Leveraging soil organic carbon credits to enhance smallholder food security and planetary health

Addressing the triple challenge of achieving food security, mi5ga5ng climate change and reducing biodiversity loss is essen5al for achieving the Sustainable Development Goals and planetary health (Te Wierik et al. 2025). Soils have substan5al poten5al in addressing those challenges. Around 95% of all consumed food is grown on soils; soils are the most species rich habitat on earth (Anthony et al. 2024). Soils also represent the largest terrestrial carbon reservoirs (FA0 2004). At the same 5me, the carbon sequestra5on poten5al of soils is considerable, achieved by taking atmospheric CO 2 and conver5ng it into soil organic carbon (ibid). Few investments provide as high a return on investment as restoring degraded land and inves5ng in soil health through SOC approaches, with es5mates of $7-$30 in benefits for every $1 invested (UNCCD 2026).Around 40% of global land is considered degraded, affec5ng around 3.2 billion people (UNCCD 2025). In some regions, e.g. Eastern Africa, agricultural land is heavily affected, with data indica5ng 65% of agricultural land in a state of degrada5on (Berrahmouni et al. 2022). For example, in Kenya only about 20% of the land suitable for crop farming is not degraded (ibid).Unsustainable agricultural land management prac5ces, overgrazing, deforesta5on and the effects of climate change are threatening soil health.Concurrently, there is ample evidence of solu5ons that could reverse this trend. Agricultural strategies which increase soil organic ma@er and revert degrada5on include minimum/no-5llage farming, cover cropping (e.g., legumes), diversifying crop rota5ons, compost applica5on, liming, agroforestry, integrated pest management and others -a combina5on of conserva5on agriculture, climate-smart farming and agroecology-labelled as Sustainable Agricultural Land Management (SALM) prac5ces (Wekesa & Jönsson 2012). A key component of soil organic ma@er is soil organic carbon (SOC) which can be sequestered through SALM prac5ces. SOC sequestra5on is one of the most cost-effec5ve means for reducing land degrada5on and food insecurity as well as climate change adapta5on and mi5ga5on (FAO 2024). SOC func5ons like a sponge: it stores large amounts of water in the soil and releases it slowly into the environment, thereby substan5ally improving the soil's water-holding capacity and helping it cope with both heavy rainfall and drought (FAO 2004). The highest poten5al for SOC sequestra5on is in croplands and in tropical moist, subtropical moist and tropical dry agroecological zones (FAO 2022); regions which suffer from food insecurity and fragility at the same 5me (FAO 2025, OECD 2025).Recently, SALM prac5ces have been linked to carbon credit standards, e.g. through Verra´s VM017 and, more recently, VM0042 standards (v2.2, VERRA 2025). SOC credits can generate carbon revenues for farmers, while incen5vizing climate change mi5ga5on and improving food security (Tennigkeit et al. 2022).However, implemen5ng SOC credit programs for smallholder farmers remains challenging.Working with smallholder farmers involves high transac5on costs, since it involves many farmers with small individual parcels of land, each genera5ng low carbon revenue. In addi5on, carbon markets are highly vola5le -for example, between 2022 and 2023, VCM transac5on volume fell by 56% (Forest Trends' Ecosystem Marketplace 2024). In addi5on, project set-up costs present substan5al barriers for entry (Schilling et al. 2023, World Bank 2021).Early smallholder SALM credi5ng under Verra's VM0017 indicates that aggrega5on via farmer groups and trusted extension services can reduce transac5on costs and enable scale in Kenya, but modest per-farm credit volumes leave projects highly exposed to fixed upfront costs for sampling, data systems, valida5on and MRV (monitoring, repor5ng and verifica5on, Tennigkeit et al. 2013, Lee 2017, World Bank 2014). Governance also remains a challenge for carbon projects, with issues of transparency, accountability and elite capture as key barriers for community benefit (Jain et al. 2025).Moreover, accurately quan5fying soil carbon sequestra5on remains technically challenging and costly. Compara5ve reviews of agricultural soil-carbon protocols across registries and countries document substan5al heterogeneity in baselines, permanence and uncertainty treatment, reinforcing the need for transparent, conserva5ve credi5ng when models are used to quan5fy SOC stock change (Schilling et al. 2026, Oldfield et al. 2021, 2022). Lessons from more mature sequestra5on schemes (e.g., the U.S. Soil Enrichment Protocol and Australia's measurementand-models soil-carbon method) highlight hybrid MRV designs-for example stra5fied sampling combined with modelling, complemented by remote sensing, which can address both affordability and quality issues (DCCEEW 2024, FAO 2020, World Bank 2021, Okoli and Birkenberg 2024).Below, we present the outcomes of a decade of work in Western Kenya through the Global Programme Soil Protec5on and Rehabilita5on for Food Security (ProSoil), coordinated by GIZ (Deutsche GesellschaW für