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 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 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.