Phosphorus (P) and potassium (K) are the major essential macronutrients required for the biological growth and development of crop. However, the concentrations of soluble P and K in soil are usually very low and the large proportions of in soil are insoluble rocks, minerals and other deposits. Microorganisms play a key role in the P and K cycle. Microbial activity may release the insoluble phosphorus and potassium accumulated in soils and makes them available for plants. Besides, bacteria may increase the soil fertility and promote the plant growth. Therefore, these potassium and phosphorus based bio-fertilizer application to soil has been the main focus of many farmers and researchers for the past few years. This book has highlighted the analytical methods of isolating and screening of bacteria solubilizing both potassium and phosphate mineral in in-vitro condition and effect on maize crop. It should furnish you with some scientific background on mineral potassium and phosphate solubilization as well. This book should be beneficial to those who are interested in organic agriculture and biofertilizer production.