Soil organic carbon is the carbon that remains in the soil after partial decomposition of any material produced by living organisms. It is a primary component of soil organic matter and is believed to be crucial in many soil functions and ecological properties. The amount of organic carbon in soil usually depends on the local geology, climatic conditions, land use, and management. Soil organic carbon is mainly present in the topsoil (2500 pg of c to 2-m depth). The amount of carbon in the soil is twice as considerable as the amount in the atmosphere; hence soil acts as an essential reservoir of carbon.
The Benefits of Soil Organic Carbon in Agriculture
Here are the seven most important benefits of soil organic carbon:
Increases water holding capacity in soils:
This builds drought resilience.
Lower soil density:
As you increase carbon, density decreases because organic compounds are less dense than the soil minerals. When soil is less dense, the roots can travel through the earth and scavenge for nutrients and water more efficiently. This makes for a healthier plant overall.
Increased water infiltration:
Organic carbon helps to form soil aggregates, where organic molecules produced by microorganisms bind mineral particles together. The no-till process helps to preserve these aggregates, increasing carbon in surface soils, which allows more aggregates to form, further stabilizing the soil structure. Tilled fields typically have less carbon and poorer water infiltration – this is evident in ponded water in areas after heavy rainfall.
Increased nutrient availability:
When microbes feed on soil organic carbon (to get energy), they release nitrogen and phosphorus tied to that carbon, providing more nutrients for the plant.
This means that the soil structure is improved, allowing farming equipment to traverse the field more days in a given year.
Increased yield stability:
Although there is not a lot of experimental data on this, many farmers have found this benefit to be true. Compared to their neighbors, who do not use soil health practices that increase carbon, farmers find they have more stable yields from year to year. This is often most evident during drought years, likely because of the greater water-holding capacity, reduced density, and other benefits that increasing soil organic carbon has for farmers.
What is soil carbon saturation, and what does it mostly depend on?
The maximum extent of carbon a soil layer can attain is called the soil carbon saturation level. The level of carbon in soil can only increase if the mechanisms through which soil organic carbon is stabilized are limited. Soil organic carbon content is mainly dependent on the soil mineralogy, the input of organic carbon, and the soil environment.
Finally, soil organic carbon increases profitability. Soil Health Institute (SHI) scientists recently interviewed 125 farmers about their profitability since they started using soil health systems. While the Institute will release those results in the coming months, Dr. Honeycutt said that almost all the farmers interviewed reported higher profitability after adopting soil health systems that increase soil organic carbon.
How to positively impact the soil organic carbon stocks?
There are myriad of different ways to increase the soil carbon stocks, which vary in degrees of technical complexity and cost. For this blog, we explore the potential vital pathways that can be taken and what their affects can be. Possible land management changes that can positively impact soil carbon stocks are:
1. Land use (e.g., crop rotation).
2. Soil amendments (e.g., adding nutrients).
3. The management of optimal groundwater level.
The increase of soil organic carbon is limited to the soil carbon saturation level. Our soil scientists can delineate the optimal pathway to increase the soil carbon on a farm level. Want to learn how to increase your soil organic carbon stock? Get in touch!