FARMERS, more than anyone else, know the true importance of the “dirt” beneath our feet – our soils. They’re the cradle of life on Earth, sustaining plant growth with vital nutrients, purifying water, and providing a habitat for billions of soil microorganisms. Today, as human activities lead to skyrocketing carbon dioxide emissions that speed up global warming, soils take on one more life-saving role of carbon-sequestering powerhouses, and so do the farmers. By implementing sustainable land management practices that protect and build up soil carbon, agricultural stakeholders can help offset greenhouse gas emissions and stave off climate change.
With 44% of the world’s soils used for agriculture, farmers have a vast mitigation potential to tap into, thereby unlocking a host of environmental benefits that will ultimately translate into more lavish yields on their side. In this article, we will delve into the intricacies of soil organic carbon (SOC) and explore state-of-the-art technologies that could hand over the reins of carbon sequestration power to the hands of smallholder farmers.
Soil Organic Carbon: The Hidden Power of Soils
Soil represents the largest terrestrial carbon reservoir that holds double the amount of all atmospheric CO2 and triple the amount of carbon found in vegetation.
In fact, carbon constantly cycles between these pools. Plants take in carbon dioxide gas from the atmosphere, turning it into plant tissue. A portion of it eventually finds its way into the ground through plant residue, leaf litter, and animal wastes decomposed by fungi and microbes inhabiting soils. Massive amounts of carbon are stored as soil organic matter (SOM), making up 45-60% of its mass, with the rest of it being comprised of other major nutrients (nitrogen, phosphorus, etc.). Higher soil organic carbon content in SOM implies greater stability and a longer carbon storage period due to increased resistance to breakdown by soil microbiota.
Basically, at any point in time, soil represents a complex mixture of organic material at various stages of breakdown, which provides an array of crucial services that enhance soil’s nutrient availability and water-holding capacity, while also improving its structure and resilience to erosion or other disturbances. Soils rich in SOM and SOC are healthier and more fertile, which is crucial for agricultural productivity and global food security.
SOC in Climate Change and Food Security: Solution or a Threat?
International organizations paint a troubling picture of the global soils: about 40% of them are degraded, and another 12 million hectares deteriorate every year mainly through poor land management. Degrading soils lose organic matter and, as a result, the ability to provide crops with nutrients, hold water, and absorb and store carbon. This affects agricultural productivity and increases CO2 emissions worldwide, putting soil degradation on par with climate change as one of the most serious threats to date.
While small- and medium-scale farmers are hit the hardest, they’re also among the ones who exacerbate the situation by practicing intensive tillage and other techniques that speed up soil erosion and soil organic carbon loss. To break out of this vicious circle, farm and ranch owners need to optimize grazing and tillage management in order to reduce soil disturbance and compaction while also supporting microbial communities through increased crop residue and compost addition. Non-inversion tillage, crop rotation, cover cropping, agroforestry, and organic fertilizer application are some of the most effective practices, which improve soil health and increase carbon sequestration in soil.
While SOC holds immense potential for reducing the concentrations of harmful GHGs and simultaneously boosting agricultural yields, measuring soil carbon is a challenging task. Due to inherent dynamics and a multitude of factors affecting the rates of carbon sequestration, soil carbon storage, and release – such as soil type, topography, climate (precipitation and temperatures), and land management – SOC content highly varies both locally and globally.
That said, leveraging the soil’s magical ability to capture and store carbon in both surface and deep layers requires a holistic approach that involves accurate SOC estimation and monitoring. The traditional method of soil sampling provides crucial input data for SOC measurement, however, is time-consuming, laborious, and expensive. This is where new testing and monitoring technologies have come to the rescue, significantly reducing the need for soil samples and enabling remote soil organic carbon assessments with a high level of accuracy and at scale.
Integrating Satellite Data And Machine Learning into the Carbon Credit Projects
Earth observation data from satellites and innovative machine learning algorithms have emerged as a cost- and time-effective alternative to costly soil sampling, providing smallholder farmers with the opportunity to take part in carbon offset projects.
With satellite imagery, they need much fewer soil samples to measure and monitor the amount of carbon sequestered on their farms to generate tradable carbon credits, as well as evaluate the effectiveness of soil carbon-enriching practices.
The combination of spaceborne data, ground truth data, and deep learning enables a better understanding of changes in SOC levels in different geographies over time, both for neutralizing global carbon emissions and supporting farmers via an additional income source – a win-win strategy, whichever way you slice it.
How Can We Monitor SOC through Remote Sensing?
Remote sensing employs sensors on satellites and drones to remotely measure energy responses of Earth’s surface features (vegetation, bare land, oceans, manmade structures, etc.) and measure their physical attributes. While the technology is not utilized to directly measure SOC levels, it proves indispensable in observing the aboveground factors and patterns that affect soil carbon storage, e.g. vegetation growth, soil moisture, topography, and climate variables.
Such satellite-derived observations provide input data for ML-based modeling of soil carbon storage across vast areas. Models trained on ground truth data taken from sample locations and remote sensing variables are further applied to satellite imagery to predict soil carbon levels for the entire area.
As such, remote sensing facilitates accurate modeling and estimation of organic soil carbon on croplands, enabling farmers to determine areas with high and low carbon sequestration potential and see how various practices influence SOC levels over time.
Important Steps To Engage More Farmers in Credit Markets
The carbon market is teeming with lucrative opportunities for smallholder farmers. To facilitate their participation in carbon offset projects and the generation/sale of carbon credits, the following activities are required:
- Development and implementation of the technology utilizing remote sensing to assess whether and to what extent the current soil management strategies affect carbon sequestration and storage;
- Creation of a unified control platform for automated monitoring of farm activities and carbon certification;
- Verification of SOC modeling methods based on remote sensing within the international accreditation organizations;
- Connecting farmers and farmer co-ops with carbon project developers and certifiers for the development of innovative ways to remunerate regenerative soil organic carbon-enriching practices.
Sustainability and Scaling Potential
As satellite imaging capabilities keep evolving, providing more detail and insight into our environment, satellite-powered SOC modeling is well-placed to play a pivotal role in promoting carbon sequestration among farmer communities on a global scale. As a novel solution that reduces the need for extensive (and expensive) on-site soil sampling, it can benefit both smallholder and large farm owners’ budgets, save time through scalability, and make carbon offset projects more appealing.
Sustainability-wise, the increased participation of agricultural stakeholders in climate mitigation activities will have a direct positive impact on the amount of carbon dioxide emissions that can be accurately monitored and predicted through remote sensing and ML technologies. Incentivized adoption of healthy soil management practices will also boost the productivity of agricultural soils, securing more food for the rising human population amidst climate change.
