1. The document discusses nutrient use efficiency and factors that affect it, such as leaching, gaseous losses, immobilization, and chemical reactions between fertilizer components.
2. It describes methods of increasing fertilizer use efficiency, including applying fertilizers at the right time and quantity, and using the proper fertilizer source and form for different crops to minimize fixation and maximize availability.
3. Integrated nutrient management is defined as maintaining soil fertility and nutrient supply through optimizing organic, inorganic, and biological components to provide balanced nutrition for crops while sustaining soil quality.