Joseph E. Boggs & Derek P Lucero 
Soil Fertility [PDF ebook] 

Soil fertility refers to the amount of nutrients in the soil, which is sufficient to support plant life. Soil fertility is critical in sustainable farming and needs to be considered not only for crop productivity but also for the protection of aquatic environments. Fertile soil has an abundance of plant nutrients including nitrogen, phosphorus and potassium, an abundance of minerals as well as an abundance of organic matter. This book discusses new developments in the field.