Integrated Fundamentals of Soil Science: Processes, Properties and Sustainable Management

This chapter examines soil fertility and nutrient management as an integrated component of sustainable soil science. It explains the classification of essential and beneficial plant nutrients, the mechanisms of nutrient acquisition in the rhizosphere, and the major biogeochemical cycles that regulate nutrient availability and loss. Particular attention is given to nitrogen, phosphorus, potassium, sulfur, and carbon because these cycles strongly influence crop productivity, nutrient use efficiency, greenhouse gas emissions, eutrophication risk, and long-term soil organic carbon dynamics. The chapter further evaluates inorganic fertilisers, organic amendments, biofertilisers, and enhanced-efficiency fertilisers, with emphasis on their soil reactions, agronomic trade-offs, and environmental implications. Soil pH is discussed as a central chemical control on nutrient solubility and fertiliser response. Conventional and emerging soil fertility assessment methods, including soil testing, plant tissue analysis, spectroscopic techniques, proximal sensing, and remote sensing, are reviewed as diagnostic tools for site-specific nutrient management. Integrated nutrient management is presented as a systems-based framework that combines organic and mineral nutrient sources, biological inputs, residue recycling, precision agriculture, and climate-smart approaches. The chapter also links soil fertility to wider soil health concepts through physical, chemical, and biological indicators. Case studies from South Asia, the US Corn Belt, sub-Saharan Africa, and Brazil illustrate how nutrient management strategies vary across contrasting agroecological and institutional contexts.