4 reasons to measure Soil Organic Carbon

At AgroCares, we develop innovative soil testing solutions and we see rising interest in Carbon monitoring in soils for carbon projects. Why is it important to measure Soil Organic Carbon? Below are four reasons to explain this trend.

What is Soil Organic Carbon?

Soil Organic Carbon (SOC) is part of the soil organic matter. Soil organic matter is built up with additions of organic fertilizers such as animal manure and compost, and also via the crop residues left in the field (roots, stems and leaves). SOC has multiple benefits on soil quality and agricultural production, and it is crucial for climate change mitigation.

Carbon gives structure and life to the soil and is essential for nutrient retention

Soil Organic Carbon (SOC) is considered the most essential parameter for healthy soil. It is the “glue and sponge” of the soil as it sticks together soil aggregates, adsorbs and desorbs nutrients, retains water, and gives habitat and energy to soil micro-organisms. Crops do not take up carbon from the soil (they absorb carbon from the atmosphere) and as such carbon (C) is not an essential nutrient. Still, it is essential and without SOC crops are vulnerable to diseases and stresses.

Carbon is a key indicator for soil water holding capacity

The capacity of soils to hold water is crucial for plant growth at the field level and can be decisive for flood control at the landscape level. Moreover, an increase in SOC content in soils most often results in an increase in soil water holding capacity. Of course, the relationship between soil water holding capacity and SOC content is strongly affected by the soil texture. Plant available water is already increased even at just 2% of SOC. In general, measuring your SOC content will give you a better idea of your soil status and facilitate correct water management. Correcting a low SOC content will improve the capacity of your soil to retain water for your crops.

Soil Organic Carbon plays a crucial role in the fight against climate change.

Climate change is often seen as something that only involves the atmosphere. Not so many people know that soil is a vital element of the climate system. Yet, the soil is the second-largest carbon store, or ‘sink’, after the oceans. Plants absorb carbon dioxide (CO2) from the atmosphere and transform it into plant tissue (leaves, stems, roots and fruits).

Soil microorganisms break down the plant residues left on the field turning it into soil organic matter which consists of SOC, hence the CO2 is sequestered from the atmosphere and becomes part of the soil system. The CO2 stored in the soil as SOC remains there in the long term if adequate agricultural practices are maintained (e.g. low tillage or applications of organic matter), this process is called soil carbon sequestration.

Soil carbon sequestration is seen as one of the most promising mitigation measures to combat climate change. The FAO (2017) estimated that soils can sequester more than 10% of the global anthropogenic greenhouse gas emissions. In fact, a new market is currently being developed called the carbon credit market. Farmers are being paid by earning and selling carbon credits when they prove that carbon is sequestered in their fields. In order to prove this careful monitoring of SOC is necessary.

However, at the same time, land-use changes and agriculture are major sources of greenhouse gas emissions. Land-use changes account for more than 10% of the global greenhouse gas emissions and mainly refer to the drainage of peatland and transforming forests into arable lands. Agriculture also accounts for more than 10% of the global GHG emission mainly through emissions from livestock and fertilizer application. Hence, the paradoxical situation of climate change and the soil is that soil is both a source and a solution for climate change.

Realizing the soils’ potential to combat climate change demands innovations that decrease emissions from soils and sequester carbon at the same time, whilst respecting the numerous and complex soil processes. To understand the net effect of these innovations careful monitoring and therefore SOC measurements are essential. In addition to monitoring, soil management practices need to be optimized so that more carbon is sequestered. At AgroCares we develop site-specific recommendations that support the build-up and maintenance of SOC.

Interested in measuring Soil Organic Carbon? Contact us