Verra VCS VM0042 v2.2 · IPCC 2019 Tier 1 N₂O · Ex-ante scenario analysis · Flood → Drip/SDI · Open Canal & Closed Canal
Four water delivery system types are modelled. Each system has a different baseline irrigation practice, pressurization requirement, water tariff structure, energy cost profile, and eligibility for the government electricity subsidy (50% discount when converting to drip). Select the active system in the top control bar to update all cost-benefit calculations.
| Attribute | Open System Gravity (Cazibe) |
Open System Motor Pump (Motopomplu) |
Closed Canal System Kapalı Basınçlı |
Self-Owned Well Kuyu / Sondaj |
|---|---|---|---|---|
| Baseline Irrigation | Flood / Furrow Salma sulama — gravity-fed, no pump |
Sprinkler Yağmurlama — pump already in place |
Flood / FurrowSprinkler Either possible (pressurized canal) |
Sprinkler Well pump powers baseline system |
| Transition Scenarios | Flood → Surface Drip Flood → SDI |
Sprinkler → Surface Drip Sprinkler → SDI |
Flood/Spr → Surface Drip Flood/Spr → SDI |
Sprinkler → Surface Drip Sprinkler → SDI |
| Pump / Pressurization | New pump required 161,864 TL one-time CAPEX — needed to pressurize drip system |
Check capacity Existing pump may be reused — verify flow rate for drip |
Not required Canal already pressurized — connects directly to drip header |
Check capacity Existing well pump may be reused at different pressure |
| Baseline Energy Cost | Zero No pump in flood/gravity baseline → 0 kWh/ha |
Normal (1.0×) Sprinkler pump: water × 0.75 MJ/m³ ÷ 3.6 kWh |
Zero Pressurized canal provides head — no separate pump energy |
High (1.5×) Well pump lifts groundwater — 1.5× surface energy |
| Project Energy Cost (Drip) | Extra cost Starts paying drip pump energy (was 0) — but 50% subsidy applies |
Saving Drip uses less water → lower energy, plus 50% subsidy |
Zero Canal pressure unchanged — no pump energy in any scenario |
Saving Drip uses less water — but no subsidy applies |
| Electricity Subsidy (50%) | ✓ Eligible Government subsidy on drip pump electricity — open canal systems |
✓ Eligible Open canal system — 50% subsidy on project energy applies |
✗ Not eligible Closed/pressurized canal — subsidy only for open canal systems |
✗ Not eligible Self-owned well — no electricity subsidy |
| Water Tariff (Baseline) | 6,300 TL/ha/yr Seasonal flat rate — DSİ/sulama birliği |
5,900 TL/ha/yr Well electricity covers pumping (no water tariff per se) |
6,300 TL/ha/yr Volumetric hidrant tariff (Netafim data) |
Zero Farmer owns groundwater — no water fee |
| Water Tariff (Drip) | 4,400 TL/ha/yr Reduced tariff for drip systems |
4,400 TL/ha/yr Netafim 2024 drip tariff data |
4,400 TL/ha/yr Netafim 2024 drip tariff data |
Zero No water tariff regardless of system type |
| Water Saving (Flood→Drip) | +1,900 TL/ha/yr ≈ $42/ha/yr at 45.43 TL/USD |
+1,500 TL/ha/yr ≈ $33/ha/yr (sprinkler baseline) |
+1,900 TL/ha/yr ≈ $42/ha/yr at 45.43 TL/USD |
Zero No tariff in any scenario |
| Surface Drip Lifetime | 1 year Annual tape replacement (open canal sediment) |
1 year Annual tape replacement |
5 years Clean pressurized water → longer tape life |
5 years Clean groundwater → longer tape life |
| SDI Lifetime | 15 years | 15 years | 15 years | 15 years |
| TKDK Subsidy (Drip CAPEX) | Surface Drip: 50% SDI: 70% |
Surface Drip: 50% SDI: 70% |
Surface Drip: 50% SDI: 70% |
Surface Drip: 50% SDI: 70% |
| SOC Credit Eligibility | Scen A (SD + tillage)Scen C (SDI) | Scen A (SD + tillage)Scen C (SDI) | Scen AScen C | Scen AScen C |
| Step / Parameter | Baseline | A | B | C | Unit |
|---|
| Step / Parameter | Baseline | A | B | C | Unit |
|---|
| Metric | Corn | Wheat | Rotation Avg |
|---|
Direct and indirect N₂O is modeled under different water and fertilization regimes, following Approach 3 in the VM0042 protocol. The transition from flood to drip reduces waterlogging frequency, shifting production from denitrification-dominated to nitrification-dominated pathways, generally lowering total emissions [1]. In this study, the switch from flood/furrow/sprinkler to surface drip irrigation and sub-surface drip irrigation (SDI) were modeled under various rotation scenarios.
