This document discusses fertilizer technology and introduces various types of fertilizers. It defines plant nutrients as elements that help plants grow, categorizing them as primary, secondary, and micro nutrients. Fertilizer is defined as a substance added to soil to increase fertility and reduce nutrient deficiencies in plants. Different types of fertilizers are described, including natural organic and inorganic, straight, compound, mixed, complex, and direct or indirect acting fertilizers. The document also outlines the qualities, benefits, and drawbacks of fertilizer use.