MY SIMULATOR

English Apple Orchard Simulator

Nurture the trees. Gather the harvest.

INTERACTIVE 3D

Virtual orchard demo with illustrative model values. No yield guarantees; not growing advice.

Season

Harvest0 apples

Lab & science

Drag to orbit, wheel / pinch to zoom, tap a glowing apple to pick it. Space = start / pause, R = reset.

Setup

Weather

Calendar speed (days per second)

Camera

Graphics (High on every device; Low = fewer leaves, 1x pixel ratio)

Live readout (model values)

Missions

Mission 5: on a day with ET0 = 4.0 mm and Kc = 0.95 in a well-watered orchard, how many mm of water does the crop use (ETc)?

The science

What you see

One apple tree in a Somerset-style orchard. The calendar runs from the chosen season. Winter chill unlocks the buds, warmth builds blossom, bees set fruit, water and warmth grow the apples, and sugars rise until fruit is ready to pick (it glows gold).

Equations

Daily mean temperature  T(d) = Tm + A cos(2 pi (d - 200)/365)
Chill hours             hours/day with 0 C <= T_h <= 7.2 C (counted from 1 Oct)
Growing degree-days     GDD = sum max(0, T - 4.5 C)
Bud break / bloom       forcing GDD after chill is met: 120 / 250
Reference ET            ET0 = 0.0023 (T + 17.8) sqrt(TR) Ra 0.408   (Hargreaves)
  Ra from FAO-56 eq. 21 (latitude 51 N)
Crop water use          ETc = Kc ET0 ,   Kc = 0.40 + 0.55 leaf cover
Soil water balance      Dr(t+1) = Dr - rain - irrigation + ETa ,  0 <= Dr <= TAW = 120 mm
Water stress            Ks = (TAW - Dr) / ((1 - p) TAW)  if Dr > p TAW   (p = 0.5)
Effective growth time   dG = GDD (0.25 + 0.75 Ks)  after bloom
Fruit diameter          D = 6 + 70 / (1 + exp(-(G - 560)/150))  mm  (crop-load factor (150/N)^0.2)
Sugar                   Brix = 5.5 + 7.5 / (1 + exp(-(G - G_r)/70))
Fruit mass              m = 0.84 pi D^3 / 6   (D in cm, g)

Assumptions & honest simplifications

Illustrative values for a mild maritime climate, not a forecast and not advice for any real orchard; cultivars differ a lot (chill need, bloom date, ripening).
Frost at bloom, wind, disease, pests, nutrition and rootstock are not modelled. Pollination is a simple bee-flight-temperature factor.
Rain is a repeatable pseudo-random series (42% wet days); soil is one bucket of 120 mm plant-available water.
No yield guarantees: apples on the hero tree are a visible sample of 260 flower clusters.
Each apple ripens within about +/-5% of the thermal time; the glow marks starch index >= 6.5 and Brix >= 11 (model).

Independent numerical checks

Also in node: node check.js.

Sources

FAO Irrigation and Drainage Paper 56 (Allen et al. 1998) for Ra, Kc and the Ks bucket; Hargreaves and Samani (1985); growing-degree-day and chill-hour concepts from tree-fruit physiology texts. All numeric constants are model values [verify before real use].

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