Skip to content

OT — Optimized Tillage (Optimering af jordbearbejdning / Pløjefri dyrkning)

Summary

Transition to reduced or no-plow tillage systems (pløjefri dyrkning) to reduce P losses via the erosion pathway. By maintaining surface residue and improving soil aggregate stability, reduced tillage limits the detachment and transport of P-bearing soil particles to watercourses. Less effective than PPC (permanent vegetation) but applicable across a much larger potential area.

Eligibility

PotV(i,"OT") = Countcy(i) × IniPotV(i) / 5

P Effect

P_Effects_erosion(i,"OT") = erosion_field(i) × 0.5 [if PotV > 0] 50% reduction in erosion P loss.

Cost

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

Mutual exclusions

Member of mem(j), pho(j). Can be combined with NPB in NPB10_OT and NPB20_OT combined measures.

Notes

  • OT combined with NPB10 or NPB20 adds the NPB P effects (macropore + matrix) to OT's erosion effect — filling gaps in what OT alone does not address.
  • The model's 50% erosion factor is conservative relative to the catalog (60–70% for reduced tillage; 70–100% for direct seeding). This may reflect uncertainty or the reality that not all fields will achieve maximum tillage optimization.
  • OT can slightly increase dissolved P losses (soil surface residues release P when frost-thawed), partially offsetting particulate P gains. The model ignores this side effect on macropore/matrix pathways.

Data sources

  • Erosion P loss (erosion_field(i)): erosion_field.inc
  • P effect factor (0.5), cost: hard-coded in TargetEcon 2026.gms

Catalog source

SR379 — DCE Scientific Report no. 379 (Andersen et al., 2020): Chapter "Optimering af jordbearbejdning, fx pløjeretning, -tidspunkt og bearbejdningsintensitet, pløjefri dyrkning" (p. 77–89). Authors: Lars Juhl Munkholm et al.

Mechanism: No-plow / reduced-till systems maintain surface residues and promote aggregate stability, reducing the detachment and transport of soil and P during rainfall events. Contour plowing and delayed tillage timing also reduce overland flow energy on slopes.

P effect from catalog: - Reduced tillage: particulate P reduced 60–70% vs fall-plowed soil (international studies) - Direct seeding (no-till): 70–100% reduction in erosion (Skaalsveen et al., 2019) - BUT: dissolved P can increase 3–4× due to surface residues releasing P - Net effect is positive (total P loss still lower under no-till), but less than particulate P figures suggest - The model's 50% erosion factor represents the net particulate benefit excluding the dissolved P offset

Target area: Practically all well-drained agricultural soils — 16% of Danish farmland already used reduced tillage in 2018 (2019 Statistics Denmark). Easiest on clay soils; problematic in organic farming (glyphosate dependency) and on very sandy soils.

Cost from catalog: - Typically negative or near zero (cost savings from skipping plowing) - Long-term trials show ~1–4% yield loss on clay; variable on sand - Model cost of 200 DKK/ha/yr may represent transaction costs and yield risk premium rather than direct cash cost

N side effect: No expected change in N leaching (the catalog confirms no significant effect when timing rules for no-till are respected).

Confidence: ** (somewhat uncertain) — good international evidence, but Danish trials show variable results especially for dissolved P.

  • NPB10, NPB20 — combined in NPB10_OT and NPB20_OT (adds macropore + matrix to OT's erosion effect)
  • PPC — stronger erosion alternative; permanent vegetation; 90% reduction vs OT's 50%
  • Combined measures
  • P loss pathways — OT targets erosion pathway only
  • P Reduction — OT erosion effect equation
  • Cost concepts — fixed cost (200 DKK/ha/yr)