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LRl — Land Retirement (Low-lying / Lavbund)

Summary

Permanent retirement of low-lying (lavbund) agricultural land — fields with high groundwater tables, often with high N leaching. The land leaves production, dramatically reducing N loads. This is the flagship lavbund measure in the Tripartite Agreement.

Eligibility

PotV(i,"LRl") = lav(i) × Countcy(i) × IniPotV(i) / 5
lav(i) = fraction of field classified as lavbund (low-lying). Only fields with lav > 0 have LRl potential. Data from new_lav_2018.inc.

N Effect

NEffM(i,"LRl") = 40 kg N/ha/yr   [flat rate for all fields]
This is a relatively conservative flat rate. ⚠️ The rationale for 40 rather than field-specific leaching is unclear — it may be that the actual N reduction from lavbund retirement is uncertain or that a consensus value was agreed for policy purposes.

P Effect

P_Effects_erosion(i,"LRl") = 0
P_Effects_macropore(i,"LRl") = 0
P effects are explicitly set to zero. Low-lying land is already wet and does not have significant erosion losses — hence no P benefit assumed.

Cost

CostM(i,"LRl"):
  livestock ≥ 0.8:  prodcost(i) + 1,016 + 200  DKK/ha/yr
  livestock < 0.8:  prodcost(i) + 1,016          DKK/ha/yr
1,016 DKK/ha/yr: fixed LRl implementation/restoration cost.

Retention type

NR (No retention) — Land retirement on low-lying fields; no landscape N retention applied (water table is high, flow is lateral near surface → no deep groundwater retention).

Mutual exclusions

  • Member of lr2(j) (partial land retirement) — contributes me(i)/2
  • Member of mem2(j) but not mem(j) — this is the key difference: LRl can be combined via mem2 rules with LRh type constraints
  • IBZ cannot be combined with LRl (mutexc13, mutexc7)
  • VP2 LRl blocks additional LRl (LRl_VP2)

Special status

The Tripartite Agreement mandates ≥51,000 ha of lavbund retirement nationwide: 

Lavbund_eq..  Sum(i, PotV(i,"LRL") × x(i,"LRL")) + exceed_lav ≥ 51,000
Note this constraint is nationwide (not restricted to catchments with N targets).

Data sources

  • Lavbund potential: new_lav_2018.inc
  • N effect, cost structure: hard-coded in TargetEcon 2026.gms

Catalog source and Danish name clarification

Danish identity (user-confirmed 2026-04-05): LRl = "Permanent udtagning på organogene drænet jord" — permanent set-aside on organogenic (peat/moor) soils that are currently drained. The "l" in LRl likely stands for lavbund (low-lying land).

Not "Styret dræning": Controlled drainage (styret dræning, DCA 174 p.330–338) was considered as a possible match but ruled out. Styret dræning = water table management for N reduction (6 kg N/ha, confidence **), with ongoing cultivation. LRl = permanent cessation of cultivation. These are fundamentally different measures.

Catalog coverage: DCA Rapport nr. 174 does NOT have a standalone chapter for "permanent udtagning på organogene jorde." The closest coverage is: 1. Chapter "Permanent udtagning og kortvarig brak" (p. 115–127) — covers mineral soils only (LRh = permanent udtagning on mineral soil = 49 kg N/ha). The chapter notes: "For landbrugsarealer på mineraljorde..." and does not quantify a separate effect for organic soils. 2. Chapter "Etablering af vådområde" (p. 344–359) — covers full wetland construction (WL), higher N effect (~150 kg N/ha) and higher cost. 3. Chapter "Paludikultur" (p.367–372) — rewetting organic soils for biomass production; N effect "not assessed," confidence . 4. p. 122 note: "Permanent udtagning af arealer på lavbund* med risiko for fosfortab, kan der evt. opnås en beskeden effekt" — only a passing mention, no N effect quantification.

LRl is therefore not directly documented in the 2020 catalogs. The 40 kg N/ha is a developer-derived policy consensus value for organic soil retirement — lower than the WL effect (~150 kg N/ha full wetland) and similar to the permanent udtagning mineral soil value (49 kg N/ha), but specific to organogenic drained fields.

Why 40 and not the mineral soil value of 49? Organogenic soils often have high N mineralization from the peat matrix, meaning residual leaching after land use change is higher than for mineral soils. The 40 kg N/ha accounts for this higher residual baseline.

Why lower cost than WL (1,016 vs 3,486 DKK/ha)? LRl requires no constructed wetland infrastructure. The 1,016 DKK/ha represents basic restoration costs (drain disconnection, fencing, minimal interventions) rather than full wetland construction.

Climate note from catalog (Paludikultur chapter, p.371): Rewetting drained organic soils reduces GHG emissions by 28–41 t CO₂-eq/ha/yr relative to arable cultivation, making LRl one of the strongest climate co-benefit measures in the model.

Open questions

  1. ✅ Why 40 kg/ha: Confirmed as deliberate policy consensus value (see catalog analysis above).
  2. Why is LRl in mem2 but not mem? This means it can be combined with measures that LRh cannot be combined with — is this intentional?
  • LRh — high-land counterpart (TR retention type; spatially differentiated N effect)
  • WL — companion NR measure (constructed wetland; higher N effect, higher cost)
  • Retention types — LRl uses NR (no retention); compare with LRh (TR)
  • Cost concepts — livestock surcharge applies; prodcost + 1,016 DKK/ha
  • P loss pathways — LRl P effects explicitly zero
  • Tripartite Agreement — LRl floor: ≥51,000 ha nationwide