Importance of organic carbon in soils

Carbon is the main element present in soil organic matter, on average making up 58% by weight.I  The carbon present in soil organic matter is referred to as organic carbon. Soil organic carbon is a vital component of productive agriculture. In addition, sequestration of carbon in agricultural soils has been recognised as a tool to mitigate climate change.

Soils can preserve organic carbon, as the main component of organic matter, by forming soil aggregates and mineral-organic complexes.

High levels of organic carbon help agricultural production by playing a positive role in maintaining soil health, increasing water infiltration and holding capacity, raising fertility, reducing erosion and encouraging soil biota. Higher soil organic matter levels cause greater soil nitrogen retention, greater microbial biodiversity, and promote the presence and growth of arbuscular mycorrhizal fungi. This penetrates the roots of crops and facilitates the movement of plant nutrients from the soil into plants improving growth and yields.I I


Soil Carbon Balance

High crop yields and appropriate crop residue management are important for maintaining or increasing soil carbon levels in cultivated soils, especially when organic carbon is not provided from external sources, such as manure. The greater the amount of crop residue (e.g. straw, stubble and roots) that can be returned to the soil, the better. Recycling as much of the residues as possible from all kinds of harvested crops (trees, cereals, grazed pastures, orchards and vineyards) is beneficial for maintaining or increasing soil carbon.III

Soil carbon levels increase when carbon-based inputs are greater than the losses. The main losses of carbon from the soil are through organic matter decomposition, soil erosion and biomass burning.IV 


Building soil organic carbon with BioAg

BioAg has a range of biostimulants containing organic carbon that have been developed as a food source for plants and are beneficial to soil micro-organisms.

BioAg Soil & Seed is formulated to improve soil microbial activity. It acts as an excellent soil inoculant, feeds and expands the volume and diversity of beneficial soil micro-organisms as a catalyst to improve plant availability of both soil borne and applied nutrients. Treated soils demonstrate improved structure, water infiltration, tilth and field capacity, along with natural plant pathogen suppression.

Independent trials in a wide variety of crops attest to its efficacy in improving yield and quality. Trials studied ‘The effect of BioAg’s Soil & Seed on a range of soil samples including sandy soil, loam, clay loam’, to ascertain Soil & Seed’s effect on microbial biomass, soil nutrients within the microbial population and soil carbon levels.

The results were a significant increase in microbial biomass, on average increasing by 77% above the control. In addition, there were increases in nutrients within the soil biomass and in the level of carbon in soils.

Details of the trial are outlined in ‘Improved Microbial Biomass with Soil & Seed’. Find this article in the Trials and Demonstrations section of our website.

Humus is the organic carbon molecules formed from the breakdown of organic residues. It plays an important role in the rehabilitation of soils by increasing soil CEC, improving tilth and porosity, water availability and retention. Humic compounds play a vital role in soil aggregation, making clay more porous, soft and aerobic, with improved drainage that results in deeper root growth of all plants. Humic substances are stable, long-lasting biomolecules.V

BioAg HydraHume (humic acid) directly contributes to humus development. It is an efficient promoter of plant growth and increased root mass, while also improving the effects of fertilisers. HydraHume rapidly accelerates the microbial activity in soils, developing soil carbon and reducing nutrient lock up. HydraHume is derived from Leonardite, one of the richest sources of humic acid available.


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II – Environmental, Energetic, and Economic Comparisons of Organic and Conventional Farming Systems  David Pimentel, Paul Hepperly, James Hanson, David Douds, Rita Seidel: BioScience, Volume 55, Issue 7, July 2005, Pages 573–582


IV – R.F. Follett, Soil management concepts and carbon sequestration in cropland soils. Soil Tillage Res., 61 (2001), pp. 77-92

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For more information about a program to suit your requirements, contact your BioAg agronomist.