Although the literature provides more precise emission factors (EFs) for flood-irrigated maize [2] and comparative analyses across irrigation systems and crop types [3], no study has explicitly evaluated EFs across comparable drip- and flood-irrigated maize scenarios. To ensure methodological consistency and avoid double counting, the IPCC default EF for all N inputs in dry climates [4], set at 0.005, is applied uniformly across all scenarios.
Indirect N₂O emission factors for atmospheric deposition (EF₄ = 0.010 kg N₂O-N kg⁻¹ NH₃-N) and leaching (EF₅ = 0.011 kg N₂O-N kg⁻¹ N leached) were adopted from IPCC (2019) Tier 1 defaults and held constant across all irrigation scenarios [4]. These factors represent biogeochemical processes occurring after reactive nitrogen leaves the field boundary — atmospheric redeposition and denitrification in receiving water bodies, respectively — and are therefore independent of on-farm irrigation management. Therefore, no scenario-specific adjustment was applied.
For the FracLEACH parameter, the IPCC default value of 0.24 [4] is applied in the baseline scenario. Empirical evidence from maize production systems under semi-arid conditions indicates that drip irrigation reduces nitrogen losses via leaching by approximately 33% compared to flood irrigation [5]. This reduction factor is therefore applied, resulting in an assumed FracLEACH value of 0.16 for drip irrigation. Due to the lack of differentiated data, the same value is also used for the SDI scenario. Furthermore, as the referenced study reports no significant difference in NH₃ volatilization between irrigation methods, FracGASF,urea and FracGASF,DAP are assumed to remain at their IPCC default values of 0.15 and 0.08, respectively, across all scenarios.
References
[1] Gültekin, R., Avağ, K., Görgiişen, C., Öztürk, Ö., Yeter, T. & Bahçeci Alsan, P. (2023). Effect of deficit irrigation practices on greenhouse gas emissions in drip irrigation. Scientia Horticulturae, 310, 111757.
[2] Franco-Luesma, S., Lafuente, V., Alonso-Ayuso, M., Bielsa, A., Kouchami-Sardoo, I., Arrúe, J.L. & Álvaro-Fuentes, J. (2022). Maize diversification and nitrogen fertilization effects on soil nitrous oxide emissions in irrigated Mediterranean conditions. Frontiers in Environmental Science, 10, 914851.
[3] Cayuela, M.L. et al. (2017). Direct nitrous oxide emissions in Mediterranean climate cropping systems: Emission factors based on a meta-analysis of available measurement data. Agriculture, Ecosystems & Environment, 238, 25–35.
[4] Baasansuren, J. et al. (2019). 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories. IPCC, Switzerland.
[5] Di, Y., Gao, Y., Yang, H., Yan, D., Tang, Y., Zhang, W., Hu, Y. & Li, F. (2024). Cutting carbon and nitrogen footprints of maize production by optimizing nitrogen management under different irrigation methods. Frontiers in Plant Science, 15, 1476710.
| Component | OC-SD | OC-SDI | CC-SD | CC-SDI |
|---|
| Crop Price %/yr (real) | OC-SD | OC-SDI | CC-SD | CC-SDI | Note |
|---|
| NPV Component | OC-SD | OC-SDI | CC-SD | CC-SDI |
|---|
| NPV Case | OC-SD | OC-SDI | CC-SD | CC-SDI | Break-even |
|---|
| Carbon Price Scenario | OC-SD | OC-SDI | CC-SD | CC-SDI | Carbon NPV add-on |
|---|
The farmer-level analysis is structured as an incremental cost-benefit analysis (CBA), comparing an enrolled farmer adopting drip or subsurface drip irrigation (SDI) under TKDK/IPARD and/or the Ziraat Bank 0% loan scheme against a counterfactual farmer continuing flood irrigation. All results are expressed as incremental differences between the two systems — CAPEX, dripline replacement, O&M, and financing costs net of subsidies, against labour savings, fertiliser savings, yield gains, and water cost savings where applicable. Carbon revenues are excluded from the base case and treated as a separate layer.
