Open Access

Johannes Meyer zu Drewer

• Facing prevalent soil degradation, population growth and climate change it is vital to wildly deploy versatile carbon farming practices [CF] to increase soil organic carbon [SOC] stocks and consecutive restore soils, increase their productivity and climate resilience while directly mitigating climate change through sequestration of greenhouse gas- [GHG] derivatives, such as CO₂-Carbon, in agricultural landscapes. The global aggregated mitigation potential of up to 11 GtCO₂eq yrˉ¹ (medium confidence) resulting from afforestation, SOC increment and biochar application in the land use sector can only be realised when including smallholder farmers which are in stewardship of 60% of the global arable lands. Currently soil carbon sequestration receives extensive attention, but efficient schemes to financially support smallholder transition towards carbon farming practices are lacking. Linking these smallholder structures to the global carbon markets by verifying and trading carbon offsets generated through climate smart farming practices is a new attempt to generate the required funding for transition – turning carbon into a new farming commodity for smallholders. This paper reviews approaches to SOC monitoring required for quantification and verification of offsets, based on the evaluation of methods used in the Nepalese smallholder carbon project: Forest Gardens for Closing the Global Carbon Cycle [FCGC]. Further it compares the project innovations of the FCGC with other distinguished case studies of current projects implementing carbon as a farming commodity in a tropical- subtropical smallholder context. A strong variability in SOC pattern as identified in the FCGC project, is inherent to smallholder systems, the cost of representative, direct measurements of such heterogeneous SOC distributions may be cost prohibitive. For smallholder carbon projects of aggregated scale, process-based models to determine SOC fluxes should be employed or the agricultural intervention be focused on tree- biomass- carbon which is quantifiable in a less resource demanding manners. Among the identified project innovations are: Real- time in-situ GIS applications, an innovative approach for monitoring fragmented areas under intervention; The household segment of the voluntary carbon market as a new target group to be explored; Biochar as a multifunctional soil amendment for long-term carbon sequestration; Participatory schemes for monitoring and extension services to build capacity and foster participation; and mobile money approaches to lower transaction costs and likelihood of corruption. The direct financial return from carbon- credits to the farmer is minor, thus it is imperative for the project design to utilize agricultural interventions fostering co-benefits, which are tangible to the farmer in the short to medium term and will serve as the main incentive for the adoption of CF techniques.