A fertile soil is a soil that has the essential nutrients, water, and air that plants need to grow and thrive. In general, a fertile soil is one that has a good tilth, or physical structure; this means that it is well-drained and has a good water-holding capacity, as well as aeration and friability. Fertile soil also has a good balance of nutrients, including nitrogen, phosphorus, and potassium, which are essential for plant growth. Other important elements, such as calcium, magnesium, and sulfur, are also necessary for plant health. Additionally, fertile soil contains beneficial microorganisms, such as bacteria, fungi, and other decomposers, which help to break down organic matter and release nutrients back into the soil.