What defines truly organic soil?
Written by
Kiana Okafor
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Genuinely organic soil is generated from natural processes with no synthetic inputs. This living system has sufficient decomposed organic matter to sustain its life-sustaining processes, including cycling nutrients and retaining moisture. It is fundamentally different from the conventional type of soil, which is dependent on chemical fertilizers. An authentically organic soil is biologically active to a measurable degree throughout the year.
The required minimum levels of organic carbon are what define 'genuine' organic soil. Research has shown that 2-3% of organic matter supports the basic functions of the soil, while 5-8% creates the ideal conditions for the full functioning of life processes. It is these levels of carbon that support the microbial populations, which are the basis of its natural fertility. Soil with less than 1% organic matter needs constant input from outside sources to maintain productivity.
Biological Indicators
- Earthworm populations exceeding 10 per cubic foot
- Visible fungal networks throughout soil profile
- Active decomposition of organic residues
- Diverse microarthropod communities
Functional Requirements
- Nutrient cycling without synthetic fertilizers
- Natural pest suppression mechanisms
- Water infiltration exceeding 2 inches per hour
- Resilience to drought and erosion
Microbial activity is the basis for the function of organic soils. Bacteria and fungal populations must exceed 108 CFU per gram of soil. These microorganisms also mineralize nutrients from organic matter, which creates natural fertilizer. I have documented a 300% increase in microbial activity in organic versus conventional soils.
Natural fertility substitutes chemical inputs through biological processes. Legumes fix nitrogen in sufficient amounts without the use of chemical nitrogen. Mycorrhizal fungi networks provide phosphorus. Potassium can be released through mineral weathering and the decomposition of organic matter.
The transition to regeneration will require a whole series of strategies to increase soil health. Introduce cover crops with deep roots to break up compacted strata. Apply compost at a rate of 10 tons per acre annually throughout the transition period. Implement rotational grazing wherever possible. Typically, soil organic matter increases by 0.5% to 1% per annum during the transition.
Read the full article: Soil Organic Matter: The Essential Guide