All cash flows are in constant 2026 USD at a fixed exchange rate of 45.43 TL/USD. A real USD framework is adopted to avoid the endogeneity problem from high and volatile Turkish inflation (64–75% in 2022–2024, currently ~30%). A nominal TL formulation would require long-term inflation assumptions that dominate NPV outcomes over a 15-year horizon and are not analytically robust. The exchange-rate conversion is treated as consistent with PPP, making real USD flows equivalent to inflation-adjusted TL flows converted at a constant rate — standard practice in international project finance and carbon market modelling.
CAPEX and OPEX items (equipment, dripline, fertiliser, electricity) are held constant in real 2026 USD. Nominal TL price increases (~20–25%/yr on dripline) are assumed offset by TL depreciation, leaving real USD costs approximately flat. Fertiliser is modelled at long-run real USD mean-reversion; the 2021–2022 spike is treated as a temporary supply shock.
Crop prices are modelled with a −1.5% annual real USD trend, reflecting structural price pressure in Turkish agriculture: input costs track global commodities and FX, while output prices are partially constrained by reference pricing (TMO) and buyer concentration. This creates a widening gap over time between input savings and yield gains under the project versus the counterfactual. Declining crop prices do not weaken the project case — both systems face the same price path, but only the project system reduces input use and improves yields per ha.
The Ziraat Bank 0% loan is modelled as the primary financing mechanism: upfront investment with repayment over five years following a one-year grace period. TKDK/IPARD grants are treated as conditional, front-loaded reimbursement schemes with a five-year minimum asset retention requirement. Given liquidity constraints and compliance risk, subsidies are assumed primarily accessible to larger farms and are not included in the base financing structure for open-canal drip upgrades.
Discount rates: 5% real USD (base), 10% (World Bank/IFC agricultural benchmark), 12% (commercial hurdle rate consistent with Turkish farm-level capital costs and TKDK/IPARD expectations). NPV is reported in three layers:
A positive Floor NPV at 12% is the primary viability threshold — independent of market prices or carbon assumptions.
MRV scaling starts with Adana: 20 farmers × 10 ha in Year 1, expanding through area increase per farmer and additional farmer recruitment from Year 2. Later regional scaling will be guided by the MCDM framework; regional soil heterogeneity will be incorporated using national soil datasets to parametrise MRV requirements and monitoring costs.
The implementer-level LCCA will be benchmarked against farmer-level CBA across scaling pathways. Farmer uptake is modelled as a function of timing of access to Ziraat Bank and TKDK/IPARD financing.
Carbon revenue remains marginal in early years; programme viability at scale is driven primarily by deployment volume rather than credit income. Farmer retention is a binding constraint due to dripline replacement cycles without sustained subsidy access. One scenario under evaluation: partial reinvestment of programme-level revenues to subsidise replacement driplines, improving retention while maintaining expansion feasibility. These financing structures will be tested under constrained and unconstrained optimisation scenarios.
The N₂O model (currently IPCC Approach 3) will be recalibrated using field data from the current season and benchmarked against Approach 1 to assess methodological sensitivity in emission reductions and resulting carbon credit potential.
| Metric | Scen A | Scen B | Scen C |
|---|
Each region's SOC measurement clock starts from its own enrollment year. Farmers joining later do not inherit existing SOC stock — the 20-year SOC transition process starts from zero.
| Region / Phase | Start Year | Initial Farms | ha/farm₀ | +Farms/yr | Max Farms | ha Growth %/yr | Max ha/farm |
|---|
| Scenario A | Scenario B | Scenario C | Scenario D | |
|---|---|---|---|---|
| SOC / N₂O approach | App 1 + App 1 | App 2 + App 1 | App 1 + App 3 | App 2 + App 3 |