Farmers use fertilizer to prime their soil for optimal plant growth. Important components of plant growth are lost when plants use them. Fertilizer restore these important elements.
The most important component of fertilizer is the nitrogen it contains. Plants need a significant amount of nitrogen to grow, and they cannot absorb it through the air. Farmers test their soil for nitrogen levels and use fertilizer with the right amount to let their plants grow as quickly as possible.
Fertilizer contains other important elements as well. Phosphorous and potassium are important for cellular function, and low levels stunt plant growth. Calcium, magnesium and sulfur are also contained in most fertilizer. Manure is sometimes used to increase the nitrogen levels of soil, but it lacks many of the other chemicals plants need.
In the wild, plants that die decompose on the ground and leave behind the elements they absorbed while they were alive. Farming, however, requires removing plants after they have grown. Soil health is an essential part of farming, and small oversights can be disastrous for farmers and for food supplies. While older farming techniques might mitigate some of the soil harm from large-scale farming, modern agriculture depends on fertilizer to prevent food shortages and famines.