Interna5onale Zusammenarbeit) and implemented by Welthungerhilfe (WHH) alongside Kenyan County Departments of Agriculture, several Kenyan NGOs, as well as na5onal and interna5onal research organiza5ons (see acknowledgements for details). The program has restored more than 87,000 hectares of degraded land, benefi5ng around 200,000 smallholder farmers through SALM. We then discuss opportuni5es and challenges for leveraging SOC credits in smallholder seUngs, illustrated with examples from ProSoil's sister project, the Western Kenya Soil Organic Carbon Project. Finally, we provide recommenda5ons and policy implica5ons for how carbon programs could be designed more effec5vely for including smallholder farmers.Agriculture in Western Kenya is dominated by subsistence farming with low inputs and yields, leading to rapid soil fer5lity loss, low incomes, and food insecurity. Maize, the region's main staple, is mostly grown by smallholder farmers, who typically use mineral fer5lisers. However, con5nuous use of these fer5lisers, combined with leaching of organic ma@er, has caused soil acidifica5on, reducing fer5liser effec5veness. The ProSoil project in Western Kenya addresses this issue.Using a landscape-level approach (see Annex 1) combined with integrated soil fer5lity management, farmers supported by ProSoil successfully implemented SALM and rehabilitated 87,000 hectares of farmland. Key success factors include the integra5on of research partners, which facilitated the promo5on of evidence-based farming prac5ces, and cost-efficient cascading extension service models. These models u5lize community resource persons to disseminate SALM prac5ces to other farmers, ensuring knowledge transfer and increasing adop5on rates across the target landscape. The engagement of community resource persons has proven instrumental in fostering peer-to-peer learning, enabling efficient dissemina5on of improved prac5ces while minimizing extension costs. The coordinated involvement of research ins5tu5ons ensured that the recommended interven5ons are scien5fically validated, enhancing the sustainability and effec5veness of farming ac5vi5es.On the farm level, applying compost at plan5ng and liquid biofer5lizer during growth, combined with minimal 5llage, has effec5vely helped to replace conven5onal mineral fer5lisers. By adop5ng these and other SALM approaches, ProSoil has improved soil health, boosted agricultural yields, diversified produc5on, strengthened food security and increased smallholder farmer income in Western Kenya (Wehinger & Lu@a 2024, GIZ 2025). Soils under treatment display less erosion, be@er water holding capacity as well as higher levels of living organisms. Moreover, SOC sequestra5on rates a@ributable to SALM are at least 1,98 t/ha/year for an implementa5on period of 20 years (Wehinger & Lu@a 2024).Star5ng in 2022, the SOC generated on farms through ProSoil & SALM has been registered, cer5fied and issued via a social business Soil-Carbon Cer5fica5on Services (SCCS) under a follow-on project referred to as the Western Kenya Soil Carbon Project (WEKSOCAP). SCCS is a dedicated social enterprise which seeks to leverage carbon finance to support long-term access to agricultural extension services for smallholders in Western Kenya (see Figure 1). SCCS is the project proponent of WEKSOCAP. The project seeks to sustain and scale the great success of ProSoil ac5vi5es in Western Kenya with the aim of improving farmers' livelihoods by improving their food security and income, building their resilience against climate change, and reducing greenhouse gas emissions. Farmers voluntarily commit to adopt SALM prac5ces on their farms, and carbon revenues are invested in provision of extension and training to farmers in SALM packages of their choice. SCCS contracts competent NGOs and community-based organiza5ons to train farmers in SALM prac5ces of their choice based on the individual commitments consolidated in group ac5on plans which are reviewed annually. Farmers also receive support in form of starter inputs including seeds and seedlings for agroforestry trees and cover crops.WEKSOCAP's objec5ve is to reach 100,000 farmers across Siaya, Kakamega, and Bungoma coun5es, facilita5ng SALM adop5on on 32,000 hectares of land. The project is es5mated to remove 3.6 million tonnes of CO 2 equivalent during the first fixed 20-year credi5ng period.Currently, the project is working with 30,473 farmers, with plans to recruit an addi5onal 70,000 in two subsequent phases. The project has successfully completed its first Verra valida5on and verifica5on process with a second verifica5on scheduled for 2026.Despite the progress, WEKSOCAP has faced several challenges. Inadequate understanding and rumours of the func5oning of carbon markets can lead to miscommunica5on about carbon projects and can create wrong expecta5ons among farmers. OWen 5melines are unclear as carbon revenue takes considerable 5melines to materialize. WEKSOCAP works with registered farmer groups, the cost and process of registering a group limits the pace of onboarding of farmers to WEKSOCAP. Unclear property rights can impede project implementa5on or cause inequitable