o Soil nitrogen – forms, symbiotic nitrogen fixation, factors affecting nitrogen fixation
o Soil phosphorus - forms, mechanism of phosphorus fixation, factors affecting phosphorus availability in soils
o Soil potassium - forms, mechanism of potassium fixation, factors affecting the potassium fixation in soils
o Micronutrients – Source of micronutrients in soils; factors affecting their availability
· Aithal, S. C. and Kulkarni, N. S. (2010). Modern Approaches in Soil, Agriculture and Environmental Microbiology. New Delhi. Himalaya Publishing House.
· Alexander, M. (1977). Introduction to Soil Microbiology. Wiley. New York.
· Bhatia, S. C. (2011). Environmental Chemistry. New Delhi. CBS Publishers and Distributors Pvt. Ltd.
· Dubey, R. C. and Maheshwari, D. K. (2013). A Textbook of Microbiology. New Delhi. S.Chand and Company Pvt. Ltd.
· Gupta, P. K. (2010). A Handbook of Soil, Fertilizer and Manure. Agrobios India.
· Kolay, A. K. (2017). Basic Concepts of Soil Science. New Delhi. New Age International (P) Ltd. Publishers.
· Krishna, K. R. (2002). Soil Fertility and Crop Production. New Delhi. Oxford and IBH Publishing Co. Pvt. Ltd.
· Maier, R. M., Pepper, I. L. and Gerba C. P. (2000). Environmental Microbiology. New York. Academic Press.
· Manisegaran, S. and Soundararajan, R. P. (2010). Pest Management in Field Crops: Principles and Practices. Agrobios India.
· Mishra, P. C. (2001). Soil Pollution and Soil Organisms. New Delhi. APH Publishing Corporation.
· Pal, S. K. (2017). A Textbook of Soil Science. New Delhi. Oxford and IPH Publishing Co. Pvt. Ltd.
· Pelczar, M. J., Chan, E. C. S. and Krieg, N. R.(2003). Microbiology. 5th Edn. Tata McGraw-Hill Publishing Company Limited. New Delhi.
· Rai, M. M. (2002). Principles of Soil Science. Macmillan India Ltd. New Delhi.
· Sharma, S. (2017). Soil and Biogeography. New Delhi. Random Publications.
· Shukla, P. K. (2017). Organic Farming Principles, Methods and Practices. Jaipur. Yking Books.
· Singh, R. P. (2015). Microbiology. New Delhi. Kalyani Publishers.
· Singh, T., Purohit, S. S. and Parihar, P. (2012). Soil Microbiology. Agrobios India.
· Sodhi, G. S. (2008). Fundamental Concepts of Environmental Chemistry. New Delhi. Narosa Publishing House.