EW — Early Sowing (Tidlig såning)¶

Summary¶

Earlier establishment of winter crops, giving them more time for root N uptake before winter leaching begins.

Eligibility¶

PotV(i,"EW") = 0.3 × Sum(cy, wc(i,cy)) / 5

Conditional on specific crop combinations in the rotation (crop codes 1, 24, or 30 present). 30% of winter-cropped area is eligible.

N Effect¶

NEffM(i,"EW") = 17 kg N/ha/yr

P Effect¶

None.

Cost¶

CostM(i,"EW") = 200 DKK/ha/yr

Retention type¶

TR

Mutual exclusions¶

Member of mem(j), lm(j).

Catalog source¶

DCA Rapport nr. 174 (Eriksen et al., 2020): Chapter "Tidlig såning af vintersæd" (p. 87–100). Authors: Ingrid K. Thomsen, Elly Møller Hansen et al.

N effect confirmed: 17 kg N/ha/yr (confidence: ***). Matches model exactly. The effect was re-evaluated in 2019 (Thomsen & Hansen, 2019) and confirmed stable at 17 kg N/ha.

Mechanism: Earlier sowing of winter grain (wheat, rye) allows greater root N uptake before the main autumn leaching period. The effect is soil-type independent — all soil types show the same 17 kg N/ha reduction. This uniform effect (unlike catch crops which vary by soil/livestock) explains why EW is modeled as a flat value.

Cost from catalog: Highly variable depending on adoption scale: - First 170,000 ha: average 1 DKK/kg N (budget), 2 DKK/kg N (welfare) — very low cost - 170,000–255,000 ha: 9 DKK/kg N (budget) - 255,000–451,000 ha: 16 DKK/kg N (budget) - 451,000–654,000 ha: 36 DKK/kg N (budget) The model's fixed cost of 200 DKK/ha corresponds to ~12 DKK/kg N, which falls in the middle range.

Confidence: *** (high)

Side-effects: Negative for pest pressure and biodiversity (earlier sowing increases crop disease and weed pressure). No P effect. Positive for climate (reduced N2O from less leaching).

Data sources¶

N effect, cost, eligibility criteria: hard-coded in TargetEcon 2026.gms
Crop rotation data (wc(i,cy)): MarkAccess2.inc

IC — intermediate crops; similar low-cost N-only measure; 25% winter-crop eligibility
CCS / CCW — catch crops (alternative N-only measures)
Retention types — EW uses TR (total retention)
Cost concepts — fixed cost only (200 DKK/ha/yr); cheapest N measure