K level in soil dropped in the last decade due to rapid development of agriculture and application of imbalanced fertilizers. Potassium is released when these minerals are slowly weathered, or, alternatively, it can be solubilized by some beneficial microorganisms and made available for plants. Several bacterial and fungal strains have been identified for their ability of high potassium solubilization. Various species of Pisolithus, Cenococcum, Piloderma, Bacillus, Paenibacillus, Acidithiobacillus, Pseudomonas, Burkholderia, Aspergillus and Clostridium have been reported to release large amount of potassium from different minerals and enhance the productivity of many crops. Co-inoculation of PSMs and KSMs in conjunction with direct application of rock P and K minerals into the soil has been reported to increase N, P and K uptake, photosynthesis and the yield of plants grown in P- and K-limited soils. Thus, identification of microbial strains capable of solubilizing potassium minerals can rapidly conserve our existing resources and escape environmental pollution hazards caused by heavy application of chemical fertilizers.