A healthy soil is one that is productive, easy to manage for the intended land use, and has properties that promote plant, animal and human health while maintaining environmental quality.
The Soil Health Knowledge Bank highlights six characteristics of healthy soils:
1. The level of soil organic matter is maintained
The amount of organic matter in a soil is an indicator of the potential sustainability of a system. The optimal level of soil organic matter for any given soil is one which supports the capacity of the soil to hold and supply water and nutrients to plants, provides energy for soil fauna, improves crop/biomass yields, and moderates net greenhouse gas emissions.
2. Balanced soil fertility
a. Nutrient additions at least match removals and losses
b. Fertility is adequate for land use
c. Nutrient storage capacity is maintained
d. Minimise nutrient loss off-site
3. Water entry, storage and supply are optimal
Production is generally limited by the capacity of soil to store and supply water to the plant. Soil texture and structure influence storage and supply.
Poor soil condition and loss of structure can result in surface sealing or compaction, reducing water entry and storage. Protection of the soil surface with groundcover and retention of organic matter will help maintain soil structure.
Healthy root growth will increase the potential to capture water moving deeper into the profile and reduce drainage and nutrient losses.
Soil compaction will decrease the ability of a soil to hold water, as well as preventing root growth.
4. Enhanced soil biological function
Organisms living in the soil assist organic matter decomposition and nutrient cycling. Factors affecting their activity include soil moisture, carbon availability, aeration, temperature, pH and plant type. A larger, more diverse microbial community competes with pathogens for nutrients and reduces the risk of disease.
5. Supports productive land uses
Soil properties and position in the landscape help determine whether the land is capable of supporting long term ecological and profitable production without degrading soil condition. Consider land uses most suitable to soil type and landscape position.
6. Enhances environmental and community health and well-being
A healthy soil provides adequate nutrients to produce healthy plant growth and produce, without the risk of contamination. Profitable whilst conserving soil resource and reducing environmental impact.
Source and more information: http://soilhealthknowledge.com.au/