Skip to content

LRh — Land Retirement (High land / Højbund)

Summary

Permanent retirement of "high" (non-low-lying) agricultural land. Less hydrologically sensitive than LRl, but still reduces N and has significant P co-benefits through erosion and macropore pathways.

Eligibility

PotV(i,"LRh") = (1 − lav(i)) × Countcy(i) × IniPotV(i) / 5
The complement of LRl: applies to the non-lavbund fraction of the field.

N Effect

Spatially differentiated by coastal catchment (k). Formula: NEffM(i,"LRH") = prodeff(i) − X where X is the catchment-specific residual N leaching.

As of 2026-04-05: differentiation_effects.inc was updated (based on Rolighed et al. 2025 September revision) to cover all 108 coastal catchments — up from the original 13. This effectively expands LRh from a targeted regional measure to a national measure, since PotV(i,"LRh") contains no explicit catchment filter (see open question below).

Range: corrections of 6 to 18 across 108 catchments.

X correction Catchments (examples) Pattern
6 16, 17, 18, 25, 29 Lowest residual — highest N effect
7–9 Most catchments (28, 34–38, 44–49, 59, 62, 68, 84–85, 92, 95–96, 142, 200–209, …) Typical range
10–12 56, 57, 74, 80, 82, 93, 101–105, 114, 122, 125, 136–141, 147, 157–160, 200s, 212–216 Moderate residual
13–17 107–113, 119–121, 123–124, 128–133, 157, 221, 225, 232–233 Higher residual
18 131 Maximum residual — lowest N effect

The original 13 LRh catchments (Limfjorden / Northern Jutland region, series 217–238) retain their prior values unchanged:

Catchment X Catchment X
217 11 232 14
219 7 233 14
221 13 234 12
222 12 235 11
224 9 236 15
225 12 238 12
231 11

Important: For the 95 catchments newly added in the 2026-04-05 update, corrections are predominantly 6–12, consistent with areas where reference leaching is lower. The original default (commented out in main .gms) was prodeff(i) − 12 flat for all; the differentiated values replace this.

P Effect

P_Effects_erosion(i,"LRh")   = (1−lav(i)) × erosion_field(i)
P_Effects_macropore(i,"LRh") = (1−lav(i)) × macropore_field(i) × 0.35
Only the non-low-lying fraction contributes.

Cost

CostM(i,"LRh"):
  livestock ≥ 0.8:  prodcost(i) + 200  DKK/ha/yr
  livestock < 0.8:  prodcost(i)          DKK/ha/yr
No additional fixed cost (unlike LRl which has +1,016). LRh is effectively just the opportunity cost.

Retention type

TR (Total retention) — unlike LRl (NR), high-land retirement uses total retention. ⚠️ This is notable: LRh and LRl have different retention types despite being similar land-retirement concepts.

Mutual exclusions

Member of lr2(j), mem(j). Cannot combine with IBZ (mutexc12). Tripartite floor: ≥17,700 ha.

Data sources

Catalog source

DCA Rapport nr. 174 (Eriksen et al., 2020): Chapter "Permanent udtagning og kortvarig brak i omdrift" (p. 115–127), same chapter as SA (kortvarig brak).

LRh corresponds to the catalog's "Permanent udtagning" (permanent set-aside) on "mineraljorde" (mineral/non-organic = højbund soils). The catalog quantifies: - N effect: 49 kg N/ha/yr (reference leaching 61 kg N/ha → residual 12 kg N/ha/yr; 2020 catalog) - Rolighed et al. 2025 update: 46 kg N/ha nationally (58 kg reference − 12 residual); differentiated for 108 catchments - CE budget: varies by soil type - Confidence: *** (reliable)

P effect from catalog (p. 122): "Permanent udtagning på højbundsjord vil i store træk have samme effekter som skovrejsning" (same as forestry) when applied to erosion and macropore risk areas. Consistent with model's use of LRh erosion and macropore P effect factors.

See DCA_diff_effekt_2025.md for the per-catchment table for the 13 original Limfjorden catchments from Rolighed et al. (2025) Appendix 3.

Open questions

  1. Why does LRh use TR while LRl uses NR? Is this because high land drains via groundwater (with full retention) while low-lying land drains via near-surface lateral flow? (Likely yes — groundwater-dominated transport on høj land vs. near-surface on lavbund.)
  2. ✅ National scope confirmed (2026-04-06): LRh is intentionally a national measure. PotV(i,"LRh") has no catchment filter, and this is by design. The original 13-catchment appearance was an artifact of the old differentiation_effects.inc file only having values for 13 Limfjorden catchments — the model would compute NEffM = 0 everywhere else, making LRh effectively non-selectable outside Limfjorden. The September 2025 update to 108 catchments corrects this. LRh is now truly national.
  3. ✅ The 13 original LRh catchments (217–238) are in the Limfjorden / Northern Jutland region: Nissum Bredning, Thisted Bredning, Nibe Bredning, Kås Bredning, Løgstør Bredning, Halkær Bredning, Lillebælt, Skagerrak, Aalborg Bugt (confirmed from Rolighed et al. 2025 Bilag 3).
  • LRl — low-lying counterpart (NR retention type vs LRh's TR; different cost structure)
  • SA — short-term set-aside; also spatially differentiated from same source file
  • Retention types — LRh uses TR (total retention); LRl uses NR
  • P loss pathways — erosion + macropore pathways LRh reduces
  • Cost concepts — livestock surcharge (200 DKK/ha/yr) applies
  • DCA differentiation effects — source document for per-catchment corrections
  • Tripartite Agreement — LRh floor: ≥17,700 ha