Eagle Ops Scheduler

What it is

Concrete seed values for annual topdressing tonnage, sand-blend specification, and organic-matter targets on UK greens, surfaced as named-club examples by four UK course managers in BIGGA's multi-supe piece (originally published Spring 2019, republished by BIGGA 2024). The four clubs span parkland, downland, and links — so the numerics below are not a single regional convention but a cross-UK pattern.

This entry is the task-layer companion to mowing-heights-cool-season: cutting height sets the surface; topdressing keeps that surface viable by diluting thatch and maintaining a firm, true putting profile. Topdressing's primary effect on Eagle AI's deviation surfaces is via greens_firmness (OM dilution → firmer surface) and greens_smoothness (sand micro-fill → smoother roll). See "Axis-coverage note" below for the OM-axis-gap discussion.

Annual tonnage — four UK clubs

The panel publishes four named-club anchors [bigga:2024-topdressing]:

Mid Sussex Golf Club (Paul Oliver): "annual aim is to work 100 tonnes of sand into the profile between April and October." Seasonal cadence: 7–8 tonnes per month during the playing season.
Elsham Golf Club (Colin Hopper): "applied 120 tonnes of sand onto the greens with around 80 tonnes of this in the playing season." Cadence: "six to 10 tonnes of sand on a two to four week basis."
Lilley Brook Golf Club (Nigel Thompson): "applying around 100 to 120 tonnes of sand onto our greens." Heavy renovation-window applications: ~40 tonnes per occasion, twice per year (March/April + August).
Murcar Links (Bob Mackay): no aggregate tonnage published; the cadence approach is the operational frame — "light fortnightly dressings as early as the end of January and increase to weekly by the end of February."

Operational read for Eagle AI's topdressing task surface:

Typical UK annual range: 100–120 tonnes/yr for a typical 18-hole greens complex.
Seasonal split: ~60–70% of the annual tonnage during the playing season (April–October) — Elsham's 80-of-120 ratio is representative.
Per-occasion bands: light fortnightly (Murcar's ~few tonnes) at one end; heavy renovation-window (Lilley Brook's ~40 tonnes) at the other; "six to 10 tonnes every 2–4 weeks" (Elsham) as the steady-state middle.

These are one panel of four UK supes — supes with different green sizes, USGA-spec vs native-soil profiles, and budget bands will diverge. Treat as the seed band for the task-cadence surface, not the universal truth. Future Curator pass should pull additional UK multi-supe tonnage data when scout queue surfaces it.

Sand-blend specification

The panel publishes one specific blend recipe — Paul Oliver, Mid Sussex [bigga:2024-topdressing]: "medium sand dressing with 65 per cent medium sand content, 30 per cent coarse sand content and five per cent fine sand, which [has] the same particle distribution as our USGA greens."

Operational read:

65 / 30 / 5 (medium / coarse / fine) is a USGA-spec-matching blend — i.e. the topdressing's particle distribution mirrors the rootzone's so the sand integrates rather than layering.
Mismatching the blend to the rootzone profile is a known layering failure mode — this is the agronomic reason the article surfaces the specific %s rather than just "USGA-spec sand."

Only Oliver's club publishes a specific blend in the panel. The other three clubs don't disclose their blend — likely because the blend is matched to whatever rootzone profile they have (which may be native soil, modified push-up, or sand-cap rather than USGA-spec deep sand). The takeaway is match the blend to the profile, not "use Mid Sussex's 65/30/5 universally."

Organic-matter target

Single named OM target in the panel — Colin Hopper, Elsham [bigga:2024-topdressing]: "managing to keep our organic matter levels in the top 20mm in the four to six per cent range."

Operational read:

4–6% OM in top 20mm is the published Elsham target band.
The 20mm depth is the operationally-relevant layer — that's where ball roll, ball mark formation, dew persistence, and disease-spore carryover all happen. OM at deeper layers (40mm+) is less directly surface-relevant.
The agronomic rationale is thatch dilution — sand topdressing pushes the percentage down by adding mineral mass to the same 20mm volume, which is why the tonnage rates above are load-bearing for hitting the OM target.

Eagle AI surfaces that consume this: if/when an organic-matter deviation axis is added to the canonical AXIS_CATALOG (currently absent — see axis-coverage note below), the Elsham 4–6% band is the seed value. Until then, OM-tracking lives at the entry level rather than the axis layer.

Why-context (purpose of topdressing)

The panel's published rationale [bigga:2024-topdressing]: topdressing "dilute[s] the layer of organic material, known as thatch… improve[s] the quality of the soil and drainage and maintain[s] a smooth and true putting surface." The reduce-quantity-increase-frequency pivot point is also captured: "to firm up, we started to reduce the quantity per application but increased our frequency."

Three operational levers in the same passage:

Thatch dilution — primary agronomic purpose; ties to OM target above.
Drainage / profile quality — sand integration improves vertical water movement.
Surface smoothness — sand micro-fill smoothes the roll-out surface; this is the greens_smoothness deviation surface in canonical terms.

The "lighter + more frequent" pivot is itself a tunable surface: heavier-less-frequent dressings smooth aggressively but disrupt play on the day; lighter-more-frequent dressings hold playability but require more passes. Eagle AI's task-scheduling layer should treat both cadence options as valid, not normative.

When to deviate from these seeds

Supe-configured topdressing schedule always overrides. Reasons to set tighter or looser cadence / heavier or lighter tonnage:

Profile type — USGA-spec sand greens need less aggressive topdressing than native-soil push-up greens (the latter accumulate OM faster, all else equal).
Species mix — poa-heavy greens tend to OM-accumulate faster than bentgrass-dominant; tonnage scales accordingly.
Budget — sand cost is non-trivial; the panel's 100–120 t/yr range assumes a typical UK budget, not a constrained one.
Climate-shift pressure — the autumn-HOC discipline (see mowing-heights-cool-season §"Autumn-cooling HOC risk") increases reliance on topdressing as the surface-smoothing alternative to lower mowing; expect tonnage pressure upward as fungicide-loss continues.

Axis-coverage note — organic-matter gap

The canonical eagle-ai-ux AXIS_CATALOG (18 keys per Track-3 retrofit PR #11) does not include an organic-matter axis. Topdressing's primary deviation-target — OM% in top 20mm — therefore has no canonical home; this entry routes via greens_firmness and greens_smoothness (the downstream surface effects) instead. Pattern parallels the soil-temperature-axis-gap (see _index/gaps.md): both are agronomic signals without a canonical axis. Curator recommendation: hold — don't add an OM axis until an Eagle AI surface explicitly demands it. See organic-matter-axis-gap in _index/gaps.md.

mowing-heights-cool-season — the cutting-height entry; topdressing is the surface-smoothing complement that lets supes hold a discipline without forcing the HOC floor lower
green-firmness-measurement — topdressing's primary measurable effect is on firmness via OM dilution
championship-greens-prep-belfry — Wade documents weekly light topdressing as part of the daily championship-prep stack; this entry's 100–120 t/yr UK seed numerics contextualise what "weekly light" implies at championship scale
withdrawn-actives-uk-reference — increased sand content is named in that entry as one of three cultural alternatives for worm-cast control (acidify / sand-up / remove clippings); topdressing is the operational mechanism