Fertilizer is a substance that is added to soil or plant tissues to provide nutrients that are essential for plant growth. There are different types of fertilizers, such as natural or organic fertilizers (e.g., manure, compost, guano) and synthetic or inorganic fertilizers (e.g., urea, ammonium nitrate, superphosphate). Fertilizers usually contain three main macronutrients: nitrogen (N), phosphorus (P), and potassium (K), which are often expressed as a ratio on the fertilizer label (e.g., 10-10-10). Fertilizers may also contain micronutrients, such as iron, zinc, copper, and manganese, which are needed in smaller amounts by plants. Fertilizers can enhance the fertility of the soil, increase crop yields, and improve the quality of agricultural products. However, fertilizers can also have negative impacts on the environment, such as water pollution, soil degradation, greenhouse gas emissions, and biodiversity loss. Therefore, fertilizers should be used wisely and according to the needs of the plants and the soil conditions.