The term soil fertility refers to the "total availability, concentration, and amount or essential plant nutrients".
Plants require 16 essential nutrients for optimal growth. Nutrients are catagorized into macronutrients, secondary macronutrients, and micronutrients. Each of these is required in various amounts for optimal plant health.
Of the essential nutrients, carbon (C), hydrogen (H), and oxygen (O2) are generally found in air, water, and soil.
Soils throughout the world vary in their nutrient availability, pH, and organic matter content. Factors influencing soil fertility include soil pH, infiltration and drainage, organic matter, rooting depth, and soil organisms.
Many plants not adapted to local soils may need additional fertilizer inputs for optimum growth and development. However, many native plants adapted to local soils, may need little or no additional fertilizer application. In addition, many native adapted plants require less water than traditionally used landscape plants.
Additional Resources:
West
Oregon - Soil Fertility and Fertilizers
Midwest
Minnesota - Overview of Essential Nutrients
Southeast
Florida - Identifying Nutrient Deficiencies in Ornamental Plants
Kentucky - Principles of Home Landscape Fertilization
