Why do you need fertilizers for gardening or farming? Do plants not grow in the wild without any fertilizers? The answer to this question lies in the fact that you want only specific species of plants to grow in a farm or a garden.
Soil, in the farms as well as the wild, has nutrients in it. But the proportion of minerals is different in different places. Within a field also, the nutrient content is not uniform. In the wild, plants most suitable to the soil and other conditions grow and you don’t have any control over their growth. However, since you want to grow only the favored variety of plants in your garden or farm, you need to add nutrients according to the needs of that variety and availability in your soil.
Moreover, in a partially covered piece of land such as a farm, the soil nutrients are taken up by the plants, but are not replenished when the plants or their leaves die. Hence you require fertilizers to enrich the nutrient-deficient soil and create artificial conditions for higher productivity of the plants.
What are these nutrients required by plants? The most commonly required plant nutrients are nitrogen (N), phosphorus (P) and potassium (K). Almost all fertilizers are categorized according to their Nitrogen-Phosphorus-Potassium or N-P-K value. Nitrogen is required for the growth of vegetative parts such as the stems and the leaves. Your plants will have healthy roots if they get sufficient phosphorus. Phosphorus is also required for good flowers and fruits. Potassium makes the plant healthy by facilitating the circulation of nutrients within the plant.
In addition to N-P-K, plants also require other nutrients such as calcium and magnesium. Since these are required in small quantities, you need not add them separately unless in exceptional cases, where your soil is really devoid of these minerals or the crop you wish to grow requires them in large quantities.
