Fertile soil is one which

Fertile soil is one that contains all essential plant nutrients in suitable proportions. Fertile soil is rich in nutrients, such as nitrogen, phosphorus, and potassium, that are essential for plant growth and development. It also contains other important minerals and organic matter that support the health of the soil and the plants growing in it. A soil that is fertile will produce a good harvest of crops, including cowpea, because the plants are able to access the nutrients they need to grow strong and healthy. In addition to being rich in nutrients, fertile soil is also well aerated and easily drained, which allows the roots of the plants to access air and water, two critical components of healthy plant growth.