Potassium Solubilizing Bacteria: An Insight

Potassium Solubilizing Bacteria: An Insight

Anandkumar Naorem, Shiva Kumar Udayana, Sachin Patel
DOI: 10.4018/978-1-7998-7062-3.ch010
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Potassium (K) is one of the essential nutrients required for plants. Although the total pool of K in the soil is generally large, the bioavailable portion is meager. There are several mechanisms through which the insoluble K can be made available through soil microbes called “potassium solubilizing bacteria” or KSB. They play an important role in increasing the solubility of K for proper crop establishment under potassium deficient soils through the production of organic and inorganic acids, acidolysis, polysaccharides, complexolysis, chelation, and exchange reactions. Moreover, they also produce specific exopolysaccharides and biofilm that enhances the weathering of the K-rich minerals and increase the K concentration in the soil solution. Hence, the production and management of biological fertilizers containing KSB can be an effective alternative to chemical fertilizers. This chapter presents the underlying mechanisms and their role in providing sufficient K to the crops.
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Factors Affecting Potassium Dynamics In The Soil

K is the most abundant cation in plant cells (White, 2003) and constitutes approximately 2.6% of the earth's crust. Naturally, igneous and sedimentary rocks are rich in K. Mineral soil K concentration could range from 0.04-3% in the lithosphere (Syers, 2003). The surface soil can contain 3000 to 1000000 kg K per hectare of soil. Around 98% of the total K is found in non-exchangeable form, and the remaining 2% is soluble and is available for plant uptake (Figure 1). The non-exchangeable form of K is firmly bound in negatively charged interlayers of the mineral, and it is moderately to sparsely available for plant uptake governed by the existing soil conditions. As there is an equilibrium between available and unavailable pools of K in the soil system, these trapped K+ is released when the K level in the soil solution decreases through plant uptake or leaching or erosion related losses. However, the release of the exchangeable and non-exchangeable K from the minerals depends on several factors (Jackson, 1964):

Key Terms in this Chapter

Potassium Fixation: The conversion of bioavailable potassium into any form of potassium that are not available to plants and soil microbes.

Potassium Solubilization: The conversion of unavailable form of potassium to bioavailable potassium through microbial or chemical induced processes.

Potassium Pools: Different types of potassium in the soil that vary in sizes and its bioavailabilty to plants and soil microbiota.

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