Fundamentals of Soil Health and Fertility

Soil health (or soil quality) has been defined as the capacity of a soil to sustain plant and animal productivity, maintain or enhance water and air quality, and support human health and habitation over a human time scale (thousands of years). Similarly, soil fertility can be viewed as a function of the biological, physical and chemical characteristics of soil. 

In more specific terms, a healthy and fertile soil must have: good tilth and drainage, sufficient depth for crop growth, sufficient exchangeable nutrient supply (not excessive or prone to leaching), small population of weeds, insect pests or plant pathogens, large population of beneficial organisms (including microbes), no toxins, and resilience to adverse conditions.