Carbon trading potential and economic viability of carbon farming practices in developing countries

Introduction

A recurring observation among agricultural development practitioners is that the same soil management practices promoted for productivity-no-till, agroforestry, cover cropping-also sequester atmospheric carbon in soil organic matter and standing biomass, creating a potential revenue stream through carbon credit markets [1,2] . The voluntary carbon market grew to US$2 billion in 2021, with agriculture and forestry projects accounting for approximately 25% of all credits issued, yet developing-country smallholders-who manage 475 million farms globallycapture less than 5% of this market value [3] . The disconnect between potential and participation reflects several barriers: high transaction costs for monitoring, reporting, and verification (MRV) relative to the small credit volumes from individual farms; uncertainty about permanence of soil carbon gains; lack of baseline data for additionality determination; and limited access to carbon registries and buyers [4,5] . These barriers are not insurmountable-satellite-based MRV, farmer aggregation cooperatives, and simplified registry protocols are rapidly evolving-but their economic implications for different farming systems and scales remain poorly quantified [6] . This research synthesized field trial data from four developing countries to model the 10-year economic performance of three carbon farming practices under realistic market conditions, including transaction costs, price scenarios, and scale effects. The objectives were to (i) quantify carbon sequestration rates and credit generation potential by practice type, (ii) compare net present values and returns on investment across practices and farm scales, and (iii) identify the transaction cost thresholds below which smallholder participation becomes economically viable [7, 8] .

Research area description

Data were synthesized from 47 peer-reviewed field trials conducted across four countries representing major developing-country agricultural zones: the Pampas region of Argentina (Humid subtropical, Mollisols), the Cerrado of Brazil (tropical savanna, Ferralsols), the western highlands of Kenya (tropical highland, Nitisols), and the Indo-Gangetic Plain of India (subtropical, Inceptisols). These regions collectively represent over 180 million hectares of cropland under diverse management intensities. The synthesis focused on trials that reported soil organic carbon changes at 0-30 cm depth over periods of 3-15 years, with clearly defined management practices and baseline carbon stocks. All monetary values were standardized to 2023 US dollars using purchasing power parity adjustments [9] .

Cost analysis and economic feasibility

The economic model used a 10-year discounted cash flow framework with a real discount rate of 8%, reflecting the opportunity cost of capital in developing-country agriculture [10] . Costs were categorized into three tiers: (i) establishment costs (equipment, seeds, seedlings, labor for practice conversion), (ii) recurring management costs (additional inputs, labor above conventional practice), and (iii) transaction costs (MRV, registry fees, aggregation, brokerage). Carbon credit revenue was modeled at three price scenarios: low (US$5 t CO₂ eq⁻¹), baseline (US$10 t CO₂ eq⁻¹), and high (US$20 t CO₂ eq⁻¹), spanning the range observed in voluntary markets for agricultural soil carbon credits during 2020-2023 [11] . Two farmscale scenarios were evaluated: smallholder (5 ha, individual MRV) and aggregated (500 ha cooperative, shared MRV), reflecting the dominant farm structures in the target regions.

Materials and Methods

Carbon sequestration rates were derived from meta-analysis of the 47 trials using random-effects models weighted by inverse variance. Rates were calculated as the annual change in soil organic carbon stock (0-30 cm) relative to a conventional practice baseline, expressed in t C ha⁻¹ yr⁻¹ and converted to CO₂ equivalents using the factor 3.67. For agroforestry, aboveground biomass carbon was estimated allometrically and added to soil carbon gains [12] . Credit volumes assumed a 20% buffer pool deduction for permanence risk, following Verra VCS methodology [13] . Transaction costs were estimated from published data on six operational agricultural carbon projects in East Africa and South America, disaggregated by MRV method (manual soil sampling vs. remote sensing), registry (Gold Standard, Verra, Plan Vivo), and aggregation model [14] . Net present value (NPV), internal rate of return (IRR), and return on investment (ROI) were calculated for each practice × price × scale combination. Sensitivity analysis tested the effect of ±30% variation in sequestration rate, carbon price, and transaction costs on NPV. Agroforestry produced the highest carbon sequestration rate (1.84 t C ha⁻¹ yr⁻¹), generating an estimated 54.0 t CO₂ eq ha⁻¹ in tradeable credits over 10 years after buffer deductions (Table 1).

Results

Table 1:

No-till and cover cropping produced more modest but consistent gains of 14.1 and 9.1 t CO₂ eq ha⁻¹, respectively. Cumulative revenue trajectories diverged sharply after year 3 (Figure 1). Agroforestry's accelerating curve reflects the exponential biomass growth of tree components, while no-till and cover cropping followed near-linear trajectories consistent with steady-state soil carbon accumulation.

complementary pathway and has proven effective in Kenyan and Brazilian pilot programs [18] .

Conclusion

All three carbon farming practices generated positive net present values under baseline market conditions at aggregated scale, with no-till agriculture offering the highest return on investment (287%) and agroforestry the highest absolute revenue (US$992 ha⁻¹ over 10 years). However, transaction costs of 18-42% of gross revenue for individual smallholders represent a critical barrier to equitable market participation. Reducing these costs through digital MRV and cooperative aggregation is essential for unlocking the estimated 180 million hectares of developingcountry cropland that could contribute to carbon markets. Carbon price remains the dominant uncertainty: below US$7 t CO₂ eq⁻¹, only no-till agriculture at aggregated scale remains viable, while prices above US$15 make all three practices profitable even for individual smallholders. These findings provide a quantitative framework for policymakers and carbon market designers seeking to integrate developing-country agriculture into global carbon trading systems.

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