benefit distribu5on among households, which require careful a@en5on. Other challenges include difficul5es in securing pre-financing as carbon revenues typically are generated 2-3 years aWer project start only. Yet the quan5ty of carbon credits, prices received and 5melines are oWen uncertain. The valida5on and verifica5on process is complex and 5meconsuming, which in our case delayed extending valida5on, verifica5on and issuance of carbon credits for over a year. The vola5lity of pricing in Voluntary Carbon Markets presents addi5onal uncertain5es.Successful projects demand comprehensive strategies that merge rigorous MRV systems with par5cipatory engagement from the beginning. Nonetheless, the carbon revenues from WEKSOCAP will be channelled into extension services and are expected to con5nue to generate benefits beyond carbon revenues, i.e., in soil health, yields, income and climate resilience.Globally, of all traded carbon credits, around 80% derive from emissions avoidance (e.g. avoided deforesta5on). However, evidence shows that only 16% of avoidance credits deliver impact (Probst et al., 2024). Sequestra5on related credits represent only around 5% of all credits.Sequestra5on credits achieve, on average, 300% higher prices than avoidance credits on carbon markets due to higher credibility and quality (Climate Seed, 2025). Yet, a key challenge is that sequestra5on may not be permanent and, if management prac5ces revert (e.g., intensive 5lling), stored carbon is rapidly released back into the atmosphere. Carbon projects need long term strategies for 5me spans of up to 20 years and more, thus, strategies to ensure that ac5vi5es are sustained are crucial.We argue that more emphasis should be placed on high-quality sequestration offsets whose impact can be empirically proved and which create long-term co-benefits for smallholder farmers beyond carbon revenue. Moreover, if carbon markets are to work for smallholder farmers, cer5fica5on standards and their underlying assump5ons need to be adapted to the reality of smallholder farmers. Voluntary carbon standard governance is predominantly expertdriven, top-down, with limited par5cipa5on from farmers or local prac55oners, and hence oWen fails to address local reali5es (Livelihoods Fund, 2025).Small farm sizes, customary land rights, diversified farming systems and geographical heterogeneity make the certification of carbon credits in smallholder croplands difficult (ACMI, 2022, Schilling et al. 2023). In fact, the certification of SOC in African crop land is still at an early stage and so far, many actors had difficulties in applying carbon standards (Wehinger & Lu@a, 2024). Against this backdrop, the WEKSOCAP project is a successful example. However, it is worth noting that the project also benefitted from considerable grant funding and was built on ten years of ProSoil implementation by its partners.The co-benefits of promo5ng SOC through land use strategies are tremendous and include among others food security and income and climate resilience (mi5ga5on and adapta5on). SOC credit programs have proved difficult to implement but standards, cer5fica5on, and measurement are developing quickly. One of the key challenges that will determine if SOC credits can be scaled for smallholders is to develop scien5fically sound but cost-efficient carbon sequestra5on quan5fica5on methods. Moreover, quality of carbon projects needs to be warranted, robust MRV systems are needed but underlying assump5ons must meet smallholder´s reali5es. Our experience shows that strong partnerships between research partners, carbon project developers and development prac55oners are key to achieving this goal.With the Nairobi (AU 2023) and Kampala declara5on (AU2025), there is poli5cal momentum for soil health; financial incen5ves for investments in soils are urgently needed at scale.Given the urgency to restore degraded land and leverage finance, and the high economic and environmental co-benefits of SOC programs, we argue that voluntary carbon credits are an important instrument to crowd in finance and promote sustainable agriculture. However, existing models need adjustments if they are to work for smallholder farmers at scale.1. Increased investment into soil protec5on and rehabilita5on of smallholder farmers is needed; soil security must become a poli5cal priority (cf. Evangelista et al. 2024).2. Increased investment in digital MRV, blockchain technology and digital extension to improve data quality, accountability, transparency and reduce transac5on costs and return more value to the community.3. An enabling environment for SOC projects to be created; domes5c standards and legisla5on and soil data to be developed. 4. Situate SOC carbon projects within a holis5c food systems approach and leverage a blended finance approach for sustainability and impact.5. Funders must develop financial models for covering high upfront investments (e.g. revolving funds, credits, pre-sale of carbon credits).6. Invest in proof of concept for benefit sharing mechanisms with robust governance structures and regula5ons, which can be scaled and replicated to maximize benefits for farmers.