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). Similar but distinct from soil health, soil fertility can be viewed as a function of the biological, physical, and chemical characteristics of soil that supply plant nutrient requirements.
Holistically, a healthy and fertile soil must have: good structure and drainage, sufficient depth for root growth, sufficient (but not excessive) nutrient availability, small weed, insect pest, and plant pathogen populations, large populations of beneficial organisms (including microbes), no toxins, and resilience to adverse conditions.